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Full text of "The descent of man, and selection in relation to sex"

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THE 



DESCENT OF MAN, 



AXD 



SELECTION IN EELATION TO SEX. 



BT 

CHARLES DARWIN, M. A., F. R. S., Etc. 



WITH ILLUSTRATIONS. 



IN TWO VOLUMES.— Yol. I. 



NEW YORK: 

D. APPLETON AND COMPANY, 

549 & 551 BROADWAY. 

1873. 



I 



CONTENTS. 



Introduction, . . D age 1 

PART I. 

THE DESCENT OR ORIGIN OF MAN. 
CHAPTER I. 

THE EVIDENCE OF THE DESCENT OF MAN FROM SOME LOWER FORM. 

Nature of the Evidence bearing on the Origin of Man. — Homologous struct- 
ures in Man and the Lower Animals. — Miscellaneous Points of Corre- 
spondence. — Development. — Rudimentary Structures, Muscles, Sense- 
organs, Hair, Bones, Reproductive Organs, etc. — The Bearing of these 
three great Classes of Pacts on the Origin of Man, . . . p. 9 

CHAPTER II. 

COMPARISON OF THE MENTAL POWEKS OF MAN AND THE LOWER ANIMALS. 

The Difference in Mental Power between the Highest Ape and the Lowest 
Savage, immense. — Certain Instincts in common. — The Emotions. — 
Curiosity. — Imitation. — Attention. — Memory. — Imagination. — Reason. 
— Progressive Improvement. — Tools and "Weapons used by Animals. 
— Language. — Self-Consciousness. — Sense of Beauty. — Belief in God, 
Spiritual Agencies, Superstitions, p. 33 

CHAPTER in. 

COMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANTMALS— 

continued. 

The Moral Sense. — Fundamental Proposition. — The Qualities of Social 
Animals. — Origin of Sociability. — Struggle between Opposed In- 
stincts. — Man a Social Animal. — The more enduring Social Instincts 
conquer other less Persistent Instincts. — The Social Virtues alone re- 



iv CONTENTS. 

garded by Savag-es. — The Self-regarding Virtues acquired at a Later 
Stage of Development. — The Importance of the Judgment of the 
Members of the same Community on Conduct. — Transmission of 
Moral Tendencies. — Summary, page 67 



CHAPTER IV. 

ON THE MANNER OF DEVELOPMENT OF MAN FROM' SOME LOWER FORM. 

Variability of Body and Mind in Man. — Inheritance. — Causes of Varia- 
bility. — Laws of Variation the same in Man as in the Lower Animals. 
— Direct Action of the Conditions of Life. — Effects of the Increased 
Use and Disuse of Parts. — Arrested Development. — Reversion. — Cor- 
related Variation. — Eate of Increase. — Checks to Increase. — Natural 
Selection. — Man the most Dominant Animal in the "World. — Impor- 
tance of his Corporeal Structure. — The Causes which have led to his 
becoming erect. — Consequent Changes of Structure. — Decrease in 
Size of the Canine Teeth. — Increased Size and Altered Shape of the 
Skull. — Nakedness. — Absence of a Tail. — Defenceless Condition of 
Man, p. 103 



CHAPTER V. 

ON THE DEVELOPMENT OF THE INTELLECTUAL AND MORAL FACULTIES 
DURING PRIMEVAL AND CIVILIZED TIMES. 

The Advancement of the Intellectual Powers through Natural Selection. — 
Importance of Imitation. — Social and Moral Faculties. — Their Develop- 
ment within the Limits of the same Tribe. — Natural Selection as af- 
fecting Civilized Nations. — Evidence that Civilized Nations were once 
barbarous, p. 152 



CHAPTER VI. 

ON THE AFFINITIES AND GENEALOGY OF MAN. 

Position of Man in the Animal Series. — The Natural System genealogical. 
— Adaptive Characters of Slight Value. — Various Small Points of Re- 
semblance between Man and the Quadrumana. — Rank of Man in the 
Natural System. — Birthplace and Antiquity of Man. — Absence of 
Fossil Connecting-links. — Lower Stages in the Genealogy of Man, as 
inferred, firstly from his Affinities and secondly from his Structure. — 
Early Androgynous Condition of the Vertebrata. — Conclusion, p. 178 



CONTENTS. v 

CHAPTEK VII. 

ON THE RACES OF MAN. 

The Nature and Value of Specific Characters. — Application to the Races 
of Man. — Arguments in favor of, and opposed to, ranking the So- 
called Kaces of Man as Distinct Species. — Sub-species. — Monogenists 
and Polygenists. — Convergence of Character. — Numerous Points of 
Eesemblance in Body and Mind between the most Distinct Kaces of 
Man. — The State of Man when he first spread over the Earth. — Each 
Pace not descended from a Single Pair. — The Extinction of Paces. — 
The Formation of Paces. — The Effects of Crossing. — Slight Influence 
of the Direct Action of the Conditions of Life. — Slight or no Influence 
of Natural Selection. — Sexual Selection, .... page 206 



PAET H. 

SEXUAL SELECTION. 
CHAPTER VIII. 

PRINCIPLES OF SEXUAL SELECTION. 

Secondary Sexual Characters. — Sexual Selection. — Manner of Action. — 
Excess of Males. — Polygamy. — The Male alone generally modified 
through Sexual Selection. — Eagerness of the Male. — Variability of 
the Male. — Choice exerted by the Female. — Sexual compared with 
Natural Selection. — Inheritance, at Corresponding Periods of Life, at 
Corresponding Seasons of the Year, and as limited by Sex. — Relations 
between the Several Forms of Inheritance. — Causes why one Sex and 
the Young are not modified through Sexual Selection. — Supplement on 
the Proportional Numbers of the two Sexes throughout the Animal 
Kingdom. — On the Limitation of the Numbers of the two Sexes 
through Natural Selection, -..«..... p. 245 

CHAPTER IX. 

SECONDARY SEXUAL CHARACTERS IN THE LOWER CLASSES OF THE ANIMAL 

KINGDOM. 

These Characters absent in the Lowest Classes. — Brilliant Colors. — Mol- 
lusca. — Annelids. — Crustacea, Secondary Sexual Characters strongly 
developed; Dimorphism; Color; Characters not acquired before 
Maturity. — Spiders, Sexual Colors of; Stridulation by the Males. — 
Myiiapoda, p. 312 



yi CONTEXTS. 

CHAPTER X. 

SECONDARY SEXUAL CHARACTERS OF INSECTS. 

Diversified Structures possessed by the Males for seizing the Females.— 
Differences between the Sexes, of which the Meaning is not under- 
stood. — Difference in Size between the Sexes. — Thysanura. — Diptera. 
— Hemiptera. — Homoptera, Musical Powers possessed by the Males 
alone. — Orthoptera, Musical Instruments of the Males, much diversi- 
fied in Structure ; Pugnacity ; Colors. — Neuroptera, Sexual Differences 
in Color. — Hymenoptera, Pugnacity and Colors. — Coleoptera, Colors ; 
furnished with Great Horns, apparently as an Ornament; Battles; 
Stridulating Organs generally common to Both Sexes, . page 331 

CHAPTER XI. 

insects, continued. — order lepidoptera. 

Courtship of Butterflies.— Battles.— Ticking Noise.— Colors common to 
Both Sexes, or more brilliant in the Males. — Examples. — Not due to 
the Direct Action of the Conditions of Life. — Colors adapted for Pro- 
tection. — Colors of Moths. — Display. — Perceptive Powers of the Lepi- 
doptera. — Variability. — Causes of the Difference in Color between 
the Males and Females.— Mimicry, Female Butterflies more brilliantly 
colored than the Males.— Bright Colors of Caterpillars.— Summary 
and Concluding Remarks on the Secondary "exual Characters of In- 
eects. — Birds and Insects compared, . .... p. 374 



INTRODUCTION. 



The nature of the following work will be best under* 
etood bv a brief account of bow it came to be written. 
During many years I collected notes on the origin or 
descent of man, without any intention of publishing on 
the subject, but rather with the determination not to 
publish, as I thought that I should thus only add to 
the prejudices against my views. It seemed to me suffi- 
cient to indicate, in the first edition of my * Origin of 
Species,' that by this work " light would be thrown on 
the origin of man and his history ; " and this implies 
that man must be included with other organic beings in 
any general conclusion respecting his manner of appear- 
ance on this earth. jN~ow the case wears a wholly dif- 
ferent aspect. When a naturalist like Carl Yogt ven- 
tures to sav in his address as President of the National 
Institution of Geneva (1869), "personne, en Europe 
au moins, n'ose plus soutenir la creation independante 
et de toutes pieces, des especes," it is manifest that at 



2 INTRODUCTION. 

least a large number of naturalists rn;;st admit that 
species are the modified descendants of other species ; 
and this especially holds good with the younger and 
rising naturalists. The greater number accept the 
agency of natural selection ; though some urge, whether 
with justice the future must decide, that I have greatly 
overrated its importance. Of the older and honored 
chiefs in natural science, many unfortunately are still" 
opposed to evolution in every form. 

In consequence of the views now adopted by most 
naturalists, and which will ultimately, as in every other 
case, be followed by other men, I have been led to put 
together my notes, so as to see how far the general 
conclusions arrived at in my former works were appli- 
cable to man. This seemed all the more desirable 
as I had never deliberately applied these views to a 
species taken singly. When we confine our attention 
to any one form, we are deprived of the weighty argu- 
ments derived from the nature of the affinities which 
connect together whole groups of organisms — their geo- 
graphical distribution in past and present times, and 
their geological succession. The homological structure, 
embryological development, and rudimentary organs of 
a- species, whether it be man or any other animal, to 
which our attention may be directed, remain to be con- 
sidered ; but these great classes of facts afford, as it 
appears to me, ample and conclusive evidence in favor 
of the principle of gradual evolution. The strong sup- 



INTRODUCTION. 3 

port derived from the other arguments should, however, 
always be kept before the mind. 

The sole object of this work is to consider, firstly, 
whether man, like every other species, is descended 
from some preexisting form ; secondly, the manner of 
his development ; and thirdly, the value of the differ- 
ences between the so-called races of man. As I shall 
confine myself to these points, it will not be necessary 
to describe in detail the differences between the several 
races — an enormous subject, which has been fully dis- 
cussed in many valuable works. The high antiquity of 
man has recently been demonstrated by the labors 
of a host of eminent men, beginning with M. Boucher 
de Perthes ; and this is the indispensable basis for 
understanding his origin. I shall, therefore, take this 
conclusion for granted, and may refer my readers to 
the admirable treatises of Sir Charles Lyell, Sir -John 
Lubbock, and others. "Nor shall I ha^ e occasion to do 
more than to allude to the amount of difference between 
man and the anthropomorphous apes ; for Prof. Huxley, 
in the opinion of most competent judges, has conclu- 
sively shown that in every single visible character man 
differs less from the higher apes than these do from the 
lower members of the same order of Primates. 

This work contains hardly any original facts in 
regard to man; but, as the conclusions at which I 
arrived, after drawing up a rough draft, appeared to 
me interesting, I thought that they might interest 



4 INTRODUCTION. 

others. It lias often and confidently been asserted, that 
man's origin can never be known : but ignorance more 
frequently begets confidence than does knowledge : it is 
those who know little, and not those who know much, 
who so positively assert that this or tHat problem will 
never be solved by science. The conclusion that man is 
the co-descendant with other species of some ancient, 
lower, and extinct form, is not in any degree new. La- 
marck long ago came to this conclusion, which has lately 
been maintained by several eminent naturalists and 
philosophers ; for instance, by Wallace, Huxley, Lyell, 
Vogt, Lubbock, Biichner, Rolle, etc., 1 and especially by 
Hackel. This last naturalist, besides his great work, 
'Generelle Morphologie' (1866), has recently (1868, 
with a second edit. 18T0) published his 'Naturliche 
Schopfungsgeschichte,' in which he fully discusses the 
genealogy of man. If this work had appeared before 

1 As the works of the first-named authors are so well known, I need 
not give the titles ; but, as those of the latter are less well known in 
England, I will give them : ' Sechs Vorlesungen fiber die Darwin'sche 
Theorie:' zwiete Auflage, 1868, von Dr. L. Biichner; translated into 
French under the title 'Conferences sur la Theorie Darwinienne,' 1869. 
'Der Mensch, im Lichte der Darwin'sche Lehre,' 1865, von Dr. F. Rolle. 
I will not attempt to give references to all the authors who have taken 
the same side of the question. Thus G. Canestrini has published (' An- 
nuario della Soc. d. Nat.,' Modena, 1867, p. 81) a very curious paper on 
rudimentary characters, as bearing on the origin of man. Another work 
has (1869) been published by Dr. Barrago Francesco, bearing in Italian 
the title of " Man, made in the image of God, was also made in the image 
of the ape." 



INTRODUCTION. 5 

my essay had been written, I should probably never 
have completed it. Almost all the conclusions at which 
I have arrived I find confirmed by this naturalist, whose 
knowledge on many points is much fuller than mine. 
Wherever I have added any fact or view from Prof. 
Hackel's writings, I give his authority in the text, other 
statements I leave as they originally stood in my manu- 
script, occasionally giving in the foot-notes references 
to his works, as a confirmation of the more doubtful or 
interesting points. 

During many years it has seemed to me highly 
probable that sexual selection has played an important 
part in differentiating the races of man ; but in- my 
1 Origin of Species ' (first edition, p. 199) I contented 
myself by merely alluding to this belief. "When I came 
to apply this view to man, I found it indispensable to 
treat the whole subject in full detail. 3 Consequently 
the second part of the present work, treating of sexual 
selection, has extended to an inordinate length, com- 
pared with the first part; but this could not be 
avoided. 

I had intended adding to the present volumes an 
essay on the expression of the various emotions by man 
and the lower animals. My attention was called to this 
subject many years ago by Sir Charles Bell's admirable 

9 Prof. Hackel is the sole author who, since the publication of the 
• Origin,' has discussed, in his various works, in a very able manner, the 
subject of sexual selection, and has seen its full importance. 



6 INTRODUCTION. 

work. This illustrious anatomist maintains that man 
is endowed with certain muscles solely for the sake 
of expressing his emotions. As this view is obviously 
opposed to the belief that man is descended from some 
other and lower form, it was necessary for me to con- 
sider it. I likewise wished to ascertain how far the 
emotions are expressed in the same manner by the dif- 
ferent races of man. But, owing to the length of the 
present work, I have thought it better to reserve my 
essay, which is partially completed, for separate pub- 
lication. 



PAET I. 

THE DESCENT OR ORIGIN OF MAN. 



THE DESCENT OF MAE". 



CHAPTER I. 

THE EVIDENCE OF- THE DESCENT OF MAN FROM SOME 

LOWER FORM. 

Nature of the Evidence bearing on the Origin of Man. — Homologous struct- 
ures in Man and the Lower Animals. — Miscellaneous Points of Corre- 
spondence. — Development. — Kudirnentary Structures, Muscles, Sense- 
organs, Hair, Bones, Eeproductive Organs, etc. — The Bearing of these 
three great Classes of Facts on the Origin of Man. • 

He who wishes to decide whether man is the modified 
descendant of some preexisting form, would probably first 
inquire whether man varies, however slightly, in bodily 
structure and in mental faculties ; and if so, whether the 
variations are transmitted to his offspring in accordance 
with the laws which prevail with the lower animals ; such 
as that of the transmission of characters to the same ap;e 
or sex. Again, are the variations the result, as far as our 
ignorance permits us to judge, of the same general causes, 
and are they governed by the same general laws, as in the 
case of other organisms ; for instance, by correlation, the 
inherited effects of use and disuse, etc. ? Is man subject to 
similar malconformations, the result of arrested develop- 
ment, of reduplication of parts, etc., and does he display 
in any of his anomalies reversion to some former and an- 
cient type of structure? It might also naturally be in- 



10 THE DESCENT OF MAN. [Part 1 

quired whether man, like so many other animals, has given 
rise to varieties and sub-races, differing but slightly from 
each other, or to races differing so much that they must be 
classed as doubtful species ? How are such races distrib- 
uted over the world ; and how, when crossed, do they react 
on each other, both in the first and succeeding genera- 
tions ? And so with many other points. 

The inquirer would next come to the important point, 
whether man tends to increase at so rapid a rate, as to 
lead to occasional severe struggles for existence, and con- 
sequently to beneficial variations, whether in body or 
mind, being preserved, and injurious ones eliminated. Do 
the races or species of men, whichever term may be ap- 
plied, encroach on and replace each other, so that some 
finally become extinct? We shall see that all these ques- 
tions, as indeed is obvious in respect to most of them, 
must be answered in the affirmative, in the same manner 
as with the lower animals. But the several considerations 
just referred to may be conveniently deferred for a time ; 
and we will first see how far the bodily structure of man 
shows traces, more or less plain, of his descent from some 
lower form. In the two succeeding chapters the mental 
powers of man, in comparison with those of the lower 
animals, will be considered. 

The Bodily Structure of Man. — It is notorious that 
man is constructed on the same general type or model 
with other mammals. All the bones in his skeleton can 
be compared with corresponding bones in a monkey, bat, 
or seal. So it is with his muscles, nerves, blood-vessels, 
and internal viscera. The brain, the most important of 
all the organs, follows the same law, as shown by Huxley 
and other anatomists. Bischoff, 1 who is a hostile witness, 
admits that every chief fissure and fold in the brain of 

1 Grosshirnwindungen dcs Henchen,' 18G8, s. 96. 



Chap. I.] HOMOLOGICAL STRUCTURE. H 

man has its analogy in that of the orang ; but he adds 
that at no period of development do their brains perfectly 
agree; nor could this be expected, for otherwise their 
mental powers would have been the same. Yulpian 2 re- 
marks : " Les differences reelles qui existent entre l'ence- 
phale de l'honime et celui des singes superieurs, sont bien 
minimes. II ne faut pas se faire d'illusions tt cet egard. 
L'homme est bien plus pres des singes anthropomorphes 
par les caracteres anatomiques de son cerveau que ceux-ci 
ne le sont non-seulement des autres mammiferes, mais 
memes de certains quadrumanes, des guenons et des ma- 
caques." But it would be superfluous here to give fur- 
ther details on the correspondence between man and the 
higher mammals in the structure of the brain and all 
other parts of the body. 

It may, however, be worth while to specify a few 
points, not directly or obviously connected with struct- 
ure, by which this correspondence or relationship is well 
shown. 

Man is liable to receive from the lower animals, and to 
communicate to them, certain diseases, as hydrophobia, 
variola, the glanders, etc. ; and this fact proves the close 
similarity of their tissues and blood, both in minute struct- 
ure and composition, far more plainly than does their com- 
parison under the best microscope, or by the aid of the 
best chemical analysis. Monkeys are liable to many of 
the same non-contagious diseases as we are ; thus Reng- 
ger, 3 who carefully observed for, a long time the Cebus 
Azarce in its native land, found it liable to catarrh, with 
the usual symptoms, and which when often recurrent led 
to consumption. These monkeys suffered also from apo 
plexy, inflammation of the bowels, and cataract in the eye. 

2 'Le?. sur la Phys.' 1866, p. 890, as quoted by M. Dally, 'L'Ordre 
des Primates et le Transformisme,' 1868, p. 29. 

3 ' Xaturgeschichte der Saugethiere von Paraguay,' 1830, s. 50. 



12 THE DESCENT OF MAN. [Part I. 

The younger ones when shedding their milk-teeth often 
died from fever. ' Medicines produced the same effect on 
them as on us. Many kinds of monkeys have a strong 
taste for tea, coffee, and spirituous liquors : they will also, 
as I have myself seen, smoke tobacco with pleasure. 
Brehm asserts that the natives of northeastern Africa 
catch the wild baboons by exposing vessels with strong 
beer, by which they are made drunk. He has seen some 
of these animals, which he kept in confinement, in this 
state ; and he gives a laughable account of their behavior 
and strange grimaces. On the following morning they 
were very cross and dismal ; they held their aching heads 
with both hands and wore a most pitiable expression ; 
when beer or wine was offerel them, they turned away 
•with disgust, but relished the juice of lemons. 4 An Amer- 
ican monkey, an Ateles, after getting drunk on brandy, 
would never touch it again, and thus was wiser than many 
men. These trifling facts prove how similar the nerves 
of taste must be in monkeys and man, and how similarly 
their whole nervous system is affected. 

Man is infested with internal parasites, sometimes 
causing fatal effects, and is plagued by external parasites, 
all of which belong to the same genera or families with 
those infesting other mammals. Man is subject like other 
mammals, birds, and even insects, to that mysterious law, 
which causes certain normal processes, such as gestation, 
as well as the maturation and duration of various diseases, 
to follow lunar periods. 6 His wounds are repaired by the 
same process of healing ; and the stumps left after the 

4 Brehm, ' Thierleben,' B. i. 1864, s. 75, 86. On the Ateles, s. 105. 
For other analogous statements, see s. 25, 107. 

6 With respect to insects see Dr. Laycock ' On a General Law of 
Vital Periodicity,' British Association, 1842. Dr. Macculloch, 'Silliman's 
North American Journal of Science,' vol. xvii. p. 305, has seen a dog suf 
fering from tertian ague. 
• 



.Ohap. I.] HOMOLOGICAL STRUCTURE. 13 

amputation of his limbs occasionally possess, especially 
during an early embryonic period, some power of regen- 
eration, as in the lowest animals. 6 

The whole process of that most important function, 
the reproduction of the species, is strikingly the same in 
all mammals, from the first act of courtship by the male 7 
to the birth and nurturing of the young. Monkeys are 
born in almost as helpless a condition as our own infants ; 
and in certain genera the young differ fully as much in 
appearance from the adults, as do our children from their 
full-grown parents. 8 It has been urged by some writers 
as an important distinction, that with man the young 
arrive at maturity at a much later age than with any other 
animal : but if we look to the races of mankind which 
inhabit tropical countries the difference is not great, for 
the orans; is believed not to be adult till the as;e of from 
ten to fifteen years. 9 Man differs from woman in size, 
bodily strength, hairyness, etc., as well as in mind, in the 
same manner as do the two sexes of many mammals. It 
is, in short, scarcely possible to exaggerate the close cor- 

6 1 have given the evidence on this head in my ' Variation of Animals 
and Plants under Domestication,' vol. ii. p. 15. 

7 "Mares e diversis generibus Quadrumanorum sine dubio dignoscunt 
feminas humanas a maribus. Primum, credo, odoratu, postea aspectu. 
Mr. Youatt, qui diu in Hortis Zoologicis (Bestiariis) medicus animalium 
erat, Vir in rebus obsei'vandis cautus et sagax, hoc mihi certissime pro- 
bavit, et curatores ejusdem loci et alii e ministris confirmaverunt. Sir 
Andrew Smith et Brehm notabant idem in Cynocephalo. Illustrissimus 
Cuvier etiam narrat multa de hac re qua ut opinor nihil turpius potest 
indicari inter omnia hominibus et Quadrumanis communia. Narrat enim 
Cynocephalum quendam in furorem incidere aspectu feminarum aliquarum, 
sed nequaquam accendi tanto furore ab omnibus. Semper eligebat ju- 
niores, et dignoscebat in turba, et advocabat voce gestuque." 

8 This remark is made with respect to Cynocephalus and the anthropo- 
morphous apes by Geoffroy Saint-Hilaire and F. Cuvier, ' Hist. Nat. dea 
Mammiferes, torn. i. 1824. 

• Huxley, 'Man's Place in Nature,' 1863, p. 34. 



14 THE DESCENT OF MAN. [Part I. 

respondence in general structure, in the minute structure 
of the tissues, in chemical composition, and. in constitution, 
between man and the higher animals, especially the an- 
thropomorphous apes. 

Embryonic Developme?it. — Man is developed from an 
ovule, about the 125th of an inch in diameter, which 
differs in no respect from the ovules of other animals. 
The embryo itself at a very early period can hardly be 
distinguished from that of other members of the verte- 
brate kingdom. At this period the arteries run in arch- 
like branches, as if to carry the blood to branchiae which 
are not present in the higher vertebrata, though the slits 
on the sides of the neck still remain (/, g, fig. 1), marking 
their former position. At a somewhat later period, when 
the extremities are developed, "the feet of lizards and 
mammals," as the illustrious Von Baer remarks, "the 
win 2f s and feet of birds, no less than the hands and feet 
of man, all arise from the same fundamental form." It 
is, says Prof. Huxley, 10 " quite in the latter stages of de- 
velopment that the young human being presents marked 
differences from the young ape, while the latter departs as 
much from the dog in its developments, as the man does. 
Startling as this last assertion may appear to be, it is de- 
monstrably true." 

As some of my readers may never have seen a draw- 
ing of an embryo, I have given one of man and another 
of a dog, at about the same early stage of development, 
carefully copied from two works of undoubted accuracy. 11 

10 ' Man's Place in Nature,' 1863, p. 61. 

11 The human embryo (upper fig.) is from Ecker, ' Icones Phys.,' 
1851-1859, tab. xxx. fig. 2. This embryo was ten lines in length, so that 
the drawing is much magnified. The embryo of the dog is from Bi- 
echoff, ' Entwicklungsgcschichte des Hunde-Eies,' 1845, tab. xi. fig. 42 b. 
This drawing is five times magnified, the embryo being 25 days old. The 



Chap. I.] 



EMBRYONIC DEVELOPMENT. 



15 





Fig. 1.— Upper figure human embryo, from Ecker. Lower figure that of a dog, 

from Bischoff. 



a. Fore-brain, cerebral hemispheres, 
etc. 

b. Mid-brain, corpora quadrigemina. 

c. Hind-brain, cerebellum, medulla 
oblongata. 

d. Eye. 

e. Ear. 



f. First visceral arch. 
Q. Second visceral arch. 
H. Vertebral columns and musclesin 
process of development. 

K. ISfiSt [ extremities. 
L. Tail or os coccyx. 



16 THE DESCENT OF MAN. [Part I. 

After the foregoing statements made by such high 
authorities, it would be superfluous on my part to give a 
number of borrowed details, showing that the embryo of 
man closely resembles that of other mammals. It may, 
however, be added that the human embryo likewise resem- 
bles in various points of structure certain low forms when 
adult. For instance, the heart at first exists as a simple 
pulsating vessel; the excreta are voided through a cloacal 
passage ; and the os coccyx projects like a true tail, " ex- 
tending considerably beyond the rudimentary legs." 12 In 
the embryos of all air-breathing vertebrates, certain glands 
called the corpora Wolfliana, correspond with and act like 
the kidneys of mature fishes. 13 Even at a later embryo- 
nic period, some striking rese?~ablances between man and 
the lower animals may be observed. Bischoff says that 
the convolutions of the brain in a human foetus at the end 
of the seventh month reach about the same stage of de- 
velopment as in a baboon when adult. 14 The great toe, 
as Prof. Owen remarks, 16 " which forms the fulcrum when 
standing or walking, is perhaps the most characteristic 
peculiarity in the human structure ; " but in an embryo, 
about an inch in length, Prof. Wyman 16 found that the 
great toe was shorter than the others, and, instead of be- 
ing parallel to them, projected at an angle from the side 
of the foot, thus corresponding with the permanent condi- 

internal viscera have been omitted, and the uterine appendages in both 
drawings removed. I was directed to these figures by Prof. Huxley, 
from whose work, ' Man's Place in Nature,' the idea of giving them was 
taken. Hackel has also given analogous drawings in his 'Schopfungs- 
geschichte.' 

12 Prof. Wyman in l Proc. of American Acad, of Sciences,' vol. iv. 
18G0, p. 17. 

13 Owen, 'Anatomy of Vetebrates,' vol. i. p. 533 

14 ' Die Grosshirnwindungen des Menschen,' 1868, s. 95 

15 * Anatomy of Vertebrates,' vol. ii. p. 553. 

16 'Proc. Soc. Nat. Hist.' Boston, 1863, voL ix. p. 185. 



Chap I.] RUDIMENTS. 17 

tion of this part in the quadrumana." I will conclude with 
a quotation from Huxley, 17 who, after asking, does man 
originate in a different way from a dog, bird, frog, or fish ? 
says, " the reply is not doubtful for a moment ; without 
question, the mode of origin and the early stages of the 
development of man are identical with those of the ani- 
mals immediately below him in the scale : without a doubt 
in these respects, he is far nearer to apes, than the apes 
are to the dog." 

Rudiments. — This subject, though not intrinsically 
more important than the last two, will for several reasons 
be here treated with more fulness. 18 Not one of the 
higher animals can be named which does not bear some 
part in a rudimentary condition ; and man forms no ex- 
ception to the rule. Rudimentary organs must be dis- 
tinguished from those that are nascent ; though in some 
cases the distinction is not easy. The former are either 
absolutely useless, such as the mammae of male quad- 
rupeds, or the incisor teeth of ruminants which never cut 
through the gums ; or they are of such slight service to 
their present possessors, that we cannot suppose that they 
were developed under the conditions which now exist. 
Organs in this latter state are not strictly rudimentary, 
but they are tending in this direction. Nascent organs, 
on the other hand, though not fully developed, are of high 
service to their possessors, and are capable of further de- 
velopment. Rudimentary organs are eminently variable ; 
and this is partly intelligible, as they are useless or nearly 

17 ' Man's Place in Nature,' p. 65. 

18 I had written a rough copy of this chapter before reading a valu- 
able paper, " Caratteri rudimentali in ordine all ' origine del uomo " ('An- 
nuario 'della Soc. d. Nat.,' Modena, 1867, p. 81), by G. Canestrini, to 
which paper I am considerably indebted. Hackel has given admirable 
discussions on this whole subject, under the title of Dyateleology, in hi« 
4 Generelle Morphologic ' and ' Schopfungsgeschichte.' 

2 



1 8 THE DESCENT OF MAN. [Part I. 

useless, and consequently are no longer subjected to nat- 
ural selection. They often become wholly suppressed. 
When this occurs, they are nevertheless liable to occa- 
sional reappearance through reversion ; and this is a cir- 
cumstance weK worthy of attention. 

Disuse at that period of life, when an organ is chiefly 
used, and this is generally during maturity, together with 
inheritance at a corresponding period of life, seem to have 
been the chief agents in causing organs to become rudi- 
mentary. The term " disuse " does not relate merely to 
the lessened action of muscles, but includes a diminished 
flow of blood to a part or organ, from being subjected to 
fewer alternations of pressure ; or from becoming in any 
way less habitually active. Rudiments, however, may 
occur in one sex of parts normally present in the other 
sex ; and such rudiments, as we shall hereafter see, have 
often originated in a distinct manner. In some cases or- 
gans have been reduced by means of natural selection, 
from having become injurious to the species under changed 
habits of life. The process of reduction is probably often 
aided through the two principles of compensation and 
economy of growth ; but the later stages of reduction, 
after disuse has done all that can fairly be attributed to it, 
and when the saving to be effected by the economy of 
growth would be very small, 19 are difficult to understand. 
The final and complete suppression of a part, already use- 
less and much reduced in size, in which case neither com- 
pensation nor economy can come into play, is perhaps in- 
telligible by the aid of the hypothesis of pangenesis, and 
apparently in no other way. But as the whole subject of 
rudimentary organs has been fully discussed and illustrated 
in my former works, 20 1 need here say no more on this head. 

19 Some good criticisms on this subject have been given by Messrs. 
Murie and Mivart, in 'Transact. Zoolog. Soc' 1869, vol. vii. p. 92. 

80 ' Variation of Animals and Plants under Domestication/ vol. ii. pp. 
817 and 39*7. See also ' Origin of Species,' 5th edit. p. 535. 



Chap. I.] RUDIMENTS. 19 

Rudiments of various muscles have been observed in 
many parts of the human body ; 21 and not a few muscles, 
which are regularly present in some of the low x er animals 
can occasionally be detected in man in a greatly reduced 
condition. Every one must have noticed the power which 
many animals, especially horses, possess of moving or 
twitching their skin ; and this is effected by the pannicu- 
lus carnosus. Remnants of this muscle in an efficient 
state are found in various parts of our bodies ; for in- 
stance, on the forehead, by which the eyebrows are raised. 
The platysma myoides, which is well developed on the 
neck, belongs to this system, but cannot be voluntarily 
brought into action. Prof Turner, of Edinburgh, has 
occasionally detected, as he informs me, muscular fasciculi 
in five different situations, namely, in the axillre, near the 
scapulae, etc., all of which must be referred to the system 
of the panniculus. He has also shown 22 that the musculus 
sternalis or stemalls brutorum, which is not an extension 
of the rectus abdominalis^ but is closely allied to the 
panniculus, occurred in the proportion of about three per 
cent, in upward of six hundred bodies : he adds, that this 
muscle affords " an excellent illustration of the statement 
that occasional and rudimentary structures are especially 
liable to variation in arrangement." 

Some few persons have the power of contracting the 
superficial muscles on their scalps ; and these muscles are 
in a variable and partially rudimentary condition. M. A. 
de Candolle has communicated to me a curious instance 
of the long-continued persistence or inheritance of this 

11 For instance, M. Richard ('Annales des Sciences Nat.' 3d series, 
Zoolog. 1852, torn, xviii. p. 13) describes and figures rudiments of what 
he calls the " muscle pedieux de la main," which he says is sometimes 
M infiniment petit." Another muscle, called " le tibial posterieur," is gen- 
erally quite absent in the hand, but appears from time to time in a more 
or less rudimentary condition. 

29 Prof. W. Turner, 'Proc. Royal Soc. Edinburgh,' 1866-67, p. 65. 



20 THE DESCENT OF MAN. [Part I. 

power, as well as of its unusual development. He knows 
a family in which one member, the present head of a 
family, could, when a youth, pitch several heavy books 
from his head by the movement of the scalp alone ; and 
he won wagers by performing this feat. His father, uncle, 
grandfather, and all his three children, possess the same 
power to the same unusual degree. This family became 
divided eight generations ago into two branches; so 
that the head of the above-mentioned branch is cousin in 
the seventh degree to the head of the other branch. This 
distant cousin resides in another part of France, and, or 
being asked whether he possessed the same faculty, im 
mediately exhibited his power. This case offers a good il 
lustration how persistently an absolutely useless faculty 
may be transmitted. 

The extrinsic muscles which serve to move the whole 
external ear, and the intrinsic muscles which move the 
different parts, all of which belong to the system of the 
panniculus, are in a rudimentary condition in man ; they 
are also variable in development, or at least in function. 
I have seen one man who could draw his ears forward, 
and another who could draw them backward ; 23 and, from 
what one of these persons told me, it is probable that most 
of us, by often touching our ears and thus directing our 
attention toward them, could by repeated trials recover 
some power of movement. The faculty of erecting the 
ears and of directing them to different points of the com- 
pass, is no doubt of the highest service to many animals, 
as they thus perceive the point of danger ; but I have never 
heard of a man who possessed the least power of erecting 
his ears — the one movement which might be of use to him. 
The whole external shell of the ear may be considered a 
rudiment, together with the various folds and prominences 

23 Canestrini quotes Hyrt. ('Armuario della Soc. dei Naturalist!, 1 
Modena, 1867, p. 97) to the same effect. 



Chap. I.] RUDIMENTS. . 21 

(helix and anti-helix, tragus and anti-tragus, Uc.) which 
in the lower animals strengthen and support the ear when 
erect, without adding much to its weight. Some authors, 
however, suppose that the cartilage of the shell serves to 
transmit vibrations to the acoustic nerve ; but Mr. Toyn- 
bee, 24 after collecting all the known evidence on this head, 
concludes that the external shell is of no distinct use. 
The ears of the chimpanzee and orang are curiously like 
those of man, and I am assured by the keepers in the Zoo- 
logical Gardens that these animals never move or erect 
them; so that they are in an equally rudimentary condi- 
tion, as far as function is concerned, as in man. Why 
these animals, as well as the progenitors of man, should 
have lost the power of erecting their ears we cannot say. 
It may be, though I am not quite satisfied with this view, 
that owing to their arboreal habits and great strength they 
were but little exposed to danger, and so during a length- 
ened period moved their ears but little, and thus gradually 
lost the power of moving them. This would be a parallel 
case with that of those large and heavy birds, which from 
. inhabiting oceanic islands have not been exposed to the 
attacks of beasts of prey, and have consequently lost the 
power of using their wings for flight. 

The celebrated sculptor, Mr. Woolner, informs me of 
one little peculiarity in the external ear, which he has 
often observed both in men and women, and of which he 
perceived the full signification. His attention was first 
called to the subject while at work on his figure of Puck, 
to which he had given pointed ears. He was thus led to 
examine the ears of various monkeys, and subsequently 
more carefully those of man. The peculiarity consists in 
a little blunt point, projecting from the inwardly-folded 
margin, or helix. Mr. Woolner made an exact model of 
one such case, and has sent me the accompanying draw- 

84 ' The Diseases of the Ear,' by J. Toynbee, F. R. S., 1860, p. 12, 



22 



THE DESCENT OF MAN. 



(Tart L 




ing. (Fig. 2.) These points not only project inward, but 
often a little outward, so that they are visible when the 
head is viewed from directly in front or behind. They are 

variable in size and somewhat in po- 
sition, standing either a little high- 
er or lower ; and they sometimes 
occur in one ear and not on the 
other. Now the meaning of these 
projections is not, I think, doubt- 
ful; but it may be thought that 
they offer too trifling a character 
to be worth notice. This thought, 
however, is as false as it is natural. 
Every character, however slight, 
Fig. 2.— Human Ear, modelled must be the result of some definite 

and drawn by Mr. Woolner. .. . „ . , 

a. The projecting point. cause ; and if it occurs in many 

individuals deserves consideration. 
The helix obviously consists of the extreme margin of the 
ear folded inward ; and this folding appears to be in some 
manner connected with the whole external ear, being per- 
manently pressed backward. In many monkeys, which 
do not stand high in the order, as baboons and some 
species of macacus, 26 the upper portion of the ear is 
slightly pointed, and the margin is not at all folded in- 
ward ; but if the margin were to be thus folded, a slight 
point would necessarily project inward and probably a 
little outward. This could actually be observed in a 
specimen of the Ateles beelzebuth in the Zoological Gar- 
dens ; and we may safely conclude that it is a similar 
structure — a vestige of formerly-pointed ears — which oc- 
casionally reappears in man. 

The nictitating membrane, or third eyelid, with its 

95 See also some remarks, and the drawings of the ears of the Lemu. 
roidea, in Messrs. Murie and Mivart's excellent paper in ' Transact. Zoo- 
,og. Soc.' vol. vii. 1869, pp. 6 and 90. 



Chap. I.] RUDIMENTS. 23 

accessory muscles and other structures, is especially well 
developed in birds, and is of much functional importance 
to them, as it can be rapidly drawn across the whole eye- 
ball. It is found in some reptiles and amphibians, and in 
certain fishes, as in sharks. It is fairly well developed in 
the two lower divisions of the mammalian series, namely, 
in the monotremata and marsupials, and in some few of 
the higher mammals, as in the walrus. But in man, the 
quadrumana, and most other mammals, it exists, as is ad- 
mitted by all anatomists, as a mere rudiment, called the 
semilunar fold. 26 

The sense of smell is of the highest importance to the 
greater number of mammals — to some, as the ruminants, 
in warning them of danger; toothers, as the carnivora, in 
finding their prey ; to others, as the wild-boar, for both 
purposes combined. But the sense of smell is of ex- 
tremely slight service, if any, even to savages, in whom it 
is generally more highly developed than in the civilized 
races. It does not warn them of danger, nor guide them 
to their food; nor does it prevent the Esquimaux from 
sleeping in the most fetid atmosphere,, nor many savages 
from eating half-putrid meat. Those who believe in the 
principle of gradual evolution, will not readily admit that 
this sense in its present state was originally acquired by 
man, as he now exists. No doubt he inherits the power 
in an enfeebled and so far rudimentary condition, from 
some early progenitor, to whom it was highly serviceable 
and by whom it was continually used. We can thus 
perhaps understand how it is, as Dr. Maudsley has truly 

26 Muller's 'Elements of Physiology,' Eng. translat., 1842, vol. ii. p. 
1117. Owen, 'Anatomy of Vertebrates,' vol. Hi. p. 260; ibid, on the 
Walrus, ' Proc. Zoolog. Soc' November 8, 1854. See also R. Knox, 
Great Artists and Anatomists,' p. 106. This rudiment apparently is 
somewhat larger in Negroes and Australians than in Europeans, see Carl 
Vogt, ' Lectures on Man,' Eng. translat. p. 129. 



24 THE DESCENT OF MAN. [Part I. 

remarked, 27 that the sense of smell in man " is singularly 
effective in recalling vividly the ideas and images of for- 
gotten scenes and places ; " for we see in those animals, 
which have this sense highly developed, such as dogs and 
horses, that old recollections of persons and places are 
strongly associated with their odor. 

Man differs conspicuously from all the other Primates 
in being almost naked. But a few short, straggling hairs 
are found over the greater part of the body in the male 
sex, and fine down on that of the female sex. In individ- 
uals belonging to the same race these hairs are highly 
variable, not only in abundance, but likewise in position : 
thus the shoulders in some Europeans are quite naked, 
while in others they bear thic 1 : tufts of hair. 28 There can 
be little doubt that the hairs thus scattered over the body 
are the rudiments of the uniform hairy coat of the lower 
animals. This view is rendered all the more probable, as 
it is known that tine, short, and pale-colored hairs on the 
limbs and other parts of the body occasionally become 
developed into " thickset, long, and rather coarse dark 
hairs," when abnormally nourished near old-standing in- 
flamed surfaces. 29 

I am informed by Mr. Paget that persons belonging 
to the same family often have a few hairs in their eye- 
brows much longer than the others ; so that this slight 
peculiarity seems to be inherited. These hairs 'apparently 
represent the vibrissa, which are used as organs of touch 
by many of the lower animals. In a young chimpanzee I 
observed that a few upright, rather long, hairs projected. 



27 'The Physiology and Pathology of Mind,' 2d edit. 1868, p. 134. 

28 Eschricht, Ueber die Richtungder Haare am menschlichen Korp er, 
'Midler's Archiv fur Anat. und Phys.' 1837, s. 47. I shall often have to 
refer to this very curious paper. 

8 * Paget, ' Lectures on Surgical Pathology,' 1853, vol. i. p. 71. 



Chap. I.J RUDIMENTS. 25 

above the eyes, where the true eyebrows, if present, would 
have stood. 

The fine wool-like hair, or so-called lanugo, with which 
the human foetus during the sixth month is thickly cov- 
ered, offers a more curious case. It is first developed 
during the fifth month, on the eyebrows and face, and es- 
pecially round the mouth, where it is much longer than 
that on the head. A mustache of this kind was observed 
by Eschricht 30 on a female foetus ; but this is not so sur- 
prising a circumstance as it may at first appear, for the 
two sexes generally resemble each other in all external 
characters during an early period of growth. The direc- 
tion and arrangement of the hairs on all parts of the foetal 
body are the same as in the adult, but are subject to much 
variability. The whole surface, including even the fore- 
head and ears, is thus thickly clothed ; but it is a signifi- 
cant fact that the palms of the ha'nds and the soles of the 
feet are quite naked, like the inferior surfaces of all four 
extremities in most of the lower animals. As this can 
hardly be an accidental coincidence, we must consider the 
woolly covering of the foetus to be the rudimental repre- 
sentative of the first permanent coat of hair in those 
mammals which are born hairy. This representation is 
much more complete, in accordance with the usual law of 
embryological development, than that afforded by the 
straggling hairs on the body of the adult. 

It appears as if the posterior molar or wisdom-teeth 
were tending to become rudimentary in the more civilized 
races of man. These teeth are rather smaller than the 
other molars, as is likewise the case with the correspond- 
ing teeth in the chimpanzee and orang ; and they have 
only two separate fangs. They do not cut through the 
gums till about the seventeenth year, and I am assured 
by dentists that they are much more liable to decay, and 

80 Eschricht, ibid. a. 40, 47. 



£6 THE DESCENT OF MAN. [PARr L 

are earlier lost, than the other teeth. It is also remark- 
able that they are much more liable to vary both in struct- 
ure and in the period of their development than the other 
teeth. 31 In the Melanian races, on the other hand, the 
wisdom-teeth are usually furnished with three separate 
fangs, and are generally sound : they also differ from the 
other molars in size less than in the Caucasian races. 3 * 
Prof. Schaaffhausen accounts for this difference between 
the races by "the posterior dental portion of the jaw being 
always shortened " in those that are civilized, 33 and this 
shortening may, I presume, be safely attributed to civil- 
ized men habitually feeding on soft, cooked food, and 
thus using their jaws less. I am informed by Mr. Brace 
that it is becoming quite a common practice in the United 
States to remove some of the molar teeth of children, as 
the jaw does not grow large enough for the perfect devel- 
opment of the normal number. 

With respect to the alimentary canal, I have met with 
an account of only a single rudiment, namely, the vermi- 
form appendage of the csecum. The cgecum is a branch 
or diverticulum of the intestine, ending in a cul-de-sac, and 
it is extremely long in many of the lower vegetable-feed- 
ing mammals. In the marsupial koala it is actually more 
than thrice as long as the whole body. 34 It is sometimes 
produced into a long, gradually-tapering point, and is 
sometimes constricted in parts. It appears as if, in conse- 
quence of changed diet or habits, the csecum had become 
much shortened in various animals, the vermiform append- 
age being left as a rudiment of the shortened part. That 

31 Dr. Webb, ' Teeth in Man and the Anthropoid Apes,' as quoted by 
Dr. C. Carter Blake in 'Anthropological Review,' July, 1867, p. 299. 

32 Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 320, 321, 325. 

33 ' On the primitive Form of the Skull,' Eng. translat. in ' Anthro 
pOiOgical Review,' Oct. 1868, p. 426. 

34 Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 416, 434, 441. 



Chap. I.] RUDIMENTS. 27 

• 

this appendage is a rudiment, we may infer from its small 
size, and from the evidence which Prof. Canestrini 35 has 
collected of its variability in man. It is occasionally quite 
absent, or again is largely developed. The passage is 
sometimes completely closed for half or two-thirds of its 
length, with the terminal part consisting of a flattened 
solid expansion. In the orang this appendage is long and 
convoluted ; in man it arises from the end of the short 
caecum, and is commonly from four to five inches in 
length, being only about the third of an inch in diameter. 
Not only is it useless, but it is sometimes the cause of 
death, of which fact I have lately heard two instances ; 
this is due to small, hard bodies, such as seeds, entering the 
passage and causing inflammation. 36 

In the Quadrumana, and some other orders of mam- 
mals, especially in the Carnivora, there is a passage near 
the lower end of the humerus, called the supra-condyloid 
foramen, through which the great nerve of the fore-limb 
passes, and often the great artery. Now, in the humerus 
of man, as Dr. Struthers ST and others have shown, there 
is generally a trace of this passage, and it is sometimes 
fairly well developed, being formed by a depending hook- 
like process of bone, completed by a, band of ligament. 
AVhen present the great nerve invariably passes through 
it, and this clearly indicates that it is the homologue and 
rudiment of the supra-condyloid foramen of the lower ani- 
mals. Prof. Turner estimates, as he informs me, that it 

35 ' Annuario della Soc. d. Nat.' Modena, 1867, p. 94. 

36 M. C. Martins (" De l'Unite Organique," in ' Revue des Deux 
Mondes,' June 15, 1862, p. 16), and Hackel ('Generelle Morphologie,' B. 
ii. s. 278), have both remarked on the singular fact of this rudiment 
sometimes causing death. 

87 • The Lancet,' Jan. 24, 1863, p. 83. Dr. Knox, ' Great Artists and 
Anatomists,' p. 63. See also an important memoir on this process by 
Dr. Grube, in the 'Bulletin de l'Acad. Imp. de St. Petersbourg, torn, sii 
1867, p. 448. 



28 THE DESCENT OF MAN. [Part I. 

occurs in about one per cent, of recent skeletons ; but, 
during ancient times, it appears to have been much more 
common. Mr. Bask 38 has collected the following evi- 
dence on this head : Prof. Broca " noticed the perforation 
in four and a half per cent, of the arm-bones collected in 
the ' Cimetiere du Sud ' at Paris ; and in the Grotto of 
Orrony, the contents of which are referred to the Bronze 
period, as many as eight humeri out of thirty-two were 
perforated ; but this extraordinary proportion, he thinks, 
might be due to the cavern having been a sort of ' family 
vault.' Again, M. Dupont found thirty per cent, of per- 
forated bones in the cayes of the Yalley of the Lesse, be- 
longing to the Reindeer period; while M. Leguay, in a 
sort of dolmen at Argenteuil, observed twenty-five per 
cent, to be perforated ; and M. Pruner-Bey found twenty- 
six per cent, in the same condition in bones from Vaureal. 
1ST or should it be left unnoticed that M. Pruner-Bey states 
that this condition is common in Guanche skeletons." 
The fact that ancient races, in this and several other 
cases, more frequently present structures which resemble 
those of the lower animals than do the modern races, is 
interesting. One chief cause seems to be that ancient 
races stand somewhat nearer than modern races in the 
long line of descent to their remote animal-like progeni- 
tors. 

The os coccyx in man, though functionless as a tail, 
plainly represents this part in other vertebrate animals. 
At an early embryonic period it is free, and, as we have 
seen, projects beyond the lower extremities. In certain 
rare and anomalous cases it has been known, according to 
Isidore Geoffroy St.-Hilaire and others, 39 to form a small 

88 " On the Caves of Gibraltar," ' Transact. Internat. Congress of 
Prehist. Arch.' Third Session, 1869, p. 54. 

39 Quatrefages has lately collected the evidence on this subject 
Revue des Cours Scientifiques.' 1867-68, p. 625. 



Chap. I.] RUDIMENTS. 29 

external rudiment of a tail. The os coccyx is short, usu- 
ally including only four vertebrae ; and these are in a rudi- 
mental conditio^ for they consist, with the exception of 
the basal one, of the centrum alone. 40 They are furnished 
with some small muscles ; one of which, as I am informed 
by Prof. Turner, has been expressly described by Theile as 
a rudimentary repetition of the extensor of the tail, which 
is so largely developed in many mammals. 

The spinal cord in man extends only as far downward 
as the last dorsal or first lumbar vertebra ; but a thread- 
like structure (the jilwn terminate) runs down the axis of 
the sacral part of the spinal canal, and even along the back 
of the coccygeal bones. The upper part of this filament, 
as Prof. Turner informs me, is undoubtedly homologous 
with the spinal cord ; but the lower part apparently con- 
sists merely of the pia mater, or vascular investing mem- 
brane. Even in this case the os coccyx may be said to 
possess a vestige o£ so important a structure as the spinal 
cord, though no longer enclosed within a bony canal. The 
following fact, for which I am also indebted to Prof. 
Turner, shows how closely the os coccyx corresponds with 
the true tail in the lower animals : Luschka has recently 
discovered at the extremity of the coccygeal bones a very 
peculiar convoluted body, which is continuous with the 
middle sacral artery ; and this discovery led Krause and 
Meyer to examine the tail of a monkey (Macacus) and of 
a cat, in both of which they found, though not at the ex- 
tremity, a similarly convoluted body. 

The leproductive system offers various rudimentary 
structures ; but these differ in one important respect from 
the fores-oins: cases. We are not here concerned with a 
vestige of a part which does not belong to the species in 
an efficient state ; but with a part which is always present 
and efficient in the one sex, being represented in the other 

40 Owen, 'On the Nature of Limb's,' 1849, p. 11-4 



30 THE DESCENT OF MAN. [Part I. 

by a mere rudiment. Nevertheless, the occurrence of 
such rudiments is as difficult to explain on the belief of the 
separate creation of each species, as in the foregoing cases. 
Herpafter I shall have to recur to these rudiments, and 
shall show that their presence generally depends merely on 
inheritance ; namely, on parts acquired by one sex having 
been partially transmitted to the other. Here I will only 
give some instances of such rudiments. It is well known 
that in the males of all mammals, including man, rudi- 
mentary mammae exist. These, in several instances, have 
become well developed, and have yielded a copious supply 
of milk. Their essential identity in the two sexes is like- 
wise shown by their occasional sympathetic enlargement 
in both during an attack of the measles. The vesicula 
prostatica, which has been observed in many male mam- 
mals, is now universally acknowledged to be the homo- 
logue of the female uterus, together with the connected 
passage. It is impossible to read Leuckart's able descrip- 
tion of this organ, and his reasoning, without admitting 
the justness of his conclusion. This is especially clear in 
the case of those mammals in which the true female ute- 
rus bifurcates, for in the males of these the vesicula like- 
wise bifurcates. 41 Some additional rudimentary structures 
belonging to the reproductive system might here have 
been adduced. 42 

The bearing of the three great classes of facts now 
given is unmistakable. But it would be superfluous here 
fully to recapitulate t]^e line of argument give» in detail 

41 Leuckart, in Todd's « Cyclop, of Anat.' 1849-'52, vol. iv. p. 1415. 
In man this organ is only from three to six lines in length, but, like so 
many other rudimentary parts, it is variable in development as well as in 
other characters. 

42 See, on this subject,. Owen, ( Anatomy of Vertebrates,' vol. iii. pp. 
675, C76, 706. 



Chap. I.] RUDIMENTS. 31 

in my ' Origin of Species.' The home-logical construction 
of the whole frame in the members of the same class is 
intelligible, if "we admit their descent from a common pro- 
genitor, together with their subsequent adaptation to di- 
versified conditions. On any other view the similarity of 
pattern between the hand of a man or monkey, the foot of 
a horse, the flipper of a seal, the wing of a bat, etc., is ut- 
terly inexplicable. It is no scientific explanation to assert 
that they have all been formed on the same ideal plan. 
With respect to development, we can clearly understand, 
on the principle of variations supervening at a rather late 
embryonic period, and being inherited at a corresponding 
period, how it is that the embryos of wonderfully different 
forms should still retain, more or less perfectly, the struct- 
ure of their common progenitor. No other explanation 
has ever been given of the marvellous fact that the embryo 
of a man, dog, seal, bat, reptile, etc., can at first hardly be 
distinguished from each other. In order to understand 
the existence of rudimentary organs, we have only to sup- 
pose that a former progenitor possessed the parts in ques- 
tion in a perfect state, and that under changed habits of 
life they became greatly reduced, either from simple dis- 
use, or through the natural selection of those individuals 
which were least encumbered with a superfluous part, aided 
by the other means previously indicated. 

Thus we can understand how it has come to pass that 
man, and all other vertebrate animals, have been con- 
structed on the same general model, why they pass through 
the same early stages of development, and why they re- 
tain certain rudiments in common. Consequently we 
ought frankly to admit their community of descent ; to 
take any other view, is to admit that our own structure, and 
that of all the animals around us, is a mere snare laid to 
entrap our judgment. This conclusion is greatly strength- 
ened, if. we look to the members of the whole animal se- 



82 THE DESCENT OF MAN. [Part L 

ries, and consider the evidence derived from their affinities 
or classification, their geographical distribution, and geo- 
logical succession. It is only our natural prejudice, and 
that arrogance which made our forefathers declare that 
they were descended from demi-gods, which lead us to 
demur to this conclusion. But the time will before long 
come when it will be thought wonderful that naturalists, 
who were well acquainted with the comparative structure 
and development of man and other mammals, should have 
believed that each was the work of a separate act of crea- 
tion. 



Chap. HI MENTAL POWERS. S3 



CHAPTER II. 

COMPARISON OF THE MENTAL POWERS OE MAN" AND THE 

LOWER ANIMALS. 

The Difference in Mental Power between the Highest Ape and the Lowest 
Savage, immense. — Certain Instincts in common. — The Emotions.— 
Curiosity. — Imitation. — Attention. — Memory. — Imagination. — Eeason. 
— Progressive Improvement. — Tools and "Weapons used by Animals. 
— Language. — Self-Consciousness. — Sense of Beauty. — Belief in God r 
Spiritual Agencies, Superstitions. 

We have seen in the last chapter that man hears in his 
bodily structure clear traces of his descent from some lower 
form ; but it may be urged that, as man differs so greatly 
in his mental power from all other animals, there must be 
some error in this conclusion. No doubt the difference in 
this respect is enormous, even if we compare the mind of 
one of the lowest savages, who has no words to express 
any number higher than four, and who uses no abstract 
terms for the commonest objects or affections, 1 with that 
of the most highly-organized ape. The difference would, 
no doubt, still remain immense, even if one of the higher 
apes had been improved or civilized as much as a dog has 
been in comparison with its parent-form, the wolf or jackal. 
The Fuegians rank among the lowest barbarians ; but I was 
continually struck with surprise how closely the three na- 

1 See the evidence on these points, as given by Lubbock, c Prehistoric 
Times,' p. 354, etc. 



84 THE DESCENT OF MAN. [Part L 

tives on board H. M. S. " Beagle," who had lived some 
years in England, and could talk a little English, resem- 
bled us in disposition, and in most of our mental faculties. 
If no organic being excepting man had possessed any men- 
tal power, or if his powers had been of a wholly different 
nature from those of the lower animals, then we should 
never have been able to convince ourselves that our high 
faculties had been gradually developed. But it can be 
clearly shown that there is no fundamental difference of 
this kind. We must also admit that there is a much 
wider interval in mental power between one of the lowest 
fishes, as a lamprey or lancelet, and one of the higher apes, 
than between an ape and man ; yet this immense interval 
is filled up by numberless gradations. 

Nor is the difference slight in moral disposition between 
a barbarian, such as the man described by the old navi- 
gator Byron, who dashed his child on the rocks for drop- 
ping a basket of sea-urchins, and a Howard or Clarkson ; 
and in intellect, between a savage who does not use any 
abstract terms, and a Newton or Shakespeare. Differences 
of this kind between the highest men of the highest races 
and the lowest savages, are connected by the finest grada- 
tions. Therefore it is possible that they might pass and 
be developed into each other. 

My object in this chapter is solely to show that there 
is no fundamental difference between man and the higher 
mammals in their mental faculties. Each division of the 
subject might have been extended into a separate essay, 
but must here be treated briefly. As no classification of 
the mental powers has been universally accepted, I shall 
arrange my remarks in the order most convenient for my 
purpose, and will select those facts which have most struck 
me, with the hope that they may produce some effect on 
the reader. 

With respect to animals very low in the scale, I shall 



Chap. II.J MENTAL POWERS. 35 

have to give some additional facts under Sexual Selection, 
showing that their mental powers are higher than might 
have been expected. The variability of the faculties in 
the individuals of the same species is an important point 
for us, and some few illustrations will here be given. But 
it would be superfluous to enter into many details on this 
head, for I have found, on frequent inquiry, that it is the 
unanimous opinion of all those who have long attended to 
animals of many kinds, including birds, that the individuals 
differ greatly in every mental characteristic. In what 
manner the mental powers were first developed in the low- 
est organisms, is as hopeless an inquiry as how life first 
originated. These are problems for the distant future, if 
they are ever to be solved by man. 

As man possesses the same senses with the lower ani- 
mals, his fundamental intuitions must be the same. Man 
has also some few instincts in common, as that of self-pres- 
ervation, sexual love, the love of the mother for her new- 
born offspring, the power possessed by the latter of suck- 
ing, and so forth. But man, perhaps, has somewhat fewer 
instincts than those possessed by the animals which come 
next to him in the series. The orang in the Eastern isl- 
ands, and the chimpanzee in Africa, build platforms, on 
which they sleep ; and, as both species follow the same 
habit, it might be argued that this was due to instinct, 
but we cannot feel sure that it is not the result of both 
animals having similar wants, and possessing similar pow- 
ers of reasoning. These apes, as we may assume, avoid 
the many poisonous fruits of the tropics, and man has no 
such knowledge ; but as our domestic animals, when taken 
to foreign lands, and when first turned out in the spring, 
often eat poisonous herbs, which they afterward avoid, we 
cannot feel sure that the apes do not learn from their own 
experience, or from that of their parents, what fruits to 
select. It is, however, certain, as we shall presently see, 



36 THE DESCENT OF MAN. [Part I. 

that apes have an instinctive dread of serpents, and prob- 
ably of other dangerous animals. 

The fewness and the comparative simplicity of the in- 
stincts in the higher animals are remarkable in contrast with 
those of the lower animals. Cuvier maintained that instinct 
and intelligence stand in an inverse ratio to each other ; and 
some have thought that the intellectual faculties of the 
higher animals have been gradually developed from their 
instincts. But Pouchet, in an interesting essay, 2 has shown 
that no such inverse ratio really exists. Those insects 
which possess the most wonderful instincts are certainly 
the most intelligent. In the vertebrate series, the least 
intelligent members, namely fishes and amphibians, do not 
possess complex instincts ; and among mammals the ani- 
mal most remarkable for its instincts, namely the beaver, 
is highly intelligent, as will be admitted by every one 
who has read Mr. Morgan's excellent account of this animal. 9 

Although the first dawnings of intelligence, according 
to Mr. Herbert Spencer, 4 have been developed through the 
multiplication and coordination of reflex actions, and al- 
though many of the simpler instincts graduate into actions 
of this kind, and can hardly be distinguished from them, 
as in the case of young animals sucking, yet the more 
complex instincts seem to have originated independently 
of intelligence. I am, however, far from wishing to deny 
that instinctive actions may lose their fixed and untaught 
character, and be replaced by others performed by the aid 
of the free will. On the other hand, some intelligent ac- 
tions — as when birds on oceanic islands first learn to avoid 
man — after being performed during many generations, be- 
come converted into instincts, and are inherited. They 

2 ' L'Instinct chez les Insectes.' ' Revue d'es Deux Mondes,' Feb. 
1870, p. 690. 

8 The American Beaver and his Works,' 1868. 

« 'The Principles of Psychology,' 2d edit. 1870, pp. 418-443. 



Chap. II.] MENTAL POWERS. 37 

may then be said to be degraded in character, for they are 
no longer performed through reason or from experience. 
But the greater number of the more complex instincts ap- 
pear to have been gained in a wholly different manner, 
through the natural selection of variations of simpler in- 
stinctive actions. Such variations appear to arise from 
the same unknown causes actings on the cerebral organiza- 
tion, which induce slight variations or individual differ- 
ences in other parts of the body ; and these variations, 
owing to our ignorance, are often said to arise sponta- 
neously. "We can, I think, come to no other conclusion 
with respect to the origin of the more complex instincts, 
when we reflect on the marvellous instincts of sterile 
worker-ants and bees, which leave no offspring to inherit 
the effects of experience and of modified habits. 

Although a high degree of intelligence is certainly 
compatible with the existence of complex instincts, as we 
see in the insects just named and in the beaver, it is not 
improbable that, they may to a certain extent interfere 
with each other's development. Little is known about 
the functions of the brain, but we can perceive that, as 
the intellectual powers become highly developed, the va- 
rious parts of the brain must- be connected by the most 
intricate channels of intercommunication ; and as a conse- 
quence each separate part would, perhaps, tend to be- 
come less well fitted to answer in a definite and uniform, 
that is instinctive, manner to particular sensations or as- 
sociations. 

I have thought this digression worth giving, because 
we may easily underrate the mental powers of the higher 
animals, and especially of man, when we compare their 
actions, founded on the memory of past events, on fore- 
eight, reason, and imagination, with exactly similar actions 
instinctively performed by the lower animals ; in this lat- 
ter case, the capacity of performing such actions having 



58 THE DESCENT OF MAN. [Part I. 

been gained, step by step, through the variability of the 
mental organs and natural selection, without any conscious 
intelligence on the part of the animal during each succes- 
sive generation. No doubt, as Mr. Wallace has argued, 6 
much of the intelligent work done by man is due to imita- 
tion, and not to reason ; but there is this great difference 
between his actions and many of those performed by the 
lower animals, namely, that man cannot, on his first trial, 
make, for instance, a stone hatchet or a canoe, through his 
power of imitation. He has to learn his work by practice ; 
a beaver, on the other hand, can make its dam or canal, 
and a bird its nest, as well, or nearly as well, the first time 
it tries, as when old and experienced. 

To return to our immediate subject : the lower animals, 
like man, manifestly feel pleasure and pain, happiness and 
misery. Happiness is never better exhibited than by 
young animals, such as puppies, kittens, lambs, etc., when 
playing together, like our own children. Even insects 
play together, as has been described by that excellent ob- 
server, P. Huber, 6 who saw ants chasing and pretending to 
bite each other, like so many puppies. 

The fact that the lower animals are excited by the same 
emotions as ourselves is so well established, that it will not 
be. necessary to weary the reader by many details. Terror 
acts in the same maimer on them as on us, causing the 
muscles to tremble, the heart to palpitate, the sphincters 
to be relaxed, and the hair to stand on end. Suspicion, 
the offspring of fear, is eminently characteristic of most 
wild animals. Courage and timidity are extremely va- 
riable qualities in the individuals of the same species, 
as is plainly seen in our dogs. Some dogs and horses 
are ill-tempered, and easily turn sulky ; others are good- 
tempered; and these qualities are certainly inherited, 

5 'Contributions to the Theory of Natural Selection,' 1870, p. 212. 

6 ' Recherches sur les Mceurs des Fourmis,' 1810, p. 1*73. 



Chap. II] MEXTAL POWERS. 39 

Every one knows how liable animals are to furious rage, 
and how plainly they show it. Many anecdotes, probably 
true, have been published on the long-delayed and artful 
revenue of various animals. The accurate Render and 
Brehm 7 state that ' the American and African monkeys 
which they kept tame, certainly revenged themselves. 
The love of a dog for his master is notorious ; in the 
agony of death he has been known to caress his master, 
and every one has heard of the dog suffering under vivi- 
section, who licked the hand of the operator ; this man, 
unless he had a heart of stone, must have felt remorse to 
the last hour of his life. As Whewell 8 has remarked, 
" who that reads the touching instances of maternal affec- 
tion, related so often of the women of all nations, and of 
the females of all animals, can doubt that the principle of 
action is the same in the twa cases ? " 

TV r e see maternal affection exhibited in the most trifline; 
details ; thus Rengger observed an American monkey (a 
Cebus) carefully driving away the flies which plagued her 
infant ; and Duvaucel saw a Hylobates washing the faces 
of her young ones in a stream. So intense is the grief of 
female monkeys for the loss of their young, that it inva- 
riably caused the death of certain kinds kept under con- 
finement by Brehm in North Africa. Orphan-monkeys were 
always adopted and carefully guarded by the other mon- 
keys, both males and females. One female baboon had so 
capacious a heart, that she not only adopted young mon- 
keys of other species, but stole young dogs and cats, which 
she continually carried about. Her kindness, however, did 
not go so far as to share her food with her adopted off- 
spring, at which Brehm was surprised, as his monkeys al- 

7 All the following statements, given on the authority of these two 
naturalists, are taken from KenggerVNaturges. der Saugethiere von 
Paraguay,' 1830, s. 41-57, and from Brehm's ' Thierleben,' B. i. s. 10-87. 

8 ' Biidgewater Treatise,' p. 263. 



40 THE DESCENT OF MAN. [Part L 

ways divided every thing quite fairly with their own 
young ones. An adopted kitten scratched the above-men- 
tioned affectionate baboon, who certainly had a fine intel- 
lect, for she was much astonished at being scratched, and 
immediately examined the kitten's feet, and without more 
ado bit off the claws. In the Zoological Gardens, I heard 
from the keeper that an old baboon (C. chacma) had 
adopted a Rhesus monkey ; but when a young drill and 
mandrill were placed in the cage, she seemed to perceive 
that these monkeys, though distinct species, were her 
nearer relatives, for she at once rejected the Rhesus and 
adopted both of them. The young Rhesus, as I saw, was 
greatly discontented at being thus rejected, and it would, 
like a naughty child, anno^ and attack the young drill 
and mandrill whenever it could do so with safety , this 
conduct exciting great indignation in the old baboon. 
Monkeys will also, according to Brehm, defend their mas- 
ter when attacked by any one, as well as dogs to whom 
they are attached, from the attacks of other dogs. But 
we here trench on the subject of synrpathy, to which I 
shall recur. Some of Brehm's monkeys took much de- 
light in teasing, in various ingenious ways, a certain old 
dog whom they disliked, as well as other animals. 

Most of the more complex emotions are common to the 
higher animals and ourselves. Every one has seen how 
jealous a dog is of his master's affection, if lavished on 
any other creature ; and I have observed the same fact 
with monkeys. This shows that animals not only love, 
but have the desire to be loved. Animals manifestly feel 
emulation. They love approbation or praise ; and a dog 
carrying a basket for his master exhibits in a high degree 
self-complacency or pride. There can, I think, be no doubt 
that a dog feels shame, as distinct from fear, and some- 
thing very like modesty when begging too often for food. 
A great dog scorns the snarling of a little dog, and this 



Chap. II.] MENTAL POWERS. 41 

may be called magnanimity. Several observers have 
stated that monkeys certainly dislike being laughed at ; 
and they sometimes invent imaginary offences. In the 
Zoological Gardens I saw a baboon who always got into 
a furious rage when his keeper took out a letter or book 
and read it aloud to him; and his rage was so violent that, 
as I witnessed on one occasion, he bit his own leg till the 
blood flowed. 

We will now turn to the more intellectual emotions 
and faculties, which are very important, as forming the 
basis for the development of the higher mental powers. 
Animals manifestly enjoy excitement and suffer from 
ennui, as may be seen with dogs, and, according to Reng- 
ger, with monkeys. All animals feel wonder, and many 
exhibit curiosity. They sometimes suffer from this latter 
quality, as when the hunter plays antics and thus attracts 
them ; I have witnessed this with deer, and so it is with 
the wary chamois, and with some kinds of wild-ducks. 
Brehm gives a curious account of the instinctive dread 
which his monkeys exhibited toward snakes ; but their 
curiosity was so great that they could not desist from oc- 
casionallv satiatino; their horror in a most human fashion, 
by lifting up the lid of the box in which the snakes were 
kept. I was so much surprised at his account, that I took 
a stuffed and coiled-up snake into the monkey-house at the 
Zoological Gardens, and the excitement thus caused was 
one of the most curious spectacles which I ever beheld. 
Three species of Cercopithecus were the most alarmed ; 
they dashed about their cages and uttered sharp signal- 
cries of danger, which were understood by the other 
monkeys. A few young monkeys and one old Anubis 
baboon alone took no notice of the snake. I then placed 
the stuffed specimen on the ground in one of the larger 
compartments. After a time all the monkeys collected 
round it in a large circle, and, staring intently, presented 
3 



42 THE DESCENT OF MAN. [Part I. 

a most ludicrous appearance. They became extremely 
nervous ; so that when a wooden ball, with which they 
were familiar as a plaything, was accidentally moved in 
the straw, under which it was partly hidden, they all in- 
stantly started away. These monkeys behaved very dif- 
ferently when a dead fish, a mouse, and some other new 
objects, were placed in their cages ; for, though at first 
frightened, they soon approached, handled and examined 
them. 1 then placed a live snake in a paper bag, with 
the mouth loosely closed, in one of the larger compart- 
ments. One of the monkeys immediately approached, 
cautiously opened the bag a little, peeped in, and in- 
stantly dashed away. Then I witnessed what Brehm has 
described, for monkey aftei monkey, with head raised 
high and turned on one side, could not resist taking mo- 
mentary peeps into the upright bag, at the dreadful object 
lying quiet at the bottom. It would almost appear as if 
monkeys had some notion of zoological affinities, for those 
kept by Brehm exhibited a strange, though mistaken, in- 
stinctive dread of innocent lizards and frogs. An orang, 
also, has been known to be much alarmed at the first 
sight of a turtle. 9 

The principle of Imitation is strong in man, and espe- 
cially in man in a barbarous state. Desor 10 has remarked 
that no animal voluntarily imitates an action performed 
by man, until in the ascending scale we come to monkeys,* 
which are well known to be ridiculous mockers. Animals, 
however, sometimes imitate each others' actions : thus two 
species of wolves, which had been reared by dogs, learned 
to bark, as does sometimes, the jackal, 11 but whether this 
can be called voluntary imitation is another question. 

9 W. C. L. Martin, « Nat. Hist, of Mammalia,' 1841, p. 405. 

10 Quoted by Vogt, 'Memoire surles Microcephales,' 1867, p. 168. 

11 ' The Variation of Animals ana Plants under Domestication,' vol i 
p. 27. 



Chap. II.] MENTAL POWERS. 43 

From one account which I have read, there is reason to 
believe that puppies nursed by cats sometimes learn to 
lick their feet and thus to clean their faces : it is* at least 
certain, as I hear from a perfectly trustworthy friend, that 
some dosrs behave in this manner. Birds imitate the 
songs of their parents, and sometimes those of other 
birds ; and parrots are notorious imitators of any sound 
which they often hear. 

Hardly any faculty is more important for the intellec- 
tual progress of man than the power of Attention. Ani- 
mals clearly manifest this power, as, when a cat watches 
by a hole and prepares to spring on its prey. Wild animals 
sometimes become so absorbed when thus engaged, that 
they may be easily approached. Mr. Bartlett has given 
me a 'curious proof how variable this faculty is in mon- 
keys. A man who trains monkeys to act used to purchase 
common kinds from the Zoological Society at the price of 
five pounds for each ; but he offered to give double the 
price, if he might keep three or four of them for a few 
days, in order to select one. When asked how he could 
possibly so soon learn whether a particular monkey would 
turn out a good actor, he answered that it all depended 
on their power of attention. If when he was talking and 
explaining any thing to a monkey, its attention was easily 
distracted, as by a fly on the wall or other trifling object, 
the case was hopeless. If he tried by punishment to 
make an inattentive monkey act, it turned sulky. On 
the other hand, a monkey which carefully attended to him 
could always be trained. 

It is almost superfluous to state that animals have ex- 
cellent Memories for persons and places. A baboon at the 
Cape of Good Hope, as I have been informed by Sir An- 
drew Smith, recognized him with joy after an absence of 
nine months. I had a dogj who was savasre and averse to 
all strangers, and I purposely tried his memory after an 



44 THE DESCENT OF MAN. [Part. I. 

absence of five years and two days. I went near the sta- 
ble where he lived, and shouted to him in my old manner; 
he showed no joy, but instantly followed me out walking 
and obeyed me, exactly as if I had parted with him only 
half an hour before. A train of old associations, dormant 
during five years, had thus been instantaneously awakened 
in his mind. Even ants, as P. Huber 12 has clearly shown, 
recognized their fellow-ants belonging to the same com- 
munity after a separation of four months. Animals can 
certainly by some means judge of the intervals of time 
between recurrent events. 

The Imagination is one of the highest prerogatives of 
man. By this faculty he unites, independently of the will, 
former images and ideas, and thus creates brilliant and 
novel results. A poet, as Jean Paul Richter remarks, 13 
" who must reflect whether he shall make a character say 
yes or no — to the devil with him ; he is only a stupid 
corpse." Dreaming gives us the best notion of this 
power ; as Jean Paul again says, " The dream is an invol- 
untary art of poetry." The value of the products of our 
imagination depends of course on the number, accuracy, 
and clearness of our impressions ; on our judgment and 
taste in selecting or rejecting the involuntary combina- 
tions, and to a certain extent on our power of voluntarily 
combining them. As dogs, cats, horses, and probably all 
the higher animals, even birds, as is stated on good au- 
thority, 14 have vivid dreams, and this is shown by their 
movements and voice, we must admit that they possess 
some power of imagination. 

Of all the faculties of the human mind, it will, I pre- 
sume, be admitted that Reason stands at the summit. 

12 'Les Moeurs des Fourmis,' 1810, p. 150. 

18 Quoted in Dr. Maudsley's ' Physiology and Pathology of Mind/ 
1808, pp. 19, 220. 

14 Dr. Jerdon, 'Birds of India,' voL i. 1862 p. xxL 



Chap. IL] MENTAL POWERS. 45 

Few persons any longer dispute that animals possess some 
power of reasoning. Animals may constantly be seen to 
pause, deliberate, and resolve. It is a significant fact, 
that the more the habits of any particular animal are 
studied by a naturalist, the more he attributes to reason 
and the less to unlearned instincts. 15 In future chapters we 
shall see that some animals extremely low in the scale 
apparently display a certain amount of reason. No doubt, 
it is often difficult to distinguish between the power of 
reason and that of instinct. Thus Dr. Hayes, in his work 
on 'The Open Polar Sea,' repeatedly remarks that his 
dogs, instead of continuing to draw the sledges in a com- 
pact body, diverged and separated when they came to 
thin ice, so that their weight might be more evenly dis- 
tributed. This was often the first warning and notice 
which the travellers received that the ice was becoming 
thin and dangerous. Now, did the dogs act thus from 
the experience of each individual, or from the example of 
the older and wiser dogs, or from an inherited habit, that 
is, from an instinct ? This instinct might possibly have 
arisen since the time, long ago, when dogs were first em- 
ployed by the natives in drawing their sledges ; or the 
Arctie wolves, the parent-stock of the Esquimaux dog, 
may have acquired this instinct, impelling them not to 
attack their prey in a close pack when on thin ice. Ques- 
tions of this kind are most difficult to answer. 

So many facts have been recorded in various works 
showing that animals possess some degree of reason, that 
I will here give only two or three instances, authenticated 
by Itengger, and relating to American monkeys, which 
stand low in their order. He states that when he first 
gave eggs to his monkeys, they smashed them and thus 

15 Mr. L. H. Morgan's work on 'The American Beaver,' 1868, offers 
a good illustration of this remark. I cannot, however, avoid thinking 
that he goes too far in underrating the power of Instinct. 



46 THE DESCENT OF MAN. [Part L 

lost much of their contents ; afterward they gently hit 
one end 'against some hard body, and picked off the bits 
of shell with their fingers. After cutting themselves only 
once with any sharp tool, they would not touch it again, 
or would handle it with the greatest care. Lumps of 
sugar were often given them wrapped up in paper ; and 
Rengger sometimes put a live wasp in the paper, so that 
in hastily unfolding it they got stung ; after this had once 
happened, they always first held the packet to their ears 
to detect any movement within. Any one who is not con- 
vinced by such facts as these, and by what he may observe 
with his own dogs, that animals can reason, would not be 
convinced by any thing that I could add. Nevertheless 
I will give one case with respect to dogs, as it rests on 
two distinct observers, and can hardly depend on the 
modification of any instinct. 

Mr. Colquhoun 16 winged two wild-ducks, which fell on 
the opposite side of a stream ; his retriever tried to bring 
over both at once, but could not succeed ; she then, though 
never before known to ruffle a feather, deliberately killed 
one, brought over the other, and returned for the dead 
bird. Colonel Hutchinson relates that two partridges 
were shot at once, one being killed, the other wounded ; 
the latter ran away, and was caught by the retriever, who 
on her return came across the dead bird ; " she stopped, 
evidently greatly puzzled, and after one or two trials, 
finding she could not take it up without permitting the 
escape of the winged bird, she considered a moment, then 
deliberately murdered it by giving it a severe crunch, and 
afterward brought away both together. This was the 
only known instance of her ever having wilfully injured 
any game." Here we have reason, though not quite per- 
fect, for the retriever might have brought the wounded 

16 ' The Moor and the Loch,' p. 45. Colonel Hutchinson on ' Dog 
Breaking,' 1850, p. 46. 



Chap. II.] MENTAL TOWERS. 47 

bird first and then returned for the dead one, as in the 
case of the two wild-ducks. 

The muleteers in South America say, " I will not give 
you the mule whose step is easiest, but la mas rational, 
— the one that reasons best ; " and Humboldt 17 adds, 
"this popular expression, dictated by long experience, 
combats the system of animated machines, better perhaps 
than all the arguments of speculative philosophy." 

It has, I think, now been shown that man and the 
higher animals, especially the Primates, have some few 
instincts in common. All have the same senses, intuitions, 
and sensations — similar passions, affections, and emotions, 
even the more complex ones ; they feel wonder and curi- 
osity ; they possess the same faculties of imitation, atten- 
tion, memory, imagination, and reason, though in very 
different degrees. Nevertheless many authors have in- 
sisted that man is separated through his mental faculties 
by an impassable barrier from all the lower animals. I 
formerly made a collection of above a score of such apho- 
risms, but they are not worth giving, as their wide differ- 
ence and number prove the difficulty, if not the impossi- 
bility, of the attempt. It has been asserted that man 
alone is capable of progressive improvement ; that he 
alone makes use of tools or fire, domesticates other ani- 
mals, possesses property, or employs language; that no 
other animal is self-conscious, comprehends itself, has the 
power of abstraction, or possesses general ideas; that 
man alone has a sense of beauty, is liable to caprice, has 
the feeling of gratitude, mystery, etc. ; believes in God, or 
is endowed with a conscience. I will hazard a few remarks 
on the more important and interesting of these points 

Archbishop Sumner formerly maintained 18 that man 

11 ' Personal Narrative,' Eng. translat., vol. iii. p: 106. 
18 Quoted by Sir C. Lyell, « Antiquity of Man,' p. 49*7. 



48 THE DESCENT OF MAN. [Part I. 

alone is capable of progressive improvement. With ani- 
mals, looking first to the individual, every one who has 
had any experience in setting traps knows that young 
animals can be caught much more easily than old ones ; 
and they can be much more easily approached by an 
enemy. Even with respect to old animals, it is impossible 
to catch many in the same place and in the same kind of 
trap, or to destroy them by the same kind of poison ; yet 
it is improbable that all should have partaken of the poi- 
son, and impossible that all should have been caught in 
the trap. They must learn caution by seeing their breth- 
ren caught or poisoned. In North America, where the 
fur-bearing animals have long been pursued, they exhibit, 
according to the unanimous testimony of all observers, an 
almost incredible amount of sagacity, caution, and cun- 
ning ; but trapping has been there so long carried on that 
inheritance may have come into play. 

If we look to successive generations, or to the race, 
there is no doubt that birds and other animals gradually 
both acquire and lose caution in relation to man or other 
enemies ; 19 and this caution is certainly in chief part an 
inherited habit or instinct, but in part the result of indi- 
vidual experience. A good observer, Leroy, 20 states that 
in districts where foxes are much hunted, the young when 
they first leave their burrows are incontestably much 
more wary than the old ones in districts where they are 
not much disturbed. 

Our domestic dogs are descended from wolves and 
jackals, 21 and though they may not have gained in cun- 

M ' Journal of Researches during the Voyage of the " Beagle," ' 1845, 
o. 398. ' Origin of Species,' 5th edit. p. 260. 

20 ' Lettres Phil, sur Tlntelligence des Animaux,' nouvelle edit. 1802, 
p. 86. 

21 See the evidence on this head in chap. i. vol. i. ' On the Variation 
ol Animals and Plants under Domestication.' 



Chap. II.] MENTAL POWERS. 49 

ning, and may have lost in wariness and suspicion, yet 
they have progressed in certain moral qualities, such as in 
affection, trustworthiness, temper, and probably in gen- 
eral intelligence. The common rat has conquered and 
beaten several other species throughout Europe, in parts 
of North America, New Zealand, and recently in For- 
mosa, as well as on the main-land of China. Mr. Swin- 
hoe," who describes these latter cases, attributes the vic- 
tory of the common rat over the large Mus coninga to 
its superior cunning ; and this latter quality may be at- 
tributed to the habitual exercise of all its faculties in 
avoiding extirpation by man, as well as to nearly all the 
less cunning or weak-minded rats having been successively 
destroyed by him. To maintain, independently of any 
direct evidence, that no animal during the course of ages 
has progressed in intellect or other mental faculties, is to 
beg the question of the evolution of species. Hereafter 
we shall see that, according to Lartet, existing mammals 
belononn^ to several orders have larger brains than their 
ancient tertiary prototypes. 

It has often been said that no animal uses any tool ; 
' but the chimpanzee in a state of nature cracks a native 
fruit, somewhat like a walnut, with a stone. 23 Rengger 24 
easily taught an American monkey thus to break open 
hard palm-nuts, and afterward of its own accord it used 
stones to open other kinds of nuts, as well as boxes. It 
thus also removed the soft rind of fruit that had a disa- 
greeable flavor. Another monkey was taught to open the 
lid of a large box with a stick, and aftecward it used the 
stick as a lever to move heavy bodies ; and I have myself 
seen a young orang put a stick into a crevice, slip his 

22 'Proc. Zoolog. Soc.' 1864, p. 186. 

23 Savage and 'Wyman in 'Boston Journal of Nat. Hist.' vol. iv. 1843 
-'44, p. 383. 

24 'Saugethiere von Paraguay,' 1830, s. 51-56. 



50 THE DESCENT OF MAN. [Part I. 

• 
hand to the other end, and nse it in the proper manner as 
a lever. In the cases just mentioned stones and sticks 
were employed as implements ; but they are likewise used 
as weapons. Brehm 25 states, on the authority of the well- 
known traveller Schimper, that in Abyssinia when the 
baboons belonging to one species ( C. gelada) descend in 
troops from the mountains to plunder the fields, they 
sometimes encounter troops of another species ( G. hama- 
dryas), and then a fight ensues. The Geladas roll down 
great stones, which the Hamadryas try to avoid, and then 
both species, making a great uproar, rush furiously 
against .each other. Brehm, when accompanying the 
Duke of Coburg-Gotha, aided in an attack with fire-arms 
on a troop of baboons in the mss of Mensa in Abyssinia. 
The baboons in return rolled so many stones down the 
mountain, some as large as a man's head, that the at- 
tackers had to beat a hasty retreat ; and the r5ass was 
actually for a time closed against the caravan. It de- 
serves notice that these baboons thus acted in concert. 
Mr. Wallace 26 on three occasions saw female orangs, ac- 
companied by their young, " breaking off branches and 
the great spiny fruit of the Durian-tree, with every ap- 
pearance of rage; causing such a shower of missiles as 
effectually kept us. from approaching too near the tree." 

In the Zoological Gardens a monkey which had weak 
teeth used to break open nuts with a stone ; and I was 
assured by the keepers that this animal, after using the 
stone, hid it in the straw, and would not let any other 
' monkey touch it.- Here, then, we have the idea of prop- 
erty ; but this idea is common to every dog with a bone, 
and to most or all birds with their nests. 

The Duke of Argyll n remarks, that the fashioning of 

25 ' Thierleben,' B. i. s. 79, 82. 

26 'The Malay Archipelago,' vol. i. 1869, p. 87. 
21 ' Primeval Man,' 1869, pp. 145, 147. 






Chap. II.] MENTAL POWERS. 51 

an implement for a special purpose is absolutely peculiar 
to man; and he considers that this forms an immeasur- 
able gulf between him and the brutes. It is no doubt a 
very important distinction, but there appears to me much 
truth in Sir J. Lubbock's suggestion, 28 that when prime- 
val man first used flint-stones for any purpose, he would 
have accidentally splintered them, and would then have 
used the sharp fragments. From this step it would be a 
small one to intentionally break the flints, and not a very 
wide step to rudely fashion them. This latter advance, 
however, may have taken long ages, if we may judge by 
the immense interval of time which elapsed before the men 
of the neolithic period took to grinding and polishing 
their stone tools. In breaking the flints, as Sir J. 'Lub- 
bock likewise remarks, sparks would have been emitted, 
and in grinding them heat would have been evolved: 
"thus the two usual methods o"f obtaining fire may have 
originated." The nature of fire would have been known 
in the many volcanic regions where lava occasionally 
flows through forests. The anthropomorphous apes, 
guided probably by instinct, build for themselves tempo- 
rary platforms ; but as many instincts are largely con- 
trolled by reason, the simpler ones, such as this of build- 
ing a platform, might readily pass into a voluntary and 
conscious act. The orang is known to cover itself at 
night with the leaves of the Pandanus ; and Brehm states 
that one of his baboons used to protect itself from the 
heat of the sun by throwing a straw mat over its head. 
In these latter habits, we probably see the first steps 
toward some of the simpler arts ; namely, rude architec- 
ture and dress, as they arose among the early progeni- 
tors of man. 

Language. — This faculty has justly been considered 
as one of the chief distinctions between man and thejower 

28 ' Prehistoric Times,' 1865, p. 473, etc. 



52 THE DESCENT OF MAN. [Past L 

animals. But man, as a highly competent judge, Arch- 
bishop Whately remarks, " is not the only animal that can 
make use of language to express what is passing in his 
mind, and can understand, more or less, what is so ex- 
pressed by another." 29 In Paraguay the Cebus azarce 
when excited utters at least six distinct sounds, which ex- 
cite in other monkeys similar emotions. 30 The movements 
of the features and gestures of monkeys are understood 
by us, and they partly understand ours, as Rengger and 
others declare. It is a more remarkable fact that the dog, 
since being domesticated, has learned to bark 81 in at least 
four or five distinct tones. Although barking is a new 
art, no doubt the wild species, the parents of the dog, ex- 
pressed their feelings by cries of various kinds. With 
the domesticated dog we have the bark of eagerness, as 
in the chase ; that of anger ; the yelping or howling bark 
of despair, as when shut up ; that of joy, as when starting 
on a walk with his master ; and the very distinct one of 
demand or supplication, as when wishing for a door or 
window to be opened. 

Articulate language is, however, peculiar to man ; but 
he uses in common with the lower animals inarticulate 
cries to express his meaning, aided by gestures and the 
movements of the muscles of the face. 32 This especially 
holds good with the more simple and vivid feelings, 
which are but little connected with our higher intelli- 
gence. Our cries of pain, fear, surprise, anger, together 
with their appropriate actions, and the murmur of a 

29 Quoted in 'Anthropological Review,' 1864, p. 158. 

30 Rengger, ibid. s. 45. 

31 See my ' Variation of Animals and Plants under Domestication,* 

rol. i. p. 27. 

32 See a discussion on this subject in Mr. E. B. Tylor's very interest- 
ing wodt, 'Researches into the Early History of Mankind,' 1665, chaps 
ii. to iv. 



Chap. II.] MENTAL POWERS. 53 

mother to her beloved child, are more expressive than any 
words. It is not the mere power of articulation that dis- 
tinguishes man from other animals, for, as every one 
knows, parrots can talk ; but it is his large power of con- 
necting definite sounds with definite ideas ; and this obvious- 
ly depends on the development of the mental faculties. 

As Home Tooke, one of the founders of the noble 
science of philology, observes, language is an art, like 
brewing or baking ; but writing would have been a much 
more appropriate simile. It certainly is not a true in- 
stinct, as every language has to be learned. It differs, 
however, widely from all ordinary arts, for man has an 
instinctive tendency to speak, as we see in the babble of 
•our young children; while no child has an instinctive 
tendency to brew, bake, or write. Moreover, no philolo- 
gist now supposes that any language has been deliberately 
invented; each has been slowly and unconsciously de- 
veloped by many steps. The sounds uttered by birds 
offer in* several respects the nearest analogy to language, 
for all the members of the same species utter the same in- 
stinctive cries expressive of their emotions ; and all the 
kinds that have the power of singing exert this power in- 
stinctively ; but the actual song, and even the call-notes, 
are learned from their parents or foster-parents. These 
sounds, as Daines Barrington 33 has proved, " are no more 
innate than language is in man." The first attempt to 
sing " may be compared to the imperfect endeavor in a 
child to babble." The young males continue practising, 
or, as the bird-catchers say, recording, for ten or eleven 
months. Their first essays show hardly a rudiment of the 
future song ; but as they grow older we can perceive what 
they are aiming at ; and at last they are said " to sing 

33 Hon. Daines Barrington in 'Philosoph. Transactions,' 1V73, p. 262. 
See also Dureau de la Malle, in ' Ann. des Sc. Nat.' 3d series, Zoolog. 
torn. x. p. 119. 



54 THE DESCENT OF MAN. [Part L 

their song round." Nestlings which have learned the song 
of a distinct species, as with the canary-birds educated in 
the Tyrol, teach and transmit their new song to their off- 
spring. TJie slight natural differences of song in the same 
species inhabiting different districts may be appositely 
compared, as Barrington remarks, "to provincial dia- 
lects ; " and the songs of allied though distinct species 
may be compared with the languages of distinct races of 
man. I have given the foregoing details to show that an 
instinctive tendency to acquire an art is not a peculiarity 
confined to man. 

With respect to the origin of articulate language, 
after having read on the one side the highly-interesting 
works of Mr. Hensleigh Wedgwood, the Rev. F. Farrar,. 
and Prof. Schleicher, 34 and the celebrated lectures of Prof. 
Max Milller on the other side, I cannot doubt that lan- 
guage owes its origin to the imitation and modification, 
aided by signs and gestures, of various natural sounds, 
the voices of other animals, and man's own instinctive 
cries. When we treat of sexual selection we shall see 
that primeval man, or rather some early progenitor of 
man, probably used his voice largely, as does one of the 
gibbon-apes at the present day, in producing true musical 
cadences, that is in singing; we may conclude frdm a 
widely-spread analogy that this power would have been 
especially exerted during the courtship of the sexes, serv- 
ing to express various emotions, as love, jealousy, triumph, 
and serving as a challenge to their rivals. The imitation 
by articulate sounds of musical cries might have given 

84 ' On the Origin of Language,' by H. "Wedgwood, 1866. • Chapters 
on Language,' by the Rev. F. W. Farrar, 1865. These works -are most 
interesting. See also ' De la Phys. et de Parole,' par Albert Lemoine, 
1855, p. 190. The work on this subject, by the late Prof. Aug. Schlei- 
cher, has been translated by Dr. Bikkers into English, under the title of 
'Darwinism tested by the Science of Language,' 1869. 



Chap. II.] MENTAL POWERS. 55 

rise to "words expressive of various complex emotions. As 
bearing on the subject of imitation, the strong tendency 
in our nearest allies, the monkeys, in microcephalous 
idiots, 36 and in the barbarous races of mankind, to imi- 
tate "whatever they hear deserves notice. As monkeys 
certainly understand much that is said to them by man, 
and as in a state of nature they utter signal-cries of dan- 
ger to their fellows, 36 it does not appear altogether incred- 
ible, that some unusually wise ape-like animal should have 
thought of imitating the growl of a beast of prey, so as 
to indicate to his fellow-monkeys the nature of the ex- 
pected danger. And this would have been a first step in 
the formation of a language. 

As the voice was used more and more, the vocal or- 
gans would have been strengthened and perfected through 
the principle of the inherited effects of use; and this 
would have reacted on the power of speech. But the 
relation between the continued use of language and the 
development of the brain has no doubt been far more im- 
portant. The mental powers in some early progenitor of 
man must have been more highly developed than in any 
existing ape, before even the most imperfect form of 
speech could have come into use ; but we may confidently 
believe that the continued use and advancement of this 
power would have reacted on the mind by enabling and 
encouraging it to carry on long trains of thought. A 
long and complex train of thought can no more be carried 
on without the aid of words, whether spoken or silent, 
than a long; calculation without the use of figures or alge- 
bra. It appears, also, that even ordinary trains of thought 

35 Vogt, ' Memoire sur les Microcephales,' 1867, p. 169. With re- 
spect to savages, I have given some facts in my ' Journal of Researches,' 
etc., 1845, p. 206. 

36 See clear evidence on this head in the two works so often quoted, 
by Brehm amd Rengger. 



56 THE DESCENT OF MAN. [Part L 

almost require some form of -language, for the dumb, deaf, 
and blind girl, Laura Bridgman, was observed to use her 
fingers while dreaming. 37 Nevertheless a long succession 
of vivid and connected ideas may pass through the mind 
without the aid of any form of language, as we may in- 
fer from the prolonged dreams of dogs. We have, also, 
seen that retriever-dogs are able to reason to a certain ex- 
tent ; and this they manifestly do without the aid of lan- 
guage. The intimate connection between the brain, as it is 
now developed in us, and the faculty of speech, is well 
shown by those curious cases of brain-disease, in which 
speech is specially affected, as when the power to remem- 
ber substantives is lost, while other words can be correctly 
used. 38 There is no more improbability in the effects of 
the continued use of the vocal and mental organs being 
inherited, than in the case of handwriting, which depends 
partly on the structure of the hand and partly on the dis- 
position of the mind; and handwriting is certainly in- 
herited. 39 

Why the organs now used for speech should have 
been originally perfected for this purpose, rather than any 
other organs, it is not difficult to see. Ants have consid- 
erable powers of intercommunication by means of their 
antennae, as shown by Huber, who devotes a whole chap- 
ter to their language. We might have used our fingers 
as efficient instruments, for a person with practice can re- 
port to a deaf man every word of a speech rapidly de- 
livered at a public meeting ; but the loss of our hands, 

37 See remarks on this head by Dr. Maudsley, ' The Physiology and 
Pathology of Mind,' 2d edit. 1868, p. 199. 

38 Many curious cases have been recorded. See, for instance, c In- 
quiries concerning the Intellectual Powers,' by Dr. Abercrombie, 1838, 
p. 150. 

39 ' The Variation of Animals and Plants under Domestication,' vol 
ii. p. 6. 



Chap. II.] MENTAL POWERS. 51 

while thus employed, would have been a serious incon- 
venience. As all the higher mammals possess vocal or- 
gans constructed on the same general plan with ours, and 
which are used as a means of communication", it was ob- 
viously probable, if the power of communication had to 
be improved, that these same organs would have been 
still further developed ; and this has been effected by the 
aid of adjoining and well-adapted parts, namely, the 
tongue and lips. 40 The fact of the higher apes not using 
their vocal organs for speech, no doubt depends on their 
intelligence not having been sufficiently advanced. The 
possession by them of organs, which with long-continued 
practice might have been used for speech, although not 
thus used, is paralleled by the case of many birds which 
possess organs fitted for singing, though they never sing. 
Thus, the nightingale and crow have vocal organs simi- 
larly constructed, these being used by the former for di- 
versified song, and by the latter merely for croaking. 41 

The formation of different Ian om ages and of distinct 
species, and the proofs that both have been developed 
through a gradual process, are curiously the same. 42 But 
we can trace the origin of many words further back than 
in the case of species, for we can perceive that they have 
arisen from the imitation of various sounds, as in allitera- 
tive poetry. We find in distinct languages striking ho- 

40 See some good remarks to this effect by Dr. Maudsley, ' The 
Physiology and Pathology of Mind,' 1868, p. 199. 

41 Macgillivray, 'Hist, of British Birds,' vol. ii. 1839, p. 29. An ex. 
cellent observer, Mr. Blackwall, remarks that the magpie learns to pro 
nounce single words, and even short sentences, more readily than almosl 
any other British bird ; yet, as he adds, after long and closely investigat 
ing its habits, he has never known it, in a state of nature, display any 
unusual capacity for imitation. 'Researches in Zoology,' 1834, p. 158. 

42 See the very interesting parallelism between the development of 
species and languages, given by Sir C. Lyell, in ' The Geolog. Evidences 
of the Antiquity of Man,' 1863, chap, xxiii. 



58 THE DESCENT OF MAN. [Part L 

mologies due to community of descent, and analogies due 
to a similar process of formation. The manner in which 
certain letters or sounds change when others change is 
very like correlated growth. We have in both cases the 
reduplication of parts, the effects of long-continued use, 
and so forth. The frequent presence of rudiments, both in 
languages and in species, is still more remarkable. The 
letter m in the word am, means I • so that in the expres- 
sion lam, a superfluous and useless rudiment has been re- 
tained. In the spelling also of words, letters often remain 
as the rudiments of ancient forms of pronunciation. Lan- 
guages, like organic beings, can be classed in groups under 
groups ; and they can be classed either naturally, accord- 
ing to descent, or artificially by other characters. Domi- 
nant languages and dialects spread widely and lead to the 
gradual extinction of other tongues. A language, like a 
species, when once extinct, never, as Sir C. Lyell remarks, 
reappears. The same language never has two birthplaces. 
Distinct languages may be crossed or blended together. 43 
We see variability in every tongue, and new words are 
continually cropping up ; but as there is a limit to the 
powers of the memory, single words, like whole languages, 
gradually become extinct. As Max Miiller 44 has well re- 
marked : " A struggle for life is constantly going on among 
the words and grammatical forms in each language. The 
better, the shorter, the easier forms are constantly gaining 
the upper hand, and they owe their success to their own 
inherent virtue." To these more important causes of the 
survival of certain words, mere novelty may, I think, be 
added ; for there is in the mind of man a strong love for 
slight changes in all things. The survival or preservation 

43 See remarks to this effect by the Rev. F. W. Farrar, in an "interest- 
ing article, entitled " Philology and Darwinism," in ' Nature,' March 24, 
1870, p. 528. 

44 'Nature,' Jan. 6, 1870, p. 257. 



Chap. II.] . MENTAL POWERS. 59 

of certain favored words in the struggle for existence is 
natural selection. 

The perfectly regular and wonderfully complex con- 
struction of the languages of many barbarous nations has 
often been advanced as a proof, either of the divine origin 
.of these languages, or of the high art and former civiliza- 
tion of their founders. Thus F. von Schlegel writes : " In 
those languages which appear to be at the lowest grade 
of intellectual culture, we frequently observe a very high 
and elaborate degree of art in their grammatical structure. 
This is especially the case with the Basque and the Lap- 
ponian, and many of the American languages." 45 But it 
is assuredly an error to speak of any language as an art 
in the sense of its having been elaborately and methodi- 
cally formed. Philologists now admit that conjugations, 
declensions, etc., originally existed as distinct words, since 
joined together; and as such words express the most ob- 
vious relations between objects and persons, it is not sur- 
prising that they should have been used by the men of 
most races during the earliest ages. With respect to per- 
fection, the following illustration will best show how easily 
we may err : a Crinoid sometimes consists of no less than 
150,000 pieces of shell, 46 all arranged with perfect symme- 
try in radiating lines ; but a naturalist does not consider 
an animal of this kind as more perfect than a bilateral one 
with comparatively few parts, and with none of these 
alike, excepting on the opposite sides of the body. He 
justly considers the differentiation and specialization of 
organs as the test of perfection. So with languages, the 
most symmetrical and complex ought not to be ranked 
above irregular, abbreviated, and bastardized languages, 
which have borrowed expressive words and useful forms 
of construction from various conquering, or conquered, or 
immigrant races. 

45 Quoted by C. S. Wake, ' Chapters on Man,' 1868, p. 101. 

46 Buckland, 'Bridgewater Treatise,' p. 411. 



60 THE DESCENT OF MAN. [Part I 

From these few and imperfect remarks, I conclude that 
the extremely complex and regular construction of many- 
barbarous languages is no proof that they owe their origin 
to a special act of creation. 47 Nor, as we have seen, does 
the faculty of articulate speech in itself offer any insuper- 
able objection to the belief that man has been developed . 
from some lower form. 

Self-consciousness, Individuality, Abstraction, General 
Ideas, etc. — It would be useless to attempt discussing these 
high faculties, which, according to several recent writers, 
make the sole and complete distinction between man and 
the brutes, for hardly two authors agree in their defini- 
tions. Such faculties could not have been fully developed 
in man until his mental powers had advanced to a high 
standard, and this implies the use of a perfect language. 
'No one supposes that one of the lower animals reflects 
whence he comes or whither he goes — what is death, or 
what is life, and so forth. But can we feel sure that an 
old dog with an excellent memory, and some power of 
imagination, as shown by his dreams, never reflects on his 
past pleasures in the chase ? and this would be a form of 
self-consciousness. On the other hand, as Buchner 48 has 
remarked, how little can the hard-worked wife of a de- 
graded Australian savage, who uses hardly any abstract 
words, and cannot count above four, exert her self-con- 
sciousness, or reflect on the nature of her own existence ! 

That animals retain their mental individuality is un- 
questionable. When my voice awakened a train of old 
associations in the mind of the above-mentioned dog, he 
must have retained his mental individuality, although 

47 See some good remarks on the simplification of languages, by Sir 
J. Lubbock, 'Origin of Civilization,' 1870, p. 278. 

48 ' Conferences sur la Theorie Darwinienne,' French translat., 186?, p. 
132. 



Chap. II.] MEXTAL POWERS. 61 

every atom of his brain had probably undergone change 
more than once during the interval of five years. This 
dog might have brought forward the argument lately ad- 
vanced to crush all evolutionists, and said, " I abide amid 
all mental moods and all material changes. . . . The 
teaching that atoms leave their impressions as legacies to 
other atoms falling into the places they have vacated is 
contradictory of the utterance of consciousness, and is 
therefore false ; but it is the teaching necessitated by evo- 
lutionism, consequently the hypothesis is a false one." 



49 



Sense of Beauty. — This sense has been declared to be 
peculiar to man. But when we behold male birds elabo- 
rately displaying their plumes and splendid colors before 
the females, while other birds not thus decorated make 
no such display, it is impossible to doubt that the females 
admire the beauty of their male partners. As women 
everywhere deck themselves with these plumes, the beauty 
of such ornaments cannot be disputed. The Bower-birds 
by tastefully ornamenting their playing-passages with 
gayly-colored objects, as do certain humming-birds their 
nests, offer additional evidence that they possess a sense 
of beauty. So with the song of birds, the sweet strains 
poured forth by the males during the season of love are 
certainly admired by the females, of which fact evidence 
will hereafter be given. If female birds had been in- 
capable of appreciating the beautiful colors, the orna- 
ments, and voices of their male partners, all the labor and 
anxiety exhibited by them- in displaying their charms be- 
fore the females would have been thrown away ; and this 
it is impossible to admit. Why certain bright colors and 
certain sounds should excite pleasure, when in harmony, 
cannot, I presume, be explained any more than why cer- 
tain flavors and scents are agreeable: but assuiedlv the 

49 The Rev. Dr. J. M'Cann, 'Anti-Darwinism,' 1€G9, p. 13. 



62 THE DESCENT OF MAN. |PartL. 

same colors and the same sounds are admired by us and 
by many of the lower animals. 

The taste for the beautiful, at least as far as female 
beauty is concerned, is not of a sp< cial nature in the hu- 
man mind ; for it differs widely in the different races of 
man, as will hereafter be shown, and is not quite the same 
even in the different nations of the same race. Judging 
from the hideous ornaments and the equally hideous music 
admired by most savages, it might be urged that their 
aesthetic faculty was not so highly developed as in certain 
animals, for instance, in birds. Obviously no animal 
would be capable of admiring such scenes as the heavens 
at night, a beautiful landscape, or refined music ; but such 
high tastes, depending as they do on culture and complex 
associations, are not enjoyed by barbarians or by unedu 
cated persons. 

Many of the faculties, which have been of inestimable 
service to man for his progressive advancement, such as 
the powers of the imagination, wonder, curiosity, an un- 
defined sense of beauty, a tendency to imitation, and the 
love of excitement or novelty, could not fail to have led 
to the most capricious changes of customs and fashions. 
I have alluded to this point, because a recent writer B0 has 
oddly fixed on Caprice " as one of the most remarkable 
and typical differences between savages and brutes." But 
not only can we perceive how it is that man is capricious, 
but the lower animals are, as we shall hereafter see, capri- 
cious in their affections, aversions, and sense of beauty. 
There is also good reason to suspect that they love nov- 
elty, for its own sake. 

Belief in God — Religion. — There is no evidence that 
man was aboriginally endowed with the ennobling belief 
in the existence of an Omnipotent God. On the contrary, 

50 *'The Spectator,' Dec. 4, 1869, p. 1430. 



Chap. II.] MENTAL POWERS. 63 

there is ampxe evidence, derived not from hasty travellers, 
but from men who have long resided with savages, that 
numerous races have existed and still exist, who have no 
idea of one or more gods, and who have no words in then- 
languages to express such an idea. 61 The question is of 
course wholly distinct from that higher one, whether there 
exists a Creator and Ruler of the universe; and this has 
been answered in the affirmative by the highest intellects 
that have* ever lived. 

If, however, we include under the term "religion " the 
belief in unseen or spiritual agencies, the case is wholly 
different ; for this belief seems to be almost universal with 
the less civilized races. Nor is it difficult to comprehend 
how it arose. As soon as the important faculties of the 
imagination, wonder, and curiosity, together with some 
power of reasoning, had become partially developed, -man 
would naturally have craved to understand what was 
passing around him, and have vaguely speculated on his 
own existence. As Mr. M'Lennan 52 has remarked, " Some 
explanation of the phenomena of life, a man must feign 
for himself; and to judge from the universality of it, the 
simplest hypothesis, and the . first to occur to men, seems 
to have been that natural phenomena are ascribable to 
the presence in animals, plants, and things, and in the 
forces of Nature, of such spirits prompting to action as 
men are conscious they themselves possess." It is prob- 
able, as Mr. Tylor has clearly shown, that dreams may 
have first given rise to the notion of spirits ; for savages 
do not readily distinguish between subjective and objec- 

51 See an excellent article on this subject by the Rev. F. "W. Farrar, in 
the 'Anthropological Review,' Aug. 1864, p. ccxvii. For further facts 
see Sir J. Lubbock, 'Prehistoric Times,' 2d edit. 1869, p. 564 ; and es- 
pecially the chapters on Religion in his 'Origin of Civilization,' 1870. 

68 The Worship of Animals and Plants, in the ' Fortnightly Review,' 
Oct. 1, 1869, p. 422 



64 THE DESCENT Otf MAN. [Part I. 

tive impressions. When a savage dreams, the figures 
which appear before him are believed to have come from 
a distance and to stand over him ; or " the soul of the 
dreamer goes out on its travels, and comes home with a 
remembrance of what it has seen." 63 But until the above- 
named faculties of imagination, curiosity, reason, etc., had 
been fairly well developed in the mind of man, his dreams 
would not have led him to believe in spirits, any more 
than in the case of a dog. 

The tendency in savages to imagine that natural ob- 
jects and agencies are animated by spiritual or living es- 
sences, is perjiaps illustrated by a little fact which I once 
noticed : My dog, a full-grown and very sensible animal, 
was lying on the lawn during a hot and still day ; but at 
a little distance a slight breeze occasionally moved an 
open parasol, which would have been wholly disregarded 
by the dog, had any one stood near it. As it was, every 
time that the parasol slightly moved, the dog growled 
fiercely and barked. He must, I think, have reasoned to 
himself in a rapid and unconscious manner, that move- 

63 Tylor, ' Early'History of Mankind,' 1865, p. 6. See also the three 
striking chapters on the Development of Religion, in Lubbock's ' Origin 
of Civilization,' 1870. In a like manner Mr. Herbert Spencer, in his in- 
genious essay in the 'Fortnightly Review' (May 1, 1870, p. 535), ac- 
counts for the earliest forms of religious belief throughout the world, by 
man being led through dreams, shadows, and other causes, to look at 
himself as a double essence, corporeal and spiritual. As the spiritual 
being is supposed to exist after death and to be powerful, it is propi- 
tiated by various gifts and ceremonies, and its aid invoked. He then 
further shows that names or nicknames given from some animal or other 
object to the early progenitors or founders of a tribe, are supposed after 
a long interval to represent the real progenitor of the tribe ; and such 
animal or object is then naturally believed still to exist as a spirit, is held 
sacred, and worshipped as a god. Nevertheless I cannot but suspect that 
there is a still earlier and ruder stage, when any thing which manifests 
power or movement is thought to be endowed with some form of life, and 
with mental faculties analogous to our own. 



Chap. II.] MENTAL POWERS 65 

ment without any apparent cause indicated the presence 
of some strange living agent, and no stranger had a right 
to be on his territory. 

The belief in spiritual agencies would easily pass into 
the belief in the existence of one or more gods. For 
6avages would naturally attribute to spirits the same pas- 
sions, the same love of vengeance or simplest form of jus- 
tice, and the same affections which they themselves expe- 
rienced. The Fuegians appear to be in this respect in an 
intermediate condition, for when the surgeon on board the 
" Beagle " shot some young ducklings as specimens, York 
Minster declared in the most solemn manner, " Oh ! Mr. 
Bynoe, much rain, much snow, blow much ; " and this was 
evidently a retributive punishment for wasting human 
food. So again he related how, when his brother killed a 
u wild man," storms long raged, much rain and snow fell. 
Yet we could never discover that the Fuegians believed 
in what we should call a God, or practised any religious 
rites ; and Jemmy Button, with justifiable pride, stoutly 
maintained that there was no devil in his land. This lat- 
ter assertion is the more remarkable, as with savages the 
belief in bad spirits is far more common than the belief in 
good sj^irits. 

The feeling of religious devotion is a highly complex 
one, consisting of love, complete submission to an exalted 
and mysterious superior, a strong sense of dependence, 54 
fear, reverence, gratitude, hope for the future, and perhaps 
other elements. No being could experience so complex an 
emotion until advanced in his intellectual and moral fac- 
ulties to at least a moderately high level. Nevertheless 
we see some distant approach to this state of mind, in the 
deep love of a dog for his master, associated with com- 
plete submission, some fear, and perhaps other feelings. 

64 See an able article on the Psychical Elements of Religion, by Mr. 
L. Owen Pike, in ' Anthropolog. Review,' April, 1810, p. briii. 
4 



66 THE DESCENT OF MAN. [Part J. 

The behavior of a clog when returning to his master after 
an absence, and, as I may add, of a monkey to his beloved 
keeper, is widely different from that toward their fellows. 
In the latter case the transports of joy appear to be some- 
what less, and the sense of equality is shown in every ac- 
tion. Prof. Braubach 6B goes so far as to maintain that a 
dog looks on his master as on a god. 

The same high mental faculties which first led man to 
believe in unseen spiritual agencies, then in fetishism, 
polytheism, and ultimately in monotheism, would infalli- 
bly lead him, as long as his reasoning powers remained 
poorly developed, to various strange superstitions and cus- 
toms. Many of these are terrible to think of — such as the 
sacrifice of human beings to a, blood-loving god ; the trial 
of innocent persons by the ordeal of poison or fire ; witch- 
craft, etc. — yet it is well occasionally to reflect on these 
superstitions, for they show us what an infinite debt of 
gratitude we owe to the improvement of our reason, to 
science, and our accumulated knowledge. 56 As Sir J. 
Lubbock has well observed, " it is not too much to say 
that the horrible dread of unknown evil hangs like a thick 
cloud over savage life, and embitters every pleasure." 
These miserable and indirect consequences of our highest 
faculties may be compared with the incidental and occa- 
sional mistakes of the instincts of the lower animals. 

65 'Religion, Moral, etc., der Darwin'schen Art-Lehre,' 1869, s. 53. 

56 ' Prehistoric Times,' 2d edit. p. 571. In this work (at p. 553) 
there will be found an excellent account of the many strange and capri. 
cious customs of savages. 



Chap III. MORAL SENSE $V 



CHAPTER III. 

COMPARISON OF THE MENTAL POWERS OF MAN AND THE 

lower animals — continued. 

The Moral Sense.— Fundamental Proposition.— The Qualities of Sociai 
Animals.— Origin of Sociability.— Struggle between Opposed In- 
stincts. — Man a Social Animal. — The more enduring Social Instincts 
conquer other less Persistent Instincts. — The Social Virtues alone re- 
garded by Savages. — The Self-regarding Virtues acquired at a Later 
Stage of Development. — The Importance of the Judgment of the 
Members of the same Community on Conduct. — Transmission of 
Moral Tendencies. — Summary. 

I fully subscribe to the judgment of those writers 1 
who maintain that, of all the differences between man and 
the lower animals, the moral sense or conscience is by far 
the most important. This sense, as Mackintosh 2 remarks, 
" has a rightful supremacy over every other principle of 
human action ; " it is summed up in that short but impe- 
rious word ought, so full of high significance. It is the 
most noble of all the attributes of man, leading him with- 
out a moment's hesitation to risk his life for that of a fel- 
low-creature ; or after due deliberation, impelled simply 
by the deep feeling of right or duty, to sacrifice it in some 
great cause. Immanuel Kant exclaims, "Duty! Won- 
drous thought, that workest neither by fond insinuation, 

1 See, for instance, on this subject, Quatrefages, ' Unite de l'Espece 
Himaine,' 1861, p. 21, etc. 

* ' Dissertation on Ethical Philosophy,' 1837, p. 231, etc. 



R8 THE DESCENT OF MAN. [Part I 

flattery, nor by any threat, but merely by holding up thy 
naked law in the soul, and so extorting for thyself always 
reverence, if not always obedience ; before whom all ap- 
petites are dumb, however secretly they rebel; whence 
thy original ? " 3 

This great question has been discussed by many writ- 
ers 4 of consummate ability ; and my sole excuse for touch- 
ing on it is the impossibility of here passing it over, and 
because, as far as I know, no one has approached it exclu- 
sively from the side of natural history. The investigation 
possesses, also, some independent interest, as an attempt 
to see how far the study of the lower animals can throw 
light on one of the highest psychical faculties of man. 

The following proposition seems to me in a high degree 
probable — namely, that any animal whatever, endowed 
with well-marked social instincts, 6 would inevitably ac- 
quire a moral sense or conscience, as soon as its intellect- 

8 ' Metaphysics of Ethics,' translated by J. W. Semple, Edinburgh, 
1836, p. 136. 

4 Mr. Bain gives a list (' Mental and Moral Science,' 1868, pp. 543-725) 
of twenty-six British authors who have written on this subject, and whose 
names are familiar to every reader ; to these, Mr. Bain's own name, and 
those of Mr. Lecky, Mr. Shadworth Hodgson, and Sir J. Lubbock, as well 
as of others, may be added. 

5 Sir B. Brodie, after observing that man is a social animal (' Psycho- 
logical Inquiries,' 1854, p. 192), asks the pregnant question, " Ought not 
this to settle the disputed question as to the existence of a moral sense ? " 
Similar ideas have probably occurred to many persons, as they did long 
ago to Marcus Aurelius. Mr. J. S. Mill speaks, in his celebrated work, 
* Utilitarianism ' (1864, p. 46), of the social feelings as a "powerful natu- 
ral sentiment," and as " the natural basis of sentiment for utilitarian mo- 
rality ; " but, on the previous page, he says, " If, as is my own belief, the 
moral feelings are not innate, but acquired, they are not for that reason 
less natural." It is with hesitation that I venture to differ from so pro- 
found a thinker, but it can hardly be disputed that the social feelings are 
instinctive or innate in the lower animals ; and why should they not be so 
in man? Mr. Bain (see, for instance, ' The Emotions and the Will," 1865, 



Chap. III. MORAL SENSE. 69 

ual powers had become as well developed, or nearly as 
well developed, as in man. For, firstly, the social in- 
stincts lead an animal to take pleasure in the society of 
its fellows, to feel a certain amount of sympathy with 
them, and to perform various services for them. The ser- 
vices may be of a definite and evidently instinctive nature; 
or there may be only a wish and readiness, as with most 
of the higher social animals, to aid their fellows in certain 
general ways. But these feelings and services are by no 
ineans extended to all the individuals of the same species, 
only to those of the same association. Secondly, as soon 
as the mental faculties had become highly developed, 
images of all past actions and motives would be inces- 
santly passing through the brain of each individual ; and 
that feeling of dissatisfaction which invariably results, as 
we shall hereafter see, from any unsatisfied instinct, Would 
arise, as often as it was perceived that the enduring and 
always present social instinct had yielded to some other 
instinct, at the time stronger, but neither enduring in its 
nature, nor leaving behind it a very vivid impression. It 
is clear that many instinctive desires, such as that of hun- 
ger, are in their nature of short duration ; and after being 
satisfied are not readily or vividly recalled. Thirdly, 
after the power of language had been acquired and the 
wishes of the members of the same community could be 
distinctly expressed, the common opinion how each mem- 
ber ought to act for the public good, would naturally be- 
come to a large extent the guide to action. But the so- 
cial instincts would still give the impulse to act for the 
good of the community, this impulse being strengthened, 
directed, and sometimes even deflected, by public opinion, 
the power of which rests, as we shall presently see, on in- 

p. 481) and others believe that the moral sense is acquired by each indi- 
vidual during his lifetime. On the general theory of evolution this is at 
least extremely improbable. 



frO THE DESCENT OF MAN. [Part I. 

stinctive sympathy. Lastly, habit in the individual would 
ultimately play a very important part in guiding the con- 
duct of each member; for the social instincts and im- 
pulses, like all other instincts, would be greatly strength- 
ened by habit, as would obedience to the wishes and judg- 
ment of the community. These several subordinate prop- 
ositions must now be discussed; and some of them at con- 
siderable length. 

It may be well first to premise that I do not wish to 
maintain that any strictly social animal, if its intellectual 
faculties were to become as active and as highly devel- 
oped as in man, would acquire exactly the same moral 
•sense as ours. In the same manner as various animals 
have some sense of beauty, though they admire widely 
different objects, so they might have a sense of right and 
wrong, though led by it to follow widely different lines of 
conduct. If, for instance, to take an extreme case, men 
were reared under precisely the same conditions as hive- 
bees, there can hardly be a doubt that our unmarried fe 
males would, like the worker-bees, think it a sacred duty 
to kill their brothers, and mothers would strive to kill their 
fertile daughters ; and no one would think of interfering. 
Nevertheless the bee, or any other social animal, would in 
our supposed case gain, as it appears to me, some feeling 
of right and wrong, or a conscience. For each individual 
would have an inward sense of possessing certain stronger 
or more enduring instincts, and others less strong or en- 
during ; so that there would often be a struggle which im- 
pulse should be followed ; and satisfaction or dissatisfac- 
tio'n would be felt, as past impressions were compared 
during their incessant passage through the mind. In this 
case an inward monitor would tell the animal that it 
would have been better to have followed the one im- 
pulse rather than the other. The one course ought 
to have been followed : the one would have been right 



Chap. III.] MORAL SENSE 71 

and the other wrong ; but to these terms I shall have to 
recur. 

Sociability. — Animals of many kinds are social; we 
find even distinct species living together, as with some 
American monkeys, and with the united flocks of rooks, 
jackdaws, and starlings. Man shows the same feeling in 
his strong love for the dog, which the dog returns with 
interest. Every one must have noticed how miserable 
horses, dogs, sheep, etc., are when separated from their 
companions ; and what affection at least the two former 
kinds show on their reunion. It is curious to speculate 
on the feelings of a dog, who will rest peacefully for hours 
. in a room with his master or any of the family, without 
the least notice being taken of him ; but, if left for a short 
time by himself, barks or howls dismally. We will con- 
fine our attention to the higher social animals, excluding: 
insects, although these aid each other in many important 
ways. The most common service which the higher ani- 
mals perform for each other, is the warning each other of 
danger by means of the united senses of all. Every 
sportsman knows, as Dr. Jaeger remarks, 6 how difficult it 
is to approach animals in a herd or troop. Wild horses 
and cattle do not, I believe, make any danger-signal; but 
the attitude of any one who first discovers an enemy, 
warns the others. Rabbits stamp loudly on the ground 
with their hind-feet as a signal : sheep and chamois do the 
6ame, but with their fore-feet, uttering likewise a whistle. 
Many birds and some mammals post sentinels, which in 
the case of seals are said 7 generally to be the females. 
The leader of a troop of monkeys acts as the sentinel, and 
utters cries expressive both of danger and of safety. 8 So- 

6 ' Die Darwin'sche Theorie,' s. 101. 
1 Mr. R. Browne in 'Proc. Zoolog. Soc' 1868, p. 409. 
8 Brehm, • Thierleben,' B. i. 1864, s. 52, 79. For the case of the mon- 
keys extracting thorns from each other, see s. 54. With respect to the 



72 THE DESCENT OF MAN. [Part L 

cial animals perform many little services for each- other : 
horses nibble, and cows lick each other, on any -spot which 
itches: monkeys search for each other's external para- 
sites ; and Brehm states that, after a troop of the Cerco* 
pithecus griseo-viridis has . rushed through a thorny 
brake, each monkey stretches itself on a branch, and 
another monkey sitting by " conscientiously " examines 
its fur and extracts every thorn or burr. 

Animals also render more important services to each 
other : thus wolves and some other beasts of prey hunt 
in packs, and aid each other in attacking their victims. 
Pelicans fish in concert. The Hamadryas baboons turn 
over stones to find insects, etc. ; and when they come to a 
large one, as many as can ptand round, turn it over to- 
gether and share the booty. Social animals mutually de- 
fend each other. The males of some ruminants come to 
the front when there is danger and defend the herd with 
their horns. I shall also in a future chapter give cases of 
two young wild-bulls attacking an old one in concert, and 
of two stallions together trying to drive away a third 
stallion from a troop of mares. Brehm encountered in 
Abyssinia a great troop of baboons which were crossing 
a valley : some had already ascended the opposite moun- 
tain, and some were still in the valley : the latter were at- 
tacked by the dogs, but the old males immediately hurried 
down from the rocks, and with mouths widely opened 
roared so fearfully, that the dogs precipitately retreated. 
They were again encouraged to the attack ; but by this 
time all the baboons had reascended the heights, except- 
ing a young one, about six months old, who, loudly calling 
tor aid, climbed on a block of rock and was surrounded. 

Hamadryas turning over stones, the fact is given (s. 76) on the evidence 
of Alvarez, whose observations Brehm thinks quite trustworthy. For the 
cases of the old male baboons attacking the dogs, see s. 79 ; and, with re- 
spect to the eagle, s. 56. 



Chap. III.] MORAL SEXSE. 73 

Now one of the largest males, a true hero, came down 
again from the mountain, slowly went to the young one, 
coaxed him, and triumphantly led him away — the dogs 
being too much astonished to make an attack. I cannot 
resist giving another scene which was witnessed by this 
same naturalist ; an eagle seized a young Cercopithecus, 
which, by clinging to a branch, was not at once carried 
off; it cried laudly for assistance, upon which the other 
members of the troop with much uproar rushed to the 
rescue, surrounded the eagle, and pulled out so many 
feathers, that he no longer thought of his prey, but only 
how to escape. This eagle, as Brehm remarks, assuredly 
would never again attack a monkey in a troop. 

It is certain that associated animals have a feeling of 
love for each other which is not felt by adult and non- 
social animals. How far in most cases they actually 
sympathize with each other's pains and pleasures is more 
doubtful, especially with respect to the latter. Mr. Bux- 
ton, however, who had excellent means of observation, 9 
states that his macaws, which lived free in Norfolk, took 
" an extravagant interest" in a pair with a nest, and, when- 
ever the female left it, she was surrounded by a troop 
" screaming: horrible acclamations in her honor." It is 
often difficult to judge whether animals have any feeling 
for each other's sufferings, Who can say what cows feel, 
when they surround and stare intently on a dying or dead 
companion ? That animals sometimes are far from feeling 
any sympathy is too certain ; for they will expel a wound- 
ed animal from the herd, or gore or worry it to death. 
This is almost the blackest fact in natural history, unless 
indeed the explanation which has been suggested is true, 
that their instinct or reason leads them to expel an in- 
jured companion, lest beasts of prey, including man, 
should be tempted to follow the troop. In this case their 

9 'Annals and Mag. of Xat. Hist.' November, 1868, p. 382. 



U THE DESCENT OF MAN. [Part I. 

conduct is not much worse than that of the North Amer- 
ican Indians who leave their feeble comrades to perigh 
on the plains, or the Feegeans, who, when their parents 
get old or fall ill, bury them alive^ 10 

Many animals, however, certainly sympathize with 
each other's distress or danger. This is the case even 
with birds ; Captain Stansbury " found, on a salt lake in 
Utah, an old and completely blind pelican, .which was very 
fat, and must have been long and well fed by his compan- 
ions. Mr. Blyth, as he informs me, saw Indian crows 
feeding two or three of their companions which were 
blind ; and I have heard of an analogous case with the 
domestic cock. We may, if we choose, call these actions 
instinctive ; but such cases arp much too rare for the de- 
velopment of any special instinct. 12 I have myself seen 
a dog, who never passed a great friend of his, a cat which 
lay sick in a basket, without giving her a few licks with 
his tongue, the surest sign of kind feeling in a dog. 

It must be called sympathy that leads a courageous 
dog to fly at any one who strikes his master, as he cer- 
tainly will. I saw a person pretending to beat a lady who 
had a very timid little dog on her lap, and the trial had 
never before been made. The little creature instantly 
jumped away, but, after the pretended beating was over, 
it was really pathetic to see how perseveringly he tried to 
lick his mistress's face and comfort her. Brehm 13 states 
that when a baboon in confinement was pursued to be 

10 Sir J. Lubbock, ' Prehistoric Times,' 2d edit. p. 446. 

11 As quoted by Mr. L. H. Morgan, ' The American Beaver,' 1868, p. 
272. Captain Stansbury also gives an interesting account of.the manner 
in which a very young pelican, carried away by a strong stream, was 
guided and encouraged in its attempts to reach the shore by half a dozen 
old birds. 

12 As Mr. Bain states, " effective aid to a sufferer springs from sym- 
pathy proper: " ' Mental and Moral Science,' 1868, p. 245. 

18 ' Thierleben,' B. i. s. 85. 



Chap. III.] MORAL SENSE. 75 

punished, the others tried to protect him. It must have 
been sympathy in the cases above given which led the. 
baboons and Cercopitheci to defend their young comrades 
from the dogs and the eagle. I will give only one other 
instance of sympathetic and heroic conduct in a little 
American monkey. Several years ago a keeper at the 
Zoological Gardens, showed me some deep and scarcely 
healed wounds on the nape of his neck, inflicted on him 
while kneeling on the floor by a fierce baboon. The little 
American monkey, who was a warm friend of this keeper, 
lived in the same large compartment, and was dreadfully 
afraid of the great baboon. Nevertheless, as soon as he 
saw his friend the keeper in peril, he rushed to the rescue, 
and by screams and bites so distracted the baboon that 
the man was able to escape, after running great risk, as 
the surgeon who attended him thought, of his life. 

Besides love and sympathy, animals exhibit other qual- 
ities which in us would be called moral ; and I agree witn 
Agassiz 14 that dogs possess something very like a con- 
science. They certainly possess some power of self-com- 
mand, and this does not appear to be wholly the result of 
fear. As Braubach 1B remarks, a dog will refrain from 
stealing food in the absence of his master. Dogs have 
long been accepted as the very type of fidelity and obedi- 
ence. All animals living in a body which defend each 
other or attack their enemies in concert, must be in some 
degree faithful to each other ; and those that follow a 
leader must be in some degree obedient. When the ba- 
boons in Abyssinia 16 plunder a garden, they silently follow 
their leader ; and if an imprudent young animal makes a 
noise, he receives a slap from the others to teach him 
silence and obedience ; but as soon as they are sure 

14 *De FEspece et de la Class.' 1869, p. 97. 

15 'Der Darwin'schen Art-Lehre,' 1869, s. 54. 

16 Brehm, « Thierleben,' B. i. s. 76. 



76 THE DESCENT OF MAN. [Part I. 

that there is no danger, all show their joy by much 
clamor. 

"With respect to the impulse which leads certain ani- 
mals to associate together, and to aid each other in many 
ways, we may infer that in most cases they are impelled 
by the same sense of satisfaction or pleasure which they 
experience in performing other instinctive actions ; or by 
the same sense of dissatisfaction, as in other cases of pre- 
vented instinctive actions. We see this in innumerable 
instances, and it is illustrated in a striking manner by the 
acquired instincts of our domesticated animals ; thus a 
young shepherd-dog delights in driving and running round 
a flock of sheep, but not in worrying them ; a young fox- 
hound delights in hunting a fcx, while some other kinds 
of dogs, as I have witnessed,' utterly disregard foxes. 
What a strong feeling of inward satisfaction must impel 
a bird, so full of activity, to brood day after day over her 
eggs ! Migratory birds are miserable if prevented from 
migrating, and perhaps they enjoy starting on their long 
flight. Some few instincts are determined solely by pain- 
ful feelings, as by fear, which leads to self-preservation, or 
is specially directed against certain enemies. No one, I pre- 
sume, can analyze the sensations of pleasure or pain. In 
many cases, however, it is probable that instincts are persist- 
ently followed from the mere force of inheritance, without 
the stimulus of either pleasure or pain. A young pointer 
when it first scents game, apparently cannot help pointing 
A squirrel in a cage who pats the nuts which it cannot eat v 
as if to bury them in the ground, can hardly be thought to 
act thus either from pleasure or pain. Hence the common 
assumption that men must be impelled to every action by 
experiencing some pleasure or pain may be erroneous. 
Although a habit may be blindly and implicitly followed, 
independently of any pleasure or pain felt at the mo- 
ment, yet if it be forcibly and abruptly checked, a vague 



Chap. III.] MORAL SENSE. 77 

sense erf dissatisfaction is generally experienced ; and this 
is especially true in regard to* persons of feeble intellect. 

It has often been assumed that animals were in the 
first place rendered social, and that they feel as a conse- 
quence uncomfortable <*vhen separated from each other, 
and comfortable while together ; but it is a more probable 
view that these sensations were first developed, in order 
that those animals which would profit by living in so- 
ciety, should be induced to live together, in the same 
manner as the sense of hunger and the pleasure of eating 
were, no doubt, first acquired in order to induce animals 
to eat. The feeling of pleasure from society is probably 
an extension of the parental or filial affections ; and this 
extension may be in chief part attributed to natural selec- 
tion, but perhaps in part to mere habit. For with those 
animals which were benefited by living in close associa- 
tion, the individuals which took the greatest pleasure in 
society would best escape various dangers ; while those 
that cared least for their comrades and lived solitary 
would perish in greater numbers. With respect to the 
origin of the parental and filial affections, which appar- 
ently lie at the basis of the social affections, it is hopeless 
to speculate ; but we may infer that they have been to a 
large extent gained through natural selection. So it has 
almost certainly been with the unusual and opposite feel- 
ing of hatred between the nearest relations, as with the 
worker-bees which kill their brother-drones, and with the 
queen-bees which kill their daughter-queens ; the desire 
to destroy, instead of loving, their nearest relations hav- 
ing been here of service to the community. 

The all-important emotion of sympathy is distinct 
from that of love. A mother may passionately love her 
sleeping and passive infant, but she can then hardly be 
said to feel sympathy for it. The love of a man for his 
dog is distinct from sympathy, and so is that of a dog 



78 THE DESCENT OF MAN. [Part L 

for his master. Adam Smith formerly argued, as has Mr. 
Bain recently, that the "basis of sympathy lies in our 
strong retentiveness of former states of pain or pleasure. 
Hence, "the sight of another person enduring hunger, 
cold, fatigue, revives in us some recollection of these 
states, which are painful even in idea." "We are thus im- 
pelled to relieve the sufferings of another, in order that 
our own painful feelings may be at the same time relieved. 
In like manner we are led to participate in the pleasures 
of others. 17 But I cannot see how this view explains the 
fact that sympathy is excited in an immeasurably stronger 
degree by a beloved than by an indifferent person. The 
mere sight of suffering, independently of love, would 
suffice to call up in us vivid r: collections and associations. 
Sympathy may at first have originated in the manner 
above suggested ; but it seems now to have become an 
instinct, which is especially directed toward beloved ob- 
jects, in the same manner as fear with animals is especial- 
► ly directed against certain enemies. As sympathy is thus 
directed, the mutual love of the members of the same 
community will extend its limits. No doubt a tiger or 
lion feels sympathy for the sufferings of its own young, 
but not for any other animal. With strictly social ani- 
mals the feeling will be more or less extended to all the 
associated members, as we know to be the case. With 
mankind selfishness, experience, and imitation, probably 
add, as Mr. Bain has shown, to the power of sympathy ; 

17 See the first and striking chapter in Adam Smith's ' Theory of 
Moral Sentiments.' Also Mr. Bain's ' Mental and Moral Science,' 1868, p. 
244, and 275-282. Mr. Bain states that "sympathy is, indirectly, a 
source of pleasure to the sympathizer ; " and he accounts for this through 
reciprocity. He remarks that " the person benefited, or others in hia 
stead, may make up, by sympathy and good offices returned, for all the 
sacrifice." But if, as appears to be the case, sympathy is strictly an in- 
stinct, its exercise would give direct pleasure, in the same manner as the 
exercise, as before remarked, of almost every other instinct. 



Chap. III.] MORAL SENSE. 79 

for we are led by the hope of receiving good in return to 
perform acts of sympathetic kindness to others ; and there 
can be no doubt that the feeling of sympathy is much 
strengthened by habit. In however complex a manner 
this feeling may have originated, as it is one of high im- 
portance to all those animals which aid and defend each 
other, it will have been increased, through natural selec- 
tion ; for those communities which included the greatest 
number of the most sympathetic members, would flourish 
best and rear the greatest number of offspring. 

In many cases it is impossible to decide whether cer- 
tain social instincts have been acquired through natural 
selection, or are the indirect result of other instincts and 
faculties, such as sympathy, reason, experience, and a ten- 
dency to imitation ; or again, whether they are simply the 
result of long-continued habit. So remarkable an instinct 
as the placing sentinels to warn the community of dan- 
ger, can hardly have been the indirect result of any other 
faculty; it must therefore have been directly acquired. 
On the other hand, the habit followed by the males of 
some social animals, of defending the community and of 
attacking their enemies or their prey in concert, may per- 
haps have originated from mutual sympathy ; but courage, 
and in most cases strength, must have been previously ac- 
quired, probably through natural selection. 

Of the various instincts and habits, some are much 
stronger than others, that is, some either give more pleas- 
ure in their performance and more distress in their preven- 
tion than others ; or, which is probably quite as important, 
they are more persistently followed through inheritance 
without exciting any special feeling of pleasure or pain. 
We are ourselves conscious that some habits are much 
more difficult to cure or change than others. Hence a strug- 
gle may often be observed in animals between different in- 
stincts, or between an instinct and some habitual disposi- 



SO THE DESCENT OF MAN. [Part I. 

tion ; as when a clog rushes after a hare, is rebuked, 
pauses, hesitates, pursues again or returns ashamed to his 
master ; or as between the love of a female dog for her 
young puppies and for her master, for she may be seen to 
slink away to them, as if half ashamed of not accompany- 
ing her nraster. But the most curious instance known to 
me of one instinct conquering another, is the migratory 
instinct conquering the maternal instinct. The former is 
wonderfully strong; a confined bird will at the proper 
season beat her breast against the wires of her cage, until 
it is bare and bloody. It causes young salmon to leap 
out of the fresh water, where they could still continue to 
live, and thus unintentionally to commit suicide. Every 
one knows how strong the maternal instinct is, leading 
even timid birds to face great danger, though with hesita- 
tion and in opposition to the instinct of self-preservation. 
Nevertheless the migratory instinct is so powerful that 
late in the autumn swallows and house-martins frequently 
desert their tender young, leaving them to perish miser- 
ably in their nests. 18 

We can perceive that an instinctive impulse, if it be 
in any way more beneficial to a species than some other 
or opposed instinct, would be rendered the more potent 
of the two through natural selection ; for the individuals 
which had it most strongly developed would survive in 

18 This fact, the Rev. L. Jenyns states (see his edition of ' White's 
Nat. Hist, of Selborne,' 1853, p. 204) was first recorded by the illus- 
trious Jenner, in ' Phil. Transact.' 1824, and has since been confirmed by 
several observers, especially by Mr. Blackball. This latter careful ob- 
server examined, late in the autumn, during two years, thirty-six nests ; 
he found that twelve contained young dead birds, five coutained eggs on 
the point of being hatched, and three eggs not nearly hatched. Many 
birds not yet old enough for a prolonged flight are likewise deserted and 
left behind. See Blackwall, 'Researches in Zoology,' 1834, pp. 108, 118. 
For some additional evidence, although this is not wanted, see Leroy, 
' T-ettres Phil.' 1802, p. 217. 



Chap. III.] MORAL SENSE. 81 

larger numbers. Whether this is the case with the misrra- 
tory in comparison with the maternal instinct, may well 
be doubted. The great persistence or steady action of 
the former at certain seasons of the year during the whole 
day, may give it for a time paramount force. 

Man a social animal, — Most persons admit that man 
is a social being. We see this in his dislike of solitude, 
and in his wish for society beyond that of his own family. 
Solitary confinement is one of the severest punishments 
which can be inflicted. Some authors suppose that man 
primevally lived in single families; but at the present 
day, though single families, or only two or three together, 
roam the solitudes of some savage lands, they are always, 
as far as I can discover, friendly with other families in- 
habiting the same district. Such families occasionally 
meet in council, and they unite for their common defence. 
It is no argument against savage man being a social ani- 
mal, that the tribes inhabiting adjacent districts are al- 
most always at war with each other ; for the social in- 
stincts never extend to all the individuals of the same 
species. Judging from the analogy of the greater num- 
ber of the Quadrumana, it is probable that the early ape- 
like progenitors of man were likewise social ; but this is 
not of much importance for us. Although man, as he 
now exists, has few special instincts, having lost any 
which his early progenitors may have possessed, this is no 
reason why he should not have retained from an extreme- 
ly remote period some degree of instinctive love and sym- 
pathy for his fellows. We are indeed all conscious that 
we do possess such sympathetic feelings ; 19 but our con- 

19 Hume remarks (' An Enquiry Concerning the Principles of Morals,' 
edit, of 1751, p. 132), "there seems a necessity for confessing that the 
happiness and misery of others are not spectacles altogether indifferent 
to us, tmt that the view of' the former . . . communicates a secret joy ; 



62 THE DESCENT OF MAN. [Part I 

sciousness does not tell us whether they are instinctive, 
having originated long ago in the same manner as with 
the lower animals, or whether they have been acquired by 
each of us during our early years. As man is a social 
animal, it is also probable that he would inherit a ten- 
dency to be faithful to his comrades, for this quality is 
common to most social animals. He would in like man- 
ner possess some capacity for self-command, and perhaps 
of obedience to the leader of the community. He would 
from an inherited tendency still be willing to defend, in 
concert with others, his fellow-men, and would be ready 
to aid tjiem in any way which did not too greatly inter- 
fere with his own welfare or his own strong desires. 

The social animals which stand at the bottom of the 
scale are guided almost exclusively, and those which stand 
higher in the scale are largely guided, in the aid which 
they give to the members of the same community, by 
special instincts ; but they are likewise in part impelled 
by mutual love and sympathy, assisted apparently by 
some amount of reason. Although man, as just remarked, 
has no special instiDcts to tell him how to aid his fellow- 
men, he still has the impulse, and with his improved in- 
tellectual faculties would naturally be much guided in this 
respect by reason and experience. Instinctive sympathy 
would, also, cause him to value highly the approbation of 
his fellow-men ; for, as Mr. Bain has clearly shown, 30 the 
love of praise and the strong feeling of glory, and the 
still stronger horror of scorn and infamy, " are due to the 
workings of sympathy." Consequently man would be 
greatly influenced by the wishes, approbation, and blame 
of his fellow-men, as expressed by their gestures and lan- 
guage. Thus the social instincts, which must have been 

the appearance of the latter . . . throws a melancholy damp over the 
imagination." 

80 'Mental and Moral Science,' 1868, p. 254. 



Chap. III. J MORAL SENSE. 83 

acquired by man in a very rude state, and probably even 
by his early ape-like progenitors, still give the impulse to 
many of his best actions ; but his actions are largely de- 
termined by the expressed wishes and judgment of his 
fellow-men, and unfortunately still oftener by his own 
strong, selfish desires. But as the feelings of love and 
sympathy and the power of self-command become strength- 
ened by habit, and as the power of reasoning becomes 
clearer so that man can appreciate the justice of the judg- 
ments of his fellow-men, he will feel himself impelled, in- 
dependently of any pleasure or pain felt at the moment, 
to certain lines of conduct. He may then say, I am the 
supreme judge of my own conduct, and, in the words of 
Kant, I will not in my own person violate the dignity of 
humanity. 

The more enduring Social Instincts conquer the less 
Persistent Instincts. — We have, however, not as yet con- 
sidered the main point, on which the whole question of 
the moral sense hinges. Why should a man feel that he 
ought to obey one instinctive desire rather than another ? 
Why does he bitterly regret if he has yielded to the strong 
sense of self-preservation, and has not risked his life to save 
that of a fellow-creature ; or why does he regret having 
stolen food from severe hunger ? 

It is evident in the first place, that with mankind the 
instinctive impulses have different degrees of strength ; a 
young and timid mother urged by the maternal instinct 
will, without a moment's hesitation, run the greatest dan 
ger for her infant, but not for a mere fellow-creature. 
Many a man, or even boy, who never before risked his life 
for another, but in whom courage and sympathy were well 
developed, has, disregarding the instinct of self-preserva- 
tion, instantaneously plunged into a torrent to save a 
drowning fellow-creature. In this case man is impelled 



84 THE DESCENT OF MAN [Part I. 

by the same instinctive motive, which caused the heroic 
little American monkey, formerly described, to attack the 
great and dreaded baboon, to save his keeper. Such ac- 
tions as the above appear to be the simple result of the 
greater strength of the social or maternal instincts than 
of any other instinct or motive ; for they are performed 
too instantaneously for reflection, or for the sensation of 
pleasure or pain ; though if prevented distress would be 
caused. 

I am aware that some persons maintain that actions 
performed impulsively, as in the above cases, do not come 
under the dominion of the moral sense, and cannot be 
called moral. They confine this term to actions done de- 
liberately, after a victory over opposing desires, or to 
actions prompted by some lofty motive. But it appears 
scarcely possible to draw any clear line of distinction of 
this kind ; though the distinction may be real. As far as 
exalted motives are # concerned, many instances have been 
recorded of barbarians, destitute of any feeling of general 
benevolence toward mankind, and not guided by any re- 
ligious motive, who have deliberately as prisoners sacri- 
ficed their lives, 21 rather than betray their comrades ; and 
surely their conduct ought to be considered as moral. As 
far as deliberation and the victory over opposing motives 
are concerned, animals may be seen doubting bet ween op- 
posed instincts, as in rescuing their offspring or comrades 
from danger; yet their actions, though done for the good 
of others, are not called moral. Moreover, an action re- 
peatedly performed by us, will at last be done without 
deliberation or hesitation, and can then hardly be distin- 
guished from an instinct; yet surely no one will pretend 
that an action thus done ceases to be moral. On the con- 

21 I have given one such case, namely, of three Patagonian Indiana 
who preferred being shot, one after*the other, to betraying the plans of 
their companions in war (' Journal of Researches,' 1845, p. 103). 



Chap. III.] MORAL SENSE. 85 

• 

trary, we all feel that an act cannot be considered as per- 
fect, or as performed in the most noble manner, unless it 
be done impulsively, without deliberation or effort, in the 
same manner as by a man in whom the requisite qualities 
are innate. He who is forced to overcome his fear or want 
of sympathy before he acts, deserves, however, in one way 
higher credit than the man whose innate disposition leads 
him to a good act without effort. As we cannot distin- 
guish between motives, we rank all aotions of a certain 
class as moral, when they are performed by a moral being. 
A moral being is one who is capable of comparing his past 
and future actions or motives, and of approving or disap- 
proving of them. We have no reason to suppose that any 
of the lower animals have this capacity ; therefore when 
a monkey faces danger to rescue its comrade, or takes 
charge of an orphan-monkey, we do not call its conduct 
moral. But in the case of man, who alone can with cer- 
tainty be ranked as a moral being, actions of a certain 
class are called moral, whether performed deliberately 
after a struggle with opposing motives, or from the effects 
of slowly-gained habit, or impulsively through instinct. 

But to return to our more immediate subject ; although 
some instincts are more powerful than others, thus leading 
to corresponding actions, yet it cannot be maintained that 
the social instincts are ordinarily stronger in man, or have 
become stronger through long-continued habit, than the 
instincts, for instance, of self-preservation, hunger, lust, 
vengeance, etc. Why, then, does man regret, even 
though he may endeavor to banish any such regret, that 
he has followed the one natural impulse, rather than the 
other ; and why does he further feel that he ought to re- 
gret his conduct ? Man in this respect differs profoundly 
from the lower animals. Nevertheless we can, I think, 
see with some degree of clearness the reason of this dif- 
ference. 



86 - THE DESCENT OF MAN. {Pakt L 

Man, from the activity of his mental faculties, cannot 
avoid reflection ; past impressions and images are inces- 
santly passing through his mind with distinctness. Now 
with those animals which live permanently in a body, the 
social instincts are ever present and persistent. Such ani- 
mals are always ready to utter the danger-signal, to de- 
fend the community, and to give aid to their fellows in 
accordance with their habits ; they feel at all times, with- 
out the stimulus of any special passion or desire, some de- 
gree of love and sympathy for them ; they are unhappy 
if long separated from them, and always happy to be in 
their company. So it is with ourselves. A man who pos- 
sessed no trace of such feelings would be an unnatural 
monster. On the other hand, the desire to satisfy hunger, 
or any passion, such as vengeance, is in its nature tempo- 
rary, and can for a time be fully satisfied. Nor is it easy, 
perhaps hardly possible, to call up with complete vivid- 
ness the feeling, for instance, of hunger ; nor, indeed, as 
has often been remarked, of any suffering. The instinct 
of self-preservation is not felt except in the presence of 
danger ; and many a coward has thought himself brave 
until he has met his enemy face to face. The wish for 
another man's property is, perhaps, as persistent a desire 
as any that can be named ; but even in this case the satis- 
faction of actual possession is generally a weaker feeling 
than the desire ; many a thief, if not an habitual one, after 
success has wondered why he stole some article. 

Thus, as man cannot prevent old impressions contin- 
ually repassing through his mind, he will be compelled to 
compare the weaker impressions of, for instance, past hun- 
ger, or of vengeance satisfied or danger avoided at the 
cost of other men, with the instinct of sympathy and good- 
will to his fellows, which is still present, and ever in some 
degree active in his mind. He will then feel in his imagi- 
nation that a stronger instinct has yielded to one which 



Chap. III.] MORAL SENSE. 87 

now seems comparatively weak ; and then that sense of 
dissatisfaction will inevitably be felt with which man is 
endowed, like every other animal, in order that his in- 
stincts may be obeyed. The case before given, of the 
p wallow, affords an illustration, though of a reversed na- 
ture, of a temporary, though for the time strongly persist- 
ent, instinct conquering another instinct which is usually 
dominant over all others. At the proper season these 
birds seem all day long to be impressed with the desire 
to migrate ; their habits change ; they become restless, are 
noisy, and congregate in flocks. "While the mother-bird 
is feeding or brooding over her nestlings, the maternal in- 
stinct is probably stronger than the migratory ; but the 
instinct which is more persistent gains the victory, and at 
last, at a moment when her young ones are not in sight, 
she takes flight and deserts them. When arrived at the 
end of her long journey, and the migratory instinct ceases 
to act, whatr an agony of remorse each bird would feel, if, 
from being endowed with great mental activity, she could 
not prevent the image continually passing before her mind 
of her young ones perishing in the bleak north from cold 
and hunger ! 

At the moment of action, man will no doubt be apt to 
follow the stronger impulse ; and, though this may occa- 
sionally prompt him to the noblest deeds, it will far more 
commonly lead him to gratify his own desires at the ex- 
pense of other men. But after their gratification, when 
past and weaker impressions are contrasted with the ever- 
enduring social instincts, retribution will surely come. 
Man will then feel dissatisfied with himself, and will re- 
solve, with more or less force, to act differently for the fu- 
ture. This is conscience ; for conscience looks backward 
and judges past actions, inducing that kind of dissatisfac 
tion, which, if weak, we call regret, and if severe, remorse 

These sensations are, no doubt, different from those 



88 THE DESCENT OF MAN |Part I- 

experienced when other instincts or desires are left unsat- 
isfied ; but every unsatisfied instinct has its own proper 
prompting sensation, as we recognize with hunger, thirst, 
etc. Man thus prompted, will through long habit acquire 
such j>erfect self-command, that his desires and passions 
will at last instantly yield to his social sympathies, and 
there will no longer be a struggle between them. The 
still hungry, or the still revengeful man will not think of 
stealing food, or of wreaking his vengeance. It is possi- 
ble, or, as we shall hereafter see, even probable, that the 
habit of self-command may, like other habits, be inherited. 
Thus at last man comes to feel, through acquired, and, 
perhaps, inherited habit, that it is best for him to obey 
his more persistent instincts. The imperious word ought 
seems merely to employ the consciousness of the existence 
of a persistent instinct, either innate or partly acquired, 
serving him as a guide, though liable to be disobeyed. We 
hardly use the word ought in a metaphorical sense when 
we say hounds ought to hunt, pointers to point, and re- 
trievers to retrieve their game. If they fail thus to act, 
they fail in their duty and act wrongly. 

If any desire or instinct, leading to an action opposed 
to the good of others, still appears- to a man, when recalled 
to mind, as strong as, or stronger than, his social instinct, 
he will feel no keen regret at having followed it ; but- he 
will be conscious that if his conduct were known to his 
fellows, it would meet with their disapprobation ; and few 
are so destitute of sympathy as not to feel discomfort when 
this is realized. If he has no such sympathy, and if his 
desires leading to bad actions are at the time strong, and 
when recalled are not overmastered by the persistent so- 
cial instincts, then he is essentially a bad man ; 22 and the 

22 Dr. Prosper Despine, in his ' Psychologie Naturelle,' 1868 (torn. i. p. 
243 ; torn. ii. p. 169), gives many curious cases of the worst criminals, who 
apparently have been entirely destitute of conscience. 



Chap. III.] MORAL SEXSE. 89 

sole restraining motive left is the fear of punishment, and 
the conviction that in the long-run it would be best for 
his own selfish interests to regard the good of others rather 
than his own. 

It is obvious that every one may with an easy con- 
science gratify his own desires, if they do not interfere 
with his social instincts, that is, with the good of others ; 
but in order to be quite free from self-reproach, or at least 
of anxiety, it is almost necessary for him to avoid the dis- 
approbation, whether reasonable or not, of his fellow-men. 
Nor must he break through the fixed habits of his life, es- 
pecially if these are supported by reason ; for if he does, 
he will assuredly feel dissatisfaction. He must likewise 
avoid the reprobation of the one God or gods, in whom, 
according to his knowledge or superstition, he may be- 
lieve ; but in this case the additional fear of divine punish- 
ment often supervenes. 

The strictly Social Virtues at first alone regarded. — 
The above view of the first origin and nature of the moral 
sense, which tells us what we ought to do, and of the con- 
science which reproves us if we disobey it, accords well 
with what we see of the early and undeveloped condition 
of this faculty in mankind. The virtues which" must be 
practised, at least generally, by rude men, so that they 
may associate in a body, are those which are still recog- 
nized as the most important. But they are practised al- 
most exclusively in relation to the men of the same tribe ; 
and their opposites are not regarded as crimes in relation 
to the men of other tribes. No tribe could hold together 
if murder, robbery, treachery, etc., were common ; conse- 
quently such crimes within the limits of the same tribe 
4 are branded with everlasting infamy ; " 2S but excite no 

23 See an able article in the ' North British Review,' 1867, p. 395. See 
also Mr. W. Bagehot's articles on the Importance of Obedience and Cohe. 
5 



90 THE DESCENT OF MAN. [Part I, 

Buch sentiment beyond these limits. A North -American 
Indian is well pleased with himself, and is honored by- 
others, when he scalps a man of another tribe ; and a Dyak 
cuts off the head of an unoffending person and dries it as 
a trophy. The murder of infants has prevailed on the 
largest scale throughout the world, 24 and has met with no 
reproach ; but infanticide, especially of females, has been 
thought to be good for the tribe, or at least not injurious. 
Suicide during former times was not generally considered 
as a crime, 25 but rather, from the courage displayed, as an 
honorable act ; and it is still largely practised by some 
semi-civilized nations without reproach, for the loss to a 
nation of a single individual is not felt ; whatever the ex- 
planation may be, suicide, as I hear from Sir J. Lubbock, 
is rarely practised by the lowest barbarians. It has been 
recorded that an Indian Thug conscientiously regretted 
that he had not strangled and robbed as many travellers 
as did his father before him. In a rude state of civilization 
the robbery of strangers is, indeed, generally considered as 
honorable. 

The great sin of Slavery has been almost universal, and 
slaves have often been treated in an infamous manner. As- 
barbarians do not regard the opinion of their women, wives 
are commonly treated like slaves. Most savages are ut- 
terly indifferent to the sufferings of strangers, or even de- 
light in witnessing; them. It is well known that the women 
and children of the North- American Indians aided in tor- 
turing their enemies. Some savages take a horrid pleasure 

rence to Primitive Man, in the 'Fortnightly Review,' 1867, p. 529, and 
18G8, p. 457, etc. 

24 The fullest account which I have met with is by Dr. Gerland, in his 
' Ueber das Aussterben der Naturvolker,' 1868 ; but I shall have to recur 
to the subject of infanticide in a future chapter. 

25 See the very interesting discussion on Suicide in Lecky's ' History 
of European Morals,' vol. i. 1869, p. 223. 



Chap. Ill] MORAL SENSE. 91 

in cruelty to animals, 26 and humanity with them is an un- 
known virtue. Nevertheless, feelings of sympathy and 
kindness are common, especially during sickness, between 
the members of the same tribe, and are sometimes extended 
bevond the limits of the tribe. Muno-o Park's touching 
account of the kindness of the negro women of the inte- 
rior to him is well known. Many instances could be 
given of the noble fidelity of savages toward each other, 
but not to strangers; common experience justifies the 
maxim of the Spaniard, " Never, never trust an Indian." 
There cannot be fidelity without truth ; and this funda- 
mental virtue is not rare between the members of the 
same tribe ; thus Munsjo Park heard the nes;ro women 
teaching their young children to love the truth. This, 
again, is one of the virtues which becomes so deeply root- 
ed in the mind that it is sometimes practised by savages, 
even at a high cost, toward strangers ; but to lie to your 
enemy, has rarely been thought a sin, as the history of 
modern diplomacy too plainly shows. As soon as a tribe 
has a recognized leader, disobedience becomes a crime, 
and even abject submission is looked at as a sacred virtue. 
As during rude times no man can be useful or faithful 
to his tribe without courage, this quality has universally 
been placed in the highest rank; and although in civilized 
countries a good, yet timid man may be far more useful 
to the community than a brave one, we cannot help in- 
stinctively honoring the latter above a coward, however 
benevolent. Prudence, on the other hand, which does not 
concern the welfare of others, though a very useful virtue, 
has never been highly esteemed. As no man can practise 
the virtues necessary for the welfare of his tribe without 
self-sacrifice, self-command, and the power of endurance, 
these qualities have been at all times highly and most 

86 See, for instance, Mr. Hamilton's account of the Kaffirs, ' Anthropo 
logical Review,' 1870, p. xv. 



92 THE DESCENT OF MAN. [Part I. 

justly valued. The American savage voluntarily submits 
without a groan to the most horrid tortures to prove and 
strengthen his fortitude and courage ; and we cannot help 
admiring him, or even an Indian Fakir, who, from a fool- 
ish religious motive, swings suspended by a hook buried 
in his flesh. 

The other self-regarding virtues, which do not obvious- 
ly, though they may really, affect the welfare of the tribe, 
have never been esteemed by savages, though now highly 
appreciated by civilized nations. The greatest intemper- 
ance with savages is no reproach. Their utter licentious- 
ness, not to mention unnatural crimes, is something as- 
tounding. 27 As soon, however, as marriage, whether po- 
lygamous or monogamous, becomes common, jealousy will 
lead to the inculcation of female virtue ; and this being 
honored, will tend to spread to the unmarried females. 
How slowly it spreads to the male sex we see at the pres- 
ent day. Chastity eminently requires self-command, there- 
fore it has been honored from a very early period in the 
moral history of civilized man. As a consequence of this, 
the senseless practice of celibacy has been ranked from a 
remote period as a virtue. 28 The hatred of indecency, 
which appears to us so natural as to be thought innate, 
and which is so valuable an aid to chastity, is a modern 
virtue, appertaining exclusively, as Sir G. Staunton re- 
marks, 29 to civilized life. This is shown by the ancient 
religious rites of various nations, by the drawings on the 
walls of Pompeii, and by the practices of many savages. 

We have now seen that actions are regarded by sav- 
ages, and were probably so regarded by primeval man, as 
good or bad, solely as they affect in an obvious manner 

27 Mr. M'Lennan has given (' Primitive Marriage,' 1865, p. 1YG) a good 
collection of facts on this head. 

28 Lecky, 'History of European Morals,' vol. i. 1869, p. 109. 
99 ' Embassy to China,' vol. ii. p. 348. 



Chap. III.] MORAL SENSE. 93 

the welfare of the tribe — not that of the species, nor that 
of man as an individual member of the tribe. This con- 
clusion agrees well with the belief that the so-called moral 
sense is aboriginally derived from the social instincts, for 
both relate at first exclusively to the community. The 
chief causes of the low morality of savages, as judged by 
our standard, are, firstly, the confinement of sympathy to 
the same tribe. Secondly, insufficient powers of reasoning, 
so that the bearing of rnanT virtues, especially of the self- 
regarding virtujes, on the general welfare of the tribe is 
not recognized. Savages, for instance, fail to trace the 
multiplied evils consequent on a want of temperance, 
chastity, etc. And, thirdly, weak power of self-command ; 
for this power has not been strengthened through long-con- 
tinued, perhaps inherited, habit, instruction, and religion. 
I have entered into the above details on the immo- 
rality of savages, 30 because some authors have recently 
taken a hisrh view of their moral nature, or have attrib- 
uted most of their crimes to mistaken benevolence. 31 
These authors appear to rest their conclusion on savages 
possessing, as they undoubtedly do possess, and often in a 
high degree, those virtues which are serviceable, or even 
necessary, for the existence of a tribal community. 

Concluding Remarks. — Philosophers of the derivative 
school of morals formerly assumed that the foundation of 
morality lay in a form of Selfishness ; but more recently 
in the " Greatest Happiness principle." According to the 
view given above, the moral sense is fundamentally iden- 

80 See on this subject copious evidence in Chap. vii. of Sir J. Lub- 
bock, ' Origin of Civilization,' 18*70. * 

31 For instance Lecky, ' Hist. European Morals,' vol. i. p. 124. 

32 This term is used in an able article in the * Westminster Review,' 
Oct. 1869, p. 493. For the Greatest Happiness principle, see J. S. Mill, 

Utilitarianism,' p. 17. 



9t THE DESCENT OF MAN. [Part I. 

tical with the social instincts ; and 'in the case of the 
lower animals it would be absurd to speak of these in- 
stincts as having been developed from selfishness, or for 
the happiness of the community. They have, however, 
certainly been developed for the general good of the com- 
munity. The term, general good, may be defined as the 
means by which the greatest possible number of individuals 
can be reared in full vigor and health, with all their facul- 
ties perfect, under the conditions to which they are exposed. 
As the social instincts both of man and the lower animals 
have no doubt been developed by the same steps, it would 
be advisable, if found practicable, to use the same defini- 
tion in both cases, and to take, as the test of morality, the 
general good or welfare of the community, rather than the 
general happiness ; but this definition would perhaps re- 
quire some limitation on account of political ethics. 

When a man risks his life to save that of a fellow- 
creature, it seems more appropriate to say that he acts for 
the general good or welfare, rather than for the general 
happiness of mankind. No doubt the welfare and the 
happiness of the individual usually coincide ; and a con- 
tented, happy tribe will flourish better than one that is 
discontented and unhappy. We have seen that, at an 
early period in the history of man, the expressed wishes 
of the community will have naturally influenced to a large 
extent the conduct of each member ; and as all wish for 
happiness, the " greatest happiness principle " will have 
become a most important secondary guide and object ; the 
social instincts, including sympathy, always serving as 
the primary impulse and guide. Thus the rej)roach of lay 
ing the foundation of the most noble part of our nature in 
the base principle of selfishness is removed ; unless indeed 
the satisfaction which every animal feels when it follows 
its proper instincts, and the dissatisfaction felt when pre- 
vented, be called selfish. 



Chap. IIL] MORAL SENSE. 95 

The expression of the wishes and judgment of the 
members of the same community, at first by oral and 
afterward by written language, serves, as just remarked, 
as a most important secondary guide of conduct, in aid of 
the social instincts, but sometimes in opposition to them. 
This latter fact is well exemplified by the Law of Ho?ior y 
that is the law of the opinion of our equals, and not of all 
our countrymen. The breach of this law, even when the 
breach is known to be strictly accordant with true moral- 
ity, has caused many a man more agony than a real crime. 
We recognize the same influence in the burning sense of 
shame which most of us have felt even after the interval 
of years, when calling to mind some accidental breach of a 
trifling though fixed rule of etiquette. The judgment of 
the community will generally be guided by some rude 
experience of what is best in the long-run for all the 
members; but this judgment will not rarely err from 
ignorance and from weak powers of reasoning. Hence the 
strangest customs and superstitions, in complete opposi- 
tion to the true welfare and happiness of mankind, have 
become all-powerful throughout the world. We see this 
in the horror felt by a Hindoo who breaks his caste, in the 
shame of a Mahometan woman who exposes her face, and 
in innumerable other instances. It would be diflicult to 
distinguish between the remorse felt by a Hindoo who has 
eaten unclean food, from that felt after committing a 
theft ; but the former would probably be the more severe. 

How so many absurd rules of conduct, as well as so 
many absurd religious beliefs, have originated we do not 
know ; nor how it is that they have become, in all quar- 
ters of the world, so deeply impressed on the mind of 
men ; but it is worthy of remark that a belief constantly 
inculcated during the early years of life, while the brain 
is impressible, appears to acquire almost the nature of an 
instinct ; and the very essence of an instinct is that it is 



96 THE DESCENT OF MAN. [Parti. 

followed independently of reason. Neither can we say 
why certain admirable virtues, such as the love of truth, 
are much more highly appreciated by some savage tribes 
than by others ; s3 nor, again, why similar differences pre- 
vail even among civilized nations. Knowing how firmly 
fixed many strange customs and superstitions have be- 
come, we need feel no surprise that the self-regarding 
virtues should now appear to us so natural, supported as 
they are by reason, as to be thought innate, although 
they were not valued by man in his early condition. 

Notwithstanding many sources of doubt, man can 
generally and readily distinguish between the higher and 
lower moral rules. The higher are founded on the social 
instincts, and relate to the welfare of others. They are 
supported by the approbation" of our fellow-men and by 
reason. The lower rules, though some of them when im- 
plying self-sacrifice hardly deserve to be called lower, 
relate chiefly to self, and owe their origin to public opinion, 
when matured by experience and cultivated ; for they are 
not practised by rude tribes. 

As man advances in civilization, and small tribes are 
united into larger communities, the simplest reason would 
tell each individual that he ought to extend his social in- 
stincts and sympathies to all the members of the same 
nation, though personally unknown to him. This point 
being once reached, there is only an artificial barrier to 
prevent his sympathies extending to the men of all nations 
and races. If, indeed, such men are separated from him 
by great differences in appearance or habits, experience 
unfortunately shows us how long it is before we look at 
them as our fellow-creatures. Sympathy beyond the con- 
fines of man, that is, humanity to the lower animals, seems 

23 Good instances are given by Mi. Wallace in 'Scientific Opinion,' 
Sept. 15, 1869; and mom fully in his 'Contributions to the Theory of 
Natural Selection,' 1870, p. 353. 



Chap. III.] MORAL SENSE. 97 

to be one of the latest moral acquisitions. It is apparently 
unfelt by savages, except toward their pets. How little 
the old Romans knew of it is shown by their abhorrent 
gladiatorial exhibitions. The very idea of humanity, as 
for as I could observe, was new to most of the Gauchos of 
the Pampas. This virtue, one of the noblest with which 
man is endowed, seems to arise incidentally from our sym- 
pathies becoming more tender and more widely diffused, 
until they are extended to all sentient beings. As soon as 
this virtue is honored and practised by some few men, it 
spreads 'through instruction and example to the young, 
and eventually through public opinion. 

The highest stasre in moral culture at which we can 
arrive, is when we recognize that we ought to control our 
thoughts, and "not even in inmost thought to think agjain 
the sins that made the past so pleasant to us." 34 What- 
ever makes any bad action familiar to the mind, renders 
its performance by so much the easier. As Marcus Aure- 
lius long ago said, " Such as are thy habitual thoughts, 
such also, will be the character of thy mind; for the soul 
is dyed by the thoughts," 35 

Our great philosopher, Herbert Spencer, has recently 
explained his views on the moral sense. He says : 36 "I 
believe that the experiences of utility organized and con- 
solidated through all past* generations of the human race, 
have been producing corresponding modifications, which, 
by continued transmission and accumulation, have become 
in us certain faculties of moral intuition — certain, emotions 
responding to right and wrong conduct, which have no 
apparent basis in the individual experiences of utility." 

34 Tennyson, ' Idylls of the King,' p. 244. 

35 ' The Thoughts of the Emperor M. Aurelius Antoninus,' Eng. trans- 
atior, 2d edit., 1869, p. 112. Marcus Aurelius was born A. D. 121. 

36 Letter to Mr. Mill in Bain's 'Mental and Moral Science,' 1868, p 
722. 



98 THE DESCENT OF MAN. [Part L 

There is not the least inherent improbability, as it seems 
to me, in virtuous tendencies being more or less strongly 
inherited ; for, not to mention the various dispositions and 
habits transmitted by many of our domestic animals, I 
have heard of cases in which a desire to steal and a ten- 
dency to lie appeared to run in families of the upper 
ranks ; and as stealing is so rare a crime in the wealthy 
classes, we can hardly account by accidental coincidence 
for the tendency occurring in two or three members of the 
same family. If bad tendencies are transmitted, it is 
probable that good ones are likewise transmitted. Ex- 
cepting through the principle of the transmission of moral 
tendencies, we cannot understand the differences believed 
to exist in this respect between the various races of man- 
kind. "We have, however, as yet, hardly sufficient evi- 
dence on this head. 

Even the partial transmission of virtuous tendencies 
would be an immense assistance to the primary iurpulse 
derived directly from the social instincts, and indirectly 
from the approbation of <?ur fellow-men. Admitting for 
the moment that virtuous tendencies are inherited, it ap- 
pears probable, at least in such .cases as chastity, temper- 
ance, humanity to animals, etc., that they become first im- 
pressed on the mental organization through habit, instruc- 
tion, and example, continued during several generations 
in the same family, and in a quite subordinate degree, or 
not at all, by the individuals possessing such virtues, 
having succeeded best in the struggle for life. My chief 
source of doubt with respect to any such inheritance, is 
that senseless customs, superstitions, and tastes, such as 
the horror of a Hindoo for unclean food, ought on the 
same principle to be transmitted. Although this in itself 
is perhaps not less probable than that animals should 
acquire inherited tastes for certain kinds of food or fear of 
certain foes, I have not met with any evidence in support 



Chap. III.] MORAL SENSE. 99 

of the transmission of superstitious customs or senseless 
habits. 

Finally, the social instincts which no doubt were ac- 
quired by man, as by the lower animals, for the good of 
the community, will from the first have given to him 
some wish to aid his fellows, and some feeling of sym- 
pathy. Such impulses will have served him at a very 
early period as a rude rule of right and wrong. But as 
man gradually advanced in intellectual power and was 
enabled to trace the more remote consequences of his ac- 
tions ; as he acquired sufficient knowledge to reject bane- 
ful customs and superstitions; as he regarded more and 
more not only the welfare but the happiness of his fellow- 
men ; as from habit, following on beneficial experience, 
instruction, and example, his sympathies became more 
tender and widely diffused, so as to extend to the men 
of all races, to the imbecile, the maimed, and other use- 
less members of society, and finally to the lower ani- 
mals — so would the standard of his morality rise higher 
and higher. And it is admitted by moralists of the de- 
rivative school and by some intuitionists, that the stand- 
ard of morality has risen since an early period in the his- 
tory of man. 37 

As a struggle may sometimes be seen going on between 
the various instincts of the lower animals, it is not sur- 
prising that there should be a struggle in man between 
his social instincts, with their derived virtues, and his 
lower, though, at the moment, stronger impulses or desires. 
This, as Mr. Galton 38 has remarked, is all the less sur- 

31 A writer in the 'Xorth British Review ' (July, 1869, p. 531), well 
capable of forming a sound judgment, expresses himself strongly to this 
effect. Mr. Lecky (' Hist, of Morals,' vol. i. p. 143) seems to a certain 
extent to coincide. 

** See his remarkable work on ' Hereditary Genius,' 1869, p. 349. 



100 THE DESCENT OF MAN. [Part L 

prising, as man has emerged from a state of barbarism 
within a comparatively recent period. After having 
yielded to some temptation, we feel a sense of dissatisfac- 
tion, analogous to that felt from other unsatisfied instincts, 
called in this case conscience ; for we cannot prevent past 
images and impressions continually passing through our 
minds , and these in their weakened state we compare with 
the ever-present social instincts, or with habits gained in 
early youth and strengthened during our whole lives, per- 
haps inherited, so that they are at last rendered almost as 
strong as instincts. Looking to future generations, there 
is no cause to fear that the social instincts will grow 
weaker, and we may expect that virtuous habits will grow 
stronger, becoming perhaps fixed by inheritance. In this 
case the struggle between our higher and lower impulses 
will be less severe, and virtue will be triumphant. 

Summary of the last two Chapters. — There can be no 
doubt that the difference between the mind of the lowest 
man and that of the highest animal is immense. An an- 
thropomorphous ape, if he could take a dispassionate view 
of his own case, would admit that though he could form 
an artful plan to plunder a garden — though he could use 
stones for fighting or for breaking open nuts, yet that the 
thought of fashioning a stone into a tool was quite beyond 
his scope. Still less, as he would admit, could he follow 
out a train of metaphysical reasoning, or solve a mathe- 
matical problem, or reflect on God, or admire a grand 
natural scene. Some apes, however, would probably de- 
clare that they could and did admire the beauty of the col- 
ored skin and fur of their partners in marriage. They 
would admit, that though they could make other apes 
understand by cries some of their perceptions and simplei 

The Duke of Argyll ('Primeval Man,' 1869, p. 188) has some good ra 
marks on the contest in man's nature between right and wrong. 



Chap. III.] MORAL SENS& 101 

wants, the notion of expressing definite ideas by definite • 
sounds had never crossed their minds. They might insist 
that they were ready to aid their fellow-apes of the same 
troop in many ways, to risk their lives for them, and to 
take charge of their orphans ; but they would be forced to 
acknowledge that disinterested love for all living creatures, 
the most noble attribute of man, was quite beyond their 
comprehension. 

N evertheless the difference in mind between man and 
the higher animals, great as it is, is certainly one of degree 
and not of kind. We have seen that the senses and intui- 
tions, the various emotions and faculties, such as love, 
memory, attention, curiosity, imitation, reason, etc., of 
which man boasts, may be found in an incipient, or even 
sometimes in a well-developed condition, rh the lower ani- 
mals. They are also capable of some inherited improve- 
ment, as we see in the domestic dog compared with the 
wolf or jackal. If it be maintained that certain powers, 
such as self-consciousness, abstraction, etc., are peculiar to 
man, it may well be that these are the incidental results 
of other highly-advanced intellectual faculties ; and these 
again are mainly the result of the continued use of a 
highly-developed language. At what age does the new- 
born infant possess the power of abstraction, or become 
self-conscious and reflect on its own existence ? We can- 
not answer ; nor can we answer in regard to the ascending 
organic scale. The half-art and half-instinct of language 
still bears the stamp of its gradual evolution. The en- 
nobling belief in God is not universal with man ; and the 
belief in active spiritual agencies naturally follows from 
his other mental powers. The moral sense perhaps affords 
the best and highest distinction between man and the 
lower animals ; but I need not say any thing on this head, 
as I have so lately endeavored to show that the social 
instincts — the prime principle of man's moral consti- 



102 THE DESCENT OF MAN. TPart L 

tution 89 — with the aid of active intellectual powers and 
the effects of habit, naturally lead to the golden rule, " As 
ye would that men should do to you, do ye' to them like- 
wise ; " and this lies at the foundation of morality. 

In a future chapter I shall make some few remarks on 
the probable steps and means by which, the several mental 
and moral faculties of man have been gradually evolved. 
That this at least is possible ought not to be denied, when 
we daily see their development in every infant ; and when 
we may trace a perfect gradation from the mind of an 
utter idiot, lower than that of the lowest animal, to the 
mind of a Newton. 

89 ' The Thoughts of Marcus Aurelius,' etc., p. 139. 



7hap. I VI MANNER OF DEVELOPMENT. 103 



CHAPTER IV. 

ON THE MANNER OF DEVELOPMENT OF MAN FROM SOME 

LOWER FORM. 

Variability of Body and Mind in Man. — Inheritance. — Causes of Varia- 
bility. — Laws of Variation the same in Man as in the Lower Animals. 
— Direct Action of the Conditions of Life. — Effects of the Increased 
Use and Disuse of Parts. — Arrested Development. — Reversion. — Cor- 
related Variation. — Rate of Increase. — Checks to Increase.— Natural 
Selection. — Man the most Dominant Animal in the World. — Impor- 
tance of his Corporeal Structure. — The Causes which have led to his 
becoming erect. — Consequent Changes of Structure. — Decrease in 
Size of the Canine Teeth. — Increased Size and Altered Shape of the 
Skull. — Nakedness. — Absence of a Tail. — Defenceless Condition of 
Man. 

We have seen in the first chapter that the homologieal 
structure of man, his embryological development and the 
rudiments which he still retains, all declare in the plainest 
manner that he is descended from some lower form. The 
possession of exalted mental powers is no insuperable ob- 
jection to this conclusion. In order that an ape-like crea- 
ture should have been transformed into man, it is neces- 
sary that this early form, as well as many successive links, 
should all have varied in mind and body. It is impossible 
to obtain direct evidence on this head ; but if it can be 
shown that man now varies — that his variations are in- 
duced by the same general causes, and obey the same 
general laws, as in the case of the lower animals — there 
can be little doubt that the preceding intermediate links 



J 04 THE DESCENT OF MAN. [Part I. 

varied in a like manner. The variations at each succes- 
sive stage of descent must, also, have been in some- man- 
ner accumulated and fixed. 

The facts and conclusions to be given in this chapter 
relate almost exclusively to the probable means by which 
the transformation of man has been effected, as far as his 
bodily structure is concerned. The following chapter will 
be devoted to the development of his intellectual and 
moral faculties. But the present discussion likewise bears 
on the origin of the different races or species of mankind, 
whichever term may be preferred.- 

It is manifest that man is now subject to much varia- 
bility. No two individuals of the same race are quite 
alike. We may compare millions of faces, and each will 
be distinct. There is an equally great amount of diversity 
in the proportions and dimensions of the various parts of 
the body ; the length of the legs being one of the most 
variable points. 1 Although in some quarters of the world 
an elongated skull, and in other quarters a short skull pre- 
vails, yet there is great diversity of shape even within the 
limits of the same race, as with the aborigines of America 
and South Australia— the latter a race " probably as pure 
and homogeneous in blood, customs, and language, as any 
in existence " — and even with the inhabitants of so con- 
fined an area as the Sandwich Islands. 3 An eminent den- 
tist assures me that there is nearly as much diversity in 
the teeth as in the features. The chief arteries so fre- 
quently run in abnormal courses, that it has been found 
useful for surgical purposes to calculate from 12,000 

1 ' Investigations in Military and Anthropolog. Statistics of American 
Soldiers,' by B. A. Gould, 1869, p. 256. 

2 With respect to the " Cranial forms of the American aborigines," 
Bee Dr. Aitken Meigs in 'Proc. Acad. Nat. Sci.' Philadelphia, May, 1866. 
On the Australians, see Huxley, in Lyell's 'Antiquity of Man,' 1863, p. 87. 
On the Sandwich Islanders, Prof. J. Wyman, ' Observations on Crania,' 
Boston. 1868,' p. 18. 



Chap. IV.] MANNER OF DEVELOPMENT. 105 

corpses how often each course prevails. 3 The muscles are 
eminently variable ; thus those of the foot were found by- 
Prof. Turner 4 not to be strictly alike in any two out of 
fifty bodies ; and in some the deviations were considerable. 
Prof. Turner adds that the power of performing the ap- 
propriate movements must have been modified in accord- 
ance with the several deviations. Mr. J. Wood has re- 
corded 8 the occurrence of 295 muscular variations in 
thirty-six subjects, and in another set of the same number 
no less than 558 variations, reckoning both sides of the 
body as one. In the last set, not one body out of the ' 
thirty-six was " found totally wanting in departures from 
the standard descriptions of the muscular system given 
in anatomical text-books." A single body presented the 
extraordinary number of twenty-five distinct abnormali- 
ties. The same muscle sometimes varies in many ways : 
thus Prof. Macalister describes 6 no less than twenty dis- 
tinct variations, in the palmaris accessorius. 

The famous old anatomist, "Wolff, 7 insists that the in- 
ternal viscera are more variable than the external parts : 
Nulla particula est quce non aliter et aliter in aliis se 
habeat hominibus. He has even written a treatise on the 
choice of typical examples of the viscera for representation. 
A discussion on the beau-ideal of the liver, lungs, kidneys, 
etc., as of the human face divine, sounds strange in our 
ears. 

The variability or diversity of the mental faculties in 
men ol the same race, not to mention the greater differ- 
ences between the men of distinct races, is so notorious 

8 ' Anatomy of the Arteries,' by R. Quain. 
4 'Transact. Royal Soc.' Edinburgh, vol. xxiv. pp. 175, 189. 
6 ' Proc. Royal Soc.' 1867, p. 544 ; also 1868, pp. 483, 524. There is 
* previous paper, 1866, p. 229. 

6 'Proc. R. Irish Academy,' vol. x. 1868, p. 141. 

7 ' Act. Acad.,' St. Petersburg, 1778, part ii. p. 217 



106 THE DESCENT OF MAN. [Part 1 

that not a word need here be said. So it is with the lower 
animals, as has been illustrated by a few examples in the 
last chapter. All who have had charge of menageries 
admit this fact, and we see it plainly in our dogs and other 
domestic animals. Brehm especially insists that each in- 
dividual monkey of those which he kept under confine- 
ment in Africa had its own peculiar disposition and tem- 
per :" he mentions one baboon remarkable for its high in- 
telligence; and the keepers in the Zoological Gardens 
pointed out to me a monkey, belonging to the New World 
•division, equally remarkable for intelligence. Rengger, 
also, insists on the diversity in the various mental charac- 
ters of the monkeys of the same species which he kept in 
Paraguay ; and this diversity, as he adds, is partly innate, 
and partly the result of the manner in which they have 
been treated or educated. 8 

I have elsewhere 9 so fully discussed the subject of In- 
heritance that I need here add hardly t any thing. A 
greater number of facts have been collected with respect 
to the transmission of the most trifling, as well as of the 
most important characters in man than in any of the lower 
animals ; though the facts are copious enough with respect 
to the latter. So in regard to mental qualities, their trans- 
mission is manifest in our dogs, horses, and other domes- 
tic animals. Besides special tastes and habits, general in- 
telligence, courage, bad and good temper, etc., are cer- 
tainly transmitted. With man we see similar facts in al- 
most every family ; and we now know through the admi- 
rable labors of Mr. Galton 10 that genius, which implies a 

8 Brehm, ' Thierleben,' B. i. s. 58, 87. Rengger, ' Siiugethiere vod 
Paraguay,' s. 5V. 

9 ' Variation of Animals and Plants under Domestication,' vol. ii. chap 
mi. 

10 ' Hereditary Genius -. an Inquiry into its Laws and Consequences, 
1869. 



Chap. IV.] MANNER OF DEVELOPMENT. 107 

wonderfully complex combination of high faculties, tends 
to be inherited ; and," on the other hand, it is too certain 
that insanity and deteriorated mental powers likewise run 
in the same families. 

With respect to the causes of variability we are in all 
cases very ignorant ; but we can see that in man as in the 
lower animals, they stand in some relation with the con- 
ditions to which each species has been exposed during 
several generations. Domesticated animals vary more 
than those in a state of nature ; and this is apparently due 
to the diversified and changing nature of their conditions. 
The different races of man resemble in this respect domes- 
ticated animals, and so do the individuals of the same 
race when inhabiting a very wide area, like that of 
America. We see the influence of diversified conditions 
in the more civilized nations, the members of which be- 
long to different grades of rank and follow different occu- 
pations, presenting a greater range of character than the 
members of barbarous nations. But the uniformity of 
savages has often been exaggerated, and in some cases can 
hardly be said to exist. 11 It is nevertheless an error to 
speak of man, even if we look only to the conditions 
to which he has been subjected, as "far more domesti- 
cated " " than any other animal. Some savage races, such 
as the Australians, are not exposed to more diversified 
conditions than are many species which have very wide 
ranges. In another and much more important respect, 
man differs widely from any strictly-domesticated animal; 

11 Mr. Bates remarks f The Naturalist on the Amazons,' 1863, vol. il 
p. 159), with respect to +.he Indians of the same South-American tribe, 
u No two of them were at all similar in the shape of the head ; one man 
had an oval visage with fine features, and another was quite Mongoliar 
in breadth and prominence of chee*, spread of nostrils, and obliquity oi ' 
tyes." 

12 Blunienbach, ' Treatises on Anthropolog.' Eng. translat,, 1805, p. 205. 



|08 THE DESCENT OF MAN. [Part I. 

for his breeding has not been controlled, either through 
methodical or unconscious selection. No race or body of 
men has oeen so completely subjugated by other men, 
that certain individuals have been preserved and thus un- 
consciously selected, from being in some way more useful 
to their masters. Nor have certain male and female in- 
dividuals been intentionally picked out and matched, ex- 
cept in the well-known case of the Prussian grenadiers ; 
and in this case man obeyed, as might have been expect- 
ed, the law of methodical selection; for it is asserted that 
many tall men were reared in the villages inhabited by 
the grenadiers with their tall wives. 

If we consider all the races of man, as forming a single 
species, his range is enormous ; but some separate races, 
as the Americans and Polynesians, have very wide ranges. 
It is a well-known law that widely-ranging species are 
much more variable than species with restricted ranges ; 
and the variability of man may with more truth be com- 
pared with that of widely-ranging species, than with that 
of domesticated animals. 

Not only does variability appear to be induced in man 
and the lower animals by the same general causes, but in 
both the same characters are affected in a closely analo- 
gous manner. This has been proved in such full detail 
by Godron and Quatrefages, that I need here only refer 
to their works. 13 Monstrosities, which graduate into 
slight variations, are likewise so similar in man and the 
lower animals, that the same classification and the same 
terms can be used for both, as may be seen in Isidore 
Geoffroy St.-Hilaire's great work. 14 This is a necessary 

13 Godron, ' De l'Espece,' 1859, torn. ii. livre 3. ' Quatrefages, 'Unite 
,de l'Espece Humaine,' 1861. Also Lectures on Anthropology, given is 

the 'Revue des Cours Scientifiques,' 1866-1868. 

14 ' Hist. Gen. et Part, des Anomalies de l'Organisation,' in three vol 
umes, torn. i. 1832. 



Chap. IV.] MANNER OF DEVELOPMENT. 109 

consequence of the same laws of change prevailing 
throughout the animal kingdom. In my work on the 
variation of domestic animals, I have attempted to ar- 
range in a rude fashion the laws of variation under 
the following heads: The direct and definite action of 
changed conditions, as shown by all or nearly all the in- 
dividuals of the same species varying in the same manner 
under the same circumstances. The effects of the long- 
continued use or disuse of parts. The cohesion of homol- 
ogous parts. The variability of multiple parts. Com- 
pensation of growth; but of this law I have found no 
good instances in the case of man. The effects of the me- 
chanical pressure of one part on another ; as of the pelvis 
on the cranium of the infant in the womb. Arrests of de- 
velopment, leading to the diminution or suppression of 
parts. The reappearance of long-lost characters through 
reversion. And lastly, correlated variation. All these 
so-called laws apply equally to man and the lower ani- 
mals ; and most of them even to plants. It would be 
superfluous here to discuss all of them ; 15 but several are 
so important for us, that they must be treated at consider- 
able length. « 

The direct and definite action of changed conditions. — 
This is a most perplexing subject. It cannot be denied 
that changed conditions produce some effect, and occa- 
sionally a considerable effect, on organisms of all kinds : 
and it seems at first probable that, if sufficient time were 
allowed, this would be the invariable result. But I have 
failed to obtain clear evidence in favor of this conclusion ; 
and valid reasons may be urged on the other side, at least 

15 1 have fully discussed these laws in my ' Variation of Animals and 
Plants under Domestication,' vol. ii. chaps, xxii. and xxiii. M. J. P. 
Durand has lately (1868) published a valuable essay, 'Del'Influenee des 
Milieux,' etc. He lays much stress on the nature of the soil 



110 THE DESCENT OF MAN. [Pari I. 

as far as the innumerable structures are concerned, which 
are adapted for special ends. There can, however, be no 
doubt that changed conditions induce an almost indefinite 
amount of fluctuating variability, by which the whole or- 
ganization is rendered in some 'degree plastic. 

In the United States, above 1,000,000 soldiers, who 
served in the late war, were measured, and the States in 
which they were born and reared recorded. 16 From this 
astonishing number of observations it is proved that local 
influences of some kind act directly on stature ; and we 
further learn that " the State where the physical growth 
has in great measure taken place, and the State of birth, 
which indicates the ancestry, seem to exert a marked in- 
fluence on the stature." For instance, it is established, 
" that residence in the Western States, during the years 
of growth, tends to produce increase of stature." On the 
other hand, it is certain that with sailors, their manner of 
life delays growth, as shown " by the great difference be- 
tween the statures of soldiers and sailors at the ages of 
seventeen and eighteen years." Mr. B. A. Gould en- 
deavored to ascertain the nature of the influences which 
thus act on stature; but he arrived only at negative 
results, namely, that they did not relate to climate, the 
elevation of the land, soil, or even "in any controlling 
degree " to the abundance or need of the comforts of life. 
This latter conclusion is directly opposed to that arrived 
at by Villerme from the statistics of the height of the con- 
scripts in different parts of France. When we compare 
the differences in stature between the Polynesian chiefs 
and the lower orders within the same islands, or between 
the inhabitants of the fertile volcanic and low barren 
coral islands of the same ocean, 17 or again between the 

16 'Investigations in Military and Anthrop. Statistics,' etc., 1869, by 
B. A. Gould, pp. 93, 101, 126, 131, 134. 

17 For the Polynesians, see Prichard's • Physical Hist, of Mankind,' 



Crap. IV.l MANNER OF DEVELOPMENT. Ill 

Fuegians on the eastern and western shores of their 
country, where the means of subsistence are very dif- 
ferent, it is scarcely possible to avoid the conclusion that 
better food and greater comfort do influence stature. 
But the preceding statements show how difficult it is 
to arrive at any precise result. Dr. Beddoe has lately 
proved that, with the inhabitants of Britain, residence in 
town and certain occupations have a deteriorating in- 
fluence on height ; and he infers that the result is to a 
certain extent inherited, as is likewise the case in the 
United States. Dr. Beddoe further believes that wherever 
a " race attains, its maximum of physical development, it 
rises highest in energy and moral vigor." 18 

Whether external conditions produce any other direct 
effect on man is not known. It might have been expected 
that differences of climate would have had a marked in- 
fluence, as the lungs and kidneys are brought into fuller 
activity under a low temperature, and the liver and skin 
under a high one. 19 It was formerly thought that the 
color of the skin and the character of the hair were de- 
termined by light or heat ; and although it can hardly be 
denied that some effect is thus produced, almost all ob- 
servers now agree that the effect has been very small, 
even after exposure during many ages. But this subject 
will be more properly discussed when we treat of the dif- 
ferent races of mankind. With our domestic animals 
there are grounds for believing that cold and damp direct- 
ly affect the growth of the hair ; but I have not met with 
any evidence on this head in the case of man. 

vol. v. 1847, pp. 145, 283. Also Godron, 'De l'Espece,' torn. ii. p. 289. 
There is also a remarkable difference in appearance between the closely- 
allied Hindoos inhabiting the Upper Ganges and Bengal ; see Elphin- 
Btone's ' History of India,' vol. i. p. 324. 

13 Memoirs, ' Anthropolog. Soc' vol. hi. 1867-'69, pp. 561, 565, 567. 

19 Dr. Brakenridge, ' Theory of Diathesis,' 'Medical Times,' June 19 
and July 17, 1869. 



112 THE DESCENT OF MAN. [Part I. 

Effects of the increased Use and Disuse of Parts. — 
It is well known that use strengthens the muscles in the 
individual, and complete disuse, or the destruction of the 
proper nerve, weakens them. When the eye is destroyed 
the optic nerve often becomes atrophied. When an artery 
is tied, the lateral channels increase not only in diameter, 
but in the thickness and strength of their coats. When 
one kidney ceases acting from disease, the other increases 
in size and does double work. Bones increase not only in 
thickness, but in length, from carrying a greater weight. 20 
Different occupations habitually followed lead to changed 
proportions in various parts of the body. Thus it was 
clearly ascertained by the United States Commission 21 
that the legs of the sailors employed in the late war were 
longer by 0.217 of an inch than those of the soldiers, 
though the sailors were on an average shorter men ; 
while their arms were shorter by 1.09 of an inch, and 
therefore out of proportion shorter in relation to their 
lesser height. This shortness of the arms is apparently 
due to their greater use, and is an unexpected result ; but 
sailors chiefly use their arms in pulling and not in sup- 
porting weights. The girth of the neck and the depth of 
the instep are greater, while the circumference of the 
chest, waist, and hips, is less in sailors than in soldiers. 

Whether the several foregoing modifications would be- 
come hereditary, if the same habits of life were followed 
during many generations, is not known, but is probable. 
Reno-o-er 22 attributes the thin les-s and thick arms of the 
Payaguas Indians to successive generations having passed 



20 1 have given authorities for these several statements in my ' Varia- 
tion of Animals under Domestication,' vol. ii. pp. 297-300. Dr. Jaeger, 
" Ueber das Langenwachsthum der Knochen," ' Jenaischen Zeitschrift,' 
B. v. Heft i. 

81 'Investigations,' etc. By B. A. Gould, 1869, p. 288. 

2£ ' Siiugethiere von Paraguay,' 1830, s. 4. 



Chap. IV.] MANNER AND DEVELOPMENT. 113 

nearly their whole lives in canoes, with their lower 
extremities motionless. Other writers have come to a 
similar conclusion in other analogous cases. Acpording 
to Cranz, 23 who lived for a long time with the Esquimaux, 
"the natives believe that ingenuity and dexterity in seal- 
catching (their highest art and virtue) is hereditary ; there 
is really something in it, for the son of a celebrated seal- 
catcher will distinguish himself though he lost his father 
in childhood." But in this case it is mental aptitude, 
quite as much as bodily structure, which appears to be 
inherited. It is asserted that the hands of English labor- 
ers are at birth larger than those of the gentry. 24 From 
the correlation which exists, at least in some cases, 25 be- 
tween the development of the extremities and of the jaws, 
it is possible that in those classes which do not labor much 
with their hands and feet, the jaws would be reduced in 
size from this cause. That they are generally smaller in 
refined and civilized men than in hard-working men or 
savages, is certain. But with savages, as Mr. Herbert 
Spencer 26 has remarked, the greater use of the jaws in 
chewing coarse, uncooked food, would act in a direct man- 
ner on the masticatory muscles and on the bones to which 
they are attached. In infants long before birth, the skin 
on the soles of the feet is thicker than on any other part 
of the body ; 27 and it can hardly be doubted that this is 
due to the inherited effects of pressure during a long 
series of generations. 

It is familiar to every one that watchmakers and en- 
gravers are liable to become short-sighted, while sailors 
and especially savages are generally long-sighted. Short- 

23 'History of Greenland,' Eng. translat. 1767, vol. i. p. 230. 

24 ' Intermarriage.' By Alex. Walker, 1 838, p. 377. 

25 • The Variation of Animals under Domestication,' vol. i. p. 173 
96 ' Principles of Biology,' vol. i. p. 455. 

,7 Paget, ' Lectures on Surgical Pathology,' vol. i, 1853, p. 209. 
6 



114 THE DESCENT OF MAN. [Fart L 

Bight and long-sight certainly tend to be inherited. 28 The 
inferiority of Europeans, in comparison with savages, in 
eye-sight and in the other senses, is no doubt the accumu- 
lated and transmitted effect of lessened use during many 
generations ; for Rengger 29 states that he has repeatedly 
observed Europeans, who had been brought up and spent 
their whole lives with the wild Indians, who nevertheless 
did not equal them in the sharpness of their senses. The 
same naturalist observes that the cavities in the skull for 
the reception of the several sense-organs are larger in the 
American aborigines than in Europeans ; and this ' no 
doubt indicates a corresponding difference in the dimen- 
sions of the organs themselves. Blumenbach has also re- 
marked on the large size of the nasal cavities in the skulls 
of the American aborigines, and connects this fact with 
their remarkably acute power of smell. The Mongolians 
of the plains of Northern Asia, according to Pallas, have 
wonderfully perfect senses ; and Prichard believes that the 
great breadth of their skulls across the zygomas follows 
from their highly-developed sense-organs. 30 

The Quechua Indians inhabit the lofty plateaux of 
Peru, and Alcide d'Orbigny states 31 that from continually 
breathing a highly rarefied atmosphere they have acquired 
chests and lungs of extraordinary dimensions. The cells, 

28 ' The Variation of Animals under Domestication,' vol. ii. p. 8. 

29 ' Saugethiere von Paraguay,' s. 8, 10. I have had good opportuni- 
ties for observing the extraordinary power of eyesight in the Fuegians. 
See also Lawrence ('Lectures on Physiology,' etc., 1822, p. 404) on this 
same subject. M. Giraud-Teulon has recently collected ('Revue des 
Cours Scientifiques,' 18*70, p. 625) a large and vrluable body of evidence 
proving that the cause of short-sight, "Vest le travail assidu, de pres." 

30 Prichard, ' Phys. Hist, of Mankind,' on the authority of Blumen- 
bach, vol i. 1851, p. 311 ; for the statement by Pallas, vol. iv. 1844, p, 
40V. 

81 Quoted by Prichard, ' Researches into the Phys. Hist, of Mankind, 
vol. v. p. 463. 



Chap. IV.] MAXNER OF DEVELOPMENT. 115 

also, of~the lungs are larger and more numerous than in 
Europeans. These observations have been doubted ; but 
Mr. D. Forbes carefully measured many Aymaras, an allied 
race, living at the height of between ten and fifteen thou- 
sand feet ; and he informs me 32 that they differ conspicu- 
ously from the men of all other races seen by him, in the 
circumference and length of their bodies. In his table of 
measurements, the stature of each man is taken at 1,000, 
and the other measurements are reduced to this standard. 
It is here seen that the extended arms of the Aymaras are 
shorter than those of Europeans, and much shorter than 
those of Negroes. The legs are likewise shorter, and they 
present this remarkable peculiarity, that in every Aymara 
measured the femur is actually shorter than the tibia. On 
an average the length of the f«mur to that of the tibia is 
as 211 to 252; while in two Europeans measured at the 
same time, the femora to the tibiae were as 244 to 230 ; 
and in three Negroes as 258 to 241.. The humerus is like- 
wise shorter relatively to the forearm. This shortening 
of that part of the limb which is nearest to the body, ap- 
pears to be, as suggested to me by Mr. Forbes, a case of 
compensation in relation with the greatly-increased length 
of the trunk. The Aymaras present some other singular 
points of structure, for instance, the very small projection 
of the heel. 

These men are so thoroughly acclimatized to their fold 
and lofty abode, that when formerly carried down by the 
Spaniards to the low eastern plains, and when now tempt- 
ed down by high wages to the gold-washings, they suffer 
a frightful rate of mortality. Nevertheless, Mr. Forbes 
found a few pure families which had survived during two 
generations ; and he observed that they still inherited 
their characteristic peculiarities. But it was manifest, 

32 Mr. Forbes's valuable paper is now published in the { Journal of the 
Ethnological Soc. of London,' new series, voL ii. 18*70, p. 193. 



[16 THE DESCENT OF MAN. [Part I. 

even without measurement, that these peculiarities had all 
decreased ; and on measurement their bodies were found 
not to be so much elongated as those of the men on the 
high plateau ; while their femora had become somewhat 
lengthened, as had their tibiae, but in a less degree. The 
actual measurements may be seen by consulting Mr. 
Forbes's memoir. From these valuable observations, there 
can, I think, be no doubt that residence during many gen- 
erations at a great elevation tends, both directly and indi- 
rectly, to induce inherited modifications in the proportions 
of the body. 83 

Although' man may not have been much modified dur- 
ing the latter stages of his existence through the increased 
or decreased use of parts, the facts now given show that 
his liability in this respecfr has not been lost ; and we posi- 
tively know that the same law holds good with the lower 
animals. Consequently we may infer that, when at a re- 
mote epoch the progenitors of man were in a transitional 
state, and were changing from quadrupeds into bipeds, 
natural selection would probably have been greatly aided 
by the inherited effects of the increased or diminished use 
of the different parts of the body. 

Arrests of Development. — Arrested development dif- 
fers from arrested growth, as parts in the former state 
continue to grow while still retaining their early condi- 
tion. Various monstrosities come under this head, and 
some are known to be occasionally inherited, as a cleft- 
palate. It will suffice for our purpose to refer to the 
arrested brain-development of microcephalous idiots, as 
described in Vogt's. great memoir. 84 Their skulls are 

33 Dr. Wilckens (' Landwirthschaft. Wochenblatt,' No. 10, 1869) has 
lately published an interesting essay showing how domestic animals, 
which live in mountainous regions, have their frames modified. 

8 * 'Memoire sur les Microcephales,' 1867, pp. 50, 125, 169, 171, 184, 
198. 



Chap. IV.] MANNER OF DEVELOPMENT. 117 

smaller, and the convolutions of the brain are less com- 
plex, than in normal men. The frontal sinus, or the pro- 
jection over the eyebrows, is largely developed, and the 
jaws are prognathous to an " effrayant " degree ; so that 
these idiots somewhat resemble the lower types of man- 
kind. Their intelligence and most of their mental facul- 
ties are extremely feeble. They cannot acquire the power 
of speech, and are wholly incapable of prolonged atten- 
tion, but are much given to imitation. They are strong 
and remarkably active, continually gambolling and jump- 
ing about, and making grimaces. They often ascend 
stairs on all-fours ; and are curiously fond of climbing up 
furniture or trees. We are thus reminded of the delight 
shown by almost all boys in climbing trees; and this 
again reminds us how lambs and kids, originally alpine 
animals, delight to frisk on any hillock, howevei small. 

Reversion. — Many of the cases to be here given might 
have been introduced under the last heading. Whenever 
a structure is arrested in its development, but still con- 
tinues growing until it closely resembles a corresponding 
structure in some lower and adult member of the same 
group, we may in one sense consider it as a case of rever- 
sion. The lower members in a group give us some idea 
how the common progenitor of the group was probably 
constructed ; and it is hardly credible that a* part arrested 
at, an early phase of embryonic development should be 
enabled to continue growing so as ultimately to perform 
its proper function, unless it had acquired this power of 
continued growth during some earlier state of existence, 
when the present exceptional or arrested structure was 
normal. The simple brain of a microcephalous idiot, in as 
far as it resembles that of an ape, may in this sense be 
said to offer a case of reversion. There are other cases 
which come more strictly under our present heading of 



118 THE DESCENT OF MAN. [Part I. 

reversion. Certain structures, regularly occurring in the 
lower members of the group to which man belongs, occa- 
sionally make their appearance in him, though not found 
in the normal human embryo ; or, if present in the nor- 
mal human embryo, they become developed in an abnor- 
mal manner, though this manner of development is proper 
to the lower members of the same group. These remarks 
will be rendered clearer by the following illustrations. 

In various mammals the uterus graduates from a double 
organ with two distinct orifices and two passages, as in the 
marsupials, into a single organ, showing no signs of double- 
ness except a slight internal fold, as in the higher apes and 
man. .The rodents exhibit a perfect series of gradations 
between these two extreme states. In all mammals the 
uterus is developed from two simple primitive tubes, the 
inferior portions of which form the cornua ; and it is in 
the words of Dr. Farre " by the coalescence of the two 
cornua at their lower extremities that the body of the 
uterus is formed in man ; while in those animals in which 
no middle portion or body exists, the cornua remain un- 
united. As the development of the uterus proceeds, the 
two cornua become gradually shorter, until at length they 
are lost, or, as it were, absorbed into the body of the 
uterus." The angles of the uterus are still produced into 
cornua, even so high in the scale as in the lower apes, and 
their allies the lemurs. 

Now in women anomalous cases are not very infre- 
quent, in which the mature uterus is furnished with cor- 
nua, or is partially divided into two organs ; and such 
cases, according to Owen, repeat "the grade of concen- 
trative development," attained by certain rodents. Here 
perhaps we have an instance of a simple arrest of embry- 
onic development, with subsequent growth and perfect 
functional development, for either side of the partially 
double uterus is capable of performing the proper office 



Chap. IV.] MANNER OF DEVELOPMENT. 119 

of gestation. In other and rarer cases, two distinct uter- 
ine cavities are formed, each having its proper orifice and 
passage. 86 No such stage is passed through during the 
ordinary development of the embryo, and it is difficult to 
believe, though perhaps not impossible, that the two sim- 
ple, minute, primitive tubes could know how (if such an 
expression may be used) to grow into two distinct uteri, 
each with a well-constructed orifice and passage, and each 
furnished with numerous muscles, nerves, glands and ves- 
sels, if they had not formerly passed through a similar 
course of development, as in the case of existing marsu- 
pials. No one will pretend that so perfect a structure as 
tho abnornal double uterus in woman could be the result 
of mere chance. But the principle of reversion, by which 
loifr-lost dormant structures are called back into exist- 
enoe, might serve as the guide for the full development 
of the organ, even after the lapse of an enormous interval 
of time. 

Prof. Canestrini, 36 after discussing the foregoing and 
various analogous cases, arrives at the same conclusion as 
that just given. He adduces, as another instance, the 
malar bone, which, in some of the Quadrumana and other 
mammals, normally consists of two portions. This is its 
condition in the two-months-old human foetus ; and thus it 
sometimes remains, through arrested development, in man 
when adult, more especially in the lower prognathous 
races. Hence Canestrini concludes that some ancient 

35 See Dr. A.Farre's well-known article in the ' Cyclop, of Anat. and 
Phys.' vol. v. 1859, p. 642. Owen, ' Anatomy of Vertebrates.' vol. iii. 
1868,' p. 687. Prof. Turner in 'Edinburgh Medical Journal,' Feb. 1865. 

36 ' Annuario della Soc. dei Naturalisti in Modena,* 1867, p. 83. Prof. 
Canestrini gives extracts on this subject from various authorities. Lau- 
rillard remarks that, as he has found a complete similarity in the form, 
proportions, and connection of the two malar bones in several human 
subjects and in certain apes, he cannot consider this disposition of the 
parts as simply accidental. 



120 THE DESCENT OF MAN. [Part I. 

progenitor of man must have possessed this bone nor- 
mally divided into two portions, which subsequently be- 
came fused together. In man the frontal bone consists of 
a single piece, but in the embryo and in children, and in 
almost all the lower mammals, it consists of two pieces sepa- 
rated by a distinct suture. This suture occasionally per- 
sists, more or less distinctly, in man after maturity, and 
more frequently in ancient than in recent crania, especially 
as Canestrini has observed in those exhumed from the Drift 
and belonging to the brachycephalic type. Here again he 
comes to the same conclusion as in the analogous case of 
the malar bones. In this and other instances presently to 
be given, the cause of ancient races approaching the lower 
animals in certain characters more frequently than do the 
modern races, appears to be that the latter stand at a 
somewhat greater distance in the long line of descent 
from their early semi-human progenitors. 

Various other anomalies in man, more or less anal- 
ogous with the foregoing, have been advanced by dif- 
ferent authors 37 as cases of reversion; but these seem not 
a little doubtful, for we have to descend extremely low in 
the mammalian series' before we find such structures nor- 
mally present. 38 

37 A whole series of cases is given by Isid. Geoffroy St.-Hilaire, 
' Hist, des Anomalies,' torn. iii. p. 437. 

38 In my 'Variation of Animals under Domestication' (vol. ii. p. 5*7) 
I attributed the not very rare cases of supernumerary mammae in women 
to reversion. I was led to this as a probable conclusion, by the additional 
mammae being generally placed symmetrically on the breast, and more 
especially from one case, in which a single efficient mamma occurred in 
the inguinal region of a woman, the daughter of another woman* with 
supernumerary mammae. But Prof. Preyer (' Der Kampf urn' das Dasein,' 
1869, s. 45) states that mammae erraticce have been known to occur in 
other situations, even on the back ; so that the force of my argument is 
greatly weakened or perhaps quite destroyed. 

With much hesitation I, in the same work (vol. ii., p. 12), attributed 
the frequent cases of polydactylism in men to reversion. I was partly led 



Chap. IV.] MAXXER OF DEVELOPMENT. 121 

In man the canine teeth are perfectly efficient instru- 
ments for mastication. But their true canine character, as 
Owen 39 remarks, "is indicated by the conical form of the 
crown, which terminates in an obtuse point, is convex out- 
ward and flat or subconcave within, at the base of which 
surface there is a feeble prominence. The conical form is 
best expressed in the Melanian races, especially the 
Australian. The canine is more deeply implanted, and by 
a stronger' fang, than the incisors." Nevertheless this tooth 
no longer serves man as a special weapon for tearing his 
enemies or prey; it may, therefore, as far as its proper 
function is concerned, be considered as rudimentary. In 
every large collection of human skulls some may be found, 
as Hackel 40 observes, with the canine teeth projecting 
considerably beyond the others in the same manner, but 
in a less degree, as in the anthropomorphous apes. In 
these cases, open spaces between the teeth in the one jaw 
are left for the reception of the canines belonging to the 
opposite jaw. An interspace of this kind in a Kaffir skull, 

to this through Prof. Owen's statement, that some of the Ichtbybpterygia 
possess more than five digits, and therefore, as I supposed, had retained 
a primordial condition ; but after reading Prof. Gegenbaur's paper 
(' Jenaischen Zeitschrift,' B. v. Heft 3, s. 341), who is the highest author- 
ity in Europe on such a point, and who disputes Owen's conclusion, I see 
that it is extremely doubtful whether supernumerary digits can thus be 
accounted for. It was the fact that such digits not only frequently occur 
and are strongly inherited, but have the power of regrowth after amputa- 
tion, like the normal digits of the lower vertebrata, that chiefly led me to 
the above conclusion. This extraordinary fact of their regrowth remains 
inexplicable, if the belief in reversion to some extremely remote pro- 
genitor must be rejected. I cannot, however, follow Prof. Gegenbaur in 
supposing that additional digits could not reappear through reversion, 
without at the same time other parts of the skeleton being simultaneous- 
.y and similarly modified ; for single characters often reappear through 
reversion. 

39 'Anatomy of Vertebrates,' voL iii. 1868, p. 323. 

40 'Generelle Morphologie,' 1866, B. ii. s. civ. 



122 THE DESCENT OF MAN. [Part L 

figured by Wagner, is surprisingly wide. 41 Considering 
how few ancient skulls have been examined in comparison 
with recent skulls, it is an interesting fact that in at least 
three cases the canines project largely ; and in the Nau- 
lette jaw they are spoken of as enormous. 42 

The males alone of the anthropomorphous aj)es have 
their canines fully developed; but in the female gorilla, 
and in a less degree in the female orang, these teeth pro- 
ject considerably beyond* the others; therefore the fact 
that women sometimes have, as I have been assured, con- 
siderably projecting canines, is no serious objection to the 
belief that their occasional great development in man is a 
case of reversion to an ape-like progenitor. He who rejects 
with scorn the belief that the shape of his own canines, 
and their occasional great development in other men, are 
due to our early progenitors having been provided with 
these formidable weapons, will probably reveal by sneer- 
ing the line of his descent. For, though he no longer in- 
tends, nor has the power, to use these teeth as weapons, 
he will unconsciously retract his "snarling muscles" (thus 
named by Sir C. Bell) 43 so as to expose them* ready for 
action, like a dog prepared to fight. 

Many muscles are occasionally developed in man, 
which are proper to the Qnadrumana or other mammals. 
Professor Vlacovich 44 examined forty male subjects, and 
found a muscle, called by him the ischiopubic, in nineteen 
of them; in three others there was a ligament which 
represented this muscle; and in the remaining eighteen 
no trace of it. Out of thirty female subjects this muscle 
was developed on both sides in only two, but in three 

• 

41 Carl Vogt's 'Lectures on Man/ Eng. translat. 1864, p. 151. 

42 C. Carter Blake, on a jaw from La Naulette, ' Anthropolog. Review, 
1867, p. 295. Schaaffhausen, ibid. 1868, p. 426. 

43 'The Anatomy of Expression,' ,1844, pp. 110, 131. 

^ 44 Quoted by Trof. Canestrini in the ' Annuario,' etc., 1867, p. 90. 



Chap. IV.] MANNER OF DEVELOPMENT. 123 

others the rudimentary ligament was present. This 
muscle, therefore, appears to he much more common in 
the male than in the female sex; and on the principle of 
the descent of man from some lower form, its presence can 
be understood ; for, it has been detected in several of the 
lower animals, and in all of these it serves exclusively to 
aid the male in the act of reproduction. 

Mr. J. Wood, in his valuable series of papers, 45 has 
minutely described a vast number of muscular variations 
in man, which resemble normal structures in the lower 
animals. Looking only to the muscles which closely re- 
semble those regularly present in our nearest allies, the 
Quadrumana, they are too numerous to be here even 
specified. In a single male subject, having a strong bodily 
frame and well-formed skull, no less than seven muscular 
variations were observed, all of which plainly represented 
muscles proper to various kinds of apes. This man, for 
instance, had on both sides of his neck a true and power- 
ful " levator claviculce" such as is found in all kinds of 
apes, and which is said to occur in about one out of sixty 
human subjects. 48 Again, this man had "a special ab- 
ductor of the metatarsal bone of the fifth digit, such 
as Prof. Huxley and Mr. Flower have shown to exist 
uniformly in the higher and lower apes." The hands and 

45 These papers deserve careful study by any one who desires to learn 
how frequently our muscles vary, and in varying come to resemble those 
of the Quadrumana. The following references relate to the few points 
touched on in my text, 'Proc. Royal Soc' vol. xiv. 1865, pp. 379-384; 
vol. xv. 1866, pp. 241, 242 ; voL xv. 1867, p. 544; vol. xvi. 1868, p. 524. 
I may here add that Dr. Murie and Mr. St. George Mivart have shown in 
their Memoir on the Lemuroidea (Transact. Zoolog. Soc.' vol. vii. 1369, 
p. 96), how extraordinarily variable some of the muscles are in these ani- 
mals, the lowest members of the Primates. Gradations, also, in the mus- 
cles leading to structures found in amimals still lower in the scale, are 
numerous in the Lemuroidea. 

46 Prof. Macalister in ' Proc." R. Irish Academy,' vol. x. 1868, p. 124. 



124 THE DESCENT OF MAN. [Part I. 

arms of man are eminently characteristic structures, but 
their muscles are extremely liable to vary, so as to re- 
semble the corresponding muscles in the lower animals. 47 
Such resemblances are either complete and perfect or im- 
perfect, yet in this latter case manifestly of a transitional 
nature. Certain variations are more common in man, and 
others in woman, without our being able to assign any 
reason. Mr. Wood, after describing numerous cases, 
makes the following pregnant remark : " Notable depart- 
ures from the ordinary type of the muscular structures 
run in grooves or directions, which must be taken to in- 
dicate some unknown factor, of much importance to a com- 
prehensive knowledge of general and scientific anatomy." 48 
That this unknown factor is reversion to a former 
state of existence may be admitted as in the highest de- 
gree probable. It is quite incredible that a man should 
through mere accident abnormally resemble, in no less 
than seven of his muscles, certain apes, if there had been 
no genetic connection between them. On the .other hand, 
if man is descended from some ape-like creature, no valid 
reason can be assigned why certain muscles should not 

47 Prof. Macalister (ibid. p. 121) has tabulated his observations, and 
finds that muscular abnormalities are most frequent in the forearms, 
secondly in the face, thirdly in the foot, etc. 

48 The Rev. Dr. Haughton, after giving (' Proc. R. Irish Academy,' 
June 27, 1864, p. 715) a remarkable case of variation in the human 
flexor pollicis longus, adds: "This remarkable example shows that man 
may sometimes possess the arrangement of tendons of thumb and fingers 
characteristic of the macaque ; but whether such a case should be re- 
garded as a macaque passing upward into a man, or a man passing 
downward into a macaque, or as a congenital freak of Nature, I cannot 
undertake to say." It is satisfactory to hear so capable an anatomist, 
and so embittered an opponent of evolutionism, admitting even the pos- 
sibility of either of his first propositions. Prof. Macalister has also de- 
scribed ('Proc.R. Irish Acad.' vol. x. 1864, p. 138) variations in the 
flexor pollicis longus, remarkable from their relations to the same muscle 
in the Quadrumana. 



Chap. IV.] MANNER OF DEVELOPMENT. ]25 

suddenly reappear after an interval of many thousand 
generations, in the same manner as with horses, asses, and 
mules, dark-colored stripes suddenly reappear on the legs 
and shoulders, after an interval of hundreds, or more prob- 
ably thousands, of generations. 

These various cases of reversion are so closely related 
to those of rudimentary organs given in the first chapter, 
that many of them might have been indifferently intro- 
duced in either chapter. Thus a human uterus furnished 
with cornua may be said to represent in a rudimentary 
condition the same organ in its 'normal state in certain 
mammals. Some parts which are rudimental in man, as 
the os coccyx in both sexes and the mammoe in the male 
sex, are always present ; while others, such - as the supra- 
condyloid foramen, only occasionally appear, and there- 
fore might have been introduced under the head of rever- 
sion. These several reversionary, as well as the strictly 
rudimentary, structures reveal the descent of man from 
some lower form in an unmistakable manner. 

Correlated Variation. — In man, as in the lower ani- 
mals, many structures are so intimately related, that when 
one part varies so does another, without our being able, 
in most, cases, to assign any reason. We cannot say 
whether the one part governs the other, or whether both 
are governed by some earlier developed part. Various 
monstrosities, as I. Geoffroy repeatedly insists, are thus 
intimately connected. Homologous structures are par- 
ticularly liable to change together, as we see on the op- 
posite sides of the body, and in the upper and lower ex- 
tremities. Meckel long ago remarked that when the 
muscles of the arm depart from their proper type, they 
almost always imitate those of the leg ; and so conversely 
with the muscles of the legs. The organs of sight and" 
hearing, the teeth and hair, the color of the skin and 



126 THE DESCENT OF MAN. [Part 1 

hair, color and constitution, are more or less correlated. 4 ' 
Prof. Schaaffhausen first drew attention to the relation 
apparently existing between a muscular frame and strong- 
ly-pronounced supra-orbital ridges, which are so char- 
acteristic of the lower races of man. 

Besides the variations which can be grouped with more 
or less probability under the foregoing heads, there is 
a large class of variations which may be provisionally 
called spontaneous, for they appear, owyig to our igno- 
rance, to arise without any exciting cause. It can, how- 
ever, be shown that such variations, whether consisting 
of slight individual differences, or of strongly-marked 
and abrupt deviations of structure, depend much more 
on the constitution of the organism than on the nature 
of the conditions to which it has been subjected. 1 



60 



Rate of Increase. — Civilized populations have been 
known under favorable conditions, as in the United States, 
to double their number in twenty-five years; and, ac- 
cording to a calculation by Euler, this might occur in a 
little over twelve years." At the former rate the present 
population of the United States, narhely, thirty millions, 
would in 657 years cover the whole terraqueous gldbe so 
thickly, that four men would have to stand on each square 
yard of surface. The primary or fundamental check to 
the continued increase of man is the difficulty of gaining 
subsistence and of living in comfort. We may infer that 
this is the case from what we see, for instance, in the 
United States, where subsistence is easy and there is 

49 The authorities for these several statements are given in my 
4 Variation of Animals under Domestication,' vol. ii. pp. 320-335. 

60 This whole subject has been discussed in chap, xxiii. vol. ii. of my 
* Variation of Animals and Plants under Domestication.' 

61 See the ever-memorable ' Essay on the Principle of Population,' 
by the Rev. T. Malthus, vol. i. 182G, pp. 6, 51V. 



^HAP. IV.] MANNER OF DEVELOPMENT. 127 

plenty of room. If such means were suddenly doubled 
in Great Britain, our number would be quickly doubled. 
"With civilized nations the above primary check acts 
chiefly by restraining marriages. The greater death-rate 
of infants in the poorest classes is also very important ; 
as well as the greater mortality at all ages, and from 
various diseases, of the inhabitants of crowded and mis- 
erable houses. The effects of severe epidemics and wars 
are soon counterbalanced, and more than counterbalanced, 
in nations placed under favorable conditions. Emigration 
also comes in aid as a temporary check, but not to any 
great extent with the extremely poor classes. 

There is reason to suspect, as Malthus has remarked, 
that the reproductive power is actually less in barbarous 
than in civilized races. We know nothing positively on 
this head, for with savages no census has been taken; 
but from the concurrent testimony of missionaries, and 
of others who have long resided with such people, it ap- 
pears that their families are usually small, and large ones 
rare. This may be partly accounted for, as it is believed, 
by the women suckling their infants for a prolonged 
period ; but it is highly probable that savages, who often 
suffer much hardship, and who do not obtain so much nu- 
tritious food as civilized men, would be actually less pro- 
lific. I have shown in a former work, &2 that all our do- 
mesticated quadrupeds and birds, and all our cultivated 
plants, are more fertile than the corresponding species in 
a state of nature. It is no valid objection to this con- 
clusion that animals suddenly supplied with an excess of 
food, or when rendered very fat, and that most plants 
when suddenly removed from very poor to very rich soil, 
are rendered more or less sterile. We miorht, therefore, 
expect that civilized men, who in one sense are highly do- 

58 ' Variation of Animals and Plants under Domestication,' vol. ii pp. 
111-113, 163. 



128 THE DESCENT OF MAN. [Part I. 

mesticated, would be more prolific than wild men. It is 
also probable that the increased fertility of civilized na- 
tions would become, as with our domestic animals, an in- 
herited character : it is at least known that with mankind 
a tendency to produce twins runs in families. 53 

Notwithstanding that savages appear to be less pro- 
lific than civilized people, they would no doubt rapidly in- 
crease if their numbers were not by some means* rigidly 
kept down. The Santali, or hill-tribes of India, have 
recently afforded a good illustration of this fact ; for they 
have increased, as shown by Mr. Hunter, 54 at an extraor- 
dinary rate since vaccination has been introduced, other 
pestilences mitigated, and war sternly repressed. This 
increase, however, would not have been possible had not 
these rude people spread into the adjoining districts and 
worked for hire. Savages almost always marry; yet 
there is some prudential restraint, for they do not com- 
monly marry at the earliest possible age. The young 
men are often required to show that they can support a 
wife, and they generally have first to earn the price with 
which to purchase her from her parents. With savages 
the difficulty of obtaining subsistence occasionally limits 
their number in a much more direct manner than with 
civilized people, for all tribes periodically suffer from se- 
vere famines. At such times savages are forced to devour 
much bad food, and their health can hardly fail to be in- 
jured. Many accounts have been published of their pro- 
truding stomachs and emaciated limbs after and during 
famines. They are then, also, compelled to wander much 
about, and their infants, as I was assured in Australia, 
perish in large numbers. As famines are periodical, de- 
pending chiefly on extreme seasons, all tribes must fluc- 

63 Mr. Sedgwick, 'British and Foreign Medico-Chirurg. Review,' July, 
1S63, p. 110. 

54 ' The Annals of Rural Bengal,' by W. W. Hunter, 1 868, p. 259. 



Chap. IV.] MAXXER OF DEYELOPMEXT. 129 

tuate in number. They cannot steadily and regalarly in- 
crease, as there is no artificial increase in the supply of 
food. Savages when hardly pressed encroach on each 
other's territories, and war is the result ; but they are in- 
deed almost always at war with their neighbors. They 
are liable to many accidents on land and water in their 
search for food ; and in some countries they must suffer 
much from the larger beasts of prey. Even in India, dis- 
tricts have been depopulated by the ravages of tigers. 

Malthus has discussed these several checks, but he 
does not lay stress enough on what is probably the most 
important of all, namely infanticide, especially of female 
infants, and the habit of procuring abortion. These prac- 
tices now prevail in many quarters of the world, and in- 
fanticide seems formerly to have prevailed, as Mr. M'Len- 
nan B5 has shown, on a still more extensive scale. These 
practices appear to have originated in savages recognizing 
the difficulty, or rather the impossibility, of supporting all 
the infants that are born. Licentiousness may also be 
added to the foregoing checks ; but this does not follow 
from failing means of subsistence ; though there is reason 
to believe that in some cases (as in Japan) it has been in- 
tentionally encouraged as a means of keeping down the 
population. 

If we look back to an extremely remote epoch, before 
man had arrived at the dignity of manhood, he would 
have been guided more by instinct and less by reason 
than are savages at the present time. Our early semi- 
human progenitors would not have practised infanticide, 
for the instincts of the lower animals are never so per- 
verted as to lead them regularly to destroy their own off- 
spring. There would have been no prudential restraint 
from marriage, and the sexes would have freely united at 
an early age. Hence the progenitors of man would have 

65 ' Primitive Marriage,' 1865. 



130 THE DESCENT OF MAN. [Paet L 

tended to increase rapidly, but checks of some kind, either 
periodical or constant, must have kept down their num- 
bers, even more severely than with existing savages. 
What the precise nature of these checks may have been, 
we cannot say, any more than with most other animals. 
We know that horses and cattle, which are not highly 
prolific animals, when first turned loose in South America, 
increased at an enormous rate. The slowest breeder of 
all known animals, namely the elephant, would in a few 
thousand years stock the whole world. The increase of 
every species of monkey must be checked by some means ; 
but not, as Brehm remarks, by the attacks of beasts of 
prey. No one will assume that the actual power of re- 
production in the wild horses and cattle of America was 
at first in any sensible degree increased ; or that, as each 
district became fully stocked, this same power was dimin- 
ished. JSTo doubt in this case, and in all others, many 
checks concur, and different checks under different circum- 
stances ; periodical dearths, depending on unfavorable 
seasons, being probably the most important of all. So it 
will have been with the early progenitors of man. 

Natural Selection. — We have now seen that man is 
variable in body and mind ; and that the variations are 
induced, either directly or indirectly, by the same general 
causes, and obey the same general laws, as with the lower 
animals. Man has spread widely over the face of the 
earth, and must have been exposed, during his incessant 
migrations, 66 to the most diversified conditions. The in- 
habitants of Tierra del Fnego, the Cape of Good Hope, 
and Tasmania in the one hemisphere, and of the Arctic 
regions in the other, must have j)assed through many cli- 
mates and changed their habits many times, before they 

68 See some good remarks to this effect by "W. Stanley Jevons, " A 
Deduction from Darwin's Theory," 'Nature,' 1869, p. 231. 



Ciiap. IV.] MANNER OF DEVELOPMENT. 131 

readied their present homes." The early progenitors of 
man must also have tended, like all other animals, to have 
increased beyond their means of subsistence ; they must 
therefore occasionally have been exposed to a struggle for 
existence, and consequently to the rigid law of natural 
selection. Beneficial variations of all kinds will thus, 
either occasionally or habitually, have been preserved, and 
injurious ones eliminated. I do not refer to strongly- 
marked deviations of structure, which occur only at long 
intervals of time, but to mere individual differences. "We 
know, for instance, that the muscles of our hands and feet, 
which determine our powers of movement, are liable, like 
those of the lower animals, 68 to incessant variability. If, 
then, the ape-like progenitors of man which inhabited any 
district, especially one undergoing some change in its con- 
ditions, were divided into two equal bodies, the one half 
which included all the individuals best adapted by their 
powers of movement for gaining subsistence or for defend- 
ing themselves, would on an average survive in greater 
number and procreate more offspring than the other and 
less well-endowed half. 

Man in the rudest state in which he now exists is the 
most dominant animal that has ever appeared on the earth. 
He has spread more widely than any other highly-organ- 
ized form ; and all others have yielded before him. He 
manifestly owes this immense superiority to his intellectual 
faculties, his social habits, which lead him to aid and de- 
fend his fellows, and to his corporeal structure. The 
supreme importance of these characters has been proved 

67 Latham, 'Man and his Migrations,' 1851, p. 135. 

6S Messrs. Murie and Mivart, in their "Anatomy of the Lemuroidea" 
( Transact. Zoolog. Soc.' vol. vii. 1869, pp. 96-98) say, " some muscles are 
bo irregular in their distribution that they cannot be well classed in any 
of the above groups." These muscles differ even on the opposite sides 
of the same individual. 



132 THE DESCENT OF MAN. [Part I. 

by the final arbitrament of the battle for life. Through 
his powers of intellect, articulate language has been 
evolved; and on this his wonderful advancement has 
mainly depended. He has invented and is able to use 
various weapons, tools, traps, etc., with which he defends 
himself, kills or catches prey, and otherwise obtains food. 
He has made rafts or canoes on which to fish or cross over 
to neighboring fertile islands. He has discovered the art 
of making fire, by which hard and stringy roots can be 
rendered digestible, and poisonous roots or herbs innocu- 
ous. This last discovery, probably the greatest, excepting 
language, ever made by man, dates from before the dawn 
of history. These several inventions, by which man in the 
rudest state has become so preeminent, are the direct re- 
sult of the development of his powers of observation, 
memory, curiosity, imagination, and reason. I cannot, 
therefore, understand how it is that Mr. "Wallace 69 main- 
tains, that "natural selection could only have endowed 
the savage with a brain a little superior to that of an 
ape." 

Although the intellectual powers and social habits of 

59 'Quarterly Review,' April, 1869, p. 392. This subject is more 
fully discussed in Mr. Wallace's ' Contributions to the Theory of Natural 
Selection,' 18*70, in which all the essays referred to in this work are re- 
published. The • Essay on Man ' has been ably criticised by Prof. Clapa- 
rede, one of the most distinguished zoologists in Europe, in an article 
published in the ' Bibliotheque Universelle,' June, 1870. The remark 
quoted in my text will surprise every one who has read Mr. Wallace's 
celebrated paper on ' The Origin of Human Races deduced from the 
Theory of Natural Selection,' originally published in the ' Anthropologi- 
cal Review,' May, 1864, p. clviii. I cannot here resist quoting a most 
just remark by Sir J.Lubbock ('Prehistoric Times,' 1865, p. 4*79) in 
reference to this paper, namely, that Mr. Wallace, "with characteristic 
unselfishness, ascribes it (i e., the idea of natural selection) unreservedly 
to Mr. Darwin, although, as is well known, he struck out the idea inde- • 
pendently, and published it, though not with the same elaboration, at the 
same time." 



Ciiap. IV.] MANNER OF DEVELOPMENT. 133 

man are of paramount importance to him, we must not 
underrate the importance of his bodily structure, to which 
subject the remainder of this chapter will be devoted. 
The development of the intellectual and social or moral 
faculties will be discussed in the following chapter. 

Even to hammer with precision is no easy matter, as 
every one who has tried to learn carpentry will admit. 
To throw a stone with as true an aim as can a Fuegian in 
defending himself, or in killing birds, requires the most 
consummate perfection in the correlated action of the 
muscles of the hand, arm, and shoulder, not to mention a 
fine sense of touch. In throwing a stone or spear, and in 
many oth£r actions, a man must stand firmly on his feet ; 
and this again demands the perfect coadaptation of nu- 
merous muscles. To chip a flint into the rudest tool, or 
to form a barbed spear or hook from a bone, demands the 
use of a perfect hand ; for, as a most capable judge, Mr. 
Schoolcraft, 60 remarks, the shaping fragments of stone into 
knives, lances, or arrow-heads, shows " extraordinary abil- 
ity and long practice." We have evidence of this in 
primeval men having practised a division of labor ; each 
man did not manufacture his own flint tools or rude pot- 
tery ; but certain individuals appear to have devoted 
themselves to such work, no doubt receiving in exchange 
the produce of "the chase. Archaeologists are convinced 
that an enormous interval of time elapsed before our an- 
cestors thought of grinding chipped flints into smooth 
tools. A man-like animal who possessed a hand and arm 
sufliciently perfect to throw a stone with precision or to 
form a flint into a rude tool, could, it can hardly be doubt- 
ed, with sufficient practice make almost any thing, as far 
as mechanical skill alone is concerned, which a civilized 

60 Quoted by Mr. Lawson Tait in his " Law of Natural Selection " — 
Dublin Quarterly Journal of Medical Science,' Feb. 1869. Dr. Keller ia 
likewise quoted to the same effect. 



134 THE DESCENT OF MAN. [Part I. 

man can make. The structure of the hand in this respect 
may be compared with that of the vocal organs, which in 
the apes are used for uttering various signal-cries, or, as in 
one species, musical cadences ; but in man closely similar 
vocal organs have become adapted through the inherited 
effects of use for the utterance of articulate language. 

Turning now to the nearest allies of man, and there- 
fore to the best representatives of our early progenitors, 
we find that the hands in the Quadrumana are constructed 
on the same general pattern as in us, but are far less per- 
fectly adapted for diversified uses. Their hands do not 
serve so well as the feet of a dog for locomotion ; as may 
be seen in those monkeys which walk on the tmter mar- 
gins of the palms, or on the backs of their bent fingers, 
as in the chimpanzee and orang. 61 Their hands, however, 
are admirably adapted for climbing trees. Monkeys seize 
thin branches or ropes, with the thumb on one side and 
the fingers and palm on the other side, in the same manner 
as we do. They can thus also carry rather large objects, 
such as the neck of a bottle, to their mouths. Baboons 
turn over stones and scratch up roots with their hands. 
They seize nuts, insects, or other small objects, with the 
thumb in opposition to the fingers, and no doubt they 
thus extract eggs and the young from the nests of birds. 
American monkeys beat the wild oranges* on the branches 
until the rind is cracked, and then tear it off with the fin- 
gers of the two hands. Other monkeys open mussel-shells 
with the two thumbs. With their fingers they pull out 
thorns and burs, and hunt for each other's parasites. In 
a state of Nature they break open hard fruits with the aid 
of stones. They roll down stones or throw them at their 
enemies ; nevertheless, they perform these various actions 
clumsily, and they are quite unable, as I have myself seen, 
to throw a stone with precision. 

61 Owen, 'Anatomy of Vertebrates,' vol. iii. p. 71. 



Chap, IV.] MANNER OF DEVELOPMENT. 135 

It seems to me far from true that because " objects are 
grasped clumsily " by monkeys, " a much less specialized 
organ of prehension " would have served them 6a as well 
as their present hands. On the contrary, I see no reason 
to doubt that a more perfectly constructed hand would 
have been an advantage to them, provided, and it is im- 
portant to note this, that their hands had not thus been 
rendered less well adapted for climbing trees. We may 
suspect that a perfect hand would have been disadvanta* 
geous for climbing ; as the most arboreal monkeys in 
the world, namely Ateles in America and Hylobates in 
Asia, either have their thumbs much reduced in size 
and even rudimentary, or their fingers partially coherent, 
so that their hands are converted into mere grasping- 
hooks. 63 

As soon as some ancient member in the great series of 
the Primates came, owing to a change in its manner of 
procuring subsistence, or to a change in the conditions 
of its native country, to live somewhat less on trees and 
more on the ground, its manner of progression would have 
been modified ; and in this case it would have had to be- 
come either more strictly quadrupedal or bipedal. Ba- 
boons frequent hilly and rocky districts, and only from 
necessity climb up high trees ; 64 and they have acquired 
almost the gait of a dog. Man alone has become a biped ; 
and we can, I think, partly see how he has come to assume 
his erect attitude, which forms one of the most conspicu- 
ous differences between him and his nearest allies. Man 
could not have attained his present dominant position in 
the world without the use of his hands, which are so ad- 

« 2 'Quarterly Review,' April, 1869, p. 392. 

63 In Hylobates syndactylies, as the name expresses, two of the digits 
regularly cohere ; and this, as Mr. Blyth informs me, is occasionally the 
case with the digits of H. agilis, lar, and leuciscus. 

w Brehm, ■ Thierleben,' B. i. s. 80. 



136 THE DESCENT OF MAN. [Part L 

mirably adapted to act in obedience to his will. As Sir 
C. Bell' 66 insists, "the hand supplies all instruments, and 
by its correspondence with the intellect gives him univer- 
sal dominion." But the hands and arms could hardly 
have become perfect enough to have manufactured weap- 
ons, or to have hurled stones and spears with a true aim, as 
long as they were habitually used for locomotion and for 
supporting the whole weight of the body, or as long as 
they were especially well adapted, as previously remarked, 
for climbing trees. Such rough treatment would also have 
blunted the sense of touch, on which their delicate use 
largely depends. From these causes alone it would have 
been an advantage to man to have become a biped ; but 
for many actions it is almost necessary that both arms and 
the whole upper part of the body should be free ; and he 
must for this end stand firmly on his feet. To gain this 
great advantage, the feet have been rendered flat, and the 
great-toe peculiarly modified, though this has entailed the 
loss of the power of prehension. It accords with the prin- 
ciple of the division of physiological labor, which prevails 
throughout the animal kingdom, that, as the hands became 
perfected for prehension, the feet should have become per- 
fected for support and locomotion. With some savages, 
however, the foot has not altogether lost its prehensile 
power, as shown by their manner of climbing trees and 
of using them in other ways. 66 

If it be an advantage to man to have his hands and 

65 "The Hand, its Mechanism," etc. ' Bridgewater Treatise,' 1833, 
p. 38. 

66 Hackel has an excellent discussion on the steps by which man be- 
came a biped: 'Natiirliche Schopfungsgeschichte,' 1868, s. 507. Dr. 
BUchner ('Conferences sur la Theorie Darwinienne,' 1869, p. 135) has 
given 'good cases of the use of the foot as a prehensile organ by man ; 
also on the manner of progression of the higher apes to which I allude 
in the following paragraph : see also Owen ('Anatomy of Vertebrates,' 
vol. iii. p. 71) on this latter subject. 



Chap. IV.] MANNER OF DEVELOPMENT. 137 

arms free and to stand firmly on his feet, of which there 
can be no doubt from his preeminent success in the battle 
of life, then I can see no reason why it should not have 
been advantageous to the progenitors of man to have be- 
come more and more erect or bipedal. They would thus 
have been better able to have defended themselves with 
stones or clubs, or to have attacked their prey, or other- 
wise obtained food. The best-constructed individuals 
would in the long-run have succeeded best, and have sur- 
vived in larger numbers. If the gorilla and a few allied 
forms had become extinct, it might have been argued with 
great force and apparent truth, that an animal could not 
have been gradually converted from a quadruped into a 
biped ; as all the individuals in an intermediate condition 
would have been miserably ill-fitted for progression. But 
we know (and this is well worthy of reflection) that sev- 
eral kinds of apes are now actually in this intermediate 
condition ; and no one doubts that they are on the whole 
well adapted for their conditions of life. Thus the gorilla 
runs with a sidelong shambling gait, but more commonly 
progresses by resting on its bent hands. The long-armed 
apes occasionally use their arms like crutches, swinging 
their bodies forward between them, and some kinds of 
Hylobates, without having been taught, can walk or run 
upright with tolerable quickness ; yet they move awk- 
wardly, and much less securely than man. We see, in 
short, with existing monkeys various gradations between 
a form of progression strictly like that of a quadruped 
and that of a biped or man. 

As the progenitors of man became more and more 
erect, with their hands and arms more and more modified 
for prehension and other purposes, with their feet and legs 
at the same time modified for firm support and progres- 
sion, endless other changes of structure would have been 

necessary. The pelvis would have had to be made broader, 

7 



138 THE DESCENT OF MAN". [Part L 

the spine peculiarly curved and the head fixed in an altered 
position, and all these changes have been attained by man. 
Prof. Schaafthausen 67 maintains that "the powerful mastoid 
processes of the human skull are the result of his erect 
position;" and these processes are absent in the orang, 
chimpanzee, etc., and are smaller in the gorilla than in 
man. Various other structures might here have been 
specified, which appear connected with man's erect posi- 
tion. It is very difficult to decide how far all these cor- 
related modifications are the result of natural selection, 
and how far of the inherited effects of the increased use of 
certain parts, or of the action of one part on another. No 
doubt these means of change act and react on each other : 
thus when certain muscles, and the crests of bone to which 
they are attached, become enlarged by habitual use, this 
shows that certain actions are habitually performed and 
must be serviceable. Hence the individuals which per- 
formed them best, would tend to survive in greater num- 
bers. 

The free use of the arms and hands, partly the cause 
and partly the result of man's erect position, appears to 
have led in an indirect manner to other modifications of 
structure. The early male progenitors of man were, as 
previously stated, probably furnished with great canine 
teeth ; but as they gradually acquired the habit of using 
stones, clubs, or other weapons, for fighting with their 
enemies, they would have used their jaws and teeth less 
and less. In this case, the jaws, together with the teeth, 
would have become reduced in size, as we may feel sure 
from innumerable analogous cases. In a future chapter we 
shall meet with a closely-parallel case, in the reduction or 
complete disappearance of the canine teeth in male rami* 

67 "On the Primitive Form of the Skull," translated in 'Anthropo- 
logical Review,' Oct. 1868, p. 428. Owen (' Anatomy of Vertebrates,' 
rol. ii. 1866, p. 551) on the mastoid processes in the higher apes. 



Chap. IV.] MANNER OF DEVELOPMENT. 139 

nants, apparently in relation with the development of 
their horns ; and in horses, in relation with their habit of 
fighting with their incisor teeth and hoofs. 

In the adult male anthropomorphous apes, as Riiti- 
meyer, 68 and others have insisted, it is precisely the effect 
which the jaw-muscles by their great development have 
produced on the skull, that causes it to differ so greatly in 
many respects from that of man, and has given to it " a 
truly frightful physiognomy." Therefore, as the jaws and 
teeth in the progenitors of man gradually become reduced 
in size, the adult skull would have presented nearly the 
same characters which it offers in the young of the an- 
thropomorphous apes, and would thus have come to 
resemble more nearly that of existing man. A great re- 
duction of the canine teeth in the males would almost cer- 
tainly, as we shall hereafter see, have affected through 
inheritance the teeth of the females. 

As the various mental faculties have gradually de- 
veloped, the brain would almost certainly have become 
larger. !N"o one, I presume, doubts that the large size of 
the brain in man, relatively to his body, in comparison to 
that of the gorilla or orang, is closely connected with his 
higher mental powers. We meet with closely-analogous 
facts with insects, in which the cerebral ganglia are of 
extraordinary dimensions in ants ; these ganglia in all the 
Hymenoptera being many times larger than in the less in- 
telligent orders^ such as beetles. 69 On the other hand, no 
one supposes that the intellect of any two animals, or of 
any two men, can be accurately gauged by the cubic con- 

68 ' Die Grenzen der Thierwelt, eine Betrachtung zu Darwin's Lehre,' 
1868, s. 51. 

69 Dujardin, ■ Annates des Sc. Nat.' 3d series, Zoolog. torn. xiv. 1850, 
p. 203. See also Mr. Lowrie, ' Anatomy and Phys. of the Musca vomito. 
via,' 18*70, p. 14. My son, Mr. F. Darwin, dissected for me the cerebral 
ganglia of the Formica rufa. 



140 THE DESCENT OF MAN. [Part L 

tents of their skulls. It is certain that there may be extraor- 
dinary mental activity with an extremely small absolute 
mass of nervous matter ; thus the wonderfully diversified 
instincts, mental powers, and affections of ants, are gen- 
erally known, yet their cerebral ganglia are not so large 
as the quarter of a small pin's head. Under this latter 
point of view, the brain of an ant is one of the most mar- 
vellous atoms of matter in the world, perhaps more mar- 
vellous than the brain of man. 

The belief that there exists in man some close relation 
between the size of the brain and the development of the 
intellectual faculties is supported by the comparison of the 
skulls of savage and civilized races, of ancient and modern 
people, and by the analogy of the whole vertebrate series. 
Dr. J. Barnard Davis has proved 70 by many careful meas- 
urements, that the mean internal capacity of the skull in 
Europeans is 92.3 cubic inches; in Americans 87.5; in 
Asiatics 87.1 ; and in Australians only 81.9 inches. Prof. 
Broca 71 found that skulls from graves in Paris of the 
nineteenth century, were larger than those from vaults of 
the twelfth century, in the proportion of 1484 to 1426; 
and Prichard is persuaded that the present inhabitants of 
Britain have "much more capacious brain-cases" than the 
ancient inhabitants. Nevertheless it must be admitted 
that some skulls of very high antiquity, such as the famous 
one of Neanderthal, are well developed and capacious. 
With respect to the lower animals, M. E. Lartet, 72 by 
comparing the crania of tertiary and recent mammals, be- 
longing to the same groups, has come to the remarkable 
conclusion that the brain is generally larger and the con- 
volutions more complex in the more recent form. On the 

70 'Philosophical Transactions,' 1869, p. 513. 

n Quoted in C. Vogt's 'Lectures on Man,' Eng. translat. 1864, pp. 88, 
90. Prichard, ' Phys. Hist, of Mankind,' vol. i. 1838, p. 305 
19 ' Coinptes Rendus des Seances,' etc., June 1, 1868. 



Chap. IT.] MANNER OF DEVELOPMENT. 141 

other hand, I have shewn 73 that the brains of domestic 
rabbits are considerably reduced in bulk, in comparison 
with those of the wild rabbit, or hare ; and this may be 
attributed to their having been closely confined during 
many generations, so that they have exerted but little 
their intellect, instincts, senses, and voluntary movements. 
The gradually-increasing weight of the brain and 
skull in man must have influenced the development of the 
supporting spinal column, more especially while he was 
becoming erect. As this change of position was being 
brought about, the internal pressure of the brain will, 
also, have influenced the form of the skull ; for many facts 
show how easily the skull is thus afteeted. Ethnologists 
believe that it is modified by the kind of cradle in which 
infants sleep. Habitual spasms of the muscles and a cic- 
atrix from a severe burn have permanently modified the 
facial bones. In young persons whose heads from disease 
have become fixed either sideways or backward, one of 
the eyes has changed its position, and the bones of the 
skull have been modified; and this apparently results 
from the brain pressing in a new direction. 74 I have shown 
that with lono;-eared rabbits, even so trifling a cause as 
the lopping forward of one ear drags forward on that side 
almost every bone of the skull ; so that the bones on the 
opposite sides no longer strictly correspond.- Lastly, if any 
animal were to increase or diminish much in general size, 
without any change in its mental powers ; or if the mental 

73 ' The Variation of Animals and Plants under Domestication,' vol. i. 
pp. 124-129. 

74 Schaaffhausen gives from Blumenbach and Busch, the cases of the 
spasms and cicatrix, in ' Anthropolog. Review,' Oct. 1868, p. 420. Dr. 
Jarrold (' Anthropologia,' 1808, pp. 115, 116) adduces from Camper and 
from his own observations, cases of the modification of the skull from 
the head being fixed in an unnatural position. He believes that certain 
trades, such as that of a shoemaker, by causing the head to be habitually 
held forward, makes the forehead more rounded and prominent. 



142 THE DESCENT OF MAN. [P^rt I. 

powers were to be much increased, or diminished, without 
any great change in the size of the body; the shape of 
the skull would almost certainly be altered. I infer this 
from my observations on domestic rabbits, some kinds of 
which have become very much larger than the wild 
animal while others have retained nearly the same size, 
but in both cases the brain has been much reduced rela- 
tively to the size of the body. Now I was at first much 
surprised by finding that in all these rabbits the skull had 
become elongated or dolichocephalic ; for instance, of two 
skulls of nearly equal breadth, the one from a wild rabbit 
and the other from a large domestic kind, the former was 
only 3.15, and the latter 4.3 inches in length. 75 One of 
the most marked distinctions in different races of man is 
that the skull in some is elongated, and in others rounded ; 
and here the explanation suggested by the case of the 
rabbits may partially hold good ; for Welcker finds that 
" short men incline more to brachycephaly, and tall men 
to dolichocophaly ; " " and tall men may be compared with 
the larger and longer-bodied rabbits, all of which have 
elongated skulls, or are dolichocephalic. 

From these several facts we can to a certain extent 
understand the means through which the great size and 
more or less rounded form of the skull has been acquired 
by man ; and these are characters eminently distinctive of 
him in comparison with the lower animals. 

Another most conspicuous difference between man and 
the lower animals is the nakedness of his skin. Whales 
and dolphins (Cetacea), dugongs (Sirenia), and the hip- 
popotamus, are naked ; and this may be advantageous to 
them for gliding through the water; nor would it be in- 

15 'Variation of Animals,' etc., vol. i. p. 117 on the elongation of the 
skull ; p. 119, on the effect of the lopping of one ear. 

" 6 Quoted by Schaaflfhausen, in * Anthropolog. Review,' Oct 18C8J 
p. 419. 



Chap. IV.] MANNER OF DEVELOPMENT. 143 

jurious to them from the loss of warmth, as the species 
which inhabit the colder regions are protected by a thick 
layer of blubber, serving the same purpose as the fur of 
seals and otters. Elephants and rhinoceroses are almost 
hairless; and, as certain extinct species which formerly 
lived under an arctic climate were covered with long wool 
or hair, it would almost appear as if the existing species 
of both genera had lost their hairy covering from expos- 
ure to heat. This appears the more probable, as the 
elephants in India which live on elevated and cool dis- 
tricts are more hairy 77 than those on the lowlands. May 
we then infer that man became divested of hair from hav- 
ing aboriginally inhabited some tropical land ? The fact 
of the hair being chiefly retained in the male sex on the 
chest and face, and in both sexes at the junction of all 
four limbs with the trunk, favors this inference, assuming 
that the hair was lost before man became erect ; for the 
parts which now retain most hair would then have been 
most protected from the heat of the sun. The crown of 
the head, however, offers a curious exception, for at all 
times it must have been one of the most exposed parts, 
yet it is thickly clothed with hair. In this respect man 
agrees with the great majority of quadrupeds, which gen- 
erally have their upper and exposed surfaces more thickly 
clothed than the lower surface. Nevertheless, the fact 
that the other members of the order of Primates, to which 
man belongs, although inhabiting various hot regions, are 
well clothed with hair, generally thickest on the upper 
surface, 78 is strongly opposed to the supposition that man 
became naked through the action of the sun. I am in- 

71 Owen, 'Anatomy of Vertebrates,' vol. iii. p. 619. 

13 Isidore Geoffroy St.-Hilaire remarks ('Hist. Nat. Generale,' torn, 
ii 1859, pp. 215-217) on the head of man being covered with long hair; 
also on the upper surfaces of monkeys and of other mammals being more 
thickly clothed than the lower surfaces. This has likewise been ob- 



144 THE DESCENT OF MAN. [Part I. 

clined to believe, as we shall see under sexual selection, 
that man, or rather primarily woman, became divested of 
hair for ornamental purposes ; and according to this belief 
it is not surprising that man should differ so greatly in 
hairiness from all his lower brethren, for characters gained 
through sexual selection often differ in closely-related 
forms to an extraordinary degree. 

According to a popular impression, the absence of a 
tail is eminently distinctive of man ; but as those apes 
which come nearest to man are destitute of this organ, 
its disappearance does not especially concern us. Never- 
theless it may be well to own that no explanation, as far 
as I am aware, has ever been given of the loss of the tail 
by certain apes and man. Its loss, however, is not sur- 
prising, for it sometimes differs remarkably in length in 
species of the same genera: thus in some species of Maca- 
cus the tail is longer than the whole body, consisting of 
twenty-four vertebrae ; in others it consists of a scarcely- 
visible stump, containing only three or four vertebra?. In 
some kinds of baboons there are twenty-five, while in the 
mandrill there are ten very small stunted caudal vertebra?, 
or, according to Cuvier, 79 sometimes only five. This great 
diversity in the structure and length of the tail in animals 
belonging to the same genera, and following nearly the 
same habits of life, renders it probable that the tail is not 
of much importance to them ; and if so, we might have ex- 
pected that it would sometimes have become more or less 
rudimentary, in accordance with what we incessantly see 

served by various authors. Prof. P. Gervais ('Hist. Nat. des Mammi- 
fcres,' torn. i. 1854, p. 28), however, states that in the Gorilla the hair ia 
thinner on the back, where it is partly rubbed off, than on the lower sur- 
face. 

19 Mr. St. George Mivart, ' Proc. Zoolog. Soc.' 1805, pp*. 562, 583. Dr. 
J. E. Gray, ' Cat. Brit. Mus. : Skeletons.' Owen, ' Anatomy of Verte- 
brates,' vol. ii. p. 517. Isidore Geoffroy, ' Hist. Nat. Gen.' torn. ii. p. 244. 



TnAP. IV.] MANNER OF DEVELOPMENT. 145 

with other structures. The tail almost always tapers 
toward the end, whether it be long or short ; and this, I 
presume, results from the atrophy, through disuse, of the 
terminal muscles, together with their arteries and nerves, 
leading to the atrophy of the terminal bones. With re- 
spect to the os coccyx, which in man and the higher apes 
manifestly consists of the few basal and tapering segments 
of an ordinary tail, I have heard it asked how could these 
have become completely embedded within the body ; but 
there is no difficulty in this respect, for in many monkeys 
the basal segments of the true tail are thus embedded. 
For instance, Mr. Marie informs me that in the skeleton ot 
a not full-grown 3Iacacus inornatus, he counted nine or 
ten caudal vertebrae, which altogether were only 1.8 inch 
in length. Of these the three basal ones appeared to have 
been embedded ; the remainder forming the free part of 
the tail, which was only one inch in length, and half an 
inch in diameter. Here, then, the three embedded caudal 
vertebrae plainly correspond with the four coalesced ver- 
tebrae of the human os coccyx. 

I have now endeavored to show that some of the most 
distinctive characters of man have in all probability been 
acquired, either directly, or more commonly indirectly, 
through natural selection. "We should bear in mind that 
modifications in structure or constitution, which are of no 
service to an organism in adapting it to its habits of life, 
to the food which it consumes, or passively to the sur- 
rounding conditions, cannot have been thus acquired. 
We must not, however, be too confident in deciding what 
modifications are of service to each being : we should re- 
member how little we know about the use of many parts, 
or what changes in the blood or tissues may serve to fit 
an organism for a new climate or some new kind of food. 
Nor must we forget the principle of correlation, by which, 



146 THE DESCENT OF MAN. [Part L 

as Isidore Geoffroy lias shown in the case of man, many 
strange deviations of structure are tied together. Inde- 
pendently oi correlation, a change in one part often leads, 
through the increased or decreased use of other parts, to 
other changes of a quite unexpected nature. It is also 
well to reflect on such facts, as the wonderful growth of 
galls on plants caused by the poison of an insect, and on 
the remarkable changes of color in the plumage of parrots 
when fed on certain fishes, or inoculated with the poison 
of toads ; 80 for we can thus see that the fluids of the 
system, if altered for some special purpose, might induce 
other strange changes. We should especially bear in 
mind that modifications acquired and continually used 
during past ages for some useful purpose would probably 
become firmly fixed and might be long inherited. 

Thus a very large yet undefined extension may safely 
be given to the direct and indirect results of natural selec- 
tion ; but I now admit, after reading the essay by Nageli 
on plants, and the remarks by various authors with respect 
to animals, more especially those recently made by Prof. 
Broca, that in the earlier editions of my ' Origin of Spe- 
cies ' I probably attributed too much to the action of natu- 
ral selection or the survival of the fittest. I have altered 
the fifth edition of the Origin so as to confine my remarks 
to adaptive changes of structure. I had not formerly 
sufficiently considered the existence of many structures 
which appear to be, as far as we can judge, neither bene- 
ficial nor injurious ; and this I believe to be one of the 
greatest oversights as yet detected in my work. I may 
be permitted to say, as some excuse, that I had two dis- 
tinct objects in view, firstly, to show that species had not 
been separately created, and secondly, that natural selec- 
tion had been the chief agent of change, though largely 

80 ' The Variation of Animals and Plants under Domestication/ \ ol. ii 
pp. 280. 282. 



Chap. IT.] MANNER OF DEVELOPMENT. 147 

aided by the inherited effects of habit, and slightly by the 
direct action of the surrounding conditions. Nevertheless 
I was not able to annul the influence of my former belief, 
then widely prevalent, that each species had been pur- 
posely created; and this led to my tacitly assuming that 
every detail of structure, excepting rudiments, was of 
some special, though unrecognized, service. Any one 
with this assumption in his mind would naturally extend 
the action of natural selection, either during past or pres- 
ent times, too far. Some of those who admit the principle 
of evolution, but reject natural selection, seem to forget, 
when criticising mv book, that I had the above two ob- 
jects in view ; hence if I have erred in giving to natural 
selection great power, which I am far from admitting, or 
in having exaggerated its power, which is in itself prob- 
able, I have at least, as I hope, done good service in aid- 
ing to overthrow the dogma of separate creations. 

That all organic beings, including man, present many 
modifications of structure which are of no service to them 
at present, nor have been formerly, is, as I can now see, 
probable. We know not what produces, the numberless 
slight differences between the individuals of each species, 
for reversion only carries the problem a few steps back- 
ward ; but each peculiarity must have had its own efficient 
cause. If these causes, whatever they may be, were to 
act more uniformly and energetically during a lengthened 
period (and no reason can be assigned why this should not 
sometimes occur), the result would probably be not mere 
slight individual differences, but well-marked, constant 
modifications. Modifications which are in no way bene- 
ficial cannot have been kept uniform through natural se- 
lection, though any which were injurious would have been 
thus eliminated. Uniformity of character would, how- 
ever, naturally follow from the assumed uniformity of the 
exciting causes, and likewise from the free intercrossing 



148 THE DESCENT OF MAN. [Part L 

of many individuals. The same organism might acquire 
in this manner during successive periods successive modi- 
fications, and these would be transmitted in a nearly uni- 
form state as long as the exciting causes remained the 
same and there was free intercrossing. With respect to 
the exciting causes we can only say, as when speaking of 
so-called spontaneous variations, that they relate much 
more closely to the constitution of the varying organism, 
than to the nature of the conditions to which it has been 
subjected. 

Conclusion. — In this chapter we have seen that as man 
at the present day is liable, like every other animal, to 
multiform individual differences or slight variations, so no 
doubt were the early progenitors of man ; the variations 
being then as now induced by the same general causes, 
and governed by the same general and complex laws. As 
all animals tend to multiply beyond their means of sub- 
sistence, so it must have been with the progenitors of 
man $ and this will inevitably have led to a struggle for 
existence and to natural selection. This latter process 
will have been greatly aided by the inherited effects of 
the increased use of parts ; these two processes incessant- 
ly reacting on each other. It appears, also, as we shall 
hereafter see, that various unimportant characters have 
been acquired by man through sexual selection. An unex- 
plained residuum of change, perhaps a large one, must be 
left to the assumed uniform action of those unknown agen- 
cies, which occasionally induce strongly-marked and ab- 
rupt deviations of structure in our domestic productions. 

Judging from the habits of savages and of the greater 
number of the Quadrumana, primeval men, and even the 
ape-like progenitors of man, probably lived in society. 
With strictly social animals, natural selection sometimes 
acts indirectly on the individual, through the preservation 



Chap. IY.] MANNER OF DEVELOPMENT. 149 

' of variations which are beneficial only to the community. 
A community including a large number of well-endowed 
individuals increases in number and is victorious over 
other and less well-endowed communities ; although each 
separate member may gain no advantage over the other 
members of the same community. With associated in- 
sects many remarkable structures, which are of little or 
no service to the individual or its own offspring, such as 
the pollen-collecting apparatus, or the sting of the worker- 
bee, or the great jaws of soldier-ants, have been thus ac- 
quired. With the higher social animals, I am not aware 
that any structure has been modified solely for the good 
of the community, though some are of secondary service 
to it. For instance, the horns of ruminants and the great 
canine teeth of baboons appear to have been acquired by 
the males as weapons for sexual strife, but they are used 
in defence of the herd or troop. In regard to certain 
mental faculties the case, as we shall see in the following 
chapter, is wholly different ; for these faculties have been 
chiefly, or even exclusively, gained for the benefit of the 
community ; the individuals composing the community 
being at the same time indirectly benefited. 

It has often been objected to such views as the fore- 
going, that man is one of the most helpless and defence- 
less creatures in the world ; and that during his early and 
less well-developed condition he would have been still 
more helpless. The Duke of Argyll, for instance, insists 81 
that "the human frame has diverged from the structure 
of brutes, in the direction of greater physical helplessness 
and weakness. That is to say, it is a divergence which of 
all others it is most impossible to ascribe to mere natural 
selection." He adduces the naked and unprotected state 

81 'Primeval Man,' 1869, p. 66. 



150 THE DESCENT OF MAN. [Part I. 

of the body, the absence of great teeth or claws for de- 
fence, the little strength of man, his small speed in run- 
ning, and his slight power of smell, by which to discover 
food or to avoid danger. To these deficiencies there 
might have been added the still more serious loss of the 
power of quickly climbing trees, so as to escape from ene- 
mies. Seeing that the unclothed Fuegians can exist under 
their wretched climate, the loss of hair would not have 
been a great injury to primeval man, if he inhabited a 
warm country. When we compare defenceless man with 
the apes, many of which are provided with formidable 
canine teeth, we must remember that these in their fully- 
developed condition are possessed by the males alone, 
being chiefly used by them for fighting with their rivals ; 
yet the females, which are not thus provided, are able to 
survive. 

In regard to bodily size or strength, we do not know 
whether man is descended from some comparatively small 
species, like the chimpanzee, or from one as powerful as 
the gorilla ; and, therefore, we cannot say whether man 
has become larger and stronger, or smaller and weaker, 
in comparison with his progenitors. We should, how- 
ever, bear in mind that an animal possessing great size, 
strength, and ferocity, and which, like the gorilla, could 
defend itself from all enemies, would probably, though 
not necessarily, have failed to become social ; and this 
would most effectually have checked the acquirement by 
man of his higher mental qualities, such as sympathy and 
the love of his fellow-creatures. Hence it might have 
been an immense advantage to man to have sprung from 
some comparatively weak creature. 

The slight corporeal strength of man, his little speed, 
his want of natural weapons, etc., are more than counter- 
balanced, firstly by his intellectual powers, through which 
he has, while still remaining in a barbarous state, formed 



Chip. IV.] MANNER OF DEVELOPMENT.. 151 

for himself weapons, tools, etc., and secondly by his social 
qualities which lead him to give aid to his fellow-men and 
to receive it in return. No country in the world abounds 
in a greater degree with dangerous beasts than Southern 
Africa; no country presents more fearful physical hard- 
ships than the Arctic regions ; yet one of the puniest races, 
namely, the Bushmen, maintain themselves in Southern 
Africa, as do the dwarfed Esquimaux in the Arctic 
regions. The early progenitors of man were, no doubt, 
inferior in intellect, and probably in social disposition, to 
the lowest existing savages ; but it is quite conceivable 
that they might have existed, or even flourished, if, while 
they gradually lost their brute-like powers, such as climb- 
ing trees, etc., they at the same time advanced in intellect. 
But granting that the progenitors of man were far more 
helpless and defenceless than any existing savages, if they 
had inhabited some warm continent, or large island, such 
as Australia or New Guinea, or Borneo (the latter island 
being now tenanted by the orang), they would not have 
been exposed to any special danger. In an area as large 
as one of these islands, the competition between tribe and 
tribe would have been sufficient, under favorable con- 
ditions, to have raised man, through the survival of the 
fittest, combined with the inherited effects of habit, to his 
present high position in the organic scale. 



152 THE DESCENT OF MAN. TP^rt I. 



CHAPTER V. 

DN THE DEVELOPMENT OF THE INTELLECTUAL AND MORAL 
FACULTIES DURING PRIMEVAL AND CIVILIZED TIMES. 

The Advancement of the Intellectual Powers through Natural Selection. — 
Importance of Imitation. — Social and Moral Faculties. — Their Develop- 
ment within the Limits of the same Tribe. — Natural Selection as af- 
fecting Civilized Nations. — Evidence that Civilized Nations were onoe 
barbarous. 

The subjects to be discussed in this chapter are of the 
highest interest, but are treated by me in a most imperfect 
and fragmentary manner. Mr. Wallace, in an admirable 
paper before referred to, 1 argues that man, after he had 
partially acquired those intellectual and moral faculties 
which distinguish him from the lower animals, would have 
been but little liable to have had his bodily structure 
modified through natural selection or any other means. 
For man is enabled through his mental faculties " to keep 
with an unchanged body in harmony with the changing 
universe." He has great power of adapting his habits to 
new conditions of life. He invents weapons, tools, and 
various stratagems, by which he procures food and de- 
fends himself. When he migrates into a colder climate 
he uses clothes, builds sheds, and makes fires ; and, by the 
aid of fire, cooks food otherwise indigestible. He aids his 
fellow-men in many ways, and anticipates future events. 



i < 



Anthropological Review,' May, 1864, p. clviii. 



Chap. V.] INTELLECTUAL FACULTIES. 153 

Even at a remote period he practised some subdivision of 
labor. 

The lower animals, on the other hand, must have their 
bodily structure modified in order to survive under great- 
ly-changed conditions. They must be rendered stronger, 
or acquire more effective teeth or claws, in order to defend 
themselves from new enemies ; or thev must be reduced 
in size so as to escape detection and danger. When they 
migrate into a colder climate they must become clothed 
with thicker fur, or have their constitutions altered. If 
they fail to be thus modified, they will cease to exist. 

The case, however, is widely different, as Mr. Wallace 
has with justice insisted, in relation to the intellectual and 
moral faculties of man. These faculties are variable ; and 
we have every reason to believe that the variations tend 
to be inherited. Therefore, if they were formerly of high 
importance to primeval man and to his ape-like pro- 
genitors, they would have been perfected or advanced 
through natural selection. Of the high importance of the 
intellectual faculties there can be no doubt, for man main- 
ly owes to them his preeminent position in the world. 
We can see that, in the rudest state of society, the indi- 
viduals who were the most sagacious, who invented and 
used the best weapons or traps, and who were best able 
to defend themselves, would rear the greatest number of 
offspring. The tribes which included the largest number 
of men thus endowed would increase in number and sup- 
plant other tribes. Numbers depend primarily on the 
means of subsistence, and this, partly on the physical 
nature of the country, but in a much higher degree on the 
arts which are there practised. As a tribe increases and 
is victorious, it is often still further increased by the ab- 
sorption of other tribes. 3 The stature and strength of the 
men of a tribe are likewise of some importance for its sue- 

8 After a time the members, or tribes, which are absorbed into an- 



154 THE DESCENT OF MAN. [Part I 

cess, and these depend in part on the nature and amount 
of the food which can be obtained. In Europe the men 
of the Bronze period were supplanted by a more powerful 
and, judging from their sword-handles, larger-handed 
race ; 3 but their success was probably due in a much 
higher degree to their superiority in the arts.- 

All that we know about savages, or may infer from 
their traditions and from old monuments, the history of 
which is quite forgotten by the present inhabitants, shows 
that from the remotest times successful tribes have sup- 
planted other tribes. Relics of extinct or forgotten tribes 
have been discovered throughout the civilized regions of 
the earth, on the wild plains of America, and on the iso- 
lated islands in the Pacific Ocean. At the present day 
civilized nations are everywhere supplanting barbarous 
nations, excepting where the climate opposes a deadly bar- 
rier; and they succeed mainly, though not exclusively, 
through their arts, which are the products of the intellect. 
It is, therefore, highly probable that with mankind the in- 
tellectual faculties have been gradually perfected through 
natural .selection ; and this conclusion is sufficient for our 
purpose. Undoubtedly it would have been very inter- 
esting to have traced the development of each separate 
faculty from the state in which it exists in the lower 
animals to that in which it exists in man ; but neither my 
ability nor knowledge permits the attempt. 

It deserves notice that as soon as the progenitors of 
man became social (and this probably occurred at a very 
early period), the advancement of the intellectual faculties 
will have been aided and modified in an important manner, 
of which we see only traces in the lower animals, namely, 
through the principle of imitation, together with reason 

other tribe assume, as Mr. Maine remarks ('Ancient Law, 1 1861, p. 131), 
that they are the co-descendants of the same ancestors. 
3 Morlot, ' Soc. Vaud. Sc. Nat.' 1860, p. 294 






Chap. Y.] INTELLECTUAL FACULTIES. 155 

and experience. Apes are much given to imitation, as are 
the lowest savages ; and the simple fact, previously re- 
ferred to, that after a time no animal can be caught in the 
same place by the same sort of trap, shows that animals 
learn by experience, and imitate each other's caution. 
Now, if some one man in a tribe, more sagacious than the 
others, invented a new snare or weapon, or other means 
of attack or defence, the plainest self-interest, without the 
assistance of much reasoning power, would prompt the 
other members to imitate him ; and all would thus profit. 
The habitual practice of each new art must likewise in 
some slight degree strengthen the intellect. If the new 
invention were an important one, the tribe would increase 
in number, spread, and supplant other tribes. In a tribe 
thus rendered more numerous there would always be a 
rather better chance of the birth of other superior and in- 
ventive members. If such men left children to inherit 
their mental superiority, the chance of the birth of still 
more ingenious members would be somewhat better, and 
in a very small tribe decidedly better. Even if they left 
no children, the tribe would still include their blood- 
relations ; and it has been ascertained by agriculturists 4 
that by preserving and breeding from the family of an 
animal, which when slaughtered was found to be valuable, 
the desired character has been obtained. 

Turning: now to the social and moral faculties. In 
order that primeval men, or the ape-like progenitors of 
man, should have become social, they must have acquired 
the same instinctive feelings which impel other animals to 
live in a body ; and they no doubt exhibited the same 
general disposition. They would have felt uneasy when 
separated from their comrades, for whom they would have 

* I have given instances in my • Variation of Animals under Domesti- 
cation,' vol. ii. p. 196. 



156 THE DESCENT OF MAN. [Part L 

felt some degree of love ; they would have warned each 
other of danger, and have given mutual aid in attack or 
defence. All this implies some degree of sympathy, fidel- 
ity, and courage. Such social qualities, the paramount 
importance of which to the lower animals is disputed by 
no one, were no doubt acquired by the progenitors of man 
in a similar manner, namely, through natural selection, 
aided by inherited habit. When two tribes of primeval 
man, living in the same country, came into competition, 
if the one tribe included (other circumstances being 
equal) a greater number of courageous, sympathetic, and 
faithful members, who were "always ready to warn each 
other of danger, to aid and defend each other, this tribe 
would without doubt succeed best and conquer the other. 
Let it be borne in mind how all-important, in the never- 
ceasing wars of savages, fidelity and courage must be. 
The advantage which disciplined soldiers have over un- 
disciplined hordes follows chiefly from the confidence 
which each man feels in his comrades. Obedience, as Mr. 
Bagehot has well shown, 6 is of the highest value, for any 
form of government is better than none. Selfish and con- 
tentious people will not cohere, and without coherence 
nothing can be effected. A tribe possessing the above 
qualities in a high degree would spread and be victorious 
over other tribes ; but in the course of time it would, 
judging from all past history, be in its turn overcome by 
some other and still more highly-endowed tribe. Thus 
the social and moral qualities would tend slowly to ad- 
vance and be diffused throughout the world. 

But it may be asked, How within the limits of the 
same tribe did a large number of members first become 
endowed with these social and moral qualities, and how 
was the standard of excellence raised ? It is extremely 

6 See a remarkable series of articles ou Physics and Politics in the 
Fortnightly Review,' Nov. 1867; April 1, 1868 ; July 1, 1869. 



Chap. V.] MORAL FACULTIES. 157 

doubtful whether the offspring of the more sympathetic 
and benevolent parents, or of those which were the most 
faithful to their comrades, would be reared in greater 
number than the children of selfish and treacherous par- 
ents of the same tribe. He who was ready to sacrifice his 
life, as many a savage has been, rather than betray his 
comrades, would often leave no offspring to inherit his 
noble nature. The bravest men, who were always willing 
to come to the front in war, and who freely risked their 
lives for others, would on an average perish in larger num- 
ber than other men. Therefore it seems scarcely possible 
(bearing in mind that we are not here speaking of one 
tribe being victorious over another) that the number of 
men gifted with such virtues, or that the standard of their 
excellence, could be increased through natural selection, 
that is, by the survival of the fittest. 

Although the circumstances which lead to an increase 
in the number of men thus endowed within the same tribe 
are too complex to be clearly followed out, we can trace 
some of the probable steps. In the first place, as the rea- 
soning powers and foresight of the members became im- 
proved, each man would soon learn from experience that, 
if he aided his fellow-men, he would commonly receive aid 
in return. From this low motive he might acquire the 
habit of aiding his fellows ; and the habit of performing 
benevolent actions certainly strengthens the feeling of 
sympathy, which gives the first impulse to benevolent ac- 
tions. Habits, moreover, followed during many genera- 
tions probably tend to be inherited. 

But there is anotner and much more powerful stimulus 
to the development of the social virtues, namely, the 
praise and the blame of our fellow-men. The love of ap- 
probation and the dread of infamy, as well as the be- 
stowal of praise or blame, are primarily due, as we have 
6een in the third chapter, to the instinct of sympathy ; 



158 THE DESCENT OF MAN. [Part L 

and this instinct no doubt was originally acquired, like all 
the other social instincts, through natural selection. At 
how early a period the progenitors of man, in the course 
of their development, became capable of feeling and being 
impelled by the praise or blame of their fellow-creatures, 
we cannot, of course, say. But it appears that even dogs 
appreciate encouragement, praise, and blame. The rudest 
savages feel the sentiment of glory, as they clearly show 
by preserving the trophies of their prowess, by their 
habit of excessive boasting, and even by the extreme care 
which they take of their personal appearance and decora- 
tions ; for unless they regarded the opinion of their com- 
rades, such habits would be senseless. 

They certainly feel shame at the breach of some of 
their lesser rules ; but how far they experience remorse is 
doubtful. I was at first surprised that I could not recol- 
lect any recorded instances of this feeling in savages ; and 
Sir J. Lubbock 6 states that he knows of none. But if we 
banish from our minds all cases given in novels and plays 
and in death-bed confessions made to priests, I doubt 
whether many of us have actually witnessed remorse; 
though we may have often seen shame and contrition for 
smaller offences. Remorse is a deeply-hidden feeling. It 
is incredible that a savage, who will sacrifice his life 
rather than betray his tribe, or one who will deliver him- 
self up as a prisoner rather than break his parole, 7 would 
not feel remorse in his inmost soul, though he might con- 
ceal it, if he had failed in a duty which he held sacred. . 

We may therefore conclude that primeval man, at a 
very remote period, would have been influenced by the 
praise and blame of his fellows. It is obvious, that the 
members of the same tribe would approve of conduct 

6 'Origin of Civilization,' 1870, p. 265. 

7 Mr. Wallace gives cases in his ' Contributions to the Theory of 
Natural Selection,' 18T0, p 354. 



Chap. V,] MORAL FACULTIES. 159 

which appeared to them to be for the general good, and 
would reprobate that which appeared evil. To do good 
unto others — to do unto others as ye would they should 
do unto you — is the foundation-stone of morality. It is, 
therefore, hardly possible to exaggerate the importance 
during rude times of the love of praise and the dread of 
blame. A man who was not impelled by any deep, in- 
stinctive feeling, to sacrifice his life for the good of others, 
yet was roused to such actions by a sense of glory, would 
by his example excite the same wish for glory in other 
men, and would strengthen by exercise the noble feeling 
of admiration. He might thus do far more good to his 
tribe than by begetting offspring with a tendency to in- 
herit his own high character. 

"With increased experience and reason, man perceives 
the more remote consequences of his actions, and the self- 
regarding virtues, such as temperance, chastity, etc., 
which during early times are, as we have before seen, 
utterly disregarded, come to be highly esteemed or even 
held sacred. I need not, however, repeat what I have 
said on this head in the third chapter. Ultimately a 
highly-complex sentiment, having its first origin in the 
social instincts, largely guided by the approbation of our 
fellow-men, ruled by reason, self-interest, and in later 
times by deep religious feelings, confirmed by instruction 
and habit, all combined, constitute our moral sense or con- 
science. 

It must not be forgotten that, although a high stand- 
ard of morality gives but a slight or no advantage to each 
individual man and his children over the other men of the 
same tribe, yet that an advancement in the standard of 
morality and an increase in the number of well-endowed 
men will certainly give an immense advantage to one 
tribe over another. There can be no doubt that a tribe 
including many members who, from possessing in a high 



160 THE DESCENT OF MAN. [Part I. 

degree the spirit of patriotism, fidelity, obedience, courage, 
and sympathy, were always ready to give aid to each 
other and to sacrifice themselves for the common good, 
would be victorious over most other tribes ; and this 
would be natural selection. At all times throughout the 
world tribes have supplanted other tribes ; and as morali- 
ty is one element in their success, the standard of morality 
and the number of well-endowed men will thus every- 
where tend to rise and increase. 

It is, however, very difficult to form any judgment 
why one particular tribe and not another has been success- 
ful and has risen in the scale of civilization. Many sav- 
ages are in the same condition as when first discovered 
several centuries ago. As Mr. Bagehot has remarked, we 
are apt to look at progress as the normal rule in human 
society ; but history refutes this. The ancients did not 
even entertain the idea ; nor do the Oriental nations at the 
present day. According to another high authority, Mr. 
Maine, 8 " the greatest part of mankind has never shown a 
particle of desire that its civil institutions should be im- 
proved." Progress seems to depend on many concurrent 
favorable conditions, far too complex to be followed out. 
But it has often been remarked, that a cool climate from 
leading to industry and the various arts has been highly 
favorable, or even indispensable for this end. The Esqui- 
maux, pressed by hard necessity, have succeeded in many 
ingenious inventions, but their climate has been too severe 
for continued progress. Nomadic habits, whether over 
wide plains, or through the dense forests of the tropics, or 
along the shores of the sea, have in every case been highly 
detrimental. While observing the barbarous inhabitants 
of Tierra del Fuego, it struck me that the possession of 
some property, a fixed abode, and the union of many fami- 

8 ' Ancient Law,' 1861, p. 22. For Mr. Bagehot's remarks, ' Fort- 
uiglitly Review,' April 1, 1868, p. 452. 



Chap. Y.] ' CIVILIZED NATIONS. 161 

lies under a chief, 'were the indispensable requisites for 
civilization. Such habits almost necessitate the cultiva- 
tion of the ground ; and the first steps in cultivation 
would probably result, as I have elsewhere shown, 9 from 
some such accident as the seeds of a fruit-tree falling on a 
heap of refuse and producing an unusually fine variety. 
The problem, however, of the first advance of savages 
toward civilization is at present much too difficult to be 
solved. 

Natural Selection as affecting Civilized Nations. — In 
the last and present chapters I have considered the ad- 
vancement of man from a former semi-human condition 
to his present state as a barbarian. But some remarks 
on the agency of natural selection on civilized nations 
may be here worth adding. This subject has been ably 
discussed by Mr. W. R Greg, 10 and previously by Mr. 
"Wallace and Mr. Galton. 11 Most of my remarks are 
taken from these three authors. With savages, the weak 
in body or mind are soon eliminated ; and those that sur- 
vive commonly exhibit a vigorous state of health. We 
civilized men, on the other hand, do our utmost to check 
the process of elimination ; we build asylums for the im- 

9 ' The Yariation of Animals and Plants under Domestication,' voL L 
p. 309. 

10 'Fraser's Magazine,' Sept. 1868, p. 353. This article seems to 
have struck many persons, and has given rise to two remarkable essays 
and a rejoinder in the ' Spectator,' Oct. 3 and 17, 1868. It has also 
been discussed in the ' Q. Journal of Science,' 1869, p. 152, and by Mr. 
Lawson Tait in the 'Dublin Q. Journal of Medical Science,' Feb. 1869, 
and by Mr. E. Ray Lankester in his ' Comparative Longevity,' 1870, p. 
128. Similar views appeared previously in the 'Australasian,' July 13, 
1867. I have borrowed ideas from several of these writers. 

11 For Mr. Wallace, see ' Anthropolog. Review,' as before cited. Mr. 
Galton in 'Macmillan's Magazine,' Aug. 1865, p. 318; also his great 
work, ' Hereditary Genius,' 1 870. 
8 



162 THE DESCENT OF MAN. [Part L 

becile, the maimed, and the sick ; we institute poor-laws ; 
and our medical men exert their utmost skill to save the 
life of every one to the last moment. There is reason to 
believe that vaccination has preserved thousands, who 
from a weak constitution would formerly have succumbed 
to small-pox. Thus the weak members of civilized socie- 
ties propagate their kind. No one who has attended to 
the breeding of domestic animals will doubt that this 
must be highly injurious to the race of man. It is sur- 
prising how soon a want of care, or care wrongly directed, 
leads to the degeneration of a domestic race ; but except- 
ing in the case of man himself, hardly any one is so igno- 
rant as to allow his worst animals to breed. 

The aid which we feel impelled to give to the helpless 
is mainly an incidental result of the instinct of sympathy, 
which was originally acquired as part of the social in- 
stincts, but subsequently rendered, in the manner pre- 
viously indicated, more tender and more widely diffused. 
Nor could we check our sympathy, if so urged by hard 
reason, without deterioration in the noblest part of our 
nature. The surgeon may harden himself while perform- 
ing an operation, for he knows that he is acting for the 
good of his patient ; but if we were intentionally to neg- 
lect the weak and helpless, it could only be for a con- 
tingent benefit, with a certain and great present evil. 
Hence we must bear without complaining the undoubtedly 
bad effects of the weak surviving and propagating their 
kind ; but there appears to be at least one check in steady 
action, namely the weaker and inferior members of society 
not marrying so freely as the sound ; and this check might 
be indefinitely increased, though this is more to be hoped 
for than expected, by the weak in body or mind refraining 
from marriage. 

In all civilized countries man accumulates property 
and bequeaths it to his children. So that the children in 



Chap. Y.] CIVILIZED NATIONS. 163 

the same country do not by any means start fair in the 
race for success. But this is far from an unmixed evil; 
for without the accumulation of capital the arts could not 
progress ; and it is chiefly through their power that the 
civilized races have extended, and are now everywhere 
extending, their range, so as to take the place of the lower 
races. Nor does the moderate accumulation of wealth 
interfere with the process of selection. When a poor man 
becomes rich, his children enter trades or professions in 
which there is struggle enough, so that the able in body 
and mind succeed best. The presence of a body of well- 
instructed men, who have not to labor for their daily 
bread, is important to a degree which cannot be over- 
estimated ; as all high intellectual work is carried on by 
them, and on such work material progress of all kinds 
mainly depends, not to mention other and higher advan- 
tages. No doubt wealth, when very great, tends to con- 
vert men into useless drones, but their number is never 
large ; and some degree of elimination here occurs, as we 
daily see rich men, who happen to be fools or profligate, 
squandering away all their wealth. 

Primogeniture with entailed estates is a more direct 
evil, though it may formerly have been a great advantage 
by the creation of a dominant class, and any government 
is better than anarchy. The eldest sons, though they 
may be weak in body or mind, generally marry, while the 
younger sons, however superior in these respects, do not 
so generally marry. ISTor can worthless eldest sons with 
entailed estates squander their wealth. But here, as else- 
where, the relations of civilized life- are so complex that 
some compensatory checks intervene. The men who are 
rich through primogeniture are able to select generation 
after generation the more beautiful and charming: women : 
and these must generally be healthy in body and active 
in mind. The evil consequences, such as they may be, of 



164 THE DESCENT OF MAN. [Part 1. 

the continued preservation of the same line of descent, 
without any selection, are checked by men of rank always 
wishing to increase their wealth and power ; and this they 
effect by marrying heiresses. But the daughters of parents 
who have produced single children, are themselves, as 
Mr. Galton has shown, 12 apt to be sterile ; and thus noble 
families are continually cut off in the direct line, and their 
wealth flows into some side-channel ; but unfortunately 
this channel is not determined by superiority of any kind. 

Although civilization thus checks in many ways the 
action of natural selection, it apparently favors, by means 
of improved food and the freedom from occasional hard- 
ships, the better development of the body. This may be 
inferred from civilized men having been found, wherever 
compared, to be physically stronger than savages. They 
appear also to have equal powers of endurance, as has 
been proved in many adventurous expeditions. Even the 
great luxury of the rich can be but little detrimental ; for 
the expectation of life of our aristocracy, at all ages and 
of both sexes, is very little inferior to that of healthy Eng- 
lish lives in the lower classes. 13 

We will now look to the intellectual faculties alone. 
If in each grade of society the members were divided 
into two equal bodies, the one including the intellectually 
superior and the other the inferior, there can be little 
doubt that the former would succeed best in all occupa- 
tions and rear a greater number of children. Even in the 
lowest walks of life, skill and ability must be of some ad- 
vantage, though in many occupations, owing to the great 
division of labor, a very small one. Hence in civilized 
nations there will be some tendency to an increase both' 

12 ' Hereditary Genius,' 1870, pp. 132-140. 

13 See the fifth and sixth columns, compiled from good authorities, in 
the table given in Mr. E. R. Lankester's 'Comparative Longevity,' 1870, 
p. 115. 



Chap. V.] CIVILIZED NATIONS. 1 65 

in the number and in the standard of the intellectually 
able. But I do not wish to assert that this tendency may 
not be more than counterbalanced in other ways, as by 
the multiplication of the reckless and improvident ; but 
even to such as these, ability must be some advantage. 

It has often been objected to views like the foregoing, 
that the most eminent men who have ever lived have left 
no offspring to inherit their great intellect. Mr. Galton 
savs, 14 " I regret I am unable to solve the simple question 
whether, and how far, men and women who are prodigies 
of genius are infertile. I have, however, shown that men 
of eminence are by no means so." Great lawgivers, the 
founders of beneficent religions, great philosophers and 
discoverers in science, aid the progress of mankind in a 
far higher degree by their works than by leaving a nu- 
merous progeny. In the case of corporeal structures, it 
is the selection of the slightly better-endowed and the 
elimination of the slightly less well-endowed individuals, 
and not the preservation of strongly-marked and rare 
anomalies, that leads to the advancement of a species." 
So it will be with the intellectual faculties, namely, from 
the somewhat 'more able men in each grade of society 
succeeding rather better than the less able, and conse- 
quently increasing in number, if not otherwise prevented. 
^Yhen in any nation the standard of intellect and the 
number of intellectual men have increased, we mav ex- 
pect from the law of the deviation from an average, as 
shown by Mr. Galton, that prodigies of genius will appear 
somewhat more frequently than before. 

In regard to the moral qualities, some elimination of 
the worst dispositions is always in progress even in the 
most civilized nations. Malefactors are executed, or im- 
prisoned for long periods, so that they cannot freely trans 

u 'Hereditary Genius,' 1870, p. 330. 

15 Origin of Species ' (fifth edition, 1869), p. 104 



106 THE DESCENT OF MAN. [Part I. 

mit their bad qualities. Melancholic and insane persona 
are confined, or commit suicide. Violent and quarrel- 
some men often come to a bloody end. Restless men who 
will not follow any steady occupation — and this relic of 
barbarism is a great check to civilization 16 — emigrate to 
newly-settled countries, where they prove useful pioneers. 
Intemperance is so highly destructive, that the expecta- 
tion of life of the intemperate, at the age, for instance, 
of thirty, is only 13.8 years; while for the rural laborers 
of England at tfhe same age it is 40.59 years. 17 Profligate 
women bear few children, and profligate men rarely 
marry ; both suffer from disease. In the breeding of do- 
mestic animals, the elimination of those individuals, though 
few in number, which are in any marked manner inferior, 
is by no means an unimportant element toward success. 
This especially holds good with injurious characters which 
tend to reappear through reversion, such as blackness in 
sheep ; and with mankind some of the worst dispositions 
which occasionally without any assignable cause make 
their appearance in families, may perhaps be reversions 
to a savage state, from which we are not removed by very 
many generations. This view seems indeed recognized in 
the common expression that such men are the black sheep 
of the family. 

With civilized nations, as far as an advanced stand- 
ard of morality, and an increased number of fairly well- 
endowed men are concerned^ natural selection apparently 
effects but little ; though the fundamental social instincts 
were originally thus gained. But I have already said 
enough, while treating of the lower races, on the causes 

56 'Hereditary Genius,' 1870, p. 347. 

17 E. Ray Lankester, 'Comparative Longevity,' 1870, p. 115. The 
table of the intemperate is from Neison's ' Vital Statistics.' In regard to 
profligacy, see Dr. Farr, "Influence of Marriage on Mortality," 'Nat 
Assoc, for the Promotion of Social Science,' 1858. 



Ciiap. V.] CIVILIZED NATIONS. 167 

which lead to the advance of morality, namely, the ap- 
probation of our fellow-men — the strengthening of our 
sympathies by habit — example and imitation — reason — 
experience and even self-interest — instruction during youth, 
and religious feelings. 

A most important obstacle in civilized countries to an 
increase in the number of men of a superior class has 
been strongly urged by Mr. Greg and Mr. Galton, 18 namely, 
the fact that the very poor and reckless, who are often 
degraded by vice, almost invariably marry early, while 
the careful and frugal, who are generally otherwise virtu- 
ous, marry late in life, so that they may be able to sup- 
port themselves and their children in comfort. Those 
who marry early produce within a given period not only 
a greater number of generations, but, as shown by Dr. 
Duncan, 19 they produce many more children. The chil- 
dren, moreover, that are born by mothers daring the 
prime of life are heavier and larger, and therefore prob- 
ably more vigorous, than those born at other periods. 
Thus the reckless, degraded, and often vicious members 
of society, tend to increase at a quicker rate than the 
provident and generally virtuous members. Or as Mr. 
Greg puts the case: "The careless, squalid, unaspiring 
Irishman multiplies like rabbits: the frugal, foreseeing, 
self respecting, ambitious Scot, stern in his morality, spir- 
itual in his faith, sagacious and disciplined in his intelli- 
gence, passes his best years in struggle and in celibacy, 
marries late, and leaves few behind him. Given a land 
originally peopled by a thousand Saxons and a thousand 

18 'Eraser's Magazine,' Sept. 1868, p. 353. 'Macmillan's Magazine,' 
Aug. 1865, p. 318. The Rev. F. W. Farrar ('Fraser's Mag.,' Aug. 1870, 
p. 264) takes a different view. 

19 " On the Laws of the Fertility 'of "Women," in' ' Transact. Royal 
Soc.' Edinburgh, vol. xxlv. p. 287. See, also, Mr. Galton, ' Hereditary 
Genius,' pp. 352-357, for observations to the above effect. 



168 THE DESCENT OF MAN. [Part I. 

Celts — and in a dozen generations five-sixths of the popu- 
lation would be Celts, but five-sixths of the property, of 
the power, of the intellect, would belong to the one-sixth 
of Saxons that remained. In the eternal * struggle for 
existence,' it would be the inferior and less favored race 
that had prevailed — and prevailed by virtue not of its 
good qualities but of its faults." 

There are, however, some checks to this downward 
tendency. We have seen that the intemperate suffer from 
a high rate of mortality, and the extremely profligate 
leave few offspring. The poorest classes crowd into towns, 
and it has been proved by Dr. Stark from the statistics of 
ten years in Scotland, 20 that at all ages the death-rate is 
higher in towns than in rural districts, "and during the 
first five years of life the town death-rate is almost ex- 
actly double that of the rural districts." As these returns 
include both the rich and the poor, no doubt more than 
double the number of births would be requisite to keep 
up the number of the very poor inhabitants in the towns, 
relatively to those in the country. With women, mar- 
riage at too early an age is highly injurious ; for it has 
been found in France that " twice as many wives under 
twenty die in the year, as died out of the same number 
of the unmarried." The mortality, also, of husbands un- 
der twenty is " excessively high," 21 but what the cause of 
this may be seems doubtful. Lastly, if the men who pru- 
dently delay, marrying until they can bring up their 
families in comfort, were to select, as they often do, wo- 
men in the prime of life, the rate of increase in the better 
class would be only slightly lessened. 

It was established from an enormous body of statistics, 

20 'Tenth Annual Report of Births, Deaths, etc., in Scotland,' 1867, 
p, xxix. 

21 These quotations are taken from our highest authority on such 
questions, namely, Dr. Farr, in his paper " On the Influence of Marriage 



Chap. V.] CIVILIZED NATIONS. 169 

taken during 1853, that the unmarried men throughout 
France, between the ages of twenty and eighty, die in a 
much larger proportion than the married: for instance, 
out of every 1,000 unmarried men, between the ages of 
twenty and thirty, 11.8 annually died, while of the married 
only 6.5 died. 22 A similar law was proved to hold good, 
during the years 1863 and 1864, with the entire popula- 
tion above the age of twenty in Scotland : for instance, 
out of every 1,000 unmarried men, between the ages of 
twenty and thirty, 14.97 annually died, while of the mar- 
ried only 7.24 died, that is, less than half. 23 Dr. Stark re- 
marks on this : " Bachelorhood is more destructive to life 
than the most unwholesome trades, or than residence in 
an unwholesome house or district where there has never 
been the most distant attempt at sanitary improvement." 
He considers that the lessened mortality is the direct re- 
sult of " marriage, and the more regular domestic habits 
which attend that state." He admits, however, that the 
intemperate, profligate, and criminal classes, whose dura- 
tion of life is low, do not commonly marry ; and it must 
likewise be admitted that men with a weak constitution, 
ill health, or any great infirmity in body or mind, will 
often not wish to marry, or will be rejected. Dr. Stark 
seems to have come to the conclusion that marriage in 
itself is a main cause of prolonged life, from finding that 
aged married men still have a considerable advantage in 
this respect over the unmarried of the same advanced age ; 

on the Mortality of the French People," read before the Nat. Assoc, for 
the Promotion of Social Science, 1858. 

2 ' 2 Dr. Farr, ibid. The quotations given below are extracted from the 
same striking paper. 

23 1 have taken the mean of the quinquennial means, given in The 
Tenth Annual Report of Births, Deaths, etc., in Scotland,' 1867. The 
quotation from Dr. Stark is copied from an article in the ' Daily News,' 
Oct. 17, 1868, which Dr. Farr considers very carefully written. 



170 THE DESCENT OF MAN. [Part 1. 

but every one must have known instances of men, who 
with weak health during youth did not marry, and yet have 
survived to old age, though remaining weak and there- 
fore always with a lessened chance of life. There is anoth- 
er remarkable circumstance which seems to support Dr. 
Stark's conclusion, namely, that widows and widowers in 
France suffer in comparison with the married a very heavy 
rate of mortality ; but Dr. Farr attributes this to the pov- 
erty and evil habits consequent on the disruption of the 
family, and to grief. On the whole we may conclude with 
Dr. Farr that the lesser mortality of married than of un- 
married men, which seems to be a general law, " is mainly 
due to. the constant elimination of imperfect types, and to 
the skilful selection of the finest individuals out of each 
successive generation ; " the selection relating only to the 
marriage state, and acting on all corporeal, intellectual, 
and moral qualities. We may, therefore, infer that sound 
and good men who out of prudence remain for a time un- 
married do not suffer a high rate of mortality. 

If the various checks specified in the two last paragraphs, 
and perhaps others as yet unknown, do not prevent the reck- 
less, the vicious, and otherwise inferior members of society 
from increasing at a quicker rate than the better class of 
men, the nation will retrograde, as has occurred too often 
in the history of the world. We must remember that prog- 
ress is no invariable rule. It is most difficult to say why one 
civilized nation rises, becomes more powerful, and spreads 
more widely, than another ; or why the same nation pro- 
gresses more at one time than at another. We can only say 
that it depends on an increase in the actual number of the 
population, on the number of the men endowed with high in- 
tellectual and moral faculties, as well as on their standard 
of excellence. Corporeal structure, except so far as vigor of 
body leads to vigor of mind, appears to have little influence. 
It has been urged by several writers that as high in- 



Chap. V.] . CIVILIZED NATIONS. m 

tcllectual powers are advantageous to a nation, the old 
Greeks, who stood some grades higher in intellect than any 
race that has ever existed, 24 ought to have risen, if the 
power of natural selection were real, still higher in the 
scale, increased in number, and stocked the whole of Eu- 
rope. Here we have the tacit assumption, so often made 
with respect to corporeal structures, that there is some in- 
nate tendency toward continued development in mind and 
body. But development of all kinds depends on many 
concurrent favorable circumstances. Natural selection 
acts only in a tentative manner. Individuals and races 
may have acquired certain indisputable advantages, and 
yet have perished from failing in other characters. The 
Greeks may have retrograded from a want of coherence 
between the many small states, from the small size of their 
whole country, from the practice of slavery, or from ex- 
treme sensuality ; for they did not succumb until " they 
were enervated and corrupt to the very core." 26 The 
western nations of Europe, who now so immeasurably sur- 
pass their former savage progenitors and stand at the sum- 
mit*of civilization, owe little or none of their superiority to 
direct inheritance from the old Greeks ; though they owe 
much to the written works of this wonderful people. 

Who can positively say why the Spanish nation, so 
dominant at one time, has been distanced in the race? The 
awakening of the nations of Europe from the dark ages is 
a still more perplexing problem. At this early period, as 
Mr. Gait on 28 has remarked, almost all the men of a gentle 

24 See the ingenious and original argument on this subject by Mr. 
Galton, ' Hereditary Genius,' pp. 340-342. 

25 Mr. Greg, ' Fraser's Magazine,' Sept. 1868, p. 357. 

26 ' Hereditary Genius,' 1870, pp. 357-359. The Rev. F. H. Farraf 
(' Fraser's Mag.', Aug. 1870, p. 257) advances arguments on the other 
side. Sir C. Lyell had already (' Principles of Geology,' vol. ii. 1868, 
p. 489) called attention, in a striking passage, to the evil influence of the 



172 THE DESCENT OF MAN.- [Part I. 

nature, those given to meditation or culture of the mind, 
had no refuge except in the bosom of the Church which 
demanded celibacy ; and this could hardly fail to have had 
a deteriorating influence on each successive generation. 
During this same period the Holy Inquisition selected with 
extreme care the freest and boldest men in order to burn 
or imprison them. In Spain alone some of the best men — ■ 
those who doubted and questioned, and without doubting 
there can be no progress — were eliminated during three 
centuries at the rate of a thousand a year. The evil which 
the Catholic Church has thus effected, though no doubt 
counterbalanced to a certain, perhaps large extent in other 
ways, is incalculable ; nevertheless, Europe has progressed 
at an unparalleled rate. 

The remarkable success of the English as colonists 
over other European nations, which is well illustrated by 
comparing the progress of the Canadians of English and 
French extraction, has been ascribed to their " daring and 
persistent energy;" but who can say how the English 
gained their energy ? There is apparently much truth in 
the belief that the wonderful progress of the United States, 
as well as the character of the people, are the results of 
natural selection ; the more energetic, restless, and coura- 
geous men from all parts of Europe having emigrated 
during the last ten or twelve generations to that great 
country, and having there succeeded best. 27 Looking to 
the distant future, I do not think that the Rev. Mr. Zincke 
takes an exaggerated view when he says: 28 "All other 
series of events — as that which resulted in the culture of 
mind in Greece, and that which resulted in the empire of 

Holy Inquisition in having lowered, through selection, the general stand- 
ard of intelligence in Europe. 

27 Mr. Galton, ' Macmillan's Magazine,' August, 1865, p. 325. Seq 
&l<?o, • Nature,'. " On Darwinism and National Life," Dec. 1869, p. 184. 

** ' Last Winter in the United States,' 1868, p. 29. 



Chap. V.] CIVILIZED NATIONS. 173 

Rome — only appear to have purpose and value when 
viewed in connection with, or rather as subsidiary to . . . 
the great stream of Anglo-Saxon emigration to the west." 
Obscure as is the problem of the advance of civilization, 
we can at least see that a nation which produced during a 
lengthened period the greatest number of highly intellec- 
tual, energetic, brave, patriotic, and benevolent men, would 
generally prevail over less favored nations. 

Natural selection follows from the struggle for exist- 
ence ; and this from a rapid rate of increase. It is impos- 
sible not bitterly to regret, but whether wisely is another 
question, the rate at which man tends to increase; for this 
leads in barbarous tribes to infanticide and many other 
evils, and in civilized nations to abject poverty, celibacy, 
and to the late marriages of the prudent. But as man 
suffers from the same physical evils with the lower animals, 
he has no right to expect an immunity from the evils con- 
sequent on the struggle for existence. Had he not been 
subjected to natural selection, assuredly he would never 
have attained to the rank of manhood. When we see in 
many parts of the world enormous areas of the most fer- 
tile land peopled by a few wandering savages, but which 
are capable oT supporting numerous happy homes, it 
might be argued that the struggle for existence had not 
been sufficiently severe to force man upward to his highest 
standard. Judging from all that we know of man and the 
lower animals, there has always been sufficient variability 
in the intellectual and moral faculties, for their steady ad- 
vancement through natural selection. No doubt such 
advancement demands many favorable concurrent circum- 
stances ; but it may well be doubted whether the most 
favorable would have sufficed, had not the rate of increase 
been rapid, and the consequent struggle for existence 
severe to an extreme degree. 



174 THE DESCENT OF HAN. [Part I. 

On the evidence that all civilized nations icere once 
barbarous. — As we have Lad to consider the steps by 
which some semi-human creature has been gradually raised 
to the rank of man in his most perfect state, the present 
subject cannot be quite passed over. But it has been 
treated in so full and admirable a manner by Sir J. Lub- 
bock, 29 Mr. Tylor, Mr. M'Lennan, and others, that I need 
here give only the briefest summary of their results. The 
arguments recently advanced by the Duke of Argyll 38 
and formerly by Archbishop Whately, in favor of the be- 
lief that man came into the world as a civilized being and 
that all savages have since undergone degradation, seem 
to me weak in comparison with those advanced on the 
other side. Many nations, no doubt, have fallen away in 
civilization, and some may have lapsed into utter bar- 
barism, though on this latter head I have not met with 
any evidence. The Fuegians were probably compelled by 
other conquering hordes to settle in their inhospitable 
country, and they may have become in consequence some- 
what more degraded ; but it would be difficult to prove 
that they have fallen much below the Botocudos who in- 
habit the finest parts of Brazil. 

The evidence that all civilized nations are the de- 
scendants of barbarians, consists, on the one side, of clear 
traces of their former low condition in still-existing cus- 
toms, beliefs, language, etc. ; and, on the other side, of 
proofs that savages are independently able to raise them- 
selves a few steps in the scale of civilization, and have 
actually thus risen. The evidence on the first head is 
extremely curious, but cannot be here given : I refer to 
such cases as that, for instance, of the art of enumeration, 
which, as Mr. Tylor clearly shows by the words still used 

29 ' On the Origin of Civilization,' ' Froc. Ethnological Soc' Nov 
26, 1867. 

30 ' Frimcval Man,' 1869. 



Chap. V.] CIVILIZED NATIONS. 175 

* 

in some places, originated in counting the fingers, first of 
one hand and then of the other, and lastly of the toes. 
We have traces of this in our own decimal system, and in 
the -Roman numerals, which after reaching to the number 
V., change into VI., etc., when the other hand no doubt 
was used. So again, " when we speak of threescore and 
ten, we are counting by the vigesimal system, each score 
thus ideally made, standing for 20 — for * one man' as 
a Mexican or Carib would put it." 31 According to a large 
and increasing school of philologists, every language bears 
the marks of its slow and gradual evolution. So it is with 
the art of writing, as letters are rudiments of pictorial 
representations. It is hardly possible to read Mr. M'Len- 
nan's work 32 and not admit that almost all civilized nations 
still retain some traces of such rude habits as the forcible 
capture of wives. What ancient nation, as the same author 
asks, can be named that was originally monogamous? 
The primitive idea of justice, as shown by the law of 
battle and other customs of which traces still remain, was 
likewise most rude. Many existing superstitions are the 
remnants of former false religious beliefs. The highest 
form of religion — the grand idea of God hating sin and 
loving righteousness — was unknown during primeval 
times. 

Turning to the other kind of evidence : Sir J. Lubbock 
has shown that some savages have recently improved a 
little in some of their simpler arts. From the extremely 

31 ' Royal Institution of Great Britain,' March 15, 1867. Also, ' Re- 
searches into the Early History of Mankind, ' 1865. 

32 ' Primitive Marriage,' 1865. See, likewise, an excellent article, 
evidently by the same author, in the ' North British Review,' July, 1869. 
Also, Mr. L. H. Morgan, "A Conjectural Solution of the Origin of the 
Class. System of Relationship," in ' Proc. American Acad, of Sciences,' 
vol. vii. Feb. 1868. Prof. Schaaff hausen (' Anthropolog. Review,' Oct 
1869, p. 373) remarks on " the vestiges of human sacrifices found both 
in Homer and the Old Testament." 



176 THE DESCENT OF MAN. [Part I. 

curious account which he gives of the weapons, tools, and 
arts, used or practised by savages in various parts of the 
world, it cannot be doubted that these have nearly all 
been independent discoveries, excepting perhaps the' art 
of making fire. 33 The Australian boomerang is a good in- 
stance of one such independent discovery. The Tahitians 
when first visited had advanced in many respects beyond 
the inhabitants of most of the other Polynesian islands. 
There are no just grounds for the belief that the high culture 
of the native Peruvians and Mexicans was derived from 
any foreign source ; 34 many native plants were there cul- 
tivated, and a few native animals domesticated. We 
should bear in mind that a wandering crew from some 
semi-civilized land, if washed to the shores of America, 
would not, judging from the small influence of most mis- 
sionaries, have produced any marked effect on the natives, 
unless they had already become somewhat advanced. 
Looking to a very remote period in the history of the 
world, we find, to use Sir J. Lubbock's well-known terms, 
a paleolithic and neolithic period ; and no one will pretend 
tnat the art of grinding rough flint tools was a borrowed 
one. In all parts of Europe, as far east as Greece, in Pal- 
estine, India, Japan, New Zealand, and Africa, including 
Egypt, flint tools have been discovered in abundance ; and 
of their use the existing inhabitants retain no tradition. 
There is also indirect evidence of their former use by the 
Chinese and ancient Jews. Hence there can hardly be a 
doubt that the inhabitants of these many countries, which 
include nearly the whole civilized world, were once in a 
barbarous condition. To believe that man was aboriginally 
civilized and then suffered utter degradation in so many 

33 Sir J. Lubbock, 'Prehistoric Times,' 2d edit. 1869, chaps, xv. and 
xv i. ei passim. 

34 Dr. F. Midler has made some good remarks to this effect in the 
Reise der Novara : Anthropolog. Theil,' Abtheil. Hi. 1868, s. 127. 



Chap. V.] CIVILIZED NATIONS. 177 

regions, is to take a pitiably low view of human nature. 
It is apparently a truer and more cheerful view that prog- 
ress has been much more general than retrogression ; that 
man has risen, though by slow and interrupted steps, from 
a lowly condition to the highest standard as yet attained 
by him in knowledge, morals, and religion. 



178 THE DESCENT OF MAN. [Part I. 



CHAPTER VI. 

ON THE AFFINITIES AND GENEALOGY OF MAN. 

Position of Man in the Animal Series. — The Natural System genealogical. 
— Adaptive Characters of Slight Value. — Various Small Points of Re- 
semblance between Man and the Quadrumana. — Rank of Man in the 
Natural System. — Birthplace and Antiquity of Maa. — Absence of 
Fossil Connecting-links. — Lower Stages in the Genealogy of Man, as 
inferred, firstly from his Affinities and secondly from his Structure. — 
Early Androgynous Condition of the Vertebrata. — Conclusion. 

Even if it be granted that the difference between man 
and his nearest allies is as great in corporeal structure as 
Borne naturalists maintain, and although we must grant 
that the difference between them is immense in mental 
power, yet the facts given in the previous chapters de- 
clare, as it appears to me, in the plainest maimer, that 
man is descended from some lower form, notwithstanding 
that connecting-links have not hitherto been discovered. 

Man is liable to numerous, slight, and diversified varia- 
tions, which are induced by the same general causes, are 
governed and transmitted in accordance with the same 
' general laws, as in the lower animals. Man tends to mul- 
tiply at so rapid a rate that his offspring are necessarily 
exposed to a struggle for existence, and consequently to 
natural selection. He has given rise to many races, some 
of which are so different that they have often been ranked 
by naturalists as distinct species. His body is constructed 
on the same homological plan as that of other mammals, 



Chap. VI] AFFINITIES AND GENEALOGY. 179 

independently of the uses to which the several parts may- 
be put. He passes through the same phases of embryo- 
logical development. He retains many rudimentary and 
useless structures, which no doubt were once serviceable. 
Characters occasionally make their reappearance in him, 
which we have every reason to believe were possessed by 
his early progenitors. If the origin of man had been 
wholly different from that of all other animals, these va- 
rious appearances would be mere empty deceptions ; but 
such an admission is incredible. These appearances, on 
the other hand, are intelligible, at least to a large extent, 
if man is the co-descendant with other mammals of some 
unknown and lower form. 

Some naturalists, from being deeply impressed with 
the mental and spiritual powers of man, have divided the 
whole organic world into three kingdoms, the Human, the 
Animal, and the Vegetable, thus giving to man a separate 
kingdom. 1 Spiritual powers cannot be compared or classed 
by the naturalist ; but he may endeavor to show, as I have 
done, that the mental faculties of man and the lower ani- 
mals do not differ in kind, although immensely in degree. 
A difference in degree, however great, does not justify us 
in placing man in a distinct kingdom, as will perhaps be 
best illustrated by comparing the mental powers of two 
insects, namely, a coccus or scale-insect and an ant, which 
undoubtedly belong to the same class. The difference is 
here greater, though of a somewhat different kind, than 
that between man and the highest mammal. The female 
coccus, while young, attaches itself by its proboscis to a 
plant ; sucks the sap, but never moves again ; is fertilized 
and lays eggs ; and this is its whole history. On the 
other hand, to describe the habits and mental powers of a 

1 Isidore Geoffroy St.-Hilaire gives a detailed account of the position 
assigned to man by various naturalists in their classifications : ' Hist 
Nat. Gen.' torn. U. 1859, pp. 170-189. 



[80 THE DESCENT OF MAN. [Part I. 

female ant, would require, as Pierre Huber has shown, a 
large volume ; I may, however, briefly specify a few points. 
Ants communicate information to each other, and several 
unite for the same work, or games of play. They recog- 
nize their fellow-ants after months of absence. They build 
great edifices, keep them clean, close the doors in the even- 
ing, and post sentries. They make roads, and even tun- 
nels under rivers. They collect food for the community, 
and when an object, too large for entrance, is brought to 
the nest, they enlarge the door, and afterward build it up 
again. 9 They go out to battle in regular' bands, and free- 
ly sacrifice their lives for the common weal. They emi- 
grate in accordance with a preconcerted plan. They cap- 
ture slaves. They keep Aphides as milch-cows. They 
move the eggs of their aphides, as well as their own eggs 
and cocoons, into warm parts of the nest, in order that 
they may be quickly hatched; and endless similar facts 
could be given. On the whole, the difference in mental 
power between an ant and a coccus is immense; yet no 
one has ever dreamed of placing them in distinct classes, 
much less in distinct kingdoms. No doubt this interval is 
bridged over by the intermediate mental powers of many 
others insects ; and this is not the case with man and the 
higher apes. But we have every reason to believe that 
breaks in the series are simply the result of many forms 
having become extinct. 

Prof. Owen, relying chiefly on the structure of the 
brain, has divided the mammalian series into four sub' 
classes. One of these he devotes to man ; in another he 
places both the marsupials and the monotremata ; so that 
he makes man as distinct from all other mammals as are 
these two latter groups conjoined. This view has not 
been accepted, as far as I am aware, by any naturalist 

8 See the very interesting article, " L'Instinct chez les Insects," by 
M. George Pouchet, ( Revue des Deux Mondes,' Feb. 18*70, p. 682. 



Chap. VI.] AFFINITIES AND GENEALOGY. 181 

capable of forming an independent judgment, and there- 
fore need not here be further considered. 

We can understand why a classification founded on 
any single character or organ — even an organ so wonder- 
fully complex and important as the brain — -or on the high 
development of the mental faculties, is almost sure to 
prove unsatisfactory. This principle has indeed been tried 
with hymenopterous insects ; but when thus classed by 
their habits or iustincts, the arrangement proved thor- 
oughly artificial. 3 Classifications may, of course, be based 
on any character whatever, as on size, color, or the ele- 
ment inhabited ; but naturalists have long felt a profound 
conviction that there is a natural system. This system, 
it is now generally admitted, must be, as far as possible, 
genealogical in arrangement — that is, the co-descendants 
of the same form must be kept together in one group, sep- 
arate from the co-descendants of any other form ; but if 
the parent-forms are related, so will be their descendants, 
and the two groups together will form a larger group. 
The amount of difference between tne several groups — 
that is, the amount of modification which each has under- 
gone — will be expressed by such terms as genera, families, 
orders, and classes. As we have no record of the lines of 
descent, these lines can be discovered only by observing 
the decrees of resemblance between the beings which are 

CD CD 

to be classed. For this object numerous points of resem- 
blance are of much more importance than the amount of 
similarity or dissimilarity in a few points. If two lan- 
guages were found to resemble each other in a multitude 
of words and points of construction, they would be uni- 
versally recognized as having sprung from a common 
source, notwithstanding that they differed greatly in some 
few words or points of construction. But with organio 
beings the points of resemblance must not consist of 

3 Westwood, ' Modern Class, of Insects,' vol. ii. 1840, p. 87. 



182 . THE DESCENT OF MAN. [Part I. 

adaptations to similar habits of life : two animals may, 
for instance, have had their whole frames modified for 
living in the water, and yet they will not be brought any 
nearer to each other in the natural system. Hence we can 
see how it is that resemblances in unimportant structures, 
in useless and rudimentary organs, and in parts not as yet 
fully developed or functionally active, are by far the most 
serviceable for classification ; for they can hardly be due 
to adaptations within a late period ; and thus they reveal 
the old lines of descent or of true affinity. 

We can further see why a great amount of modifica- 
tion in some one character ought not to lead us to sepa- 
rate widely any two organisms. A part which already 
differs much from the same part in other allied forms has 
already, according to the theory of evolution, varied 
much ;- consequently it would (as long as the organism 
remained exposed to the same exciting conditions) be 
liable to further variations of the same kind ; and these, 
if beneficial, would be preserved, and thus continually 
augmented. In many cases the continued development 
of a part, for instance, of the beak of a bird, or the teeth 
of a mammal, would not be advantageous to the species 
for gaining its food, or for any other object ; but with man 
we can see no definite limit, as far as advantage is con- 
cerned, to the continued development of the brain and 
mental faculties. Therefore in determining the position 
of man in the natural or genealogical system, the extreme 
development of his brain ought not to outweigh a multi- 
tude of resemblances in other less important or quite, un- 
important points. 

The greater number of naturalists w T ho have taken 
into consideration the whole structure of man, including 
his mental faculties, have followed Blumenbach and Cu- 
vier, and have placed man in a separate Order, under the 
title of the Bimana, and therefore on an equality with the 



Chap XL] AFFINITIES AND GENEALOGY. 183 

Orders of the Quadrumana, Carnivora, etc. Recently 
many of our best naturalists have recurred to the view 
first propounded by Linnaeus, so remarkable for his sa- 
gacity, and have placed man in the same Order with the 
Quadrumana, under the title of the Primates. The justice 
of this conclusion will be admitted if, in the first place, 
we bear in mind the remarks just made on the compara- 
tively small importance for classification of the great de- 
velopment of the brain in man; bearing, also, in mind 
that the strongly-marked differences between the skulls of 
man and the Quadrumana (lately insisted upon by Bi- 
schoff, Aeby, and others) apparently follow from their dif- 
ferently-developed brains. In the second place, we must 
remember that nearly all the other and more important 
differences between man and the Quadrumana are mani- 
festly adaptive in their nature, and relate chiefly to the 
erect position of man ; such as the structure of his hand, 
foot, and pelvis, the curvature of his spine, and the po- 
sition of his head. The family of seals offers a good il- 
lustration of the small importance of adaptive characters 
for classification. These animals differ from all other Car- 
nivora in the form of their bodies and in the structure of 
their limbs, far more than does man from the higher apes ; 
yet in every system, from that of Cuvier to- the most re- 
cent one by Mr. Flower, 4 seals are ranked as a mere family 
in the Order of the Carnivora. If man had not been his 
own classifier, he would never have thought of founding a 
separate order for his own reception. 

It would be beyond my limits, and quite beyond my 
knowledge, even to name the innumerable points of struct- 
ure in which man agrees with the other Primates. Our 
great anatomist and philosopher, Prof. Huxley, has fully 
discussed this subject, 6 and has come to the conclusion 

4 ' Proc. Zoolog. Soc' 1869, p. 4. 

6 ' Evidence as to Man's Place in Nature,' 1863, p. 70, et passim. 



184 . THE DESCENT OF MAN. [Part I. 

that man in all parts of his organization differs less from 
the higher apes, than these do from the lower members of 
the same group. Consequently there " is no justification 
for placing man in a distinct order." 

In an early part of this volume I brought forward 
various facts, showing how closely man agrees in consti- 
tution with the higher mammals ; and this agreement, no 
doubt, depends on our close similarity in minute structure 
and chemical composition. I gave, as instances, our lia- 
bility to the same diseases, and to the attacks of allied 
parasites ; our tastes in common for the same stimulants, 
and the similar effects thus produced, as well as by various 
drugs ; and other such facts. 

As small unimportant points of resemblance between 
man and the higher apes are not commonly noticed in 
systematic works, and as, when numerous, they clearly 
reveal our relationship, I will specify a few such points. 
The relative positions of the features are manifestly the 
same in man and the Quadrumana ; and the various emo- 
tions are displayed by nearly similar movements of the 
muscles and skin, chiefly above the eyebrows and round 
the mouth. Some few expressions are, indeed, almost the 
same, as in the weeping of certain kinds of monkeys, and 
in the laughing noise made by others, during which the 
corners of the mouth are drawn backward, and the lower 
eyelids wrinkled. The external ears are curiously alike. In 
man the nose is much more prominent than in most mon^ 
keys ; but we may trace the commencement of an aquiline 
curvature in the nose of the Hoolock Gibbon ; and this in 
the Semnopithecus nasica is carried to a ridiculous extreme. 

The faces of many monkeys are ornamented with 
beards, whiskers, or mustaches. The hair on the head 
grows to a great length in some species of Semnopithe- 
cus ; 6 and in the Bonnet monkey (Macacus radiatus) it 

6 Isid. Geoffroy, ' Hist. Nat. Gen.' torn. ii. 1859, p. 217 



Chap. VI.] AFFINITIES AND GENEALOGY. 185 

radiates from a point on the crown, with a parting down 
the middle, as in man. It is commonly said that the fore- 
head gives to man his noble and intellectual appearance ; 
but the thick hair on the head of the Bonnet monkey ter- 
minates abruptly downward, and is succeeded by such 
short and fine hair, or down, that at a little distance the. 
forehead, with the exception of the eyebrows, appears 
quite naked. It has been erroneously asserted that eye- 
brows are not present in any monkey. In the species just 
named the degree of nakedness of the forehead differs in 
different individuals, and Eschricht states 7 that in our 
children the limit between the hairy scalp and the naked 
forehead is sometimes not well defined ; so that here we 
seem to have a trifling case of reversion to a progenitor, 
in whom the forehead had not as yet become quite naked. 
It is well known that the hair on our arms tends to 
converge from above and below to a point at the elbow. 
This curious arrangement, so unlike that in most of the 
lower mammals, is common to the gorilla, chimpanzee, 
orang, some species of Hylobates, and even to some few 
American monkeys. But in Hylobates agilis the hair 
on the forearm is directed downward or toward the wrist 
in the ordinary manner ; and in H. lar it is nearly erect, 
with only a very slight forward inclination ; so that in 
this latter species it is in a transitional state. It can 
hardly be doubted that with most mammals the thickness 
of the hair and its direction on the back is adapted to 
throw off the rain ; even the transverse hairs on the fore- 
legs of a dog may serve for this end when he is coiled up 
asleep. Mr. Wallace remarks that the convergence of the 
hair toward the elbow on the arms of the orang (whose 
habits he has so carefully studied) serves to throw off the 
rain, when, as is tMe custom of this animal, the arms are 

7 " Ueber die Richtung der Haare," etc., Muller's ' Archiv fur Anat 
and Phys.' 1837, s. 51. 
9 



186 THE DESCENT OF MAN. [Part I 

bent, with the hands clasped round a branch or over its 
own head. We should, however, bear in mind that the 
attitude of an animal may perhaps be in part determined 
by the direction of the hair ; and not the direction of the 
hair by the attitude. If the above explanation is correct 
in the case of the orang, the hair on our forearms offers a 
curious record of our former state ; for no one supposes that 
it is now of any use in throwing off the rain, nor in our pres- 
ent erect condition is it properly directed for this purpose. 

It would, however, be rash to trust too much to the 
principle of adaptation in regard to the direction of the 
hair in man or his early progenitors ; for it is impossible 
to study the figures given by Eschricht of the arrange- 
ment of the hair on the human foetus (this being the same 
as in the adult) and not agree with this excellent observer 
that other and more complex causes have intervened. 
The points of convergence seem to stand in some relation 
to those points in . the embryo which are last closed in 
during development. There appears, also, to exist some 
relation between the arrangement of the hair on the limbs, 
and the course of the medullary arteries. 8 

It must not be supposed that the resemblances be- 
tween man and certain apes in the above and many other 
points — such as in having a naked forehead, long tresses 
on the head, etc. — are all necessarily the result of un- 
broken inheritance from a common progenitor thus charac- 
terized, or of subsequent reversion. Many of these resem- 
blances are more probably due to analogous variation, 
which follows, as I have elsewhere attempted to show, 9 

8 On the hair in Hylobates, see ' Nat. Hist, of Mammals,' by C. L. 
Martin, 1841, p. 415. Also, Isid. Geoffroy on the American monkeys and 
other kinds, 'Hist. Nat. Gen.' vol. ii. 1859, pp. 216, 243. Eschricht, ibid- 
B. 46, 55, 61. Owen, 'Anat. of Vertebrates,' vol. iii. p. 619. Wallace, 
'Contributions to the Theory of Natural Selection,' 1870, p. 344. 

9 ' Origin of Species,' 5th edit. 1869, p. 194. ' The Variation of Ani 
tnals and Plants under Domestication,' voL ii. 1868, p. 348. 



Chap. VI.] AFFINITIES AND GENEALOGY. 187 

from co-descended organisms having a similar constitution 
and having been acted on by similar causes inducing 
variability. With respect to the similar direction of the 
hair on the forearms of man and certain monkeys, as tins 
character is common to almost all the anthropomorphous 
apes, it may probably be attributed to inheritance ; but 
not certainly so, as some very distinct American monkeys 
are thus characterized. The same remark is applicable to 
the tailless condition of man ; for the tail is absent in all 
the anthropomorphous apes. Nevertheless this character 
cannot with certainty be attributed to inheritance, as the 
tail, though not absent, is rudimentary in several other 
Old World and in some New World species, and is quite 
absent in several species belonging to the allied group of 
Lemurs. 

Although, as we have now seen, man has no just right 
to form a separate Order for his own reception, he may 
perhaps claim a distinct Sub-order or Family. Prof. Hux- 
ley, in his last work, 10 divides the Primates into three Sub- 
orders : namely, the Anthropidaa with man alone, the 
Simiadse including monkeys of all kinds, and the Lemu- 
ridse with the diversified genera of lemurs. As far as dif- 
ferences in certain important points of structure are con- . 
cerned, man may no doubt rightly claim the rank of a 
Sub-order ; and this rank is too low, if we look chiefly to 
his mental faculties. Nevertheless, under a genealogical 
point of view it appears that this rank is too high, and 
that man ought to form merely a Family, or possibly even 
only a Sub-family. If we imagine three lines of descent 
proceeding from a common source, it is quite conceivable 
that two of them might after the lapse of ages be so 
slightly changed as still to remain as species of the same 
genus ; while the third line might become so greatly 
modified as to deserve to rank as a distinct Sub-family, 

10 ' An Introduction to the Classification of Animals,' 1869, p. 99. 



188 THE DESCENT OF MAN. [Part I. 

Family, or even Order. But in this case it is almost cer- 
tain that the third line would still retain through inheri- 
tance numerous small points of resemblance with the 
other tw T o lines. Here, then, would occur the difficulty, at 
present insoluble, how much weight we ought to assign in 
our classifications to strongly-marked differences in some 
few points — that is, to the amount of modification under- 
gone ; and how much to close resemblance in numerous 
unimportant points, as indicating the lines of descent or 
genealogy. The former alternative is the most obvious, 
and perhaps the safest, though the latter appears the most 
correct as giving a truly natural classification. 

To form a judgment on this head, with reference to 
man we must glance at the classification of the Simiadse. 
This family is divided by almost all naturalists into the 
Catarhine group, or Old World monkeys, all of which are 
characterized (as their name expresses) Iby the peculiar 
structure of their nostrils and by having four premolars 
in each jaw ; and into the Platyrhine group or New World 
monkeys (including, two very distinct sub-groups), all of 
which are characterized by differently-constructed nostrils 
and by having six premolars in each jaw. Some other 
. small differences might be mentioned. Now man unques- 
tionably belongs in his dentition, in the structure of his 
nostrils, and some other respects, to the Catarhine or Old 
World division ; nor does he resemble the Platyrhines 
more closely than the Catarhines in any characters, ex- 
cepting in a few of not much importance and apparently 
of an adaptive nature. Therefore it would be against all 
probability to suppose that some ancient New World 
species had varied, and had thus produced a "man-like 
creature with all the distinctive characters proper to the 
Old World division ; losing at the same time all its own 
distinctive characters. There can consequently hardly be 
a doubt that man is an offshoot from the Old World Sim- 



Chap. VI.] AFFINITIES AND GENEALOGY. 189 

ian stem ; and that, under a genealogical point of view, 
he must be classed with the Catarhine division. 11 

The anthropomorphous apes, namely the gorilla, chim- 
panzee, orang, and hylobates, are separated as a distinct 
sub-group from the other Old World monkeys by most 
naturalists. I am aware that Gratiolet, relying on the 
structure of the brain, does not admit the existence of this 
sub-group, and no doubt it is a broken one ; thus the orang, 
as Mr. St. G. Mivart remarks, 12 " is one of the most peculiar 
and aberrant forms to be found in the order." The re- 
maining, non-anthropomorphous, Old World monkeys, are 
again divided by some naturalists into two or three 
smaller sub-groups ; the genus Semnopithecus, with its 
peculiar sacculated stomach, being the type of one such 
snb-group. But it appears from M. Gaudry's wonderful dis- 
coveries in Attica, that during the Miocene period a form 
existed there, which connected Semnopithecus and Maca- 
cus ; and this probably illustrates the manner in which 
the other and higher groups were once blended together. 

If the anthropomorphous apes be admitted to form a 
natural sub-group, then as man agrees with them, not 
only in all those characters which he possesses in common 
with the whole Catarhine group, but in other peculiar 
characters, such as the absence of a tail and of callosities 
and in general appearance, we may infer that some ancient 
member of the anthropomorphous sub-group gave birth 
to man. It is not probable that a member of one of the 
other lower sub-groups should, through the law of analo- 
gous variation, have given rise to a man-like creature, 

11 This is nearly the same classification as that provisionally adopted 
by Mr. St. George Mivart (' Transact, Philosoph. Soc.' 1867, p. 300). 
who, after separating the Lemurida?, divides the remainder of the 
Primates into the Hominidoe, the Simiadse answering to the Catarhines, 
the Cebidae, and the Hapalidae — these two latter groups answering to the 
Platyrhines. 

12 'Transact. Zoolog. Soc' vol. vi. 1867, p. 214. 



190 THE DESCENT OF MAN. [Part L 

resembling the higher anthropomorphous apes in so many 
respects. No doubt man, in comparison with most of his 
allies, has undergone an extraordinary amount of modifi- 
cation, chiefly in consequence of his greatly-developed 
brain and erect position; nevertheless, we should bear in 
mind that he " is but one of several exceptional forms of 
Primates." 13 

Every naturalist, who believes in the principle of 
evolution, will grant that the two main divisions of the 
Simiadoe, namely the Catarhine and Platyrhine monkeys, 
with their sub-groups, have all proceeded from some one 
extremely ancient progenitor. The early descendants of 
this progenitor, before they had diverged to any con- 
siderable extent from each other, would still have formed 
a single natural group ; but some of the species or incipi- 
ent genera would have already begun to indicate by their 
diverging characters the future distinctive marks of the 
Catarhine and Platyrhine divisions. Hence the members 
of this supposed ancient group would not have been, so 
uniform in their dentition or in the structure of their 
nostrils, as are the existing Catarhine monkeys in one way 
and the Platyrhines in another way, but would have 
resembled in this respect the allied Lemuridse which differ 
greatly from each other in the form of their muzzles, 14 and 
to an extraordinary degree in their dentition. 

The Catarhine and Platyrhine monkeys agree in a 
multitude of characters, as is shown by their unques- 
tionably belonging to one and the same order. The many 
characters which they possess in common can hardly 
have been independently acquired by so many distinct 
species ; so that these characters must have been inherited. 
But an ancient form which possessed many characters 

13 Mr. St. G. Mivart, 'Transact. Phil. Soc.' 1867, p. 410. 

14 Messrs. Murie and Mivart on the Lemuroidea, ' Transact. Zoolog, 
Soc. 1 vol. vii. 1869, p. 5. 



Chap. VI. J AFFINITIES AND GENEALOGY. 191 

common to the Catarhine and Platyrhine monkeys, and 
others in an intermediate condition, and some few perhaps 
distinct from those now present in either group, would 
undoubtedly have been ranked, if seen by a naturalist, as 
an ape or monkey. And as man under a genealogical 
point of view belongs to the Catarhine or Old World 
stock, we must conclude, however much the conclusion 
may revolt our pride, that our early progenitors would 
have been properly thus designated. 16 But we must not 
fall into the error of supposing that the early progenitor of 
the whole Simian stock, including man, was identical with, 
or even closely resembled, any existing ape or monkey. 

On the Birthplace and Antiquity of .Man. — We are 
naturally led to inquire where was the birthplace of man 
at that stage of descent when our progenitors diverged 
from the Catarhine stock. The fact that they belonged 
to this stock clearly shows that they inhabited the Old 
World ; but not Australia nor any oceanic island, as we 
may infer from the laws of geographical distribution. In 
each great region of the world the living mammals are 
closely related to the extinct species of the same region. 
It is therefore probable that Africa was formerly inhab- 
ited by extinct apes closely allied to the gorilla and chim- 
panzee ; and as these two species are now man's nearest 
allies, it is somewhat more probable that our early pro- 
genitors lived on the African Continent than elsewhere. 
But it is useless to speculate on this subject, for an ape 
nearly as large as a man, namely, the Dryopithecus of 
Lartet, which was closely allied to the anthropomorphous 

15 Hiickel has come to this same conclusion. See ' Ueber die Ent- 
Btehung des Menschengeschlechts,' in Virchow's ' Sammlung. gemein. 
wissen. Vortrage,' 1868, s. 61. Also his 'Natiirliche Schopfungs- 
geschichte,' 1868, in which he gives in detail his views on the genealogy 
of man. 



192 THE DESCENT OF MAN. [Part X. 

Hylobates, existed in Europe during the Upper Miocene 
period ; and since so remote a period the earth has cer- 
tainly undergone many great revolutions, and there has 
been ample time for migration on the largest scale. 

At the period and place, whenever and wherever it 
may have been, when man first lost his hairy covering, ho 
probably inhabited a hot country ; and this would have 
been favorable for a frugiferous diet, on which, judging 
from analogy, he subsisted. We are far from knowing 
how long ago it was when man first diverged from the 
Catarhine stock ; but this may have occurred at an epoch 
as remote as the Eocene period ; for the higher apes had 
diverged from the lower apes as early as the Upper Mio- 
cene period, as shown by the existence of the Dryopithe- 
cus. We are also quite ignorant at how rapid a rate or- 
ganisms, whether high or low in the scale, may under 
favorable circumstances be modified : we know, however, 
that some have retained the same form during an enor- 
mous lapse of time. From what we see going on under 
domestication, we learn that within the same period some 
of the co-descendants of the same species may be not at 
all changed, some a little, and some greatly changed. 
Thus it may have been with man, who has undergone a 
great amount of modification in certain characters in com- 
parison with the higher apes. 

The great break in the organic chain between man and 
his nearest allies, which cannot be bridged over by any 
extinct or living species, has often been advanced as a 
grave objection to the belief that man is descended from 
some lower form ; but this objection will not appear of 
much weight to those who, convinced by general reasons, 
believe in the general principle of evolution. Breaks in- 
cessantly occur in all parts of the series, some being wide, 
sharp, and defined, others less so in various degrees ; as 
between the orang and its nearest allies — between the 



Chap. YL] AFFINITIES AND GENEALOGY. 1 93 

Tarsius and the other Lemurida3 — between the elephant 
and in a more striking manner between the Ornithorhyn- 
chns or Echidna, and other mammals. But all these 
breaks depend merely on the number of related forms 
which have become extinct. At some future period, not 
very distant as measured by centuries, the civilized races 
of man will almost certainly exterminate and replace 
'throughout the world the savage races. At the same 
time the anthropomorpnous apes, as Prof. Schaaffhausen 
has remarked, 18 will no doubt be exterminated. The 
break will then be rendered wider, for it will intervene 
between man in a more civilized state, as we may hope, 
than the Caucasian, and some ape as low as a baboon, in- 
stead of as at present between the negro or Australian 
and the gorilla. 

With respect to the absence of fossil remains, serving 
to connect man with his ape-like progenitors, no one will 
lay much stress on this fact, who will read Sir C. Lyell's 
discussion, 17 in which he shows that in all the vertebrate 
classes the discovery of fossil remains has been an ex- 
tremely slow and fortuitous process. Nor should it be 
forgotten that those regions which are the most likely to 
afford remains connecting man with some extinct ape-like 
creature, have not as yet been searched by geologists. 

Lower Stages in the Genealogy of Man. — We have 
seen that man appears to have diverged from the Cata- 
rhine or Old World division of the Simiadae, after these 
had diverged from the Xew World division. We will 
now endeavor to follow the more remote traces of his 
genealogy, trusting in the first place to the mutual affini- 
ties between the various- classes and orders, with some 

16 'Anthropological Keview,' April, 1867, p. 236. 

17 'Elements of Geology,' 1865, pp. 583-585. 'Antiquity of Man,' 
1S63, p. 145. 



194 THE DESCENT OF MAN. [Part I 

Blight aid from the periods, as far as ascertained, of their 
successive appearance on the earth. The Lemuridse stand 
below and close to the Sirniadse, constituting a very dis- 
tinct family of the Primates, or, according to Hackel, a 
distinct Order. This group is diversified and broken to 
an extraordinary degree, and includes many aberrant 
forms. It has, therefore, probably suffered much extinc- 
tion. Most of the remnants survive on islands, namely, iu 
Madagascar and in the islands of the Malayan archipelago, 
where they have not been exposed to such severe compe- 
tition as they would have been on well-stocked continents. 
This group likewise presents many gradations, leading, as 
Huxley remarks, 18 " insensibly from the crown and sum- 
mit of the animal creation down to creatures from which 
there is but a step, as it seems, to the lowest, smallest, 
and least intelligent of the placental mammalia." From 
these various considerations it is probable that the Simiadae 
were originally developed from the progenitors of the ex- 
isting Lemuridse ; and these in their turn from forms stand- 
ing very low in the mammalian series. 

The Marsupials stand in many important characters 
below the placental mammals. They appeared at an 
earlier geological period, and their range was formerly 
much more extensive than what it now is. Hence the 
Placentata are generally supposed to have been derived 
from the Implacentata or Marsupials ; not, however, from 
forms closely like the existing Marsupials, but from their 
early progenitors. The Monotremata are plainly allied to 
the Marsupials ; forming a third and still lower division in 
the great mammalian series. They are represented at the 
present day solely by the Ornithorhynchus and Echidna ; 
and these two forms may be safely considered as relics of 
a much larger group which have been preserved in Austra- 
lia through some favorable concurrence of circumstances. 

18 ' Man's Place in Nature,' p. 105. 



Chap. VI.] AFFINITIES AND GENEALOGY 195 

The Monotremata are eminently interesting, as in several 
important points of structure they lead toward the class 
of reptiles 

In attempting to trace the genealogy of the Mam- 
malia, and therefore of man, lower down in the series, we 
become involved in greater and greater obscurity. He 
who wishes to see what ingenuity and knowledge can 
effect, may consult Prof. Hackel's works. 19 I will con- 
tent myself with a few general remarks. Every evolu- 
tionist will admit that the five great vertebrate classes, 
namely, mammals, birds, reptiles, amphibians, and fishes, 
are all descended from some one prototype ; for they have 
much in common, especially during their embryonic state. 
As the class of fishes is the most lowly organized and ap- 
peared before the others, we may conclude that all the 
members of the 'vertebrate kingdom are derived from some 
fish-like animal, less highly organized than any as yet 
found in the lowest known formations. The belief that 
animals so distinct as a monkey or elephant and a hum- 
ming-bird, a snake, frog, and fish, etc., could all have 
sprung from the same parents, will appear monstrous to 
those who have not attended to the recent progress of 
natural history. For this belief implies the former ex- 
istence of links closely binding together all these forms, 
now so utterly unlike. 

Nevertheless, it is certain that groups of animals have 
existed, or do now exist, which serve to connect more or 
less closely the several great vertebrate classes. We have 

19 Elaborate tables are given in his ' Generelle Morphologie ' (B. it 
s. cliii. and s. 425) ; and with more especial reference to man in his 
'Natiirliche Schbpfungsgeschichte,' 1868. Prof. Huxley, in reviewing 
this latter work ('The Academy,' 1869, p. 42) says that he considers 
the phylum or lines of descent of the Vertebrata to be admirably dis- 
cussed by Hackel, although he differs on some points. He expresses, 
also, his high estimate of the value of the general tenor and spirit of the 
whole work. 



196 THE DESCENT OF MAN. [Part L 

seen that the Ornithorhynchus graduates toward reptiles ; 
and Prof. Huxley has made the remarkable discovery, 
confirmed by Mr. Cope and others, that the old Dinosau- 
rians are intermediate in many important respects between 
certain reptiles and certain birds — the latter consisting of 
the ostrich-tribe (itself evidently a widely-diffused rem- 
nant of a larger group) and of the Archeopteryx, that 
strange Secondary bird having a long tail like that of the 
lizard. Again, according to Prof. Owen, 20 the Ichthy- 
osaurians — great sea-lizards furnished with paddles — pre- 
sent many affinities with fishes, or rather, according to 
Huxley, with amphibians. This latter class (including in 
its highest division frogs and toads) is plainly allied to 
the Ganoid fishes. These latter fishes swarmed during 
the earlier geological periods, and were constructed on 
what is called a highly-generalized type, that is, they pre- 
sented diversified affinities with other groups of organisms. 
The amphibians and fishes are also so closely united by 
the Lepidosiren, that naturalists long disputed in which 
of these two classes it ought to be placed. The Lepido- 
siren and some few Ganoid fishes have been preserved 
from utter extinction by inhabiting our rivers, which are 
harbors of refuge, bearing the same relation to the great 
waters of the ocean that islands bear to continents. 

Lastly, one single member of the immense and diver- 
sified class of fishes, namely, the lancelet or amphioxus*, is 
so different from all other fishes, that Hackel maintains 
that it ought to form a distinct class in the vertebrate 
kingdom. This fish is remarkable for its negative charac- 
tors ; it can hardly be said to possess a brain, vertebral col- 
umn, or heart, etc. ; so that it was classed by the older 
naturalists among the worms. Many years ago Prof. 
Goodsir perceived that the lancelet presented some affini- 
ties with the Ascidians, which are invertebrate, hermaphro- 

20 ' Palaeontology,' 1860, p. 199. 



Chap. VI.] AFFINITIES AXD GENEALOGY. 197 






•lite, marine creatures permanently attached to a support. 
They hardly appear like animals, and consist of a simple, 
tough, leathery sack, with two small projecting orifices. 
They belong to the Molluscoida of Huxley — a lower di- 
vision of the great kingdom of the Mollusca ; but they 
have recently been placed by some naturalists among the 
Vermes or worms. Their larvae somewhat resemble tad- 
poles in shape, 21 and have the power of swimming freely 
about. Some observations lately made by M. Kowa- 
levsky, 22 since confirmed by Prof. Kuppfer, will form a 
discovery of extraordinary interest, if still further ex- 
tended, as I hear from M. Kowalevsky in Naples he has 
now effected. The discovery is that the larvae of As- 
cidians are related to the Vertebrata, in their manner of 
development, in the relative position of the nervous sys- 
tem, and in possessing a structure closely like the chorda 
dorsalls of vertebrate animals. It thus appears, if we 
may rely on embryology, which has always proved the 
safest guide in classification, that we have at last gained 
a clew to the source whence the Vertebrata have been de- 
rived. We should thus be justified in believing that at 
an extremely remote period a group of animals existed, 
resembling in many respects the larvae of our present As- 
cidians, which diverged into two great branches — the one 
retrograding in development and producing the present 

21 I had the satisfaction of seeing, at the Falkland Islands, in April, 
1833, and therefore some years before any other naturalist, the locomo- 
tive larvse of a compound Ascidian, closely allied to, but apparently gen- 
erically distinct from, Synoicum. The tail was about five times as long 
as the oblong head, and terminated in a very fine filament. It was 
plainly divided, as sketched by me under a simple microscope, by trans- 
verse opaque partitions, which I presume represent the great cells figured 
by Kowalevsky. At an early stage of development the tail was closely 
coiled round the head of the larva. 

22 ' Memoires de l'Acad. des Sciences de St. Petersbourg,' torn. x. No, 
15, 1866. 



198 THE DESCENT OJ MAN. [Part I 

class of Ascidians, the pther rising to the crown and summit 
of the animal kingdom by giving birth to the Vertebrata. 

We have thus far endeavored rudely to trace the 
genealogy of the Vertebrata by the aid of their mutual 
affinities. We will now look to man as he exists ; and we 
shall, I think, be able partially to restore during successive 
periods, but not in due order of time, the structure of our 
early progenitors. This can be effected by means of the 
rudiments which man still retains, by the characters which 
occasionally make their appearance in him through rever- 
sion, and by the aid of the principles of morphology 
and embryology. The various facts, to which I shall here 
allude, have been given in the previous chapters. The 
early progenitors of man were no doubt once covered with 
hair, both sexes having beards ; their ears were pointed 
and capable of movement ; and their bodies were provided 
with a tail, having the proper muscles. Their limbs 
and bodies were also acted on by many muscles which 
now only occasionally reappear, but are normally present in 
the Quadrumana. The great artery and nerve of the hu- 
merus ran through a supra-condyloid foramen. At this or 
some earlier period, the intestine gave forth a much larger 
diverticulum or csecum than that now existing. The foot, 
judging from the condition of the great-toe in the foetus, 
was then prehensile ; and our progenitors, no doubt, were 
arboreal in their habits, frequenting some warm, forest-clad 
land. The males were provided with great canine teeth, 
which served them as formidable weapons. 

At a much earlier period the uterus was double ; the 
excreta were voided through a cloaca ; and the eye was 
protected by a third eyelid or nictitating membrane. At 
a still earlier period the progenitors of man must have 
been aquatic in their habits ; for morphology plainly tells 
us that our lungs consist of a modified swim-bladder, which 



Chap. VL] AFFINITIES AND GENEALOGY. 199 

once served as a float. The clefts on the neck in the embryo 
of man show where the branchiae once existed. At about 
this period the true kidneys were replaced by the corpora 
wolftiana. The heart existed as a simple pulsating vessel ; 
and the chorda dorsalis took the place of a vertebral col- 
umn. These early predecessors of man, thus seen in the 
dim recesses of time, must have been as lowly organized 
as the lancelet or amphioxus, or even still more lowly or- 
ganized. 

There is one other point- deserving a fuller notice. It 
has Ions; been known that in the vertebrate kingdom one 
sex bears rudiments of various accessory parts, appertain- 
ing to the reproductive system, which properly belong to 
the opposite sex ; and it has now been ascertained that at 
a very early embryonic period both sexes possess true 
male and female glands. Hence some extremely remote 
progenitor of the whole vertebrate kingdom appears to 
have been hermaphrodite or androgynous. 23 But here we 
encounter a singular difficulty. In the maftnmalian class 
the males possess in their vesiculae prostatica rudiments 
of a uterus with the adjacent passage ; they bear also 
rudiments of mammae, and some male marsupials have 
rudiments of a marsupial sack. 24 Other analogous facts 
could be added. Are we, then, to suppose that some ex- 
tremely ancient mammal possessed organs proper to both 
sexes, that is, continued androgynous after it had acquired 

23 This is the conclusion of one of the highest authorities in com- 
parative anatomy, namely, Prof. Gegenbaur : ' Grundziige der vergleich. 
Anat.' 1870, s. 876. The result has been arrived at chiefly from the 
study of the Amphibia ; but it appears from the researches of Waldeyer 
(as quoted in Humphry's ' Journal of Anat. and Phys.' 1869, p. 161), 
that the sexual organs of even " the higher vertebrata are, in their early 
condition, hermaphrodite." Similar views have long been held by some 
authors, though until recently not well based. 

24 The male Thylacinus offers the best instance. Owen, ' Anatomy 
of Vertebrates,' vol. iii. p. 771. 



200 THE DESCENT OF MAN. [Part L 

the chief distinctions of its proper class, and therefore after 
it had diverged from the lower classes of the vertebrate 
kingdom ? This seems improbable in the highest degree ; 
for, had this been the case, we might have expected that 
some few members of the two lower classes, namely fishes 24 
and amphibians, would still have remained androgynous. 
We must, on the contrary, believe that when the five ver- 
tebrate classes diverged from their common progenitor the 
sexes had already become separated. To account, how- 
ever, for male mammals possessing rudiments of the accesso- 
ry female organs, and for female mammals possessing rudi- 
ments of the masculine organs, we need not suppose that 
their early progenitors were still androgynous after they had 
assumed their chief mammalian characters. It is quite possi- 
ble that, as the one sex gradually acquired the accessory or- 
gans proper to it, some of the successive steps or modifi- 
cations were transmitted to the opposite sex. When we 
treat of sexual selection, we shall meet with innumerable 
instances of tnis form of transmission — as in the case of 
the spurs, plumes, and brilliant colors, acquired by male 
birds for battle or ornament, and transferred to the fe- 
males in an imperfect or rudimentary condition. 

The possession by male mammals of functionally in> 
perfect mammary organs is, in some respects, especially 
curious. The Monotremata have the proper milk-secret- 
ing glands with orifices, but no nipples ; and, as these 
animals stand at the very base of the mammalian series, 
it is probable that the progenitors of the class possessed, 
in like manner, the milk-secreting glands, but no nipples. 
This conclusion is supported by what is known of their . 

25 Serranus is well known often to be in an hermaphrodite condition ; I 
but Dr. Giinther infoqjns me that he is convinced that this is not its nor- 
mal state. Descent from an ancient androgynous prototype would, how- 
c^er, naturally favor and explain, to a certain extent, the recurrence of 
this condition in these fishes. 



Chap. VL] AFFINITIES AND GENEALOGY. 201 

manner of development ;. for Professor Turner informs me, 
on the authority of Kolliker and Lauger, that in the em- 
bryo the mammary glands can be distinctly traced before 
the nipples are in the least visible ; and it should be borne 
in mind that the development of successive parts in th€ 
individual generally seems to represent and accord with 
the development of successive beings in the same line of 
descent. The Marsupials differ from the Monotremata by 
possessing nipples ; so that these organs were probably first 
acquired by the Marsupials after they had diverged from, 
and risen above, the Monotremata, and were then trans- 
mitted to the placental mammals. No one will suppose 
that after the Marsupials had approximately acquired 
their present structure, and therefore at a rather late pe- 
riod in the development of the mammalian series, any of 
its members still remained androgynous. We seem, there- 
fore, compelled to recur to the foregoing view, and to con- 
clude that the nipples were first developed in the females 
of some very early marsupial form, and were then, in ac- 
cordance with* a common law of inheritance, transferred 



in a functionally imperfect condition to the males. 

Nevertheless, a suspicion has sometimes crossed my 
mind that long after the progenitors of the whole mam- 
malian class had ceased to be androgynous, both sexes 
might have yielded milk and thus nourished their young ; 
and, in the case of the Marsupials, that both sexes might 
have carried their young in marsupial sacks. This will 
not appear utterly incredible, if we reflect that the males 
of syngnathous fishes receive the eggs of the females in 
their abdominal pouches, hatch them, and afterward, as 
some believe, nourish the young; 26 that certain other 

08 Mr. Lockwood believes (as quoted in ' Quart. Journal of Science,' 
April, 1868, p. 269), from what he has observed of the development of 
Hippocampus, that the walls of the abdominal pouch of the male in some 
Tay afford nourishment. On male fishes hatching the ova in their 



202 THE DESCENT OF MAN. [Part I. 

male fishes hatch the eggs within their mouths or bran- 
chial cavities ; that certain male toads take the chaplets 
of ejxofs from the females and wind them round their own 
thighs, keeping them there until the tadpoles are born ; 
that certain male birds undertake the whole duty of incu- 
bation, and that male pigeons, as well as the females, feed 
their nestlings with a secretion from their crops. But the 
above suspicion first occurred to me from the mammary 
glands in male mammals being developed so much more 
perfectly than the rudiments of those other accessory re- 
productive parts, which are found in the one sex though 
proper to the other. The mammary glands and nipples, 
as they exist in male mammals, can indeed hardly be 
called rudimentary; they are simply not fully developed 
and not functionally active. They are sympathetically 
affected under the influence of certain diseases, like the 
same organs in the female. At birth they often secrete a 
few drops of milk ; and they have been known occasion- 
ally in man and other mammals to become well devel- 
oped, and to yield a fair supply of milk. Now if we sup- 
pose that during a former prolonged period male mam- 
mals aided the females in nursing their offspring, and that 
afterward from some cause, as from a smaller number of 
young being produced, the males ceased giving this aid, 
disuse of the organs during maturity would lead to their 
becoming inactive; and from two well-known principles 
of inheritance this state of inactivity would probably be 
transmitted to the males at the corresponding age of ma- 
turity. But at all earlier ages these organs would be left 
unaffected, so that they would be equally well developed 
in the young of both sexes. 

mouths, see a very interesting paper by Prof. Wyman, in * Proc. Boston 
Soc. of Nat. Hist.' Sept. 15, 185V; also Prof. Turner, in 'Journal of ' 
Anat. and Phys.' Nov. 1, 1866, p. 78. Dr. Giintherhas likewise described 
similar cases. 



Chap. VI.] AFFINITIES AND GENEALOGY. 203 

Conclusion. — The best definition of advancement or 
progress in the organic scale ever given, is that by Von 
Baer ; and this rests on the amount of differentiation and 
specialization of the several parts of the same being, when 
arrived, as I should be inclined to add, at maturity. Now 
as organisms have become slowly adapted by means of 
natural selection for diversified lines of life, their parts 
will have become, from the advantage gained by the di- 
vision of physiological labor, more and more differentiated 
and specialized for various functions. The same part ap- 
pears often to have been modified, first for one purpose, 
and then long afterward for some other and quite distinct 
purpose ; and thus all the parts are rendered more and 
more complex. But each organism will still retain the 
general type of structure of the progenitor from which it 
was aboriginally derived. In accordance with this view 
it seems, if we turn to geological evidence, that organiza- 
tion on the whole has advanced throughout the world by 
slow and interrupted steps. In the great kingdom of the 
Vertebrata it has culminated in man. It must not, how- 
ever, be supposed that groups of organic beings are al- 
ways supplanted and disappear as soon as they have 
given birth to other and more perfect groups. The latter, 
though victorious over their predecessors, may not have 
become better adapted for all places in the economy of 
Nature. Some old forms appear to have survived from in- 
habiting protected sites, where they have not been ex- 
posed to very severe competition ; and these often aid us 
in constructing our genealogies, by giving us a fair idea 
of former and lost populations. But we must not fall into 
the error of looking at the existing members of any lowly- 
organized group as perfect representatives of their ancient 
predecessors. 

The most ancient progenitors in the kingdom of the 
Vertebrata, at which we are able to obtain an obscure 



204 THE DESCENT OF MAN. [Part I. 

glance, apparently consisted of a group of marine ani- 
mals, 27 resembling the larvae of existing Ascidians. These 
animals probably gave rise to a group of fishes, as lowly 
organized as the lancelet ; and from these the Ganoids, 
and other fishes like the Lepidosiren, must have been de- 
veloped. From such fish a very small advance would 
carry us on to the amphibians. We have seen that birds 
and reptiles were once intimately connected together ; and 
the Monotremata now, in a slight degree, connect mam- 
mals with reptiles. But no one can at present say by 
what line of descent the three higher and related classes, 
namely, mammals, birds, and reptiles, were derived from 
either of the two lower vertebrate classes, namely am- 
phibians and fishes. In the class of mammals the steps 
are not difficult to conceive which led from the ancient 
Monotremata to the ancient Marsupials ; and from these 
to the early progenitors of the placental mammals. We 
may thus ascend to the Lemuridse ; and the interval is not 
wide from these to the Simiadaa. The Simiadse then 
branched off into two great stems, the New World and 
Old World monkeys ; and from the latter, at a remote 

27 All vital functions tend to run their course in fixed and recurrent 
periods, and with tidal animals the periods would probably be lunar ; for 
such animals must have been left dry or covered deep with water — sup- 
plied with copious food or stinted — during endless generations, at regular 
lunar intervals. If, then, the vertebrata are descended from an animal 
allied to the existing tidal Ascidians, the mysterious fact that, with the 
higher and now terrestrial Vertebrata, not to mention other classes, many 
normal and abnormal vital processes run their course according to lunar 
periods, is rendered intelligible. A recurrent period, if approximately 
of the right duration, when once gained, would not, as far as we can 
judge, be liable to be changed ; consequently it might be thus transmitted 
during almost any number of generations. This conclusion, if it could 
be proved sound, would be curious ; for we should then see that the pe- 
riod of gestation in each mammal, and the hatching of each bird's eggs, 
and many other vital processes, still betrayed the primordial birthplace 
of these animals. 



Cea?. vl.] AFFINITIES AND GENEALOGY. 205 

period, Man, the wonder and glory of the Universe, pro- 
ceeded. 

Thus we have given to man a pedigree of prodigious 
length, but not, it may be said, of noble quality. The 
world, it has often been remarked, appears as if it had 
long been preparing for the advent of man ; and this, in 
one sense is strictly true, for he owes his birth to a long 
line of progenitors. If any single link in this chain had 
never existed, man would not have been exactly what he 
now is. Unless we wilfully close our eyes, we may, with 
our present knowledge, approximately recognize our par- 
entage : nor need we feel ashamed of it. The most hum- 
ble organism is something much higher than the inorganic 
dust under our feet ; and no one with an unbiassed mind 
can study any living creature, however humble, without 
being struck with enthusiasm at its marvellous structure 
and properties. 



206 THE DESCENT OF MAN. f Past I. 



CHAPTER VII. 

ON THE RACES OF MAN. 

The Nature and Value of Specific Characters. — Application to the Eaces 
of Man. — Arguments in favor of, and opposed to, ranking the So- 
called Eaces of Man as Distinct Species. — Sub-species. — Monogenists 
and Polygenists. — Convergence of Character. — Numerous Points of 
Besemblance in Body and Mind between the most Distinct Eaces of 
Man. — The State of Man when he first spread over the Earth. — Each 
Eace not descended from a Single Pair. — The Extinction of Eaces. — 
The Formation of Eaces. — The Effects of Crossing. — Slight Influence 
of the Direct Action of % the Conditions of Life. — Slight or no Influence 
of Natural Selection. — Sexual Selection. 

It is not my intention here to describe the several so- 
called races of men ; but to inquire what is the value of 
the differences between them under a classificatory point 
of view, and how they have originated. In determining 
whether two or more allied forms ought to be ranked as 
species or varieties, naturalists are practically guided by 
the following considerations : namely, the amount of dif- 
ference between them, and whether such differences relate 
to few or many points of structure, and whether they are 
of physiological importance ; but more especially whether 
they are constant. Constancy of character is what is 
chiefly valued and sought for by naturalists. Whenever 
it can be shown, or rendered probable, that the forms in 
question have remained distinct for a long period, this be- 
comes an argument of much weight in favor of treating 
them as species. Even a slight degree of sterility between 



Chap. VII.] THE RACES OF MAN. 207 

any two forms when first crossed, or in their offspring, is 
generally considered as a decisive test of their specific 
distinctness; and their continued persistence without 
blending within the same area, is usually accepted as 
sufficient evidence, either of some degree of mutual steril- 
ity, or in the case of animals of some repugnance to 
mutual pairing. 

Independently of blending from intercrossing, the 
complete absence, in a well-investigated region, of varie- 
ties linking together any two closely-allied forms, is 
probably the most important of all the criterions of their 
specific distinctness ; and this is a somewhat different con- 
sideration from mere constancy of character, for two 
forms may be highly variable and yet not yield inter- 
mediate varieties. Geographical distribution is often un- 
consciously and sometimes consciously brought into play ; 
so that forms living in two widely-separated areas, in 
which most of the other inhabitants are specifically dis- 
tinct, are themselves usually looked at as distinct ; but in 
truth this affords no aid in distinguishing geographical 
races from so-called good or true species. 

Xow let us apply these generally-admitted principles 
to the races of man, viewing him in the same spirit as a 
naturalist would any other animal. In regard to the 
amount of difference between the races, we must make 
some allowance for our nice powers of discrimination 
gained by the long habit of observing ourselves. In India, 
as Elphinstone remarks, 1 although a newly-arrived Euro- 
pean cannot at first distinguish the various native races, 
yet they soon appear to him extremely dissimilar; and 
the Hindoo cannot at first perceive any difference be- 
tween the several European nations. Even the most dis- 
tinct races of man, with the exception of certain negro 

1 'History of India,' 1841, vol. i. p. 323. Father Ripa makes exactly 
the same remark with respec* to the Chinese. 



208 THE DESCENT OF MAN. [Part I. 

tribes, are much more like each other in form than would 
at first be supposed. This is well shown by the French 
photographs in the Collection Anthropologique du Museum 
of the men belonging to various races, the greater number 
of which, as many persons to whom I have shown them 
have remarked, might pass for Europeans. Nevertheless, 
these men if seen alive would undoubtedly- appear very 
distinct, so that we are clearly much influenced in our 
judgment by the mere color of the skin and hair, by 
slight differences in the features, and by expression. 

There is, however, no doubt that the various races, 
when carefully compared and measured, differ much from 
each other — as in the texture of the hair, the relative pro- 
portions of all parts of the body, 2 the capacity of the 
lungs, the form and capacity of the skull, and even in 
the convolutions of the brain. 3 But it would be an endless 
task to specify the numerous points of structural differ- 
ence. The races differ also in constitution, in acclimatiza- 
tion, and in liability to certain diseases. Their mental 
characteristics are likewise very distinct ; chiefly as it 
would appear in their emotional, but partly in their intel- 
lectual, faculties. Every one who has had the opportunity 
of comparison, must have been struck with the contrast 
between the taciturn, even morose, aborigines of South 
America and the light hearted, talkative negroes. There 
is a nearly similar contrast between the Malays and the 
Papuans, 4 who live under the same physical conditions, 

2 A vast number of measurements of Whites, Blacks, and Indians, are 
given in the ' Investigations in the Military and Anthropolog. Statistics 
of American Soldiers,' by B. A. Gould, 1869* pp. 298-358 ; on the ca- 
pacity of the lungs, p. 471. See also the numerous and valuable tables, 
by Dr. Weisbach, from the observations of Dr. Scherzer and Dr. Schwarz, 
in the 'Reise der Novara: Anthropolog. Theil,' 1867. 

3 See, for instance, Mr. Marshall's account of the brain of a Bush- 
woman, in ' Phil. Transact.' 1864, p. 519. 

4 Wallace, 'The Malay Archipelago,' vol. ii. 1869, p. 178. 



Ceap. YIL] THE RACES OF MAN. 209 

and are separated from each other only by a narrow space 
of sea. 

We will first consider the arguments which may be 
advanced in favor of classing the races of man as distinct 
species, and then those on the other side. If a naturalist, 
who had never before seen such beings, were to compare 
a Xegro, Hottentot, Australian, or Mongolian, he would 
at once perceive that they differed in a multitude of 
characters, some of slight and some of considerable im- 
portance. On inquiry he would find that they were adapted 
to live under widely-different climates, and that they dif- 
fered somewhat in bodily constitution and mental dispo- 
sition. If he were then told that hundreds of similar 
specimens could be brought from the same countries, he 
would assuredly declare that they were as good species as 
many to which he had been in the habit of affixing specific 
names. This conclusion would be greatly strengthened as 
soon as he had ascertained that these forms had all re- 
tained the same character for many centuries; and that 
negroes, apparently identical with existing negroes, had 
lived at least 4,000 years ago. 5 He would also hear from 

5 "With respect to the figures of the famous Egyptian caves of Abou- 
Shribel, M. Pouchet says (' The Plurality of the Human Races,' English 
translat. 1864, p. 50), that he was far from finding recognizable repre- 
sentations of the dozen or more nations which some authors believe that 
they can recognize. Even some of the most strongly-marked races can- 
not be identified with that degree of unanimity which might have been 
expected from what has been written on the subject. Thus Messrs. Xott 
and Gliddon (' Types of Mankind,' p. 148) state that Rameses II., or the 
Great, has features superbly European ; whereas Knox, another firm be- 
liever in the specific distinction of the races of man (' Races of Man,' 
1850, p. 201), speaking of young Memnon (the same person with Rameses 
II., as I am informed by Mr. Birch) insists in the strongest manner that 
he is identical in character with the Jews of Antwerp. Again, while 
looking in the British Museum with two competent judges, officers of the 
establishment, at the statue of Amunoph III., we agreed that he had a 

10 



210 THE DESCENT OF MAN. [Pakt I. 

an excellent observer, Dr. Lund, 6 that the human skulls 
found in the caves of Brazil, entombed with many extinct 
mammals, belonged to the same type as that now prevail- 
ing throughout the American Continent. 

Our naturalist would then, perhaps, turn to geograph- 
ical distribution, and he would probably declare that 
forms differing not only in appearance, but fitted for the 
hottest and dampest or driest countries, as well as for the 
Arctic regions, must be distinct species. He might appeal 
to the fact that no one species in the group next to man, 
namely, the Quadrumana, can resist a low temperature or 
any considerable change of climate ; and that those species 
which come nearest to man have never been reared to 
maturity, even under the temperate climate of Europe. 
He would be deeply impressed with the fact, first noticed 
by Agassiz, 7 that the different races of man are distributed 
over the world in the same zoological provinces, as those 
inhabited by undoubtedly distinct species and genera of 
mammals. This is manifestly the case with the Australian, 
Mongolian, and Negro races of man ; in a less well-marked 
manner with the Hottentots ; but plainly with the Papuans 
and Malays, who are separated, as Mr. Wallace has 
shown, by nearly the same line which divides the great 
Malayan and Australian zoological provinces. The ab- 
origines of America range throughout the continent ; and 
this at first appears opposed to the above rule, for most 
of the productions of the Southern and Northern halves 
differ widely ; yet some few living forms, as the opossum, 

strongly negro cast of features ; but Messrs. Nott and Gliddon (ibid. p. 
146, fig. 53) describe him as "a hybrid, but not of negro intermixture." 

• As quoted by Nott and Gliddon, ' Types of Mankind,' 1854, p. 439. 
They give also corroborative evidence ; but C. Yogt thinks that the sub- 
ject requires further investigation. 

1 " Diversity of Origin of the Human Races," in" the ' Christian Ex- 
aminer,' July, 1850. 



Chap. VII.] THE RACES OF MAN. 211 

range from the one into the other, as did formerly some 
of the gigantic Edentata. The Esquimaux, like other 
Arctic animals, extend round the whole polar regions. It 
should be observed that the mammalian forms which in- 
habit the several zoological provinces, do not differ from 
each other in the same degree ; so that it can hardly be 
considered as an anomaly that the Negro differs more, 
and the American much less, from the other races of man 
than do the mammals of the same continents from those 
of the other provinces. Man,, it may be added, does not 
appear to have aboriginally inhabited any oceanic island ; 
and in this respect he resembles the other members of his 
class. 

In determining whether the varieties of the same kind 
of domestic animal should be ranked as specifically dis- 
tinct, that is „ whether any of them are descended from 
distinct wild species, every naturalist would lay much 
stress on the fact, if established, of their external parasites 
being specifically distinct. All the more stress would be 
laid on this fact, as it would be an exceptional one, for I 
am informed by Mr. Denny that the most different kinds 
of dogs, fowls, and pigeons, in England, are infested by 
the same species of Pediculi or lice. Now Mr. A. Murray 
has carefully examined the Pediculi collected in different 
countries from the different races of man ; 8 and he finds 
that they differ, not only in color, but in the structure of 
their claws and limbs. In every case in which numerous 
specimens were obtained the differences were constant. 
The surgeon of a whaling-ship in the Pacific assured me 
that when the Pediculi, with which some Sandwich Island- 
ers on board swarmed, strayed on to the bodies of the 
English sailors, they died in the course of three or four 
days. These Pediculi were darker colored and appeared 
different from those proper to the natives of Chiloe in 

• ' Transact. R. Soc. of Edinburgh,' voL xxii. 1861, p. 567. 



212 TEE DESCENT OF MAN [Part I. 

South America, of which he gave me specimens. These, 
again, appeared larger and much softer than European lice. 
Mr. Murray procured four kinds from Africa, namely from 
the Negroes of the Eastern and Western coasts, from the 
Hottentots and Caffres ; two kinds from the natives of 
Australia ; two from North, and two from South America. 
In these latter cases it may be presumed that the Pediculi 
came from natives inhabiting different districts. With 
insects slight structural differences, if constant, are gen- 
erally esteemed of specific value : and the fact of the races 
of man being infested by parasites, which appear to be 
specifically distinct, might fairly be urged as an argument 
that the races themselves ought to be classed as distinct 
species. 

Our supposed naturalist, having proceeded thus far in 
his investigation, would next inquire whether the races of 
men, when crossed, were in any degree sterile. He might 
consult the work 9 of a cautious and philosophical ob- 
server, Prof. BroCa ; and in this he would find good evi- 
dence that some races were quite fertile together; but 
evidence of an opposite nature in regard to other races. 
Thus it has been asserted that the native women of Aus- 
tralia and Tasmania rarely produce children to European 
men ; the evidence, however, on this head has now been 
shown to be almost valueless. The half-castes are killed 
by the pure blacks ; and an account has lately been pub- 
lished of eleven half-caste youths murdered and burnt at 
the same time, whose remains were found by the police. 10 

9 ' On the Phenomena of Hybridity in the Genus Homo,' Eng. trans- 
lation, 1864. 

10 See the interesting letter by Mr. T. A. Murray, in the ' Anthropo- 
log. Review,' April, 1868, p. liii. In this letter Count Strzelecki's state- 
ment, that Australian women who have borne children to a white man 
are afterward sterile with their own race, is disproved. M. A. de Qua- 
trefages has also collected ('Revue des Cours Scientifiques,' March, 1869, 



Chap. TIL] THE RACES OF MAN. 213 

Again, it has often been said that when mulattoes inter- 
marry they produce few children ; on the other hand, Dr. 
Bachman of Charleston " positively asserts that he has 
known mulatto families which have intermarried for sev- 
eral generations, and have continued on an average as 
fertile as either pure whites or pure blacks. Inquiries 
formerly made by Sir C. Lyell on this subject led him, as 
he informs me, to the same conclusion. In the United 
States the census for the year 1854 included, according to 
Dr. Bachman, 405,751 mulattoes; and this number, con- 
sidering all the circumstances of the case, seems small ; 
but it may partly be accounted for by the degraded and 
anomalous position of the class, and by the profligacy of 
the women. A certain amount of absorption of mulattoes 
into negroes must always be in progress ; and this would 
lead to an apparent diminution of the former. The in- 
ferior vitality of mulattoes is spoken of in a trustworthy 
work 12 as a well-known phenomenon ; but this is a dif- 
ferent consideration from their lessened fertility ; and can 
hardly be advanced as a proof of the specific distinctness 
of the parent races. Xo doubt both animal and vegetable 
hybrids, when produced from extremely distinct species, 
are liable to premature death; but the parents of mulat- 
toes cannot be put under the category of extremely dis- 
tinct species. The common Mule, so notorious for long 
life and vigor, and yet so sterile, shows how little necessary 
connection there is in hybrids between lessened fertility 
and vitality : other analogous cases could be added. 

Even if it should hereafter be proved that all the races 

p. 239) much evidence that Australians and Europeans are not sterile 
when crossed. 

11 ' An Examination of Prof. Agassiz's Sketch of the Nat. Provinces 
of the Animal World,' Charleston, 1855, p. 44. 

12 ' Military and Anthropolog. Statistics of American Soldiers,' by 
B. A. Gould, 1869, p. 319. 



214 THE DESCENT OF MAN. [Part I. 

of men were perfectly fertile together, lie who was inclined 
from other reasons to rank them as distinct species, might 
with justice argue that fertility and sterility are not safe 
criterions of specific distinctness. We know that these 
qualities are easily affected by changed conditions of life 
or by close inter-breeding, and that they are governed by 
highly complex laws, for instance that of the unequal fer- 
tility of reciprocal crosses between the same two species. 
With forms which must be ranked as undoubted species, 
a perfect series exists from those which are absolutely 
sterile when crossed, to those which are almost or quite 
fertile. The degrees of sterility do not coincide strictly 
with the degrees of difference in external structure or hab- 
its of life. Man in many respects may be compared with 
those animals which have long been domesticated, and a 
large body of evidence can be advanced in favor of the 
Pallasian doctrine, 13 that domestication tends to eliminate 

13 ' The Variation of Animals and Plants under Domestication,' vol. ii. 
p. 109. I may here remind the reader that the sterility of species when 
crossed is not a specially-acquired quality ; but, like the incapacity of 
certain trees to be grafted together, is incidental on other acquired dif- 
ferences. The nature of these differences is unknown, but they relate 
more especially to the reproductive system, and much less to external 
structure or to ordinary differences in constitution. \ One important ele- 
ment in the sterility of crossed species apparently lies in one or both 
having been long habituated to fixed conditions ; for we know that 
.changed conditions have a special influence on the reproductive system, 
and we have good reason to believe (as before remarked) that the fluctu- 
ating conditions of domestication tend to eliminate that sterility which is 
so general with species in a natural state when crossed. It has elsewhere 
been shown by me (ibid. vol. ii. p. 185, and ' Origin of Species,' 5th edit, 
p. 317) that the sterility of crossed species has not been acquired through 
natural selection : we can see that when two forms have already been 
rendered very sterile, it is scarcely possible that their sterility should be 
augmented by the preservation or survival of the more and more sterile 
individuals ; for as the sterility increases fewer and fewer offspring will 
be produced from which to breed, and at last only single individuals will 
be produced, at the rarest intervals But there is even a higher 



Chap. YU.] THE RACES OF MAN. 215 

the sterility which is so general a result of the crossing of 
species in a state of nature. From these several consid- 
erations, it may be justly urged that the perfect fertility 
of the intercrossed races of man, if established, would 
not absolutely preclude us from ranking them as distinct 
species. 

Independently of fertility, the character of the offspring 
from a cross has sometimes been thought to afford evidence 
whether the parent-forms ought to be ranked as species or 
varieties ; but after carefully studying the evidence, I have 
come to the conclusion that no general rules of this kind 
can be trusted. Thus with mankind the offspring of dis- 
tinct races resemble in all respects the offspring of true 
species and of varieties. This is shown, for instance, by 
the manner in which the characters of both parents are 
blended, and by one form absorbing another through re- 
peated crosses. In this latter case the progeny both of 
crossed species and varieties retain for a long period a ten- 
dency to revert to their ancestors, especially to that one 
which is prepotent in transmission. When any character 
has suddenly appeared in a race or species as the result 
of a single act of variation, as. is general with monstrosi- 
ties, 14 and this race is crossed with another not thus char- 
acterized, the characters in question do not commonly ap- 

grade of sterility than this. Both Gartner and Kolreuter have proved 
that in genera of plants including numerous species, a series can be 
formed from species which when crossed yield fewer and fewer seeds, 
to species which never produce a single seed, but yet are affected by the 
pollen of the other species, for the germen swells. It is here manifestly 
impossible to select the more sterile individuals, which have already 
ceased to yield seeds ; so. that the acme of sterility, when the germen 
•alone is affected, cannot be gained through selection. This acme, and 
no doubt the other grades of sterility, are the incidental results of certain 
unknown differences in the constitution of the reproductive system of the 
species which are crossed. 

14 ' The Variation of Animals,' etc., vol. ii. .p. 92. 



216 THE DESCENT OF MAN. [Part L 

pear in a blended condition in the young, but are trans- 
mitted to them either perfectly developed or not at all. 
As with the crossed races of man cases of this kind rarely 
or never occur, this may be used as an argument against 
the view suggested by some ethnologists, namely, that 
certain characters, for instance the blackness of the neoro. 
first appeared as a sudden variation or sport. Had this 
occurred, it is probable that mulattoes would often have 
been born either completely black or completely white. 

We have now seen that a naturalist might feel himself 
fully justified in ranking the races of man as distinct spe- 
cies ; for he has found that they are distinguished by many 
differences in structure and constitution, some being of im- 
portance. These differences have, also, remained nearly 
constant for very long periods of time. He will have been 
in some degree influenced by the enormous range of man, 
which is a great anomaly in the class of mammals, if man- 
kind be viewed as a single species. He will have been 
struck with the distribution of the several so-called races, 
in accordance with that of other undoubtedly distinct 
species of mammals. Finally, he might urge that the mu- 
tual fertility of all the races has not yet been fully proved ; 
and even if proved would not be an absolute proof of their 
specific identity. 

On the other side of the question, if our supposed natu- 
ralist were to inquire whether the forms of man kept dis- 
tinct like ordinary species, when mingled together in' large 
numbers in the same country, he would immediately dis- 
cover that this was by no means the case. In Brazil he 
would behold an immense mongrel j>opulation of Negroes 
and Portuguese ; in Chiloe and other parts of South Amer- 
ica he would behold the whole population consisting ' of 
Indians and Spaniards blended in various degrees. 16 s In 

16 M. de Quatrefages has given (' Anthropolo-g. Review,' Jan. 1809, 



Chap. TIL] THE RACES OF MAN. 217 

• 

many parts of the same continent he would meet with 
the most complex crosses between Negroes, Indians, and 
Europeans ; and such triple crosses afford the severest 
test, judging from the vegetable kingdom, of the mutual 
fertility of the parent-forms. In one island of the Pacific 
he would find a small population of mingled Polynesian 
and English blood ; and in the Viti Archipelago a popu- 
lation of Polynesians and Negritos crossed in all degrees. 
Many analogous cases could be added, for instance, in 
South Africa. Hence the races of man are not sufficient- 
ly distinct to coexist without fusion ; and this it is which, 
in all ordinary cases, affords the usual test of specific dis- 
tinctness. 

Our naturalist would likewise be much disturbed as 
soon as he perceived that the distinctive characters of 
every race of man were highly variable. This strikes 
every one when he first beholds the negro-slaves in Brazil, 
who have been imported from all parts of Africa. The 
same remark holds good with the Polynesians, and with 
many other races. It may be doubted whether any char- 
acter can be named which is distinctive of a race and is 
constant. Savages, even within the limits of the same 
tribe, are not nearly so uniform in character as has often 
been said. ' Hottentot women offer certain peculiarities, 
more strongly marked than those occurring in any other 
race, but these are known not to be of constant occurrence. 
In the several American tribes, color and hairiness differ 
considerably ; as does color to a certain degree, and the 
shape of the features greatly, in the Negroes of Africa. 
The shape of the skull varies much in some races ; 16 and 

p. 22) an interesting account of the success and energy of the Paulistas 
in Brazil, who are a much crossed race of Portuguese and Indians, witb 
a mixture of the blood of other races. 

16 For instance with the aborigines of America and Australia. Prof 
Huxley says (' Transact. Internat. Congress of Prehist. Arch.' 1868, p 



218 THE DESCENT OF MAN. [Part I. 

bo it is with every other character. Now all naturalists 
have learned, by dearly-bought experience, how rash it 
is to attempt to define species by the aid of inconstant 
characters. 

But the most weighty of all the arguments against 
treating the races of man as distinct species, is that they 
graduate into each other, independently in many cases, as 
far as we can judge, of their having intercrossed. Man 
has been studied more carefully than any other organic 
being, and yet there is the greatest possible diversity 
among capable judges whether he should be classed as a 
single species or race, or as two (Virey), as three (Jacqui- 
not), as four (Kant), five (Blumenbach), six (Buffon), seven 
(Hunter), eight (Agassiz), eleven (Pickering), fifteen (Bory 
St. Vincent), sixteen (Desmoulins), twenty-two (Morton), 
sixty (Crawfurd), or as sixty-three, according to Burke. 17 
This diversity of judgment does not prove that the races 
ought not to be ranked as species, but it shows that they 
graduate into each other, and that it is hardly possible to 
discover clear distinctive characters between them. 

Every naturalist who has had the misfortune to under- 
take the description of a group of highly-varying organ- 
isms, has encountered cases (I speak after experience) 
precisely like that of man ; and if of a cautious disposi- 
tion, he will end by uniting all the forms which graduate 
into each other as a single species ; for he will say to him- 
self that he has no right to give names to objects which 
he cannot define. Cases of this kind occur in the Order 
which includes man, namely, in certain genera of monkeys ; 

105) that the skulls of many South Germans and Swiss are " as short and 
as broad as those of the Tartars," etc. 

17 See a good discussion on this subject in Waitz, ' Introduct. to An- 
thropology,' Eng. translat. 1863, pp. 198-208, 227. I have taken some 
of the above statements from H. Tuttle's ' Origin and Antiquity of Physical 
Man,' Boston, 1866, p. 35. 



Chap. YII.] TEE RACES OF MAN. ' 219 

while in other genera, as in Cercopithecus, most of the 
species can be determined with certainty. In the Ameri- 
can genus Cebns, the various forms are ranked by some 
naturalists as species, by others as mere geographical 
races. Now, if numerous specimens of Cebus were col- 
lected from all parts of South America, and those forms 
which at present appear to be specifically distinct, were 
found to graduate into each other by close steps, they 
would be ranked by most naturalists as mere varieties or 
races ; and thus the greater number of naturalists have . 
acted with respect to the races of man. Nevertheless it 
must be confessed that there are forms, at least in the 
vegetable kingdom, 18 which we cannot avoid naming as 
species, but which are connected together, independently 
of intercrossing, by numberless gradations. 

Some naturalists have lately employed the term " sub- 
species " to designate forms which possess many of the 
characteristics of true species, but which hardly deserve 
so high a rank. Now, if we reflect on the weighty argu- 
ments, above given, for raising the races of man to the 
dignity of species, and the insuperable difficulties on the 
other side in defining them, the term " sub-species " might 
here be used with much propriety. But from long habit 
the terni "race" will perhaps always be employed. The 
choice of terms is only so far important as it is highly de- 
sirable to use, as far as that may be possible, the same 
terms for the same degrees of difference. Unfortunately, 
this is rarely possible ; for within the same family the 
larger genera generally include closely-allied forms, which 
can be distinguished only with much difficulty, while the 
smaller genera include forms that are perfectly distinct ; 

18 Prof. Nageli has carefully described several striking cases in his 
'Botanische Mittheilungen,' B. ii. 1866, s. 294-369. Prof. Asa Gray has 
made analogous remarks on some intermediate forms in the Composites 
of Xorth America. 



220 THE DESCENT OF MAN [Part I, 

yet all must equally be ranked as species. So again the 
species within the same large genus by no means resemble 
each other to the same degree : on the contrary, in most 
cases some of them can be arranged in little groups round 
other species, like satellites round planets." 

The question whether mankind consists of one or sev- 
eral species has of late years been much agitated by an- 
thropologists, who are divided into two schools of mono- 
genists and polygenists. Those who do not admit the 
principle of evolution, must look at species either as sep- 
arate creations or as in some manner distinct entities; 
and they must decide what forms to rank as species by 
the analogy of other organic being's which are commonly 
thus received. But it is a hopeless endeavor to decide 
this point on sound grounds, until some definition of the 
term " species " is generally accepted ; and the definition 
must not include an element which cannot possibly be as- 
certained, such as an act of creation. We might as well 
attempt without any definition to decide whether a cer- 
tain number of houses should be called a village, or town, 
or city. We have a practical illustration of the difficulty 
in the never-ending doubts whether many closely-allied 
mammals, birds, insects, and plants, which represent each 
other in North America and Europe, should be ranked 
species or geographical races ; and so it is with the pro- 
ductions of many islands situated at some little distance 
from the nearest continent. 

Those naturalists, on the other hand, who admit the 
principle of evolution, and this is now admitted by the 
greater number of rising men, will feel no doubt that all 
the races of man are descended from a single primitive 
stock ; whether or not they think fit to designate them as 
distinct species, for the sake of expressing their amount 

19 ' Origin of Species,' 5tb edit. p. 68. 



Chap. TIL] " THE RACES OF MAN. 221 

• 

of difference. 20 With our domestic animals the question 
whether the various races have arisen from one or more 
species is different. Although all such races, as well as 
all the natural species within the same genus, have un- 
doubtedly sprung from the same primitive stock, yet it is 
a fit subject for discussion, whether, for instance, all the 
domestic races of the dog have acquired their present 
differences since soine one species was first domesticated 
and bred by man; or whether they owe some of their 
characters to inheritance from distinct species, which had 
already been modified in a state of nature. With man- 
kind no such question can arise, for he cannot be said to 
have been domesticated at any particular period. 

When the races of- man diverged at an extremely re- 
mote epoch from their common progenitor, they will have 
differed but little from each other, and been few in num- 
ber ; consequently they will then, as far as their distin- 
guishing characters are concerned, have had less claim to 
rank as distinct species, than the existing so-called races. 
Nevertheless such early races would perhaps have been 
ranked by some naturalists as distinct species, so arbitrary 
is the term, if their differences, although extremely slight, 
had been more constant than at present, and had not 
graduated into each other. 

It is, however, possible, though far from probable, 
that the early progenitors of man might at first have di- 
verged much in character, until they became more unlike 
each other than are any existing races ; but that subse- 
quently, as suggested by Yogt, 21 they converged in char- 
acter. When man selects for the same object the off- 
spring of two distinct species, he sometimes induces, as 
far as general appearance is concerned, a considerable 

80 See Prof. Huxley to this effect in the 'Fortnightly Review/ 1865, 
p. 275. 

21 ' Lectures on Man,' Eng. translat. 1864, p. 468. 



222 THE DESCENT OF MAN. [Part I. 

amount of convergence. This is the case, as shown by 
Von Nathusius, 22 with the improved breeds of pigs, which 
are descended from two distinct species ; and in a less 
well-marked manner with the improved breeds of cattle. 
A great anatomist, Gratiolet, maintains that the anthro- 
pomorphous apes do not form a natural sub-group ; but 
that the orang is a highly-developed gibbon or semno- 
pithecus ; the chimpanzee a highly-developed macacus ; and 
the gorilla a highly-develoj>ed mandrill. If this conclu- 
sion, which rests almost exclusively on brain-characters, 
be admitted, we should have a case of convergence at 
least in external characters, for the anthropomorphous 
apes are certainly more like each ojher in many points 
than they are to other apes. All analogical resemblances, 
as of a whale to a fish, may indeed be said to be cases of 
convergence ; but this term has never been applied to 
superficial and adaptive resemblances. It would be ex- 
tremely rash in most cases to attribute to convergence 
close similarity in many points of structure in beings 
which had once been widely different. The form of a 
crystal is determined solely by the molecular forces, and 
it is not surprising that dissimilar substances should some- 
times assume the same form ; but with organic beings we 
should bear in mind that the form of each depends on an 
infinitude of complex relations, namely, on the variations 
which have arisen, these being due to causes far too intri- 
cate to be followed out — on the nature of the variations 
which have been preserved, and this depends on the sur- 
rounding physical conditions, and in a still higher degree 
on the surrounding organisms with which each has come 
into competition — and lastly, on inheritance (in itself a 
fluctuating element) from innumerable progenitors, all of 

22 'Die Racen des Schweines,' 1860, s. 46. 'Yo-rstudien fur Ge- 
echichte, etc., Schweineschadel,' 1864, s. 104. With respect to cattle, 
Bee M. de Quatrefages, 'Unite de l'Espece Huraaine,' 1861, p. 119. 



Chap. YIL] THE RACES OF MAN. 223 

which have had their forms determined through equally- 
complex relations. It appears utterly incredible that two 
organisms, if differing in a marked manner, should ever 
afterward converge so closely as to lead to a near ap- 
proach to identity throughout their whole organization. 
In the case of the convergent pigs above referred to, evi- 
dence of their descent from two primitive stocks is still 
plainly retained, according to Yon Nathusius, in certain 
bones of their skulls. If the races of man were descended, 
as supposed by some naturalists, from two or more dis- 
tinct species, which had differed" as much, or nearly as 
much, from each other, as the orang differs from the go- 
rilla, it can hardly be doubted that marked differences in 
the structure of certain bones would still have been dis- 
coverable in man as he now exists. 

Although the existing races of man differ in many re- 
spects, as in color, hair, shape of skull, proportions of the 
body, etc., yet if their whole organization be taken into 
consideration they are found to resemble each other closely 
in a multitude of points. Many of these points are of 
so unimportant or of so singular a nature, that it is ex- 
tremely improbable that they should have been indepen- 
dently acquired by aboriginally distinct species or races. 
The same remark holds good with equal or greater force 
with respect to the numerous points of mental similarity 
between the most distinct races of man. The American 
aborigines, Negroes, and Europeans, differ as much from 
each other in mind as any three races that can be named ; 
yet I was incessantly struck, while living with the Fue- 
gians on board the " Beagle," with the many little traits 
of character, showing how similar their minds were to 
ours ; and so it was with a full-blooded negro with whom 
I happened once to be intimate. 

He who will carefully read Mr. Tylor's and Sir J. Lub- 



224 THE DESCENT OF MAN. [Part I. 

hock's interesting works 23 can hardly fail to be deeply im- 
pressed with the close similiarity between the men of all 
races in tastes, dispositions, and habits. This is shown by 
the pleasure which they all take in dancing, rude music, 
acting, painting, tattooing, and otherwise decorating them 
selves — in their mutual comprehension of gesture-language 
— and, as I shall be able to show in a future essay, by the 
same expression in their features, and by the same inar- 
ticulate cries, when they are excited by various emotions. 
This similarity, or rather identity, is striking, when con- 
trasted with the different expressions which may be ob- 
served in distinct species of monkeys. There is good 
evidence that the art of shooting with bows and arrows 
has not been handed down from any common progenitor 
of mankind, yet the Istone arrow-heads, brought from the 
most distant parts of the world and manufactured at the 
most remote periods, are, as Nilsson has shown, 24 almost 
identical ; and this fact can only be accounted for by the 
various races having similar inventive or mental powers. 
The same observation has been made by archaeologists 26 
with respect to certain widely-prevalent ornaments, such 
as zigzags, etc. ; and with respect to various simple beliefs 
and customs, such as the burying of the dead under 
megalithic structures. I remember observing in South 
America, 26 that there, as in so many other parts of the 
world, man has generally chosen the summits of lofty hills, 
on which to throw up piles of stones, either for the sake of 
recording some remarkable event, or for burying his dead. 

23 Tylor's 'Early History of Mankind,' 1865 ; for the evidence with 
respect to gesture-language, see p. 54. Lubbock's ' Prehistoric Times,' 
2d edit. 1869. 

24 ' The Primitive Inhabitants of Scandinavia,' Eng. translat. edited 
by Sir J. Lubbock, 1868, p. 104. 

25 Hodder M. Westropp, on Cromlechs, etc., ' Journal of Ethnological 
Soc.' as given in 'Scientific Opinion,' June 2, 1869, p. 3. 

96 ' Journal of Researches : Voyage of the *' Beagle," ' p. 46. 



Chap. VII.] THE RACES OF MAN. 225 

Now, when naturalists observe a close agreement in 
numerous small details of habits, tastes, and dispositions, 
between two or more domestic races, or between nearly- 
allied natural forms, they use this fact as an argument 
that all are descended from a common progenitor who 
was thus endowed ; and consequently that all should be 
classed under the same species. The same argument may 
be applied with much force to the races of man. 

As it is improbable that the numerous and unimportant 
points of resemblance between the several races of man 
in bodily structure and mental faculties (I do not here re- 
fer to similar customs) should all have been independently 
acquired, they must have been inherited from progenitors 
who were thus characterized. We thus gain some insight 
into the early state of man, before he had spread step by 
step over the face of the earth. The spreading of man to 
regions widely-separated* by the sea, no doubt, preceded 
any considerable amount of divergence of character in 
the several races ; for otherwise we should sometimes 
meet with the same race in distinct continents ; and this 
is never the case. Sir J. Lubbock, after comparing the 
arts now practised by savages in all parts of the world, 
specifies those which man could not have known, when he 
first wandered from his original birthplace ; for if once 
learned they would never have been forgotten. 27 He thus 
shows that " the spear, which is but a development of the 
knife-point, and the club, which is but a long hammer, are 
the only things left." He admits, however, that the art 
of making fire probably had already been discovered, for 
it is common to all the races now existing, and was known 
to the ancient cave-inhabitants of Europe. Perhaps the 
art of making rude canoes or rafts was likewise known ; 
but as man existed at a remote epoch, when the land in 
many places stood at a very different level, he would have 

87 ' Prehistoric Times,' 1869, p. 574. 



226 THE DESCENT OF MAN. [Part I. 

4 

been able, without the aid of canoes, to have spread widely. 
Sir J. Lubbock further remarks how improbable it is that 
our earliest ancestors could have " counted as high as ten, 
considering that so many races now in existence cannot 
get beyond four." Nevertheless, at this early period, the 
intellectual and social faculties of man could hardly have 
been inferior in any extreme degree to those now. pos- 
sessed by the lowest savages ; otherwise primeval man 
could not have been so eminently successful in the 
struggle for life, as proved by his early and wide dif- 
fusion. 

From the fundamental differences between certain lan- 
guages, some philologists have inferred that when man 
first became widely diffused he was not a speaking ani- 
mal ; but it may be suspected that languages, far less per- 
fect than any now spoken, aided by gestures, might have 
been used, and yet have left no traces on subsequent and 
more highly-developed tongues. Without the use of some 
language, however imperfect, it appears doubtful whether 
man's intellect could have risen to the standard implied 
by his dominant position at an early period. 

Whether primeval man, when he possessed very few 
arts of the rudest kind, and when his power of language 
was extremely imperfect, would have deserved to be 
called man, must depend on the definition which we em- 
ploy. In a series of forms graduating insensibly from 
some ape-like creature to man as he now exists, it would 
be impossible to fix on any definite point when the term 
" man " ought to be used. But this is a matter of very 
little importance. So again it is almost a matter of in- 
difference whether the so-called races of man are thus 
designated, or are ranked as species or sub-species ; but 
the latter term appears the most appropriate. Finally, we 
may conclude that when the principles of evolution are 
generally accepted, as they surely will be before long, the 



Chap. VII.] THE RACES OF MAN. 227 

dispute between the monogenists and the polygenists will 
die a silent and unobserved death. 

One other question ought not to be passed over with- 
out notice, namely, whether, as is sometimes assumed, each 
sub-species or race of man has sprung from a single pair 
of progenitors. With our domestic animals a new race 
can readily be formed from a single pair possessing some 
new character, or even from a single individual thus - char- 
acterized, by carefully matching the varying offspring; 
but most of our races have been formed* not intentionally 
from a selected pair, but unconsciously by the preservation 
of many individuals which have varied, however slightly, 
in some useful or desired manner. If in one country 
stronger and heavier horses, and in another country light- 
er and fleeter horses, were habitually preferred, we may 
feel sure that two distinct sub-breeds would, in the course 
of time, be produced, without any particular pairs or indi- 
viduals having been separated and bred from in either 
country. Many races have been thus formed, and their 
manner of formation is closely analogous with that of natu- 
ral species. We know, also, that the horses which have 
been brought to the Falkland Islands have become, during 
successive generations, smaller and weaker, while those 
which have run wild on the Pampas have acquired larger 
and coarser heads ; and such changes are manifestly due, 
not to any one pair, but to all the individuals having been 
subjected to the same conditions, aided, perhaps, by the 
principle of reversion. The new sub-breeds in none of 
these cases are descended from any single pair, but from 
many individuals which have varied in different degrees, 
but in the same general manner ; and we may conclude 
that the races of man have been similarly produced, the 
modifications being either the direct result of exposure to 
different conditions, or the indirect result of some form of 



228 THE DESCENT OF MAN. [Part I. 

selection. But to this latter subject we shall presently re- 
turn. 

On the Extinction of the Races of Man. — The partial 
and complete extinction of many races and sub-races of 
man are historically known events. Humboldt saw in 
South America a parrot which was the sole living creature 
that could speak the language of a lost tribe. Ancient 
monuments and stone implements found in all parts of the 
world, of which no tradition is preserved by the present 
inhabitants, indicate much extinction. Some small and 
broken tribes, remnants of former races, still survive in 
isolated and generally mountainous districts. In Europe 
the ancient races were all, according to Schaaffhausen, 29 
" lower in the scale than the rudest living savages ; " they 
must therefore have differed, to a certain extent, from any 
existing race. The remains described by Prof. Broca 29 
from Les Eyzies, though they unfortunately appear to 
have belonged to a single family, indicate a race with a 
most singular combination of low or simious and high 
characteristics, and is " entirely different from any other 
race, ancient or modern, that we have ever heard of." It 
differed, therefore, from the quaternary race of the caverns 
of Belgium. 

Unfavorable physical conditions appear to have had 
but little effect in the extinction of races. 30 Man has long 
lived in the extreme regions of the North, with no wood 
wherewith to make his canoes or other implements, and 
with blubber alone for burning and giving him warmth, 
but more especially for melting the snow. In the South- 

28 Translation in 'Anthropological Review,' Oct. 1868, p. 431. 

29 'Transact. Internat. Congress of Prehistoric Arch.' 1868, pp. 172- 
175. See also Broca (translation) in 'Anthropological Review,' Oct. 
1868, p. 410. 

80 Dr. Gerland, ' Ueber das Aussterben der Naturvolker,' 1868, s. 8a 



Chap. VII.] THE RACES OF MAN" 229 

era extremity of America the Fuegians survive without 
the protection of clothes, or of any building worthy to be 
called a hovel. In South Africa the aborigines wander 
over the most arid plains, where dangerous beasts abound. 
Man can withstand the deadly influence of the Terai at 
the foot of the Himalaya, and the pestilential shores of 
tropical Africa. 

Extinction follows chiefly from the competition of tribe 
with tribe, and race with race. Various checks are always 
in action, as specified in a former chapter, which serve to 
keep down the numbers of each savage tribe — such as 
periodical famines, the wandering of the parents and the 
consequent deaths of infants, prolonged suckling, the steal- 
ing of women, wars, accidents, sickness, licentiousness, es- 
pecially infanticide, and, perhaps, lessened fertility from 
less nutritious food, and many hardships. If from any 
cause any one of these checks is' lessened, even in a slight 
degree, the tribe thus favored will tend to increase ; and 
when one of two adjoining tribes becomes more numerous 
and powerful than the other, the contest is soon settled 
by war, slaughter, cannibalism, slavery, and absorption. 
Even when a weaker tribe is not thus abruptly swept 
away, if it once begins to decrease, it generally goes on 
decreasing until it is extinct. 31 

When civilized nations come into contact with barba- 
rians the struggle is short, except where a deadly climate 
gives its aid to the native race. Of the causes which lead 
to the victory of civilized nations, some are plain and some 
very obscure. We can see that the cultivation of the land 
will be fatal in many ways to savages, for they cannot, or 
will not, change their habits. New diseases and vices are 
highly destructive ; and it appears that in every nation a 
new disease causes much death, until those who are most 
susceptible to its destructive influence are gradually weed- 

31 Gerland (ibid. s. 12) gives facts in support of this statement. 



230 THE DESCENT OF MAN. [Part L 

ed out ; 32 and so it may be with the evil effects from spir- 
ituous liquors, as well as with the unconquerably strong 
taste for them shown by so many savages. It further ap- 
pears, mysterious as is the fact, that the first meeting of 
distinct and separated people generates disease. 33 Mr. 
Sproat, who in Vancouver Island closely attended to the 
subject of extinction, believes that changed habits of life, 
which always follow from the advent of Europeans, in- 
duces much ill-health. He lays, also, great stress on so tri- 
fling- a cause as that the natives become "bewildered and 
dull by the new life around them ; they lose the motives 
for exertion, and get no new ones in their place." 34 

The grade of civilization seems a most important ele- 
ment in the success of nations which come in competition. 
A few centuries ago Europe feared the inroads of Eastern 
barbarians ; now, any such fear would be ridiculous. It 
is a more curious fact that savages did not formerly waste 
away, as Mr. Bagehot has remarked, before the classical 
nations, as they now do before modern civilized nations ; 
had they done so, the old moralists would have mused 
over the event ; but there is no lament in any writer of 
that period over the perishing barbarians. 36 

Although the gradual decrease and final extinction of 
the races of man is an obscure problem, we can see that 
it depends on many causes, differing in different places 
and at different times. It is the same difficult problem as 
that presented by the extinction of one of the higher ani- 

32 See remarks to this effect in Sir H. Holland's ' Medical Notes and 
Reflections,' 1839, p. 390. 

33 I have collected (' Journal of Researches, Voyage of the "Beagle,"' 
p. 435) a good many cases bearing on this subject: see also Gerland, 
ibid. s. 8. Poeppig speaks of the " breath of civilization as poisonous 
to savages." 

34 Sproat, 'Scenes and Studies of Savage Life,' 1868, p. 284. 

35 Bagehot, " Physics and Politics," ' Fortnightly Review,' April 1, 
1868, p. 455. 



/ 



Chap. Vn.] THE RACES OF MAN. 231 

mals — of the fossil horse, for instance, which disappeared 
from South America, soon afterward to be replaced, with- 
in the same districts, by countless troops of the Spanish 
horse. The New-Zealander seems conscious of this paral- 
lelism, for he compares his future fate with that of the 
native rat almost exterminated by the European rat. 
The difficulty, though great to our imagination, and real- 
ly great if we wish to ascertain the precise causes, ought 
not to be so to our reason, as long as we keep steadily in 
mind that the increase of each species and each race is 
constantly hindered by various checks ; so that if any new 
check, or cause of destruction, even a slight one, be super- 
added, the race will surely decrease in number ; and as it 
has everywhere been observed that savages are much op- 
posed to any change of habits, by which means injurious 
checks could be counterbalanced, decreasing numbers will 
sooner or later lead to extinction ; the end, in most cases, 
being promptly determined by the inroads of increasing 
and conquering tribes. 

On the Formation of the Maces of Man. — It may be 
premised that when we find the same race, though broken 
up into distinct tribes, ranging over a great area, as over 
America, we may attribute their general resemblance to 
descent from a common stock. In some cases the cross- 
ing of races already distinct has led to the formation of 
new races. The singular fact that Europeans and Hin- 
doos, who belong to the same Aryan stock and speak a 
language fundamentally the same, differ widely in ap- 
pearance, while Europeans differ but little from Jews, who 
belong to the Semitic stock and speak quite another lan- 
guage, has been accounted for by Broca 36 through the 
Aryan branches having been largely crossed during their 

36 " On Anthropology," translation, ' Anthropolog. Review,' Jan. 1868, 
p. 38. 



232 THE DESCENT OF MAN. [Part L 

wide diffusion by various indigenous tribes. When two 
races in close contact cross, the first result is a heterogene- 
ous mixture : thus Mr. Hunter, in describing the Santali 
or hill-tribes of India, says that hundreds of impercep- 
tible gradations may be traced "from the black, squat 
tribes of the mountains to the tall olive-colored Bramin, 
with his intellectual brow, calm eyes, and high but nar- 
row head ; " so that it is necessary in courts of justice to 
ask the witnesses whether they are Santalis or Hindoos. 87 
Whether a heterogeneous people, such as the inhabitants 
of some of the Polynesian islands, formed by the cross- 
ing of two distinct races, with few or no pure members 
left, would ever become homogeneous, is not known from 
direct evidence. But, as with our domesticated animals, 
a crossed breed can certainly, in the course of a few gen- 
erations, be fixed and made uniform by careful selection, 38 
we may infer that the free and prolonged intercrossing 
during many generations of a heterogeneous mixture 
would supply the place of selection, and overcome any 
tendency to reversion, so that a crossed race would ulti- 
mately become homogeneous, though it might not par- 
take in an equal degree of the characters of the two par- 
ent-races. 

Of all the differences between the races of man, the 
color of the skin is the most conspicuous and one of the 
best marked. Differences of this kind, it was formerly 
thought, could be accounted for by long exposure under 
different climates ; but Pallas first showed that this view 
is not tenable, and he has been followed by almost all an- 
thropologists. 39 The view has been rejected chiefly be- 

37 'The Annals of Rural Bengal,' 18G8, p. 134. 

38 ' The Yariation of Animals and Plants under Domestication,' voL 
ii. p. 95. 

89 Pallas, 'Act. Acad. St. Petersburg,' 1780, part ii. p. 69. He was 
followed by Rudolphi, in his ' Beytrage zur Anthropologic,' 1812. An 



Chap. VIL] THE RACES OF MAN. 233 

cause the distribution of the variously-colored races, most 
of whom must have long inhabited their present homes, 
does not coincide with corresponding differences of cli- 
mate. Weight must also be given to such cases as that 
of the Dutch families, who, as we hear on excellent au- 
thority, 40 have not undergone the least change of color, 
after residing for three centuries in South Africa. The 
uniform appearance in various parts of the world of gyp- 
sies and Jews, though the uniformity of the latter has 
been somwhat exaggerated, 41 is likewise an argument on 
the same side. A very damp or a very dry atmosphere 
has been supposed to be more influential in modifying the 
color of the skin than mere heat ; but as D'Orbigny in 
South America, and Livingstone in Africa, arrived at di- 
ametrically opposite conclusions with respect to dampness 
and dryness, any conclusion on this head must be consid- 
ered as very doubtful. 43 

Various facts, which I have elsewhere given, prove 
that the color of the skin and hair is sometimes corre- 
lated in a surprising manner with a complete immunity 
from the action of certain vegetable poisons and from the 
attacks of certain parasites. Hence it occurred to me, 
that negroes and other dark races might have acquired 
their dark tints by the darker individuals escaping during 
a long series of generations from the deadly influence of 
the miasmas of their native countries. 

I afterward found that the same idea had long ago oc- 
curred to Dr. Wells. 43 That negroes, and even mulattoes, 

excellent summary of the evidence is given by Godron, 'De l'Espece,' 
1859, voL ii. p. 246, etc. 

40 Sir Andrew Smith, as quoted by Knox, ' Races of Man,' 1850, p. 473. 

41 See De Quatrefages on this head, ' Revue des Cours Scientifiques,' 
Oct, 1Y, 1868, p. 131. 

42 Livingstone's ' Travels and Researches in S. Africa,' 1857, p. 338, 
S29. D'Orbigny, as quoted by Godron, ' De l'Espece,' vol. ii. p. 266. 

43 See a paper read before the Royal Soc. in 1813, and published iD 

11 



234 THE DESCENT OF MAN. [Part I 

are almost completely exempt from the yellow fever, which 
is so destructive in tropical America, has long been known. 44 
They likewise escape to a large # extent the fatal intermit- 
tent fevers that prevail along, at least, 2,600 miles of the 
shores of Africa, and which annually cause one-fifth of the 
white settlers to die, and another fifth to return home in- 
valided." This immunity in the negro seems to he partly 
inherent, depending on some unknown peculiarity of con- 
stitution, and partly the result of acclimatization. Pou- 
chet 46 states that the negro regiments, borrowed from the 
Viceroy of Egypt for the Mexican War, which had been 
recruited near the Soudan, escaped the yellow fever al- 
most equally well with the negroes originally brought 
from various parts of Africa, and accustomed to the cli- 
mate of the West Indies. That acclimatization plays a 
part is shown by the many cases in which negroes, af- 
ter having resided for some time in a colder climate, 
have become to a certain extent liable to tropical fevers. 47 
The nature of the climate under which the white races 
have long resided, likewise has some influence on them ; 
for, during the fearful epidemic of yellow fever in Deme- 
rara during 1837, Dr. Blair found that the death-rate of 
the immigrants was proportional to the latitude of the 
country whence they had come. With the negro the im- 
munity, as far as it is the result of acclimatization, implies 

his Essays in 1818. I have given an account of Dr. Wells's views in the 
Historical Sketch (p. xvi.) to my ' Origin of Species.' Various cases of 
color correlated with constitutional peculiarities are given in my ' Va- 
riation of Animals under Domestication,' vol. ii. pp. 227, 335. 

44 See, for instance, Nott and Gliddou, ' Types of Mankind,' p. 68. 

45 Major Tulloch, in a paper read before the Statistical Society, April 
20, 1840, and given in the ' Athenaeum,' 1840, p. 353. 

46 ' The Plurality of the Human Race ' (translat.), 1864, p. 60. 

47 Quatrefages, 'Unite de l'Espece Humaine,' 1861, p. 205. Waitz, 
' Introduct to Anthropology,' translat. vol. i. 1863, p 124. Livingstone 
gives analogous cases in his ' Travels.' 



Chap. VIL] THE RACES OF MAN. 235 

exposure during a prodigious length of time; for the 
aborigines of tropical America, who have resided there 
from time immemorial, are not exempt from yellow fever ; 
and the Rev. B. Tristram states that there are districts in 
Northern Africa which the native inhabitants are com- 
pelled annually to leave, though the negroes can remain 
with safetv. 

That the immunity of the negro is in any degree cor- 
related with the color of his skin is a mere conjecture : 
it may be correlated with some difference in his blood, 
nervous system, or other tissues. Nevertheless, from the 
facts above alluded to, and from some connection appar- 
ently existing between complexion and a tendency to con- 
% sumption, the conjecture seemed to me not improbable. 
Consequently I endeavored, with but little success, 48 to 

48 In the spring of 1862 I. obtained permission from the Director- 
General of the Medical Department of the Army, to transmit to the sur- 
geons of the various regiments on foreign service a blank table, with the 
following appended remarks, but I have received no returns : " As several 
well-marked cases have been recorded with our domestic animals of a re- 
lation between the color of the dermal appendages and the constitution ; 
and it being notorious that there is some limited degree of relation be- 
tween the color of the races of man and the climate inhabited by them, 
the following investigation seems worth consideration, namely, whether 
there is any relation in Europeans between the color of their hair and 
their liability to the diseases of the tropical countries. If the surgeons 
of the several regiments, when stationed in unhealthy tropical districts, 
would be so good as first to count, as a standard of comparison, how 
many men, in the force whence the sick are drawn, have dark and fight 
colored hair, and hair of intermediate or doubtful tints ; and if a similar 
account were kept by the same medical gentlemen of all the men who 
suffered from malarious and yellow fevers, or from dysentery, it would 
Boon be apparent, after some thousand cases had been tabulated, whether 
there exists any relation between the color of the hair and constitutional 
liability to tropical diseases. Perhaps no such relation would be discov- 
ered, but the investigation is well worth making. In case any positive 
result were obtained, it might be of some practical use in selecting men 
for any particular service. Theoretically the result would be of high 



236 THE DESCENT OF MAN [Part 1. 

ascertain how far it held good. The late Dr. Daniell, 
who had long lived on the West Coast of Africa, told me 
that he did not believe in any such relation. He was 
himself unusually fair, and had withstood the climate in 
a wonderful manner. When he first arrived as a boy on 
the coast, an old and experienced negro chief predicted 
from his appearance that this would prove the case. Dr. 
Nicholson, of Antigua, after having attended to this sub- 
ject, wrote to me that he did not think that dark-colored 
Europeans escaped the yellow fever better than those that 
were light-colored. Mr. J. M. Harris altogether denies 49 
that Europeans with dark hair withstand a hot climate 
better than other men; on the contrary, experience has 
taught him, in making a selection of men for service on 4 
the coast of Africa, to choose those with red hair. As far, 
therefore, as these slight indications serve, there seems no 
foundation for the hypothesis, which has been accepted by 
several writers, that the color of the black races may have 
resulted from darker and darker individuals having sur- 
vived in greater numbers, during their exposure to the 
fever-generating miasmas of their native countries. 

Although with our present knowledge we cannot ac- 
count for the strongly-marked differences in color between 
the races of man, either through correlation with consti- 
tutional peculiarities, or through the direct action of cli- 
mate ; yet we must not quite ignore the latter agency, for 
there is good reason to believe that some inherited effect 
is thus produced. 50 

interest, as indicating one means by which a race of men inhabiting from 
a remote period an unhealthy tropical climate, might have become dark- 
colored by the better preservation of dark-haired or dark-complexioned 
individuals during a long succession of generations." 

49 'Anthropological Review,' Jan. 1866, p. xxi. 

£0 See, for instance, Quatrefages (' Revue des Cours Scientifiques,' 
Oct. 10, 1868, p. 724) on the effects of residence in Abyssinia and Arabia, 
and other analogous cases. Dr. Rolle (Der Mensch, seine Abstammung, 



Chap. VII.] THE RACES OF MAN. 237 

AYe have seen in our third chapter that the conditions 
of life, such as abundant food and general comfort, affect 
in a direct manner the development of the "bodily frame, 
the effects being transmitted. Through the combined in- 
fluences of climate and changed habits of life, European 
settlers in the United States undergo, as is generally ad- 
mitted, a slight but extraordinarily rapid change of ap- 
pearance. There is, also, a considerable body of evidence 
showing that in the Southern States the house-slaves of 
the third generation present a markedly different appear 
ance from the field-slaves." 

If, however, we look to the races of man, as distributed 
over the world, we must infer that their characteristic 
differences cannet be accounted for bv the direct action 
ol different conditions of life, even after exposure to them 
for an enormous period of time. The Esquimaux live ex- 
clusively on animal food ; they are clothed in thick fur, 
and are exposed to intense cold and to prolonged dark- 
ness ; yet they do not differ in any extreme degree from 
the inhabitants of Southern China, who live entirely on 
vegetable food and are exposed almdst naked to a hot, 
glaring climate. The unclothed Fuegians live on the 
marine productions of their inhospitable shores ; the Bo- 
tocudos of Brazil wander about the hot forests of the in- 
terior and live chiefly on vegetable productions ; yet these 
tribes resemble each other so closely that the Fuegians on 
board the "Beagle" were mistaken by some Brazilians 
for Botocudos. The Botocudos, again, as well as the other 

etc., 1865, s. 99) states, on the authority of Khanikof, that the greater 
number of German families settled in Georgia have acquired in the course 
of two generations dark hair and eyes. Mr. D. Forbes informs me that 
the Quichuas in the Andes vary greatly in color, according to the posi- 
tion of the valleys inhabited by them. 

51 Harlan, ' Medical Researches,' p. 532. Quatrefages (Unite de 
1'Espece H»maine,' 1861, p. 128) has collected much evidence on thia 
head. 



238 THE DESCENT OF MAN. [Part L 

inhabitants of tropical America, are wholly different from 
the Negroes who inhabit the opposite shores of the At- 
lantic, are exposed to a nearly similar climate, and follow 
nearly the same habits of life. 

Nor can the differences between the races of man be 
accounted for, except to a quite insignificant degree, by 
the inherited effects of the increased or decreased use of 
parts. Men who habitually live in canoes may have their 
legs somewhat stunted ; those who inhabit lofty regions 
have their chests enlarged ; and those who constantly use 
certain sense-organs have the cavities in which they are 
lodged somewhat increased in size, and their features con- 
sequently a little modified. With civilized nations, the 
reduced size of the jaws from lessened use, the habitual 
play of different muscles serving to express different emo- 
tions, and the increased size of the brain from greater in- 
tellectual activity, have together produced a considerable 
effect on their general appearance, in comparison with 
savages. 52 It is also possible that increased bodily stature, 
with no corresponding increase in the size of the brain, 
may have given td some races (judging from the pre- 
viously adduced cases of the rabbits) an elongated skull 
of the dolichocephalic type. 

Lastly, the little-understood principle of correlation 
will almost certainly have come into action, as in the case 
of great muscular development and strongly-projecting 
supra-orbital ridges. It is not improbable that the texture 
of the hair, which differs much in the different races, may^ 
stand in some kind of correlation with the structure of 
the skin ; for the color of the hair and skin are certainly 
correlated, as is its color and texture with the Mandans. 68 

52 See Prof. Schaaffhausen, translat. in 'Anthropological Review,' 
Oct. 1868, p. 429. 

63 Mr. Catlin states (' North American Indians,' 3d edit. 1842, vol. i. p. 
49) that, in the whole tribe of the Mandans, about one in ten or twelve 



Chap. VII.] THE RACES OF MAN. 239 

The color of the skin and the odor emitted by it are like- 
wise in some manner connected. With the breeds of 
sheep the number of hairs within a given space and the 
number of the excretory pores stand in some relation to 
each other. 64 If we may judge from the analogy of our 
domesticated animals, many modifications of structure in 
man probably come under this principle of correlated 
growth. 

We have now seen that the characteristic differences 
between the races of man cannot be accounted for in a 
satisfactory manner by the direct action of the conditions 
of life, nor by the effects of the continued use of parts, nor 
through the principle of correlation. We are therefore 
led to inquire whether slight individual differences, to 
which man is eminently liable, may not have been pre- 
served and augmented during a long series of generations 
through natural selection. But here we are at once met 
by the objection that beneficial variations alone can be 
thus preserved ; and as far as we are enabled to judge 
(although always liable to error on this head) not one of 
the external differences between the races of man are of 
any direct or special service to him. The intellectual and 
moral or social faculties must of course be excepted from 
this remark ; but differences in these faculties can have 
had little or no influence on external characters. The 
variability of all the characteristic differences between 
tlie races, before referred to, likewise indicates that these 
differences cannot be of much importance ; for, had they 

of the members of all ages and both sexes have bright silvery gray hair, 
which is hereditary. Now this hair is as coarse and harsh as that of a 
horse's mane, while the hair of other colors is fine and soft. 

64 On the odor of the skin, Godron, ' Sur l'Espece,' torn. iL p. 217. 
On the pores in the skin, Dr. Wilckens, • Die Aufgaben der landwirth. 
Zootechnik,' 1869, s. 1. 



240 THE DESCENT OF MAN. [Part I. 

been important, they would long ago have been either 
fixed and preserved, or eliminated. In this respect man 
resembles those forms, called by naturalists .protean or 
polymorphic, which have remained extremely variable, 
owing, as it seems, to their variations being of an indif- 
ferent nature, and consequently to their having escaped 
the action of natural selection. 

We have thus far been baffled in all our attempts to 
account for the differences between the races of man ; but 
there remains one important agency, namely, Sexual Selec- 
tion, which appears to have acted as powerfully on man 
as on many other animals. I do not intend to assert that 
sexual selection will account for all the differences be- 
tween the races. An unexplained residuum is left, about 
which we can in our ignorance only say that, as individ- 
uals are continually born with, for instance, heads a little 
rounder or narrower, and with noses a little longer or 
shorter, such slight differences might become fixed and 
uniform, if the unknown agencies which induced them 
were to act in a more constant manner, aided by long-con- 
tinued intercrossing;. Such modifications come under the 
provisional class, alluded to in our fourth chapter, which 
for the want of a better term have been called sponta- 
neous variations. Nor do I pretend that the effects of 
sexual selection can be indicated with scientific precision ; 
but it can be shown that it would be an inexplicable fact 
if man had not been modified by this agency, which has 
acted so powerfully on innumerable animals, both high 
and low in the scale. It can further be shown that the 
differences between the races of man, as in color, hairi- 
ness, form of features, etc., are of the nature which it 
might have been expected would have been acted on by 
sexual selection. But in order to treat this subject in a 
fitting manner, I have found it necessary to pass the 
whole animal kingdom in review; I have therefore de- 



Chap. VII. ] THE RACES OF MAN. 241 

voted to it the Second Part of this work. At the close I 
shall return to man, and, after attempting to show how 
far he has been modified through sexual selection, will 
give a brief summary of the chapters in this First Part. 



PAET II. 

SEXUAL SELECTION. 



SEXUAL SELECTION. 



CHAPTER VIII. 

PRINCIPLES OF SEXUAL SELECTION. 

Secondary Sexual Characters. — Sexual Selection. — Manner of Action. — 
Excess of Males. — Polygamy. — The Male alone generally modified 
through Sexual Selection. — Eagerness of the Male. — Variability of 
the Male. — Choice exerted by the Female. — Sexual compared with 
Natural Selection. — Inheritance, at Corresponding Periods of Life, at 
Corresponding Seasons of the Year, and as limited by Sex. — Eelations 
between the Several Forms of Inheritance.' — Causes why one Sex and 
the Young are not modified through Sexual Selection. — Supplement on 
the Proportional Numbers of the two Sexes throughout the Animal 
Kingdom. — On the Limitation of the Numbers of the two Sexes 
tbrough Natural Selection. 

With animals which have their sexes separated, the 
males necessarily differ from the females in their organs 
of reproduction ; and these afford the primary sexual char- 
acters. But the sexes often differ in what Hunter has 
called secondary sexual characters, which are not directly 
connected with the act of reproduction ; for instance, in 
the male possessing certain organs of sense or locomotion, 
of which the female is quite destitute, or in having them 
more highly developed, in order that he may readily find 
or reach her ; or again, in the male having special organs 
of prehension so as to hold her securely. These latter 
organs of infinitely-diversified kinds graduate into, and in 
some cases can hardly be distinguished from, those which 



246 THE PRINCIPLES OF [Part II. 

are commonly ranked as primary, such as the complex ap- 
pendages at the apex of the abdomen in male insects. 
Unless indeed we confine the term " primary " to the re- 
productive glands, it is scarcely possible to decide, as far 
as the organs of prehension are concerned, which ought 
to be called primary and which secondary. 

The female often differs from the male in having or- 
gans for the nourishment or protection of her young, as 
the mammary glands of mammals, and the abdominal 
sacks of the marsupials. The male, also, in some few 
cases differs from the female in possessing analogous or- 
gans, as the receptacles for the ova possessed by the 
males of certain fishes, and those temporarily developed 
in certain male frogs. Female bees have a special appa- 
ratus for collecting and carrying pollen, and their oviposi- 
tor is modified into a sting for the defence of their larvae 
and the community. In the females of many insects the 
ovipositor is modified in the most complex manner for the 
safe placing of the eggs. Numerous similar cases could 
be given, but they do not here concern us. There are, 
however, other sexual differences quite disconnected with 
the primary organs with which we are more especially 
concerned — such as the greater size, strength, and pug- 
nacity of the male, his weapons of offence or means of 
defence against rivals, his gaudy coloring and various 
ornaments, his power of song, and other such charac- 
ters. 

Besides the foregoing primary and secondary sexual 
differences, the male and female sometimes differ in struct- 
ures connected with different habits of life, and not at all, 
or only indirectly, related to the reproductive functions. 
Thus the females of certain flies (Culicidae and Tabanidas) 
are blood-suckers, while the males live on flowers and 
have their mouths destitute of mandibles. 1 The males 

1 Westwood, ' Modern Class, of Insects,' vol. ii. 1840, p. 541. In 



Chap. VIIL] SEXUAL SELECTION. 247 

alone of certain moths and of some crustaceans (e. g., Ta- 
nais) have imperfect, closed mouths, and cannot feed. 
The complemental males of certain Cirripedes live like 
epiphytic plants either on the female or hermaphrodite 
form, and are destitute of a mouth and prehensile limbs. 
In these cases it is the male which has been modified and 
has lost certain important organs, which the other mem- 
bers of the same group possess. In other cases it is the 
female which has lost such parts ; for instance, the female 
glowworm is destitute of wings, as are many female 
moths, some of which never leave their cocoons. Many 
female parasitic crustaceans have lost their natatory legs. 
In some weevil-beetles (Curculionidae) there is a great 
difference between the male and female in the length of 
the rostrum or snout; 2 but the meaning of this, and 
of many analogous differences, is not at all understood. 
Differences of structure between the two sexes in relation 
to different habits of life are generally confined to the 
lower animals ; but with some few birds the beak of the 
male differs from that of the female. No doubt in most, 
but apparently not in all these cases, the differences are 
indirectly connected with the propagation of the species : 
thus a female which has to nourish a multitude of ova 
will require more, food than the male, and consequently 
will require special means for procuring it. A male ani- 
mal which lived for a very short time might without det- 
riment lose through disuse its organs for procuring food ; 
but he would retain his locomotive organs in a perfect 
state, so that he might reach the female. The female, on 
the other hand, might safely lose her organs for flying, 
swimming, or walking, if she gradually acquired habits 
which rendered such powers useless. 

regard to the statement about Tanais, mentioned below, I am indebted to 
Fritz Miiller. 

J Kirby and Spence, ' Introduction to Entomology,' vol. iii. 1826, p. 309. 



248 THE PRINCIPLES OF [Pakt II. 

"We are, however, here concerned only with that kind 
of selection which I have called sexual selection. This 
depends on the advantage which certain individuals have 
over other individuals of the same sex and species, in ex- 
clusive relation to reproduction. When the two sexes 
differ in structure in relation to different habits of life, as 
in the cases above mentioned, they have no doubt been 
modified through natural selection, accompanied by inher- 
itance limited to one and the same sex. So, again, the 
primary sexual organs, and those for nourishing or pro- 
tecting the young, come under this same head ; for those 
individuals which generated or nourished their offspring 
best, would leave, cceteris paribus, the greatest number to 
inherit their superiority ; while those which generated or ' 
nourished their offspring badly, would leave but few to 
inherit their weaker powers. As the male has to search 
for the female, he requires for this purpose organs of sense 
and locomotion, but if these organs are necessary for the 
other purposes of life, as is generally the case, they will 
have been developed through natural selection. When 
the male has found the female he sometimes absolutely 
requires prehensile organs to hold her; thus Dr. Wallace 
informs me that the males of certain moths cannot unite 
with the females if their tarsi or feet are broken. The 
males of many oceanic crustaceans have their legs and 
antennae modified in an extraordinary manner for the pre- 
hension of the female ; hence we may suspect that owing 
to these animals being washed about by the waves of the 
open sea, they absolutely require these organs in order to 
propagate their kind, and if so their development will 
have been the result of ordinary or natural selection. 

When the two sexes follow exactly the same habits 
of life, and the male has more highly-developed sense or 
locomotive organs than the female, it may be that these 
in their perfected state are indispensable to the male for 



Chap. VIE.] SEXUAL SELECTION. 249 

finding the female ; but in the vast majority of cases, they 
serve only to give one male an advantage over another, 
for the less well-endowed males, if time were allowed them, 
would succeed in pairing with the females; and they 
would in all other respects, judging from the structure 
of the female, be equally well adapted for their ordinary 
habits of life. In such cases sexual selection must have 
come into action, for the males have acquired their pres- 
ent structure, not from being better fitted to survive in 
the struggle for existence, but from having gained an ad- 
vantage over other males, and from having transmitted 
this advantage to their male offspring alone. It was the 
importance of this distinction which led me to designate 
this form of selection as sexual selection. So, again, if the 
chief service rendered to the male by his prehensile organs 
is to prevent the escape of the female before the arrival 
of other males, or when assaulted by them, these organs 
will have been perfected through sexual selection, that is, 
by the advantage acquired by certain males over their 
rivals. But in most cases it is scarcely possible to distin- 
guish between the effects of natural and sexual selection. 
Whole chapters could easily be filled with details on the 
differences between the -sexes in their sensory, locomotive, 
and prehensile organs. As, however, these structures are 
not more interesting than others adapted for the ordinary 
purposes of life, I shall almost pass them over, giving only 
a few instances mnder each class. 

There are many other structures and instincts which 
must have been developed through sexual selection — such 
as the weapons of offence and the means of defence pos- 
sessed by the males for fighting with and driving away 
their rivals — their courage and pugnacity — their orna- 
ments of many kinds — their organs for producing vocal 
or instrumental music — and their glands for emitting 
odors ; most of these latter structures serving only to al- 



250 THE PRINCIPLES OF [Part II. 

lure or excite the female. That these characters are the 
result of sexual and not of ordinary selection is clear, as 
unarmed, unornamented, or unattractive males would suc- 
ceed equally well in the battle for life and in leaving a 
numerous progeny, if better-endowed males were not 
present. We may infer that this would be the case, for 
the females, which are unarmed and unornamented, are 
able to survive and procreate their kind. Secondary sex- 
ual characters of the kind just referred to, will be fully 
discussed in the following chapters, as they are in many 
respects interesting, but more especially as they depend 
on the will, choice, and rivalry of the individuals of either 
sex. When we behold two males fighting for the posses- 
sion of the female ; or several male birds displaying their 
gorgeous plumage, and performing the strangest antics 
before an assembled body of females, we cannot doubt 
that, though led by instinct, they know what they are 
about, and consciously exert their mental and bodily 
powers. 

In the same manner as man can improve the breed of 
his game-cocks by the selection of those birds which are 
victorious in the cockpit, so it appears that the strongest 
and most vigorous males, or those provided with the best 
weapons, have prevailed under Nature, and have led to the 
improvement of the natural breed or species. Through 
repeated deadly contests, a slight degree of variability, 
if it led to some advantage, however slight, would suffice 
for the work of sexual selection ; and it is certain that 
secondary sexual characters are eminently variable. In 
the same manner as man can give beauty, according to 
his standard of taste, to his male poultry — can give to the 
Sebright bantam a new and elegant plumage, an erect and 
peculiar carriage — so it appears that in a state of nature 
female birds, by having long selected the more attractive 
males, have added to their beauty. No doubt this im- 



Chap. YIIL] SEXUAL SELECTION. 251 

plies powers of discrimination and taste on the part of the 
female which will at first appear extremely improbable ; 
but I hope hereafter to show that this is not the case. 

From our ignorance on several points, the precise man- 
ner in which sexual selection acts is to a certain extent 
uncertain. Nevertheless if those naturalists who already 
believe in the mutability of species, will read the following 
chapters," they will, I think, agree with me that sexual se- 
lection has played an important part in the history of the 
organic world. It is certain that with almost all animals 
there is a struggle between the males for the possession of 
the female. This fact is so notorious that it would be su- 
perfluous to give instances. Hence the females, supposing 
that their mental capacity sufficed for the exertion of a 
choice, could select one out of several males. But in nu- 
merous cases it appears as if it had been specially arranged 
that there should be a struggle between many males. 
Thus with migratory birds, the males generally arrive be- 
fore the females at their place of breeding, so that many 
males are ready to contend for each female. The bird- 
catchers assert that this is invariably the case with the 
nightingale and blackcap, as I am informed by Mr. Jenner 
Weir, who confirms the statement with respect to the lat- 
ter species. 

Mr. Swaysland, of Brighton, who has been in the habit, 
during the last forty years, of catching our migratory 
birds on their first arrival, writes to me that he has never 
known the females of any species to arrive before their 
males. During one spring he shot thirty-nine males of 
Ray's wagtail (Budytes Bail) before he saw a single fe- 
male. Mr. Gould has ascertained by dissection, as he in- 
forms me, that male snipes arrive in this country before 
the females. In the case of fish, at the period when the 
salmon ascend our rivers, the males in large numbers are 
ready to breed before the females. So it apparently is 



252 THE PRINCIPLES OF [Part IL 

with lrogs and toads. Throughout the great class of in- 
sects the males almost always emerge from the pupal state 
before the other sex, so that they generally swarm for a 
time before any females can be seen. 3 The cause of this 
difference between the males and females in their periods 
of arrival and maturity is sufficiently obvious. Those males 
which annually first migrated into any country, or -which 
in the spring were first ready to breed, or were the most 
eager, would leave the largest number of offspring ; and 
.these would tend to inherit similar instincts and constitu- 
tions. On the whole, there can be no doubt that with al- 
most all animals, in which the sexes are separate, there is a 
constantly recurrent struggle between the males for the 
possession of the females. 

Our difficulty in regard to sexual selection lies in un- 
derstanding how it is that the males which conquer other 
males, or those which prove the most attractive to the fe- 
males, leave a greater number of offspring to inherit their 
superiority than the beaten and less attractive males. 
Unless this result followed, the characters which gave to 
certain males an advantage over others, could not be per- 
fected and augmented through sexual selection. When 
the sexes exist in exactly equal numbers, the worst-endowed 
males will ultimately find females (excepting where polyg- 
amy prevails), and leave as many offspring, equalfy well 
fitted for their general habits of life, as the best-endowed 
males. From various facts and considerations, I former- 
ly inferred that with most animals, in which secondary 

3 Even with those of plants in which the sexes are separate, the male 
flowers are .generally mature before the female. Many hermaphrodite 
plants are, as first shown by C. K. Sprengel, dichogamous ; that is, their 
male and female organs are not ready at the same time, so that they can- 
uot be self-fertilized. Now with such plants the pollen is generally ma- 
ture in the same flower before the stigma, though there are some excep- 
tional species in which the female organs are mature before the male. 



Chap. VIII.] SEXUAL SELECTION. 253 

sexual characters were well developed, the males considera- 
bly exceeded the females in number ; and this does hold 
good in some few cases. If the males were to the females 
as two to one, or as three to two, or even in a somewhat 
lower ratio, the whole affair would be simple : for the bet- 
ter-armed or more attractive males would leave the lar- 
gest number of offspring. But after investigating, as far 
as possible, the numerical proportions of the sexes, I do 
not believe that any great inequality in number commonly 
exists. In most cases sexual selection appears to have 
been effective in the following manner : 

Let us take any species, a bird for instance, and di- 
vide the females inhabiting a district into two equal 
bodies : the one consisting of the more vigorous and bet- 
ter-nourished individuals, and the other of the less vigor- 
ous and healthy. The former, there can be little doubt, 
would be ready to breed in the spring before the others ; 
and this is the opinion of Mr. Jenner Weir, who has dur- 
ing many years carefully attended to the habits of birds. 
There can also be no doubt that the most vigorous, 
healthy, and best-nourished females would on an average 
succeed in rearing the largest number of offspring. The 
males, as we have seen, are generally ready to breed be- 
fore the females ; of the males the strongest, and with 
some species the best armed, drive away the weaker 
males ; and the former would then unite with the more 
vigorous and best-nourished females, as these are the first 
to breed. Such vigorous pairs would surely rear a larger 
number of offspring than the retarded females, which 
would be compelled, supposing the sexes to be numeri- 
cally equal, to unite with the conquered and less powerful 
males ; and this is all that is wanted to add, in the course 
of successive generations, to the size, strength, and cour- 
age of the males, or to improve their weapons. 

But in a multitude of cases the males which conquer ' 



254 THE PRINCIPLES OF [Part U 

other males do not obtain possession of the females, in- 
dependently of choice on the part of the latter. The 
courtship of animals is by no means so simple and short 
an affair as might be thought. The females are most ex- 
cited by, or prefer pairing with, the more ornamented 
males, or those which are the best songsters, or play the 
best antics; but it is obviously probable, as has been 
actually observed in some cases, that they would at the 
same time prefer the more vigorous and lively males. 4 
Thus the more vigorous females, which are the first to 
breed, will have the choice of many males ; and though 
they may not always select the strongest or best armed, 
they will select those which are vigorous and well armed, 
and in other respects the most attractive. Such early 
pairs would have the same advantage in rearing offspring 
on the female side as above explained, and nearly the 
same advantage on the male side. And this apparently 
has sufficed during a long course of generations to add not 
only to the strength and fighting-powers of the males, but 
likewise to their various ornaments or other attractions. 

In the converse and much rarer case of the males se- 
lecting particular females, it is plain that those which were 
the most vigorous and had conquered others, would have 
the freest choice ; and it is almost certain that they would 
select vigorous as well as attractive females. Such pairs 
would have an advantage in rearing offspring, more es- 
pecially if the male had the power to defend the female 
during the pairing-season, as occurs with some of the 
higher animals, or aided in providing for the young. The 
same principles would apply if both sexes mutually pre- 
ferred and selected certain individuals of the opposite sex ; 

4 I have received information, hereafter to be given, to this effect with 
respect to poultry. Even with birds, such as pigeons, which pair for life, 
the female, as I hear from Mr. Jenner Weir, will desert her mate if he is 
injured or grows weak. 



Chap. VIII.] SEXUAL SELECTION. 255 

supposing that they selected not only the more attractive, 
but likewise the more vigorous individuals. 

Numerical Proportion of the Two Sexes.— I have re- 
marked that sexual selection would be a simple affair if 
the males considerably exceeded in number the females. 
Hence I was led to investigate, as far as I could, the pro- 
portions between the two sexes of as many animals as 
possible ; but the materials are scanty. I will here give 
only a brief abstract of the results, retaining the details 
for a supplementary discussion, so as not to interfere with, 
the course of my argument. Domesticated animals alone 
afford the opportunity of ascertaining the proportional 
numbers at birth ; but no records have been specially kept 
for this purpose. By indirect means, however, I have col- 
lected a considerable body of statistical data, from which 
it appears that with most of our domestic animals the 
sexes are nearly equal at birth. Thus with race-horses, 
25,560 births have been recorded during twenty-one years, 
and the male births have been to the female births as 99.7 
to 100. With greyhounds the inequality is greater than 
with any other animal, for during twelve years, out of 
6,878 births, the male births have been as 110.1 to 100 
female births. It is, however, in some degree doubtful 
whether it is safe to infer that the same proportional num- 
bers would hold good under natural conditions as under 
domestication ; for slight and unknown differences in the 
conditions affect to a certain extent the proportion of the 
sexes. Thus with mankind, the male births in England 
are as 104.5, in Russia as 108.9, and with the Jews of 
Livonia as 120 to 100 females. The proportion is also 
mysteriously affected by the circumstance of the births 
being legitimate or illegitimate. 

For our present purpose we are concerned with the 
proportion of the sexes, not at birth, but at maturity, and 



256 THE PRINCIPLES OF [Part II. 

this adds another element of doubt ; for it is a well-ascer- 
tained fact that with man a considerably larger proportion 
of males than of females die before or during birth, and 
during the first few years of infancy. So it almost cer- 
tainly is with male lambs, and so it may be with the males 
of other animals. The males of some animals kill each 
other by fighting ; or they drive each other about until 
they become greatly emaciated. They must, also, while 
wandering about in eager search for the females, be often 
exposed to various dangers. With many kinds of fish the 
males are much smaller than the females, and they are be- 
lieved often to be devoured by the latter or by other fishes. 
With some birds the females appear to die in larger pro- 
portion- than the males: they are also liable to be de- 
stroyed on their nests, or while in charge of their young. 
With insects the female larvss are often larger than those 
of the males, and would consequently be more likely to 
be devoured : in some cases the mature females are less 
active and less rapid in their movements than the males, 
and would not be so well able to escape from danger. 
Hence, with animals in a state of nature, in order to judge 
of the proportions of the sexes at maturity, we must rely 
on mere estimation ; and this, except perhaps when the 
inequality is strongly marked, is but little trustworthy. 
Nevertheless, as far as a judgment can be formed, we may 
conclude, from the facts given in the supplement, that the 
males of some few mammals, of many birds, of some fish 
and insects, considerably exceed in number the females. 

The proportion between the sexes fluctuates slightly 
during successive years : thus with race-horses, for every 
100 females born, the males varied from 107.1 in one year 
to 92.6 in another year, and with greyhounds from 116.3 
to 95.3. But had larger numbers been tabulated through- 
out a more extensive area than England, these fluctuations 
would probably have disappeared ; and such as they are, 



Chap. VIII.] SEXUAL SELECTION. 257 

they would hardly suffice to lead under a state of nature 
to the effective action of sexual selection. Nevertheless 
with some few wild animals, the proportions seem, as 
shown in the supplement, to fluctuate either during differ- 
ent seasons or in different localities in a sufficient degree 
to lead to such action. For it should be observed that 
any advantage gained during certain years or in certain 
localities by those males which were able to conquer other 
males, or were the most attractive to the females, would 
probably be transmitted to the offspring and would not 
subsequently be eliminated. During the succeeding sea- 
sons, when from the equality of the sexes every male was 
everywhere able to procure a female, the stronger or more 
attractive males previously produced would still have at 
least as good a chance of leaving offspring as the less 
strong or less attractive. 

Polygamy. — The practice of polygamy leads to the 
same results as would follow from an actual inequality in 
the number of the sexes ; for if each male secures two or 
more females, many males will not be able to pair; and 
the latter assuredly will be the weaker or less attractive 
individuals. Many mammals and some few birds are 
polygamous, but with animals belonging to the lower 
classes I have found no evidence of this habit. The intel- 
lectual powers of such animals are, perhaps, not sufficient 
to lead them to collect and guard a harem of females. 
That some relation exists between polygamy and the de- 
velopment of secondary sexual characters, appears nearly 
certain ; and this supports the view that a numerical pre- 
ponderance of males would be eminently favorable to the 
action of sexual selection. Nevertheless many animals, 
especially birds, which are strictly monogamous, display 
strongly-marked secondary sexual characters ; while some 
few animals, which are polygamous, are not thus charac- 
terized. 



258 THE PRINCIPLES OF [Part II. 

We will first briefly run through the class of mammals, 
and then turn to birds. The gorilla seems to be a polyg- 
amist, and the male differs considerably from the female ; 
so* it is with some baboons which live in herds containing 
twice as many adult females as males. In South America 
the Mycetes caraya presents well-marked sexual differ- 
ences in color, beard, and vocal organs, and the male gen- 
erally lives with two or three wives: the male of the 
Cebus capucinus differs somewhat from the female, and 
appears to be polygamous. 5 Little is known on this head 
with respect to most other monkeys, but some species are 
strictly monogamous. The ruminants are eminently polyg- 
amous, and they more frequently present sexual differ- 
ences than almost any other group of mammals, especially 
in their weapons, but likewise in other characters. Most 
deer, cattle, and sheep, are polygamous ; as are most ante- 
lopes, though some of the latter are monogamous. Sir 
Andrew Smith, in speaking of. the antelopes of South 
Africa, says that in herds of about a dozen there was 
rarely more than one mature male. The Asiatic Antilope 
saiga appears to be the most inordinate polygamist in the 
world ; for Pallas 6 states that the male drives away all 
rivals, and collects a herd of about a hundred, consisting 
of females and kids : the female is hornless and has softer 
hair, but does not otherwise differ much from the male. 
The horse is polygamous, bub, except in his greater size 
and in the proportions of his body, differs but little from 

5 On the Gorilla, Savage and Wyman, ' Boston Journal of Nat. Hist.' 
vol. v. 1845-1847, p. 423. On Cynocephalus, Brehm, 'Must. Thierleben,' 
B. i. 1864, s. 77. On Mycetes, Rengger, ' Naturgesch. : Saugethiere von 
Paraguay,' 1830, s. 14, 20. On Cebus, Brehm, ibid. s. 108. 

6 Pallas, ' Spicilegia Zoolog., Ease. xii. 1777, p. 29. Sir Andrew 
Smith, 'Illustrations of the Zoology of South Africa,' 1849, pi. 29, on the 
Kobus. Owen, in his ' Anatomy of Vertebrates ' (vol. iii. 1868, p. 633), 
gives a table incidentally showing which species of Antelopes pair and 
which are gregarious. 



Chap VIII.] SEXUAL SELECTION. 259 

the marc. The wild-boar, in his great tusks and some 
other characters, presents well-marked sexual characters ; 
in Europe and in India he leads a solitary life, except dur- 
ing the breeding-season ; but at this season he consorts 
in India with several females, as Sir W. Elliot, who -has 
had large experience in observing this animal, believes : 
whether this holds good in Europe is doubtful, but is sup- 
ported by some statements. The adult male Indian ele- 
phant, like the boar, passes much of his time in solitude ; 
but when associating with others, " it is rare to find," as 
Dr. Qampbell states, " more than one male with a whole 
herd of females." The larger males expel or kill the 
smaller and weaker ones. The male differs from the fe- 
male by his immense tusks and greater size, strength, and 
endurance ; so great is the difference in these latter re- 
spects, that the males when caught are valued at twenty 
per cent, above the females. 7 With other pachydermatous 
animals the sexes differ very little or not at all, and they 
are not, as far as knowu, polygamists. Hardly a single 
species among the Cheiroptera and Edentata, or in the 
great Orders of the Rodents and Insectivora, presents 
well-developed secondary sexual differences; and I can 
find no account of any species being polygamous, except- 
ing, perhaps, the common rat, the males of which, as some 
rat-catchers affirm, live with several females. 

The lion in South Africa, as I hear from Sir Andrew 
Smith, sometimes lives with a single female, but gener- 
ally with more than one, and, in one case, was found with 
as many as five females, so that he is polygamous. He is, 
as far as I can discover, the sole p«iygamist in the whole 
group of the terrestrial Carnivora, and he alone presents 
well-marked sexual characters. If, however, we turn to 

7 Dr. Campbell, in ' Proc. Zoolog. Soc.' 1869, p. 138. See also an 
interesting paper, by Lieut. Johnstone, in ' Proc. Asiatic Soc. of Bengal,' 
May, 1868. 



260 THE PRINCIPLES OF [Part II. 

the marine Carnivora, the case is widely different ; for 
many species of seals offer, as we shall hereafter see, ex- 
traordinary .sexual differences, and they are eminently 
polygamous. Thus the male sea-elephant of the Southern 
Ocean always possesses, according to Peron, several fe- 
males, and the sea-lion of Forster is said to* be surrounded 
by from twenty to thirty females. In the North, the 
male sea-bear of Steller is accompanied by even a greater 
number of females. 

With respect to birds, many species, the sexes of which 
differ greatly from each other, are certainly monogamous. 
In Great Britain we see well-marked sexual differences in, 
for instance, the wild-duck, which pairs with a single fe- 
male, with the common blackbird, and with the bullfinch, 
which is said to pair for life. So it is, as I am informed 
by Mr. Wallace, with the Chatterers or Cotingidas of South 
America, and numerous other birds. In several groups I 
have not been able to discover whether the species are 
polygamous or monogamous. Lesson says that birds of 
paradise, so remarkable for their sexual differences, are 
polygamous, but Mr. Wallace doubts whether he had suf- 
ficient evidence. Mr. Salvin informs me that he has been 
led to believe that humming-birds are polygamous. The 
male widow-bird, remarkable for his caudal plumes, cer- 
tainly seems to be a polygamist. 8 I have been assured, by 
Mr. Jenner Weir and by others, that three starlings not 
rarely frequent the same nest ; but whether this is a, case 
of polygamy or polyandry has not been ascertained. 

The Gallinacese present almost as strongly-marked 
sexual differences as ]^irds of paradise or humming-birds, 

8 ' The Ibis,' vol. iii. 1861, p. 133, on the Progne Widow-bird. See 
also on the Vidua axillaris, ibid. vol. ii. 1860, p. 211, On the polygamy 
of the Capercailzie and Great Bustard, see L. Lloyd, ' Game Birds of 
Sweden,' 1867, pp. 19, 128. Montagu and Selby speak of the Black 
Grouse as polygamous, and of the Bed Grouse as monogamous. 






Chap. VIII.] SEXUAL SELECTION. 261 

and many of the species are, as is well known, polyga- 
mous ; others being strictly monogamous. What a con- 
trast is presented between the sexes by the polygamous 
peacock or pheasant, and the monogamous guinea-fowl 
or partridge ! Many similar cases could be given, as in 
the grouse-tribe, in which the males of the polygamous 
capercailzie and black-cock differ greatly from the fe- 
males ; while the sexes of the monogamous red grouse 
and ptarmigan differ very little. Among the Cursores, no 
great number of species offer strongly-marked sexual 
differences, except the bustards, and the great bustard 
( Otis tarda) is said to be polygamous. With the Gralla- 
tores, extremely few species differ sexually, but the ruff 
(Jlachetes pugnax) affords a strong exception, and this 
species is believed by Montagu to be a polygamist. Hence 
it appears that with birds there often exists a close rela- 
tion between polygamy and the development of strongly- 
marked sexual differences. On asking Mr. Bartlett, at 
the Zoological Gardens, who has had such large experi- 
ence with birds, whether the male tragopan (one of the 
Gallinacese) was polygamous, I was struck by his answer- 
ing, " I do not know, but should think so from his splen- 
did colors." 

It deserves notice that the instinct of pairing with 
a single female is easily lost under domestication. The 
wild-duck is strictly monogamous, the domestic duck 
highly polygamous. The Rev. W. D. Fox informs me 
that with some half-tamed wild-ducks, kept on a large 
pond in his neighborhood, so many mallards were shot by 
the gamekeeper that only one was left for every seven or 
eight females ; yet unusually large broods were reared. 
The o-uinea-fowl is strictlv monogamous ; but Mr. Fox 
finds that his birds succeed best when he keeps one cock 
to two or three hens. 9 Canary-birds pair in a state of na- 

9 The Rev. E S. Dixon, however, speaks positively (' Ornamental 



262 THE PRINCIPLES OF [Part IL 

ture, but the breeders in England successfully put one 
male to four or five females ; nevertheless the first female, 
as Mr. Fox has been assured, is alone treated as the wife, 
she and her young ones being fed by him ; the others are 
treated as concubines. I have noticed these cases, as it 
renders it in some degree probable that monogamous spe- 
cies, in a state of nature, might readily become either tem- 
porarily or permanently polygamous. 

With respect to reptiles and fishes, too little is known 
of their habits to enable us to speak of their marriage- 
arrangements. The stickle-back (Gasterosteus), however, 
is said to be a polygamist ; 10 and the male during the 
breeding-season differs conspicuously from the female. 

To sum up on the means through which, as far as we 
can judge, sexual selection has led to the development of 
secondary sexual characters. It has been shown that the 
largest number of vigorous offspring will be reared from 
the pairing of the strongest and best-armed males, which 
have conquered other males, with the most vigorous and 
best-nourished females, which are the first to breed in the 
spring. Such females, if they select the more attractive, 
and at the same time vigorous, males, will rear a larger 
number of offspring than the retarded females, which 
must pair with the less vigorous and less attractive males. 
So it will be if the more vigorous males select the more 
attractive and at the same time healthy and vigorous fe- 
males ; and this will especially hold good if the male de- 
fends the female, and aids in providing food for the young. 
The advantage thus gained by the more vigorous pairs in 
rearing a larger number of offspring has apparently suf- 
ficed to render sexual selection efficient. But a large pre- 
ponderance in number of the males over the females would 

Poultry,' 1848, p. 76) about the eggs of the guinea-fowl being infertile 
when more than one female is kept with the same male. 
10 Noel Humphreys, ' River Gardens,' 1857. 



Chap. VIII.] SEXUAL SELECTION. 263 

be still more efficient ; whether the preponderance was 
only occasional and local, or permanent ; whether it oc- 
curred at birth, or subsequently from the greater destruc- 
tion of the females ; or whether it indirectly followed from 
the practice of polygamy. 

The Male generally move modified than the Female. — 
Throughout the animal kingdom, when the sexes differ 
from each other in external appearance, it is the male 
which, with rare exceptions, has been chiefly modified; 
for the female still remains more like the young of her 
own species, and more like the other members of the same 
group. The cause of this seems to lie in the males of 
almost all animals having stronger passions than the fe- 
males. Hence it is the males that fight together and sedu- 
lously display their charms before the females ; and those 
which are victorious transmit their superiority to their 
male offspring. Why the males do not transmit their 
characters to both sexes will hereafter be considered. 
That the males of all mammals eagerly pursue the females 
is notorious to every one. So it is with birds ; but many 
male birds do not so much pursue the female, as display 
their plumage, perform strange antics, and pour forth 
their song, in her presence. With the few fish which have 
been observed, the male seems much more eager than the 
female; and so it is with alligators, and apparently with 
Batrachians. Throughout the enormous class of insects, 
as Kirby remarks, 11 " the law is, that the male shall seek 
the female.'" With spiders and crustaceans, as I hear 
from two great authorities, Mr. Blackwall and Mr. C. 
Spence Bate, the males are more active and more erratic 
in their habits than the females. With insects and crus- 
taceans, when the organs of sense or locomotion are pres- 

11 Kirby and Spence, ' Introduction to Entomology,' vol iil 1826 t 
p. 342. 



264 THE PRINCIPLES OF [Part II. 

ent in the one sex and absent in the other, or when, as is 
frequently the case, they are more highly developed in the 
one than the other, it is almost invariably the male, as far 
as I can discover, which retains such organs, or has them 
most devoloped ; and this shows that the male is the more 
active member in the courtship of the sexes. 12 

The female, on the other hand, with the rarest excep- 
tion, is less easier than the male. As the illustrious Hun- 
ter 13 long ago observed, she generally " requires to be 
courted ; " she is coy, and may often be seen endeavoring 
for a long time to escape from the male. Every one who 
has attended to the habits of animals will be able to call 
to mind instances of this kind. Judging from various 
facts, hereafter to be given, and from the results which 
may fairly be attributed to sexual selection, the female, 
though, comparatively passive, generally exerts some 
choice and accepts one male in preference to others. Or 
she may accept, as appearances would sometimes lead us 
to believe, not the male which is the most attractive to 
her, but the one which is the least distasteful. The ex- 
ertion of some choice on the part of the female seems 
almost as general a law as the eagerness of the male. 

We are naturally led to inquire why the male in so 
many and such widely-distinct classes has been rendered 
more eager than the female, so that he searches for her 
and plays the more active part in courtship. It would be 

12 One parasitic Hymenopterous insect (Westwood, ' Modern Class, 
of Insects,' vol. ii. p. 160) forms an exception to the rule, as the male 
baa rudimentary wings, and never quits the cell in which it is born, 
while the female has well-developed wings. Audouin believes that the 
females are impregnated by the males which are born in the same cells 
with them ; but it is much more probable that the females visit other 
cells, and thus avoid close interbreeding. We shall hereafter meet with 
a few exceptional cases, in various classes, in which the female, instead 
of the male, is the seeker and wooer. 

13 \ Essays and Observations,' edited by Owen, vol. i. 1861, p. 194. 



Chap. VIII.] SEXUAL SELECTION. 265 

no advantage and some loss of power if both sexes were 
mutually to search for each other ; but why should the 
male almost always be the seeker? With plants, the 
ovules after fertilization have to be nourished for a time; 
hence the pollen is necessarily brought to the female or- 
gans — being placed on the stigma, through the agency of 
insects or of the wind, or by the spontaneous movements 
of the stamens ; and with the Algae, etc., by the locomo- 
tive power of the antherozooids. "With lowly-organized 
animals permanently affixed to the same spot and having 
their sexes separate, the male element is invariably 
brought to the female ; and we can see the reason ; for 
the ova, even if detached before being fertilized and not 
requiring subsequent nourishment or protection, would 
be, from their larger relative size, less easily transported 
than the male element. Hence plants 14 and many of the 
lower animals are, in this respect, analogous. In the case 
of animals not affixed to the same spot, but enclosed 
within a shell with no power of protruding any part of 
their bodies, and in the case of animals having little 
power of locomotion, the males must trust the fertilizing 
element to the risk of at least a short transit through the 
waters of the sea. It would, therefore, be a great advan- 
tage to such animals, as their organization became per- 
fected, if the males when ready to emit the fertilizing ele- 
ment, were to acquire the habit of approaching the female 
as closely as possible. The males of various lowly-organ- 
ized animals having thus aboriginally acquired the habit 
of approaching and seeking the females, the same habit 
would naturally be transmitted to their more highly-de- 
veloped male descendants ; and in order that they should 

14 Prof. Sachs ('Lehrbuch der Botanik,' 1870, s. 633) in speaking of 
the male and female reproductive cells, remarks : " Verhalt sich die eine 
boi der Vereinigung activ, . .70Lie andere erscheint bei der V-jreini- 
gung pasaiv." 



266 THE PRINCIPLES OF [Part IL 

become efficient seekers, they would have to be endowed 
with strong passions. The acquirement of such passions 
would naturally follow from the more eager males leaving 
a larger number of offspring than the less eager. 

The great eagerness of the male has thus indirectly 
led to the much more frequent development of secondary 
sexual characters in the male than in the female. But 
the development of such characters will have been much 
aided, if the conclusion at which I arrived, after studying 
domesticated animals, can be trusted, namely, that the 
male is more liable to vary than the female. I am aware 
how difficult it is to verify a conclusion of this kind. 
Some slight evidence, however, can be gained by compar- 
ing the two sexes in mankind, as man has been more care- 
fully observed than any other animal. During the No- 
vara Expedition 1& a vast number of measurements of va- 
rious parts of the body in different races were made, and 
the men were found in almost every case to present a 
greater range of variation than the women; but I shall 
have to recur to this subject in a future chapter. Mr. J. 
Wood, 16 who has carefully attended to the variation of the 
muscles in man, puts in italics the conclusion that " the 
greatest number of abnormalities in each subject is found 
in the males." He had previously remarked that " alto- 
gether in 102 subjects the varieties of redundancy were 
found to be half as many again as in females, contrasting 
widely with the greater frequency of deficiency in females 
before described." Prof. Macalister likewise remarks " 

15 'Reise der Novara : Anthropolog. Theil,' 1867, s. 216-269. The 
results were calculated by Dr. Weisbach from measurements made by 
Drs. K. Scberzer and Schwarz. On the greater variability of the males 
of domesticated animals, see my ' Variation of Animals and Plants under 
Domestication,' vol. ii. 1868, p. 75. 

16 'Proceedings Royai Soc' vol. xvi. July, 1868, pp. 519, 524. 

17 'Proc. Royal Irish Academy,' vol. x. 1868, p. 123. 



Chap. VIII.] SEXUAL SELECTION. 267 

that variations in the muscles " are probably more com- 
mon in males than females." Certain muscles which are 
not normally present in mankind are also more frequently 
developed in the male than in the female sex, although 
exceptions to this rule are said to occur. Dr. Burt Wild- 
er 18 has tabulated the cases of 152 individuals with su- 
pernumerary digits, of which 86 were males, and 39, or less 
than half, females ; the remaining 27 being of unknown 
sex. It should not, however, be overlooked that women 
would more frequently endeavor to conceal a deformity 
of this kind than men. Whether the large proportional 
number of deaths of the male offspring of man and appar- 
ently of sheep, compared with the female offspring, be- 
fore, during, and shortly after birth (see supplement), has 
any relation to a stronger tendency in the organs of the 
male to vary and thus to become abnormal in structure or 
function, I will not pretend to conjecture. 

In various classes of animals a few exceptional cases 
occur, in which the female instead of the male has ac- 
quired well-pronounced secondary sexual characters, such 
as brighter colors, greater size, strength, or pugnacity. 
With birds, as we shall hereafter see, there has sometimes 
been a complete transposition of the ordinary characters 
proper to each sex ; the females having become the more 
eager in courtship, the males remaining comparatively 
passive, but apparently selecting, as we may infer from 
the results, the more attractive females. Certain female 
birds have thus been rendered more highly colored or 
otherwise ornamented, as well as more powerful and pug- 
nacious, than the males, these characters being transmit- 
ted to the female offspring alone. 

It may be suggested that in some cases a double pro- 
cess .of selection has been carried on ; the males having 

18 'Massachusetts Medical Soc' vol. ii. No. 3, 1868, p. 9. 



268 THE rULVCirLES OF [Part II. 

selected the more attractive females, and the latter the 
more attractive males. This process, however, though it 
might lead to the modification of both sexes, would not 
make the one sex different from the other, unless indeed 
their taste for the beautiful differed ; but this is a suppo- 
sition too improbable in the case of any animal, excepting 
man, to be worth considering. There are, however, many 
animals, in which the sexes resemble each other, both 
being furnished with the same ornaments, which analogy 
would lead us to attribute to the agency of sexual selec- 
tion. In such cases it may be suggested with more 
plausibility, that there has been a double or mutual pro- 
cess of sexual selection ; the more vigorous and precocious 
females having selected the more attractive and vigorous 
males, the latter having rejected all except the more at- 
tractive females. But, from what we know of the habits 
of animals, this view is hardly probable, the male being 
generally eager to pair with any female. It is more 
probable that the ornaments common to both sexes were 
acquired by one sex, generally the male, and then trans- 
mitted to the offspring of both sexes. If, indeed, during 
a lengthened period the males of any species were greatly 
to exceed the females in number, and then during anothei 
lengthened period under different conditions the reverse 
were to occur, a double, but not simultaneous, process of 
sexual selection might easily be carried on, by which the 
two sexes might be rendered widely different. 

We shall hereafter see that many animals exist, of 
which neither sex is brilliantly colored or provided with 
special ornaments, and yet the members of both sexes or 
of one alone have probably been modified through sexual 
selection. The absence of bright tints or other ornaments 
may be the result of variations of the right kind never 
having occurred, or of the animals themselves preferring 
simple colors, such as plain black or white. Obscure 



Chap. VIII.] SEXUAL SELECTION. 209 

colors have often been acquired through natural selection 
for the sake of protection, and the acquirement through 
sexual selection of conspicuous colors, may have been 
checked from the danger thus incurred. But in other 
cases the males have probably struggled together during 
long ages, through brute force, or by the display of their 
charms, or by both means combined, and ye't no effect 
will have been produced unless a larger number of off- 
spring were left by the more successful males to inherit 
their superiority, than by the less successful males ; and 
this, as previously shown, depends on various complex 
contingencies. 

Sexual selection acts in a less rigorous manner than 
natural selection. The latter produces its effects by the 
life or death at all agjes of the more or less successful 
individuals. Death, indeed, not rarely ensues from the 
conflicts of rival males. But generally the less successful 
male merely fails to obtain a female, or obtains later in 
the season a retarded and less vigorous female, or, if polyg- 
amous, obtains fewer females ; so that they leave fewer, 
or less vigorous, or no offspring. In regard to structures 
acquired through ordinary or natural selection, there is in 
most cases, as long as the conditions of life remain the 
same, a limit to the amount of advantageous modification 
in relation to certain special ends ; but in regard to struct- 
ures adapted to make one male victorious over another, 
either in fighting or in charming the female, there is no 
definite limit to the amount of advantageous modification ; 
so that as long as the proper variations arise the work of 
sexual selection will go on. This circumstance may part- 
ly account for the frequent and extraordinary amount 
of variability presented by secondary sexual characters. 
Xevertheless, natural selection will determine that charac- 
ters of this kind shall not be acquired by the victorious 
males, which would be injurious to them in any high 



270 THE PRINCIPLES OP [Part II. 

degree, either "by expending too much of their vital 
powers, or by exposing them to any great danger. The 
development, however, of certain structures — of the horns, 
for instance, in certain stags — has been carried to a won- 
derful extreme ; and in some instances to an extreme 
which, as far as the general conditions of life are con- 
cerned, must be slightly injurious to the male. From this 
fact we learn that the advantages which favored males 
have derived from conquering other males in battle or 
courtship, and thus leaving a numerous progeny, have 
been in the long-run greater than those derived from 
rather more perfect adaptation to the external conditions 
of life. We shall further see, and this could never have 
been anticipated, that the power to charm the female has 
been in some few instances more important than the 
power to conquer other males in battle. 

LAWS OF INHERITANCE. 

In order to understand how sexual selection has acted, 
and in the course of ages has produced conspicuous re- 
sults with many animals of many classes, it is necessary 
to bear in mind the laws of inheritance, as far as they are 
known. Two distinct elements are included under the 
term "inheritance," namely, the transmission and the 
development of characters ; but as these generally go to- 
gether, the distinction is often overlooked. We see this 
distinction in those characters which are transmitted 
through the early years of life, but are developed only at 
maturity or during old age. We see the same distinction 
more clearly with secondary sexual characters, for these 
are transmitted through both sexes, though developed in 
one alone. That they are present in both sexes, is mani- 
fest when two species, having strongly-marked sexual 
characters, are crossed, for each transmits the characters 



Ohap. VIIL] SEXUAL SELECTION. 271 

proper to its own male and female sex to the hybrid off- 
spring of both sexes. The same fact is likewise manifest, 
when characters proper to the male are occasionally de- 
veloped in the female when she grows old or becomes 
diseased ; and so conversely with the male. Again, char- 
acters occasionally appear, as if transferred from the male 
to the female, as when, in certain breeds of the fowl, spurs 
regularly appear in the young and healthy females ; but 
in truth they are simply developed in the female ; for in 
every breed each detail in the structure of the spur is 
transmitted through the female to her male offspring. In 
all cases of reversion, characters are transmitted through 
two, three, or many generations, and are then under cer- 
tain unknown favorable conditions developed. This im- 
portant distinction between transmission and development 
will be easiest kept in mind by the aid of the hypothesis 
of pangenesis, whether or not it be accepted as true. Ac- 
cording to this hypothesis, every unit or cell of the body 
throws off gemmules or undeveloped atoms, which are 
transmitted to tne offspring of both sexes, and are multi- 
j)lied by self-division. They may remain undeveloped 
during the early years of life or during successive genera- 
tions ; their development into units or cells, like those 
from which they were derived, depending on their affinity 
for, and union with, other units or cells previously devel- 
oped in the due order of growth. 

Inheritance at Corresponding Periods of Life. — This 
tendency is well established. If a new character appears 
in an animal while young, whether it endures throughout 
life or lasts only for a time, it will reappear, as a general 
rule, at the same as-e and in the same manner in the off- 
Bpring. If, on the other hand, a new character appears at 
maturity, or even during old age, it tends to reappear in 
the offspring at the same advanced age. When deviations 



272 THE PRINCIPLES OF [Part 11 

from this rule occur, 'the transmitted characters much of- 
tener appear before than after the corresponding age. As 
I have discussed this subject at sufficient length in another 
work, 19 1 will here merely give two or three instances, for 
the sake of recalling the subject to the reader's mind. In 
several breeds of the Fowl, the chickens while covered 
with down, in their first true plumage, and in their adult 
plumage, differ greatly from each other, as well as from 
their common parent-form, the Gallus bankiva y and these 
characters are faithfully transmitted by each breed to their 
offspring at the corresjDonding period of life. For instance, 
the chickens of spangled Hamburgs, while covered with 
down, have a few dark spots on the head and rump, but 
are not longitudinally striped, as in many other breeds ; in 
their first true plumage, " they are beautifully pencilled." 
that is, each feather is transversely marked by numerous 
dark bars ; but in their second plumage the feathers all 
become spangled or tipped with a dark round spot. 20 
Hence in this breed variations have occurred and have 
been transmitted at three distinct periods of life. The 
Pigeon offers a more remarkable case, because the abori- 
ginal parent-species does not undergo with advancing age 
any change of plumage, excepting that at maturity the 
breast becomes more iridescent ; yet there are breeds which 
do not acquire their characteristic colors until they have 
moulted two, three, or four times ; and these modifications 
of plumage are regularly transmitted. 

19 'The Variation of Animals and Plants under Domestication,' vol. ii. 
1868, p. 75. In the last chapter but one, the provisional hypothesis of 
pangenesis, above alluded to, is fully explained. 

20 These facts are given on the high authority of a great breeder, Mr. 
Teebay, in Tegetmeier's 'Poultry Book,' 1868, p. 158. On the characters 
of chickens of different breeds, and on the breeds of the pigeon, alluded 
to in the above paragraph, see ' Variation of Animals,' etc. vol. i. pp. 160, 
249 ; vol ii. p. 11. 



Chap. VIII.] SEXUAL SELECTION. 273 

Inheritance at Corresponding Seasons of the Year. — 
With animals in a state of nature innumerable instances 
occur of characters periodically appearing at different sea- 
sous. We see this with the horns of the stag, and with 
the fur of arctic animals which becomes thick and white 
during the winter. Numerous birds acquire bright colors 
and other decorations during the breeding-season alone. I 
can throw but little light on this form of inheritance from 
facts observed under domestication. Pallas states 21 that, in 
Siberia, domestic cattle and horses periodically become 
lio-hter-colored during the winter; and I have observed a 
similar marked change of color in certain ponies in Eng- 
land. Although I do not know that this tendency to as- 
sume a differently-colored coat during different seasons of 
the year is transmitted, yet it probably is so, as all shades 
of color are strongly inherited by the horse. Nor is this 
form of inheritance, as limited by'season, more remarkable 
than inheritance as limited by age or sex. 

| 

Inheritance as Limited by Sex. — The equal transmis- 
sion of characters to both sexes is the commonest form of 
inheritance, at least with those animals which do not pre- 
sent strongly-marked sexual differences, and indeed with 
many of these. But characters are not rarely transferred 
exclusively to that sex, in which they first appeared. 
Ample evidence on this head has been advanced in my 
work on Variation under Domestication; but a few in- 
stances may here be given. There are breeds of the sheep 
and goat, in which the horns of the male differ greatly in 
shape from those of the female ; and these differences, ac- 
quired under domestication, are regularly transmitted to 

21 ' Novae species Quadrupedum e Glirium ordine,' 1778, p. 7. On the 
transmission of color by the horse, see ' Variation of Animals, etc., under 
Domestication,' vol. i. p. 21. Also vol. ii. p. 71, for a general discussion 
on Inheritance as limited by Sex. 



2H THE PRINCIPLES OF [Part II. 

the same sex. With tortoise-shell cats the females alone, 
as a general rule, are thus colored, the males being rusty- 
red. With most breeds of the fowl, the characters proper 
to each sex are transmitted to the same sex alone. So 
general is this form of transmission that it is an anomaly 
when we see in certain breeds variations transmitted equal- 
ly to both sexes. There are also certain sub-breeds of the 
fowl in which the males can hardly be distinguished from 
each other, while the females differ considerably in color. 
With the pigeon the sexes of the parent-species do not 
differ in any external character; nevertheless in certain 
domesticated breeds the male is differently colored from 
the female. 22 The wattle in the English Carrier-pigeon 
and the crop in the Pouter are more highly developed in 
the male than in the female ; and although these characters 
have been gained through long-continued selection by man, 
the difference between the two sexes is wholly due to the 
form of inheritance which has prevailed ; for it has arisen, 
not from, but rather in opposition to, the wishes of the 
breeder. 

Most of our domestic races have been formed by the 
accumulation of many slight variations ; and as some of 
the successive steps have been transmitted to one sex 
alone, and some to both sexes, we find in the different 
breeds of the same species all gradations between great 
sexual dissimilarity and complete similarity. Instances 
have already been given with the breeds of the fowl and 
pigeon ; and under Nature analogous cases are of fre- 
quent occurrence. With animals under domestication, but 
whether under Nature I will not venture to say, one sex 
may lose characters proper to it, and may thus come to 
resemble to a certain extent the opposite sex ; for in- 
stance, the males of some breeds of the fowl have lost 

22 Dr. Chapuis, 'Le Pigeon Yoyageur Beige,' 1865, p. 87. Boitard 
et Corbie, 'Les Pigeons de Voliere,' etc., 1824, p 173 



Chap. VIII.] SEXUAL SELECTION. 275 

their masculine plumes and hackles. On the other hand, 
the differences between the sexes may be increased under 
domestication, as with merino sheep, in which the ewes 
have lost their horns. Again, characters proper to one 
sex may suddenly appear in the other sex ; as with those 
sub-breeds of the fowl in which the hens while young ac- 
quire spurs ; or, as in certain Polish sub-breeds, in which 
the females, as there is reason to believe, originally ac- 
quired a crest, and subsequently transferred it to the 
males. All these cases are intelligible on the hypothesis 
of pangenesis ; for they depend on the gemmules of certain 
units of the body, although present in both sexes, becoming 
through the influence of domestication dormant in the one 
sex ; or, if naturally dormant, becoming developed. 

There is one difficult question which it will be conven- 
ient to defer to a future chapter ; namely, whether a char- 
acter, at first developed in both sexes, can be rendered 
through selection limited in its development to one sex 
alone. If, for instance, a breeder observed that some of 
his pigeons (in which species characters are usually trans- 
ferred in an equal degree to both sexes) varied into pale 
blue ; could he by long-continued selection make a breed, 
in which the males alone should be of this tint while the 
females remained unchanged ? I will here only say that 
this, though perhaps not impossible, would be extremely 
difficult ; for the natural result of breeding from the pale- 
blue males would be to change his whole stock, including 
both sexes, into this tint. If, however, variations of the 
desired tint appeared, which were from the first limited 
in their development to the male sex, there would not be 
the least difficulty in making a breed characterized by the 
two sexes being of a different color, as indeed has been 
effected with a Belgian breed, in which the males alone 
are streaked with black. In a similar manner, if any vari- 
ation appeared in a female pigeon, which was from the 



276 THE PRINCIPLES OF [Part II. 

first sexually limited in its development, it would be easy 
to make a breed with the females alone thus character- 
ized ; but if the variation was not thus originally limited, 
the process would be extremely difficult, perhaps impos- 
sible. 

On the Relation between the period of Development of 
a Character and its transmission to one sex or to both 
sexes. — Why certain characters should be inherited by 
both sexes, and other characters by one sex alone, namely, 
by that sex in which the character first appeared, is in 
most cases quite unknown. We cannot even conjecture 
why with certain sub-breeds of the pigeon, black striae, 
though transmitted through the female," should be de- 
veloped in the male alone, while every other character is 
equally transferred to both sexes. Why, again, with cats, 
the tortoise-shell color should, with rare exceptions, be 
developed in the female alone. The very same characters, 
such as deficient or supernumerary digits, color-blindness, 
etc., may with mankind be inherited by the males alone 
of one family, and in another family by the females alone, 
though in both cases transmitted through the opposite as 
well as the same sex. 23 Although we are thus ignorant, 
two rules often hold good, namely, that variations which 
first appear in either sex at a late period of life, tend to 
be developed in the same sex alone ; while variations 
which first appear early in life in either sex tend to be 
developed in both sexes. I am, however, far from sup- 
posing that this is the sole determining cause. As I have 
not elsewhere discussed this subject, and as it has an im- 
portant bearing on sexual selection, I must here enter 
into lengthy and somewhat intricate details. 

It is in itself probable that any character appearing at 

43 References are given in my ' Variation of Animals under Domssti- 
cation,' vol. ii. p. 72. 



Chap. VIII.] SEXUAL SELECTION. 277 

an early age would tend to be inherited equally by both 
sexes, for the sexes do not differ much in constitution, be- 
fore the power of reproduction is gained. On the other 
hand, after this power has been gained and the sexes have 
come to differ in constitution, the gemnmles (if I may 
again use the language of pangenesis) which are cast off 
from each varying part in the one sex would be much 
more likely to possess the proper affinities for uniting 
with the tissues of the same sex, and thus becoming de- 
veloped, than with those of the opposite sex. 

I was first led to infer that a relation of this kind ex- 
ists, from the fact that whenever and in whatever manner 
the adult male has come to differ from the • adult female, 
he differs in the same manner from the young of both 
sexes. The generality of this fact is quite remarkable : it 
holds good with almost all mammals, birds, amphibians, 
and fishes ; also with many crustaceans, spiders, and some 
few insects, namely, certain orthoptera and libellulce,. In 
all these cases the variations, through the accumulation of 
which the male acquired his proper masculine characters, 
must have occurred at a somewhat late period of life; 
otherwise the young males would have been similarly 
characterized ; and conformably with our rule, they are 
transmitted to and developed in the adult males alone. 
When, on the other hand, the adult male closely resem- 
bles the young of both sexes (these, with rare exceptions, 
being alike), he generally resembles the adul^ female; 
and in most of these cases the variations through which 
the young and old acquired their present characters, prob- 
ably occurred in conformity with our rule during y outh. 
But there is here room for doubt, as characters are some- 
times transferred to the offspring at an earlier age than 
that at which they first appeared in the parents, so that 
the parents may have varied when adult, and have trans- 
ferred their characters to their offspring while young. 



278 THE PRINCIPLES OF [Past II. 

There are, moreover, many animals, in which the two 
sexes closely resemble each other, and yet both differ 
from their young ; and here the characters of the adults 
must have been acquired late in life ; nevertheless, 4hese 
characters in apparent contradiction to our rule, are trans- 
ferred to both sexes. "We must not, however, overlook 
the possibility or even probability of successive variations 
of the same nature sometimes occurring, under exposure 
to similar conditions, simultaneously in both sexes at a 
rather late period of life ; and in this case the variations 
would be transferred to the offspring of both sexes at a 
corresponding late age ; and there would be no real con- 
tradiction to our rule of the variations which occur late in 
life being transferred exclusively to the sex in which they 
first appeared. This latter rule seems to hold true more 
generally than the second rule, namely, that variations 
which occur in either sex early in life tend to be trans- 
ferred to both sexes. As it was obviously impossible even 
to estimate in how large a number of cases throughout the 
animal kingdom these two propositions hold good, it oc- 
curred to me to investigate some striking or crucial in- 
stances, and to rely on the result. 

An excellent case for investigation is afforded by the 
Deer Family. In all the species, excepting one, the horns 
are developed in the male alone, though certainly trans- 
mitted through the female, and capable of occasional ab- 
normal development in her. In the reindeer, on the other 
hand, the female is provided with horns ; so that in this 
species, the horns ought, according to our rule, to appear 
early in life, long before the two sexes had arrived at 
maturity and had come to differ much in constitution. In 
all the other species of deer the horns ought to appear 
later in life, leading to their development in that sex 
alone, in which they first appeared in the progenitor of 
the whole Family. Now, in seven species, belonging to 



Chap. VIII.] SEXUAL SELECTION. 279 

distinct sections of the family and inhabiting different 
regions, in which the stags alone bear horns, I find that 
the horns first appear at periods varying from nine months 
after birth in the roebuck to ten or twelve more months 
in the stags of the six other larger species. 24 But with 
the reindeer the case is widely different, for as I hear from 
Prof. Nilsson, who kindly made special inquiries for me 
in Lapland, the horns appear in the young animals within 
four or five weeks after birth, and at the same time in 
both sexes. So that here we have a structure, developed 
at a most unusually early age in one species of the family, 
and common to both sexes in this one species. 

In several kinds of antelopes the males alone are pro- 
vided with horns, while in the greater number both sexes 
have horns. With respect to the period of development, 
Mr. Blyth informs me that there lived at one time in the 
Zoological Gardens a young koodoo (Ant. strepsiceros)^ 
in which species the males alone are horned, and the 
young of a closely-allied species, viz., the eland (Ant. 
orec&s), in which both sexes are horned. Now in strict 
conformity with our rule, in the young male koodoo, al- 
though arrived at the age of ten months, the horns were 
remarkably small considering the size ultimately attained 
by them : while in the young male eland, although only 
three months old, the horns were already very much larger 
than in the koodoo. It is also worth notice that in the 



24 I am much obliged to Mr. Cupples for having made inquiries for 
me in regard to the Roebuck and Red Deer of Scotland from Mr. Rob- 
ertson, the experienced head-forester to the Marquis of Breadalbane. In 
regard to Fallow-deer, I am obliged to Mr. Eyton and others for informa- 
tion. For the Cervus alces of North America, see ' Land and Water,' 186S, 
pp. 221 and 254 ; and for the C. Virginianus and slrongyloceros of the 
same continent, see J. D. Caton, in ' Ottawa Acad, of Nat. Sc' 1868, p. 
13. For Cervus Eldi of Pegu, see Lieut. Beavan, 'Proc. Zoolog. Soc.' 
1867, p. 762. 



280 THE PRINCIPLES OF [Part II. 

prong-horned antelope, 26 in which species the horns, though 
present in both sexes, are almost rudimentary in the 
female, they do not appear until about five or six months 
after birth. With sheep, goats, and cattle, in which the 
horns are well developed in both sexes, though not quite 
equal in size, they can be felt, or even seen, at birth, or 
soon afterward. 26 Our rule, however, fails in regard to 
some breeds of sheep, for instance, merinos, in which the 
rams alone are horned ; for I cannot find on inquiry, 27 that 
the horns are developed later in life in this breed than in 
ordinary sheep in which both sexes are horned. But with 
domesticated .sheep the presence or absence of horns is 
not a firmly-fixed character ; a certain proportion of the 
merino ewes bearing small horns, and some of the rams 
being hornless ; while with ordinary sheep hornless ewes 
are occasionally produced. 

In most of the species of the splendid family of the 
Pheasants, the males differ conspicuously from the females, 
and they acquire their ornaments at a rather late period of 
life. The eared pheasant (Crossvjytilon aurituni), how- 
ever, offers a remarkable exception, for both sexes possess 

25 Antilocapra Americana. Owen, ' Anatomy of Vertebrates,' vol. 
iii. p. 627. 

26 1 have been assured that the horns of the sheep in North Wales 
can always be felt, and are sometimes even an inch in length, at birth. 
With cattle Youatt says (' Cattle,' 1834, p. 277) that the prominence of 
the frontal bone penetrates the cutis at birth, and that the horny matter 
is soon formed over it. 

27 1 am greatly indebted to Prof. Victor Carus for having made in- 
quiries for me, from the highest authorities, with respect to the merino 
sheep of Saxony. On the Guinea coast of Africa there is a breed of 
sheep in which, as with merinos, the rams alone bear horns ; and Mr. 
Winwood Reade informs me that in the one case observed, a young ram 
born on February 10th first showed horns on March 6th, so that in this 
instance the development of the horns occurred at a later period of life, 
conformably with our rule, than in the Welsh sheep, in which both sexes 
are horned. 



Chap. V7JI.] SEXUAL SELECTION. 281 

the fine caudal plumes, the large ear-tufts and the crimson 
velvet about the head ; and I find on inquiry in the Zo- 
ological Gardens that all these characters, in accordance 
with our rule, appear very early in life. The adult male 
can, however, be distinguished from the adult female by 
one character, namely, by the presence of spurs ; and 
conformably with our rule, these do not begin to be de- 
veloped, as I am assured by Mr. Bartlett, before the age 
of six months, and even at this age, can hardly be dis- 
tinguished in the two sexes. 28 The male and female 
Peacock differ conspicuously from each other in almost 
every part of their plumage, except in the elegant head- 
crest, which is common to both sexes ; and this is de- 
veloped very early in life, long before the other orna- 
ments which are confined to the male. The wild-duck 
offers an analogous case, for the beautiful green speculum 
on the wings is common to both sexes, though duller and 
somewhat smaller in the female, and it is developed early 
in life, while the curled tail-feathers and other ornaments 
peculiar to the male are developed later. 29 Between such 

28 In the common peacock (Pavo cristatus) the male alone possesses 
spurs, while both sexes of the Java peacock (P. muticus) offer the unu- 
sual case of being furnished with spurs. Hence I fully expected that in 
the latter species they would have been developed earlier in life than in 
the- common peacock ; but M. Hegt, of Amsterdam, informs me that, 
with young birds of the previous year, belonging to both species, com- 
pared on April 23, 1869, there was no difference in the development of 
the spurs. The spurs, however, were as yet represented merely by slight 
knobs or elevations. I presume that I should have been informed if 
any difference in the rate of development had subsequently been ob- 
served. 

29 In some other species of the Duck Family the speculum in the two 
sexes differs in a greater degree ; but I have not been able to discover 
whether its full development occurs later in life in the males of such spe- 
cies, than in the male of the common duck, as ought to be the case ac- 
cording to our rule. "With the allied Mergus cucullatus we have, however, 
a case of this kind : the two sexes differ conspicuously in general plu- 

13 



282 THE PRINCIPLES OF [Part II. 

extreme cases of close sexual resemblance and wide dis- 
similarity, as those of the Crossoptilon and peacock, many 
intermediate ones could be given, in which the characters 
follow in their order of development our two rules. 

As most insects emerge from their pupal state in a 
mature condition, it is doubtful whether the period of de- 
velopment determines the transference of their characters 
to one or both sexes. But we do not know that the col- 
ored scales, for instance, in two species of butterflies, in 
one of which the sexes differ in color, while in the other 
they are alike, are developed at the same relative age in 
the cocoon. Nor do we know whether all the scales are 
simultaneously developed on the wings of the same spe- 
cies of butterfly, in which certain colored marks are con- 
fined to one sex, while other marks are common to both 
sexes. A difference of this kind in the period of develop- 
ment is not so improbable as it may at first appear ; for, 
with the Orthoptera, which assume their adult state, not 
by a single metamorphosis, but by a succession of moults, 
the young males of some species at first resemble the fe- 
males, and acquire their distinctive masculine characters 
only during a later moult. Strictly analogous cases occur 
during the successive moults of certain male crustaceans. 

We have as ^yet only considered the transference of 
characters, relatively to their period of development, with 
species in a natural state ; we will now turn to domesti- 
cated animals; first touching on monstrosities and dis- 
eases. The presence of supernumerary digits, and the 

mage, and to a considerable degree in the speculum, which is pure white 
in the male and grayish-white in the female. Now the young males at 
ri^st resemble, in all respects, the female, and have a grayish-white spec- 
\iiim, but this becomes pure white at an earlier age than that at which 
the adult male acquires his other more strongly-marked sexual differ- 
ences in plumage : see Audubon, ' Ornithological Biography,' vol. iii 
1835, pp. 249, 250 



Chap. VIII.] SEXUAL SELECWON. 283 

absence of certain phalanges, must be determined at an 
early embryonic period — the tendency to profuse bleeding 
is at least congenital, as is probably color-blindness — yet 
these peculiarities, and other similar ones, are often limit- 
ed in their transmission to one sex ; go that the rule that 
characters which are developed at an early period tend to 
be transmitted to both sexes, here wholly fails. But this 
rule, as before remarked, does not appear to be nearly so 
generally true as the converse proposition, namely, that 
characters which appear late in life in one sex are trans- 
mitted exclusively to the same sex. From the fact of the 
above abnormal peculiarities becoming attached to one 
sex, long before the sexual functions are active, we may 
infer that there must be a difference of some kind between 
the sexes at an extremely early age. With respect to 
sexually-limited diseases, we know too little of the period 
at which they originate, to draw any fair conclusion. 
Gout, however, seems to fall under our rule ; for it is gen- 
erally cause/L by intemperance after early youth, and is 
transmitted from the father to his sons in a much more 
marked manner than to his daughters. 

In the various domestic breeds of sheep, goats, and 
cattle, the mules differ from their respective females in 
the shape or development of their horns, forehead, mane, 
dewlap, tail, and hump on the shoulders ; and these pecu- 
liarities, in accordance with our rule, are not fully devel- 
oped until rather late in life. With dogs, the sexes do 
not differ, except that in certain breeds, especially in the 
Scotch deer-hound, the male is much larger and heavier 
than the female ; and, as we shall see in a future chapter, 
the male goes on increasing in size to an unusually late 
period of life, which will account, according to our rule, 
for his increased size bein^ transmitted to his male off- 
spring alone. On the other hand, the tortoise-shell color 
of the hair, which is confined to female cats, is quite clis- 



284 THE' PRINCIPLES OF [Part II. 

tinct at birth, and this case violates our rule. There is a 
breed of pigeons in which the males alone are streaked 
with black, and the streaks can be detected even in the 
nestlings ; but they become more conspicuous at each suc- 
cessive moult, so that this case partly opposes and partly 
supports the rule. With the English Carrier and Pouter 
pigeon the full development of .the wattle and the crop 
occurs rather late in life, and these characters, conform- 
ably with our rule, are transmitted in full perfection to 
the males alone. The following cases perhaps come with- 
in the class previously alluded to, in which the two sexes 
have varied in the same manner at a rather late period of 
life, and have consequently transferred their new charac- 
ters to both sexes at a corresponding late period ; and if 
so, such cases are not opposed to our rule. Thus there 
are sub-breeds of the pigeon, described by Neumeister, 30 
both sexes of which change color after moulting twice or 
thrice, as does likewise the Almond Tumbler ; neverthe- 
less these changes, though occurring rather*late in life, 
are common to both sexes. One variety of the Canary-bird, 
namely, the London Prize, offers a nearly analogous case. 
With the breeds of the Fowl the inheritance of various 
characters by one sex or by both sexes seems generally 
determined by the period at which such characters are 
developed. Thus, in all the many breeds in which the 
adult male differs greatly in color from the female and 
from the adult male parent-species, he differs from the 
young male, so that the newly-acquired characters must 
have appeared at a rather late period of life. On the 
other hand, with most of the breeds in which the two 
sexes resemble each other, the young are colored in nearly 
the same manner as their parents, and this renders it proba- 

30 'Das Ganze der Taubenzucht,' 1837, s. 21, 24. For the case of the 
etreaked pigeons, see Dr. Chapuis, 'Le Pigeon Voyageur Beige,' 1865, 
p. 87 



Chap. VIII.] SEXUAL SELECTION. 285 

ble that their colors first appeared early in life. We have 
instances of this fact in all black and white breeds, in 
which the young and old of both sexes are alike ; nor can 
it be maintained that there is something peculiar in a 
black or white plumage, leading to its transference to 
both sexes ; for the males. alone of mgfny natural species 
are either black or white, the females being very differ- 
ently colored. "With the so-called Cuckoo sub-breeds of 
the fowl, in which the feathers are transversely pencilled 
with dark stripes, both sexes and the chickens are colored 
in nearly the same manner. The laced plumage of the 
Sebright bantam is the same in both sexes, and in the 
chickens the feathers are tipped with black, which makes 
a near approach to lacing. Spangled Hamburgs, however, 
offer a partial exception, for the two sexes, though not 
quite alike, resemble each other more closely than do the 
sexes of the aboriginal parent-species, yet they acquire 
their characteristic plumage late in life, for the chickens 
are distinctly pencilled. Turning to other characters be- 
sides color : the males alone of the wild parent-species and 
of most domestic breeds possess a fairly well-developed 
comb, but in the young of the Spanish fowl it is largely 
developed at a very early age, and apparently in conse- 
quence of this it is of unusual size m the adult females. 
In the Game breeds pugnacity is developed at a wonder- 
fully early age, of which curious proofs could be given ; 
and this character is transmitted to both sexes, so that 
the hens, from their extreme pugnacity, are now generally 
exhibited in separate pens. With the Polish breeds the 
bony protuberance of the skull which supports the crest is 
partially developed even before the chickens are hatched, 
and the crest itself soon begins to grow, though at first 
feebly ; S1 and in this breed a great bony protuberance 

81 For full particulars and references on all these points respecting 
the several breeds of the Fowl, see ' Variation of Animals and Plants un- 



286 THE PRINCIPLES OF [Part II. 

and an immense crest characterize the adults of both 
sexes. 

Finally, from what we have now seen of the relation 
which exists in many natural species and domesticated 
races, between the period of the development of their 
characters and the* manner of iheir transmission — for ex- 
ample, the striking fact of the early growth of the horns 
in the reindeer, in which both sexes have horns, in com- 
parison with their much later growth in the other species 
in which the male alone bears horns — we may conclude 
that one cause, though not the sole cause, of characters 
being exclusively inherited by one sex, is their develop- 
ment at a late age. And secondly, that one, though ap- 
parently a less efficient, cause of characters being in- 
herited by both sexes is their development at an early 
age, while the sexes differ but little in constitution. It 
appears, however, that some difference must exist between 
the sexes even during an early embryonic period, for char- 
acters developed at this age not rarely become attached 
to one sex. 

Summary and concluding remarks. — From the fore- 
going discussion on the various laws of inheritance, we 
learn that characters often or even generally tend to be- 
come developed in the same sex, at the same age, and pe- 
riodically at the same season of the year, in which they 
first appeared in the parents. But these laws, from un- 
known causes, are very liable to change. Hence the suc- 
cessive steps in the modification of a species might readily 
be transmitted in different ways ;*some of the steps being 
transmitted to one sex, and some to both ; some to the 
offspring at one age, and some at all ages. Not only are 

der Domestication,' vol. i. pp. 250, 256. In regard to the higher ani- 
mate, the sexual differences which have arisen under domestication ars 
described in the same work under the head of each species. 



Chap. VIII.] SEXUAL SELECTION. 287 

the laws of inheritance extremely complex, but so are the 
causes which induce and govern variability. The varia- 
tions thus caused are preserved and accumulated by sexual 
selection, which is in itself an extremely complex affair, 
depending, as it does, on ardor in love, courage, and the 
rivalry of the males, and on the powers of perception, 
taste, and will, of the female. Sexual selection will also* 
be dominated by natural selection for the general welfare 
of the species. Hence the manner in which the individu- 
als of either sex or of both sexes are affected through 
sexual selection cannot fail to be complex in the highest 
degree. 

When variations occur late in life in one sex, and are 
transmitted to the same sex at the same age, the other sex 
and the young are necessarily left unmodified. When 
they occur late in life, but are transmitted to both sexes 
at the same age, the young alone are left unmodified. 
Variations, however, may occur at any period of life in 
one sex or in both, and be transmitted to both sexes at 
all ages, and then all the individuals of the species will 
be similarly modified. In the following chapters it will 
be seen that all these cases frequently occur under nature. 

Sexual selection can never act on any animal while 
young, before the age for reproduction has arrived. From 
the great eagerness of the male it has generally acted on 
this sex and not on the females. The males have thus be- 
come provided with weapons for fighting with their rivals, 
or with organs for discovering and securely holding the 
female, or for exciting and charming her. When the sexes 
differ in these respects, it is also, as we have seen, an ex- 
tremely general law that the adult male differs more or 
less from the young male ; and we may conclude fropi this 
fact that the successive variations, by which the adult 
male became modified, cannot have occurred much before 
the age for reproduction. How, then, are we to account 



288 THE PRINCIPLES OF [P^t II. 

for this general and remarkable coincidence between the 
period of variability and that of sexual selection — princi- 
ples which are quite independent of each other ? I think 
we can see the cause : it is not that the males have never 
varied at an early age, but that such variations have com- 
monly been lost, while those occurring at a later age have 
'been preserved. 

All animals produce more offspring than can survive 
to maturity ; and we have every reason to believe that 
death falls heavily on the weak and inexperienced young. 
If, then, a certain proportion of the offspring were to vary 
at birth or soon afterward, in some manner which at this 
age was of no service to them, the chance of the preser- 
vation of such variations would be small. We have good 
evidence under domestication how soon variations of all 
kinds are lost, if not selected. But variations which oc- 
curred at or near maturity, and which were of immediate 
service to either sex, would probably be preserved ; as 
would similar variations occurring at an earlier period in 
any individuals which happened to survive. As this prin- 
ciple has an important bearing on sexual selection, it may 
be advisable to give an imaginary illustration. We will 
take a pair of animals, neither very fertile nor the reverse, 
and assume that after arriving at maturity they live on an 
average for five years, producing each year five young. 
They would thus produce 25 offspring ; and it would not, 
I think, be an unfair estimate to assume that 18 or 20 out 
of the 25 would perish before maturity, while still young 
and inexperienced ; the remaining seven or five sufficing 
to keep up the stock of mature individuals. If so, we can 
see that variations which occurred during youth, for in- 
stance, in brightness, and which were not of the least ser- 
vice to the young, would run a good chance of being 
utterly lost. While similar variations, which occurring 
at or near maturity in the comparatively few individuals 



Chap. Till.] SEXUAL SELECTION. . 289 

surviving to this age, and which immediately gave an ad- 
vantage to certain males, by rendering them more attrac- 
tive to the females, would be likely to be preserved. No 
doubt some of the variations in brightness which occurred 
at an earlier age would by chance be preserved, and 
eventually give to the male the same advantage as those 
which appeared later; and this will account for the young 
males commonly partaking to a certain extent (as may be 
observed with many birds) of the bright colors of their 
adult male parents. If only a few of the successive varia- 
tions in brightness were to occur at a late age, the adult 
male would be only a little brighter than the young male ; 
and such cases are common. 

In this illustration I have assumed that the young 
varied in a maimer which was of no service to them ; but 
many characters proper to the adult male would be actu- 
ally injurious to the young — as bright colors from making 
them conspicuous, or horns of large size from expending 
much vital force. Such variations in the young would 
promptly be eliminated through natural selection. With 
the adult and experienced males, on the other hand, the 
advantage thus derived in their rivalry with other males 
would often more than counterbalance exposure to some 
degree of danger. Thus we can understand how it is that 
variations which must originally*have appeared rather late 
in life have alone or in chief part been preserved for the 
development of secondary sexual characters ; and the re- 
markable coincidence between the periods of variability 
and of sexual selection is intelligible. 

As variations which give to the male an advantage in 
fighting with other males, or in finding, securing, or charm- 
ing the female, would be of no use to the female, they will 
not have been preserved in this sex either during youth or 
maturity. Consequently such variations would be ex- 
tremely liable to be lost ; and the female, as far as these 



290 THE PRINCIPLES OF [Pari II. 

characters are concerned, would be left unmodified, except- 
ing in so far as she may have received them by transference 
from the male. "No doubt if the female varied and trans- 
ferred serviceable characters to her male offspring, these 
would be favored through sexual selection ; and then both 
sexes would thus far be modified in the same manner. But 
I shall hereafter have to recur to these more intricate con- 
tingencies. 

In the following chapters, I shall treat of the secondary 
sexual characters in animals of all classes, and shall en- 
deavor in each case to apply the principles explained in 
the present chapter. The lowest classes will detain us for 
a very short time, but the higher animals, especially birds, 
must be treated at considerable length. It should be borne 
in mind that, for reasons already assigned, I intend to give 
only a few illustrative instances of the innumerable struct- 
ures by the aid of which the male finds the female, or, 
when found, holds her. On the other hand, all structures 
and instincts by which the male conquers other males, 
and by which. he allures or excites the female, will be fully 
discussed, as these are in many ways the most interesting. 



Supplement on the proportional numbers of the two sexes 
in animals belonging to various classes. 

As no one, as far as I can discover, has paid attention 
to the relative numbers of the two sexes throughout the 

CD 

animal kingdom, I will here give such materials as I have 
been able to collect, although they are extremely imper- 
fect. They consist in only a few instances of actual enu- 
meration, and the numbers are not very large. As the 
proportions are known with certainty on a large scale in 
the case of man alone, I will first give them, as a standard 
of comparison. 



Chap VIII. J SEXUAL SELECTION. 291 

Man. — In England during ten years (from 1857 to 
I860) 707,120 children on an annual average have been 
born alive, in the proportion of 104.5 males to 100 fe- 
males. But in 1857 the male births throughout England 
were as 105.2, and 1865 as 104.0 to 100. Looking to 
separate districts, in Buckinghamshire (where on an aver- 
age 5,000 children are annually born) the mean propor- 
tion of male to female births, during the whole period of 
the above ten years, was as 102.8 to 100 ; while in North 
Wales (where the average annual births are 12,873) it was 
as high as 106.2 to 100. Taking a still smaller district, 
viz., Rutlandshire (where the annual births average only 
739), in 1864 the male births were as 114.6, and in 1862 as 
97.0 to 100 ; but even in this small district the average of 
the 7,385 births during the whole ten years was as 104.5 
to 100 ; that is, in the same ratio as throughout England. 32 
The proportions are sometimes slightly disturbed by un- 
known causes ; thus Prof. Faye states that " in some dis- 
tricts of Norway there has been during a decennial period 
a steady deficiency of boys, while in others the opposite 
condition has existed." In France during forty-four years 
the male to the female births have been as 106.2 to 100; 
but during this period it has occurred five times in one de- 
partment, and six times in another, that the female births 
have exceeded the males. In Russia the average propor- 
tion is as high as 108.9 to 100. 33 It is a singular fact that 
with Jews the proportion of male births is decidedly larger 
than with Christians ; thus in Prussia the proportion is as 
113, in Breslau as 114, and in Livonia as 120 to 100; the 
Christian births in these countries being the same as usual, 

32 ' TVenty-ninth Annual Report of the Registrar-General for 1866.' 
In this report (p. xii) a special decennial table is given. 

33 For Xorway and Russia, see abstract of Prof. Faye's researches in 
British and Foreign Medico-Chirurg. Review,' April, 1867, pp. 343, 345 

For France, the ' Annuaire pour l'An 1867,' p. 213. 



292 ' THE PRINCIPLES OF [Part II. 

for instance, in Livonia as 104 to 100. 34 It is a still more 
singular fact that in different nations, under different con- 
ditions and climates, in Naples, Prussia, Westphalia, 
France, and England, the excess of male over female 
births is less when they are illegitimate than when legiti- 
mate. 35 

In various parts of Europe, according to Prof. Faye 
and other authors, " a still greater preponderance of males 
would be met with, if death struck both sexes in equal 
proportion in the womb and during birth. But the fact 
is that, for every 100 still-born females, we have in sev- 
eral countries from 134.6 to 144.9 still-born males." More- 
over during the first four or five years of life more male 
children die than females ; for example, in England, dur- 
ing the first year, 126 boys die for every 100 girls — a pro- 
portion which in France is still more unfavorable." 38 As 
a consequence of this excess in the death-rate of male 
children, and of the exposure of men when adult to vari- 
ous dangers, and of their tendency to emigrate, the fe- 
males in all old-settled countries, where statistical records 
have been kept, 37 are found to preponderate considerably 
over the males. 

34 In regard to the Jews, see M. Thury, ( La Loi de Production des 
Sexes,' 1863, p. 25. 

35 Babbage, 'Edinburgh Journal of Science,' 1829, vol. i. p. 88; also 
p. 90, on still-born children. On illegitimate children in England, see 
'Report of Registrar-General for 1866,' p. xv. 

86 'British and Foreign Medico-Chirurg. Review,' Api-il, 186*7, p. 343. 
Dr. Stark also remarks (' Tenth Annual Report of Births, Deaths, etc., in 
Scotland,' 1867, p. xxviii.) that "these examples may suffice to show that, 
at almost every stage of life, the males in Scotland have a greater liabil- 
ity to death and a higher death-rate than the females. The fact, how- 
ever, of this peculiarity being most strongly developed at that infantile 
l«wiod of life when the dress, food, and general treatment of both sexes 
ate alike, seems to prove that the higher male death-rate is an impressed,, 
■natural, and constitutional peculiarity due to sex alone." 

37 With the savage Guaranys of Paraguay, according to the accurate 



Chap. Vin.] SEXUAL SELECTION. 293 

It has often been supposed that the relative ages of 
the parents determine the sex of the offspring ; and Prof. 
Leuckart 38 has advanced what he considers sufficient evi- 
dence, with respect to man and certain domesticated ani- 
mals, to show that this is one important factor in the 
result. So, again, the period of impregnation has been 
thought to be the efficient cause ; but recent observations 
discountenance this belief. Again, with mankind polyg- 
amy has been supposed to lead to the birth of a greater 
proportion of female infants ; but Dr. J. Campbell 39 care- 
fully attended to this subject in the harems of Siam, and 
he concludes that the proportion of male to female births 
is the same as from monogamous unions. Hardly any 
animal has been rendered so highly polygamous as our 
English race-horses, and we shall immediately see that 
their male and female offspring are almost exactly equal 
in number. 

Horses. — Mr. Tegetmeier has been so kind as to tabulate for 
me from the 'Bating Calendar' the births of race-horses during 
a period of twenty-one years, viz., from 1846 to 1867; 1849 being 
omitted, as no returns were that year published. The total births 
have been 25,560, 40 consisting of 12,763 males and 12,797 females, 
or in the proportion of 99.7 males to 100 females. As these num- 

Azara ('Voyages dans l'Amerique mend.,' torn. ii. 1809, pp. 60, 179), 
the women in proportion to the men are as 14 to 13. 

38 Leuckart (in Wagner, ' Handworterbuch der Phys.' B. iv. 1853, s 
774). 

39 Anthropological Review, April, 1870, p. cviii. 

40 During the last eleven years a record has been kept of the number 
of mares which have proved barren or prematurely slipped their foals ; 
and it deserves notice, as showing how infertile these highly-nurtured 
and rather closely-interbred animals have become, that not far from one- 
third of the mares failed to produce living foals. Thus, during 1866, 809 
male colts and 816 female colts were born, and 743 mares failed to pro. 
duce offspring. During 1867, 836 males and 902 females were born, and 
791 mares failed. 



294 THE PRINCIPLES OF [Part II. 

bers are tolerably large, and as they are drawn from all parts of 
England, during several years, we may with much confidence 
conclude that with the domestic horse, or at least with the race- 
horse, the two sexes are produced in almost equal numbers. The 
fluctuations in the proportions during successive years are closely 
like those which occur with mankind, when a small and thinly- 
populated area is considered: thus in 1856 the male horses were' 
as 107.1, and in 1867 as only 92.6 to 100 females. In the tabu- 
lated returns the proportions vary in cycles, for the males ex- 
ceeded the females during six successive years ; and the females 
exceeded the males during two periods each of four years : this, 
however, may be accidental ; at least I can detect nothing of the 
kind with man in the decennial table in the Registrar's Report for 
1866. I may add that certain mares, and this holds good with 
certain cows and with women, tend to produce more of one sex 
than of the other ; Mr. "Wright, of Yeldersley House, informs me 
that one of his Arab mares, though put seven times to different 
horses, produced seven fillies. 

Dogs. — During a period of twelve years, from 1857 to 1868, 
the births of a large number of greyhounds, throughout England, 
have been sent to the 'Field' newspaper; and I am again in- 
debted to Mr. Tegetmeier for carefully tabulating the results. 
The recorded births have been 6,878, consisting of 3,605 males 
and 3,273 females, that is, in the proportion of 110.1 males to 100 
females. The greatest fluctuations occurred in 1864, when the 
proportion was as 95.3 males, and in 1867, as 116.3 males to 100 
females. The above average proportion of 110.1 to 100 is prob- 
ably nearly correct in the case of the greyhound, but whether it 
would hold with other domesticated breeds is in some degree 
doubtful. Mr. Cupples has inquired from several great breeders 
of dogs, and finds that all without exception believe that females 
are produced in excess; he suggests that this belief may have 
arisen from females being less valued and the consequent disap- 
pointment producing a stronger impression on the mind. 

Sheep. — The sexes of sheep are not ascertained by agricultur- 
ists until several months after birth, at the period when the males 
sire castrated ; so that the following returns do not give the pro- 
portions at birth. Moreover, I find that several great breeders 
in Scotland, who annually raise some thousand sheep, are firmly 



Chap. VIII.] SEXUAL SELECTION. 29£ 

convinced that a larger proportion of males than of females die 
during the first one or two years ; therefore the proportion of 
males would be somewhat greater at birth than at the age of cas- 
tration. This is a remarkable coincidence with what occurs, as 
we have seen, with mankind, and both cases probably depend on 
some common cause. I have received returns from four gentle- 
men in England who have bred lowland sheep, chiefly Leicesters, 
during the last ten or sixteen years; they amount altogether to 
8,965 births, consisting of 4,407 males and 4,558 females; that is, 
in the proportion of 96.7 males to 100 females. "With respect to 
Cheviot and black-faced sheep bred in Scotland, I have received 
returns from six breeders, two of them on a large scale, chiefly 
for the years 1867-1869, but some of the returns extending back 
to 1862. The total number recorded amounts # to 50,685, consist- 
ing of 25,071 males and 25,614 females, or in the proportion of 
97.9 males to 100 females. If we take the English and Scotch 
returns together, the total number amounts to 59,650, consisting 
of 29,478 males and 30,172 females, or as 97.7 to 100. So that 
with sheep at the age of castration the females are certainly in 
excess of the males; but whether this would hold good at birth 
is doubtful, owing to the greater liability in the males to early 
death. 41 

Of Cattle I have received returns from nine gentlemen of 982 
births, too few to be trusted ; these consisted of 477 bull-calves 
and 505 cow-calves; i. e., in the proportion of 94.4 males to 100 
females. The Rev. W. D. Fox informs me that in 1867 out of 84 
calves bom on a farm in Derbyshire only one was a bull. Mr. 
Harrison Weir writes to me that he has inquired from several 
breeders of Pigs, and most of them estimate the male to the fe- 
male births as about 7 to 6. This same gentleman has bred Rab- 
bits for many years, and has noticed that a far greater number of 
bucks are produced than does. 

41 I am much indebted to Mr. Cupples for having procured for me the 
above returns from Scotland, as well as some of the following returns on 
cattle. Mr. R. Elliot, of Laighwood, first called my attention to the 
premature deaths of the males — a statement subsequently confirmed by 
Mr. Aitchison and others. To this latter gentleman, and to Mr. Payau, 
I owe my thanks for the larger returns on sheep. 



296 ■ THE PRINCIPLES OP [Part II. 

Of mammalia in a state of nature i have been able to learn 
very little. In regard to the common rat, I have received con- 
flicting statements. Mr. R. Elliot, of Laighwood, informs me that 
a rat-catcher assured him that he had always found the males in 
great excess, even with the young in the nest. In consequence 
of this, Mr. Elliot himself subsequently examined some hundred 
old ones, and found the statement true. Mr. F. Buckland has 
bred a large number of white rats, and he also believes that the 
males greatly exceed the females. In regard to Moles, it is said 
that " the males are much more numerous than the females ; " 49 
and as the catching of these animals is a special occupation, the 
statement may perhaps be trusted. Sir A. Smith, in describing 
an antelope of South Africa 43 {Kobus ellipsiprymnus), remarks, 
that in the herds^of this and other species, the males are few in 
number compared with the females - , the natives believe that they 
are born in this proportion ; others believe that the younger males 
are expelled from the herds, and Sir A. Smith says, that though 
he has himself never seen herds consisting of young males alone, 
others affirm that this does occur. It appears probable that the 
young males, when expelled from the herd, would be likely to fall 
a prey to the many beasts of prey of the country. 

BIKDS. 

"With respect to the Fowl, I have received only one account, 
namely, that out of 1,001 chickens of a highly-bred stock of Co- 
chins, reared during eight years by Mr. Stretch, 487 proved males 
and 514 females: i. e., as 94.7 fc> 100. In regard to domestic pig- 
eons there is good evidence that the males are produced in excess, 
or that their lives are longer ; for these birds invariably pair, and 
single males, as Mr. Tegetmeier informs me, can alway be pur- 
chased cheaper than females. Usually the two birds reared from 
the two eggs laid in the same nest consist of a male and female; 
but Mr. Harrison "Weir, who has been so large a breeder, says that 
he has often bred two cocks from the same nest, and seldom two 
hens ; moreover, the hen is generally the weaker of the two, and 
more liable to perish. 

42 Bell, ' History of British Quadrupeds,' p. 100. 

48 'Illustrations of the Zoology of South Africa,' 1849, pi. 29. 



Chap. VIII.] SEXUAL SELECTION. 297 

With respect to birds in a state of nature, Mr. Gould and 
others 44 are convinced that the males are # generally the more 
numerous; and as the young males of many species resemble the 
females, the latter would naturally appear to be the most numer- 
ous. Large numbers of pheasants are reared by Mr. Baker, of 
Leadenhall, from eggs laid by wild birds, and he informs Mr. Jen- 
ner Weir that four or five males to one female are generally pro- 
duced. An experienced observer remarks 45 that in Scandinavia 
the broods of the capercailzie and black-cock contain more males 
than females ; and that with the Dal-ripa (a kind of ptarmigan) 
more males than females attend the leks or places of courtship ; 
but this latter circumstance is accounted for by some observers 
by a greater number of hen-birds being killed by vermin. From 
various facts given by White of Selbourne, 46 it seems clear that the 
males of the partridge must be in considerable excess in the south 
of England ; and I have been assured that this is the case in Scot- 
land. Mr. Weir, on inquiring from the dealers who receive at 
certain seasons large numbers of ruffs {Machetes pugnax), was told 
that the males are much the most numerous. This same natural- 
ist has also inquired for me from the bird-catchers, who annually 
catch an astonishing number of various small species alive for the 
London market, and he was unhesitatingly answered by an old 
and trustworthy man, that with the chaffinch the males are in 
large excess ; he- thought as high as 2 males to 1 female, or at 
least as high as 5 to 3. 47 The males of the blackbird, he likewise 
maintained, were by far the most numerous, whether caught by 
traps or by netting at' night. These statements may apparently 
be trusted, because the same man said that the sexes are about 
equal with the lark, the twite (Linaria montana), and goldfinch. 

44 3rehm (' Elust. Thierleben,' B. iv. s. 990) comes to the same con- 
clusion. 

45 On the authority of L. Lloyd, 'Game Birds of Sweden,' 1867, pp. 
12, 132. 

46 ' Nat. Hist, of Selbourne,' letter xxix. edit, of 1825, vol. i. p. 139. 

47 Mr. Jenner Weir received similar information, on making inquiries 
during the following year. To show the number of chaffinches caught, 1 
may mention that in 1869 there was a match between two experts; and 
one man caught in a day 62, and another 40, male chaffinches. The 
greatest number ever caught by one man in a single day was 70. 



208 THE PRINCIPLES OF [Part II. 

On the other hand, he is certain that with the common linnet, the 
females preponderate greatly, hut unequally during different years; 
during some years he has found the females to the males as four 
to one. It should, however, be borne in mind, that the chief sea- 
son for catching birds does not begin till September, so that with 
some species partial migrations may have begun, and the flocks 
at this period often consist of hens alone. .Mr. Salvin paid par- 
ticular attention to the sexes of the humming-birds in Central 
America, and he is convinced that with most of the species the 
males are in excess ; thus, one year he procured 204 specimens 
belonging to ten species, and these consisted of 166 males and of 
38 females. With two other species the females were in excess : 
but the proportions apparently vary either during different sea- 
sons or in different localities ; for on one occasion the males of 
Campylopterus hemileucurus were to the females as five to two, 
and on another occasion 48 in exactly the reversed ratio. As bear- 
ing on this latter point, I may add that Mr. Powys found in Corfu 
and Epirus the sexes of the chaffinch keeping apart, and " the fe- 
males by far the most numerous; " while in Palestine Mr. Tris- 
tram found " the male flocks appearing greatly to exceed the fe- 
male in number." 49 So again with the Quiscalus major, Mr. G-. 
Taylor 60 says that in Florida there were " very few females in 
proportion to the males," while in Honduras the proportion was 
the other way, the species there having the character of a po- 
lygamic. 

FISH. 

With fish the proportional numbers of the sexes can be ascer- 
tained only by catching them in the adult or nearly adult state ; 
and there are many difficulties in arriving at any just conclusion. 51 
Infertile females might readily be mistaken for males, as Dr. Gun- 
ther has remarked to me in regard to trout. With some species 

48 ' Ibis,' vol. ii. p. 260, as quoted in Gould's ' Trochilidse,' 1861, p. 52. 
For the foregoing proportions, I am indebted to Mr. Salvin for a table of 
his results. 

49 'Ibis,' 1860, p. 137; and 1867, p. 369 
60 'Ibis,' 1862, p. 137. 

61 Leuckart quotes Bloch (Wagner, ' Handworterbuch der PLys.' B. 
TV. 1853, s. 775), that with fish there are twice as many males as females. 



Chap. Till.] SEXUAL SELECTION. 299 

the males are believed to die soon after fertilizing the ova. With 
many species the males are of much smaller size than the females, 
so that a large number of males would escape from the same net 
by which the females were caught. M. Carbonnier, 62 who has 
especially attended to the natural history of the pike (Esox lucius) 
states that many males, owing to their small size, are devoured by 
the larger females ; and he believes that the males of almost all 
fish are exposed from the same cause to greater danger than the 
females. Nevertheless, in the few cases in which the proportional 
numbers have been actually observed, the males appear to be 
largely in excess. Thus, Mr. R. Buist, the superintendent of the 
Stormontfield experiments, says that in 1865, out of 70 salmon 
first landed for the purpose of obtaining the ova, upward of 60 
were males. In 1867 he again " calls attention to the vast dispro- 
portion of the males to the females. "We had at the outset at 
least ten males to one female." Afterward sufficient females for 
obtaining ova were procured. He adds, "From the great propor- 
tion of the males, they are constantly fighting and tearing each 
other on the spawning-beds." 53 " This disproportion, no doubt, 
can be accounted for in part, but whether wholly is very doubtful, 
by the males ascending the rivers before the females. Mr. F. 
Buckland remarks in regard to trout, that "it is a curious fact 
that the males preponderate very largely in number over the fe- 
males. It invariably happens that when the first rush of fish is 
made to the net, there will be at least seven or eight males to one 
female found captive. I cannot quite account for this ; either the 
males are more numerous than w the females, or the latter seek 
safety by concealment rather than flight." He then adds that, by 
carefully searching the banks, sufficient females for obtaining ova 
can be found. 54 Mr. H. Lee informs me that out of 212 trout, 
taken for this purpose in Lord Portsmouth's park, 150 were males 
and 62 females. 

With the Cyprinidfe the males likewise seem to be in excess; 
but several members of this family, viz., the carp, tench, bream, 

52 Quoted in the 'Farmer,' March 18, 1869, p. 369. 
BS ' The Stormontfield Piscicultural Experiments,' 1866, p. 23. The 
'Field' newspaper, June 29, 1867. 
M ' Land and Water,' 1868, p. 41. 



300 THE PRINCIPLES OF [Part il. 

and minnow, appear regularly to follow the practice, rare in the 
animal kingdom, of polyandry; for the female "while spawning is 
always attended by two males, one on each side, and in the case 
of the bream by three or four males. This fact is so well known, 
that it is always recommended to stock a pond with two male 
tenches to one female, or at least with three males to two females. 
"With the minnow, an excellent observer states that on the spawn- 
ing-beds the males are ten times as numerous as the females; 
when a female comes among the males, "she is immediately 
pressed closely by a male on each side ; and when they have been 
in that situation for a time, are superseded by other two males." 55 

INSECTS. 

In this class, the Lepidoptera alone afford the means of judg- 
ing of the proportional numbers of the sexes ; for they have been 
collected with special care by many good observers, and have 
been largely bred from the egg or caterpillar state. I had hoped 
that some breeders of silk-moths might bave kept an exact record, 
but after writing to France and Italy, and consulting various 
treatises, I cannot find that this has ever been done. The gen- 
eral opinion appears to be that the sexes are nearly eqiial but 
in Italy, as I hear from Prof. .Oanestrini, many breeders are 
convinced that the females are produced in excess. The same 
naturalist, however, informs me, that in the two yearly broods 
of the Ailantus silk-moth (Borribyx cyntMa), the males greatly 
preponderate jn the first, while in the second the two 'sexes are 
nearly equal, or the females rather in excess. 

In regard to Butterflies in a state of nature, several observers 
have been much struck by the apparently enormous preponder- 
ance of the males. 56 Thus Mr. Bates, 67 in speaking of the species, 

£5 Yarrell, ' Hist. British Fishes,' vol. i. 1836, p. 307 ; on the Cyprinw 
tarpio, p. 331 ; on the Tinea vulgaris, p. 331 ; on the Abramis brama, p. 
336. See, for the minnow (Leuciscus phoxinus), 'Loudon's Mag. of Nat. 
Hist.' vol. v. 1832, p. 682. 

. 56 Leuckart quotes Meinecke (Wagner, ' Handworterbuch der Phys.' 
B. iv. 1853, s. 775) that with Butterflies the males are three or foui 
tines as numerous as the females. 

6; « The Naturalist on the Amazons,' vol. ii. 1863, pp. 228, 347. 



Chap. VIII.] SEXUAL SELECTION. 301 

no less than about a hundred in number, which inhabit the 
Upper Amazons, says that the males are much more numerous 
than the females, even in the proportion of a hundred to one. 
In North America, Edwards, who had great experience, esti- 
mates in the genus Papilio the males to the females as four to 
one ; and Mr. Walsh, who informed me of this statement, says 
that with P. turnus this is certainly the case. In South Africa, 
Mr. P. Trimen found the males in excess in nineteen species ; 68 
and in one of these, which swarms in open places, he estimated 
the number of males as fifty to one female. With another spe- 
cies, in which the males are numerous iu. certain localities, he 
collected during seven years only five females. In the island of 
Bourbon, M. Maillard states that the males of one species of 
Papilio are twenty times as numerous as the females. 59 Mr. 
Trimen informs* me that as far as he has himself seen, or heard 
from others, it is rare for the females of any butterfly to exceed 
in number the males ; but this is perhaps the case with three 
South African species. Mr. Wallace 60 states that the females of 
Ornitlioptera crcesus, in the Malay archipelago, are more common 
and more easily caught than the males ; but this is a rare butter- 
fly. I may here add, that in Hyperythra, a genus of moths, 
Guene'e says, that from four to five females are sent in collections 
from India for one male. 

When this subject of the proportional numbers of the sexes 
of insects was brought before the Entomological Society, 61 it was 
generally admitted that the males of most Lepidoptera, in the 
adult or imago state, are caught in greater numbers than the 
females ; but this fact was attributed by various observers to the 
more retiring habits of the females, and to the males emerging 
earlier from the cocoon. This latter circumstance is well known 
to occur with most Lepidoptera, as well as with other insects. 
So that, as M. Personnat remarks, the males of the domesticated 
Boinbyx yama-mai are lost at the beginning of the season, and 

68 Four of these cases are given by Mr. Trimen in his ' Rhopalocera 
Africa? Australis.' 

69 Quoted by Trimen, ' Transact. Ent. Soc.' vol. v. part iv. 1866, p. 
830. 

60 ' Transact, Linn. Soc.' vol. xxv. p. 37. 
61 ' Proc. Entomolog. Soc.' Feb. 17, 1868. 



302 THE PRINCIPLES OF [Part II. 

the females at the end, from the want of mates. 62 I cannot, how- 
ever, persuade myself that these causes suffice to explain the great 
excess of males in the cases, above given, of butterflies which are 
extremely common in their native countries. Mr. Stainton, who 
has paid such close attention during many years to the smaller 
moths, informs me that when he collected them in the imago 
state, he thought that the males were ten times as numerous as 
the females, but that, since he has reared them on a large scale 
from the caterpillar state, he is convinced that the females are 
the most numerous. Several entomologists concur in this view. 
Mr. Doubleday, however, and some others, take an opposite view, 
and are convinced that they have reared from the egg and cater- 
pillar states a larger proportion of males than of females. 

Besides the more active habits of the males, their earlier 
emergence from the cocoon, and their frequenting in some cases 
more open stations, other causes may be assigned for an apparent 
or real difference in the proportional numbers of the sexes of 
Lepidoptera, when captured in the imago state, and when reared 
from the egg or caterpillar state. It is believed by many breeders 
in Italy, as I hear from Prof. Canestrini, that the female cater- 
pillar of the silk-moth suffers more from the recent disease than 
the male ; and Dr. Staudinger informs me that in rearing Lepi- 
doptera more females die in the cocoon than males. With many 
species the female caterpillar is larger than the male, and a col- 
lector would naturally choose the finest specimens, and thus un- 
intentionally collect a larger number of females. Three collect- 
ors have told me that this was their practice ; but Dr. "Wallace 
is sure that most collectors take all the specimens which they can 
find of the rarer kinds, which alone are worth the trouble of 
rearing. Birds, when surrounded by caterpillars, would prob- 
ably devour the largest ; and Prof. Canestrini informs me that in 
Italy some breeders believe, though on insufficient evidence, that 
in the first brood of the Ailantus silk-moth, the wasps destroy a 
larger number of the female than of the male caterpillars. Dr. 
Wallace further remarks that female caterpillars, from being 
larger than the males, require more time for their development, 

62 Quoted by Dr. Wallace in 'Proc. Eat. Soc.' 3d series, vol. v. 1867, 
p. 487. 



Chap. VIIL] SEXUAL SELECTION. 303 

and consume more food and moisture ; and thus they would he 
exposed during a longer time to danger from ichneumons, hirds, 
etc., and in times of scarcity would perish in greater numhers. 
Hence it appears quite possible that, in a state of nature, fewer 
female Lepidoptera may reach maturity than males ; and for our 
special ohject we are concerned with the numhers at maturity, 
when the sexes are ready to propagate their kind. 

The manner in which the males of certain moths congregate 
in extraordinary numhers round a single female, apparently indi- 
cates a great excess of males, though this fact may perhaps he 
accounted for by the earlier emergence of the males from their 
cocoons. Mr. Stainton informs me that from twelve to twenty 
males may often be seen congregated round a female ElacMsta 
rufocinerea. It is well known that if a virgin Lasiocampa quereus 
or Saturnia carpini be exposed in a cage, vast numbers of males 
collect round her, and if confined in a room will even come down 
the chimney to her. Mr. Doubleday believes that he has seen 
from fifty to a hundred males of both these species attracted in 
the course of a single day by a female under confinement. Mr. 
Trimen exposed in the Isle of Wight a box in which a female of 
the Lasiocampa had Been confined on the previous day, and five 
males soon endeavored to gain admittance. M. Verreaux, in 
Australia, having placed the female of a small Bombyx in a box 
in his pocket, was followed by a crowd of males, so that about 
two hundred entered the house with him. 63 

Mr. Doubleday has called my attention to Dr. Staudinger's 6 * 
list of Lepidoptera, which gives the prices of the males and 
females of 300 species or well-marked varieties of (Rhopalocera) 
butterflies. The prices for both sexes of the very common species 
are of course the same; but with 114 of the rarer species they 
differ ; the males being in all cases, excepting one, the cheapest. 
On an average of the prices of the 113 species, the price of the 
male to that of the female is as 100 to 149 ; and this apparently 
indicates that inversely the males exceed the females in number 
in the same proportion. About 2,000 species or varieties of 
moths (Heterocera) are catalogued, those with wingless females 

63 Blanchard, 'Metamorphoses, Moeurs des Insectes,' 1868, pp. 225, 226, 

64 ' Lepidopteren-Doubblettren Liste,' Berlin, No. x. 1866. 



304 THE PRINCIPLES OF [Part II. 

being here excluded on account of the difference in habits of the 
two sexes : of these 2,000 species, 141 differ in price according to 
sex, the males of 130 being cheaper, and the males of only 11 
being dearer than the females. The average price of the males 
of the 130 species, to that of the females, is as 100 to 143. With 
respect to the butterflies in this priced list, Mr. Doubleday thinks 
(and no man in England has had more experience) that there is 
nothing in the habits of the species which can account for the 
difference in the prices of the two sexes, and that it can be ac- 
counted for only by an excess in the numbers of the males. But 
I am bound to add that Dr. Staudinger himself, as he informs me, 
is of a different opinion. He thinks that the less active habits of 
the females and the earlier emergence of the males wiil account 
for his collectors securing a larger number of males than of 
females, and consequently for the lower prices of the former. 
With respect to specimens reared from the caterpillar-state, Dr. 
Staudinger believes, as previously stated, that a greater number 
of females than of males die under confinement in the cocoons. 
He adds that with certain species one sex seems to preponderate 
over the other during certain years. 

Of direct observations on the sexes of Lepidoptera, reared 
either from eggs or caterpillars, I have received only the few fol- 
lowing cases : 

Males. Females. 

The Rev. J. Hellins, 65 of Exeter, reared, during 1868, imagos of 73 

species, which consisted of 153 137 

Mr. Albert Jones, of Eltham, reared, during 1868, imagos of 9 species, 

which consisted of 159 128 

During 1869 he reared imagos from 4 species, consisting of 114 112 

Mr. Buckler, of Emsworth', Hants, during 1869, reared imagos from 

74 species, consisting of 180 169 

Dr. Wallace, of Colchester, reared from one brood of Bombyx 

cynthia 52 48 

Dr. Wallace raised, from cocoons of Bombyx Pernyi sent from 

China, during 1869 224 123 

Dr. Wallace raised, during 1868 and 1869, from two lots of cocoons 

of Bombyx yama-mai 52 46 

Total 934 761 

So that in these eight lots of cocoons and eggs, males were 
produced in excess. Taken together, the proportion of males is . 

65 This naturalist has been so kind as to send me some results from 
former years, in which the females seemed to preponderate ; but so many 
of the figures were estimates, that I found it impossible to tabulate them 



Chip. VIIL] SEXUAL SELECTION. 305 

as 122.7 to 100 females. But the numbers are hardly largo 
enough to be trustworthy. 

On the whole, from the above various sources of evidence, 
all pointing to the same direction, I infer that, with most species 
of Lepidoptera, the males in the imago state generally exceed the 
females in number, whatever the proportions may be at their first 
emergence from the egg. 

With reference to the other Orders of insects, I have been 
able to collect very little reliable information. With the stag- 
beetle {Lucanus cervus) " the males appear to be much more 
Dumerous than the females ; " but when, as Cornelius remarked 
during 1867, an unusual number of these beetles appeared in one 
part of Germany, the females appeared to exceed the males as 
six to one. With one of the Elateridos, the males are said to be 
much more numerous than the females, and " two or three are 
often found united with one female ; " 66 so that here polyandry 
seems to prevail. With Siagonium (Staphylinidse), in which the 
males are furnished with horns, " the females are far more 
numerous than the opposite sex." Mr. Janson stated at the 
Entomological Society that the females of the bark-feeding 
Tomicus villosus are so common as to be a plague, while the 
males are so rare as to be hardly known. In other Orders, from 
unknown causes, but apparently in some instances owing to 
parthenogenesis, the males of certain species have never been 
discovered, or are excessively rare, as with several of the Cyni- 
pidffi. 67 In all the gall-making Cynipidos known to Mr. Walsh, 
the females are four or five times as numerous as the males ; and 
so it is, as he informs me, with the gall-making Cecidomyiiaa 
(Diptera). With some common species of Saw-flies (Tenthre- 
dinae) Mr. F. Smith has reared hundreds of specimens from larvaa 
of all sizes, but has never reared a single male: on the other' 
hand, Curtis says, 68 that with certain species (Athalia), bred by 

66 Giinther's ' Record of Zoological Literature,' 1867, p. 260. On the 
excess of female Lucanus, ibid. p. 250. On the males of Lucanus in Eng- 
land, Westwood, c Modern Class, of Insects,' vol. i. p. 187. On the Sia- 
gonium, ibid, p 1*72. 

67 Walsh, in ' The American Entomologist,' vol. i. 1869, p. 103. F 
Smith, 'Record of Zoological Literature,' 1867, p. 328. 

68 • Farm Insects,' pp. 45, 46. 

14 



SO 6 THE PRINCIPLES OP [Part II. 

him, the males to the females were as six to one ; while exactly 
the reverse occurred with the mature insects of the same species 
caught in the fields. With the Neuroptera, Mr. Walsh states that 
in many, hut hy no means in all, the species of the Odonatous 
groups (Ephemerina), there is a great overplus of males ; in the 
genus Hetaerina, also, the males are generally at least four times 
as numerous as the females. In certain species in the genus 
Gomphus the males are equally numerous, while in two other 
species the females are twice or thrice as numerous as the males. 
In some European species of Psocus thousands of females may he 
collected, without a single male, while with other species of the 
same genus both sexes are common. 69 In England, Mr. Mac- 
Lachlan has captured hundreds of the female Apatania muliebris, 
but has never seen the male ; and of Boreus hy emails only four 
or five males have been here seen. 70 With most of these species 
(excepting, as I have heard, with the Tenthredinae), there is no 
reason to suppose that the females are subject to parthenogene- 
sis ; and thus we see how ignorant we are on the causes of the 
apparent discrepancy in the proportional numbers of the two 
sexes. 

In the other Classes of the Articulata I have been able to col- 
lect still less information. With Spiders, Mr. Blackwall, who has 
carefully attended to this class during many years, writes to me 
that the males, from their more erratic habits, are more com- 
monly seen, and therefore appear to be the more numerous. 
This is actually the case with a few species ; but he mentions 
several species in six genera, in which the females appear to be 
much more numerous than the males. 71 The small size of the 
males in comparison with- the females, which is sometimes car- 
ried to an extreme degree, and their widely-different appearance, 
may account in some instances for their rarity in collections. 73 

M ' Observations on N. American Neuroptera,' by H. Hagan and B. D. 
Walsh, 'Proc. Ent. Soc. Philadelphia,' Oct. 1863, pp. 168, 223, 239. 

70 Proc. Ent, Soc. London,' Feb. 17, 1868. 

71 Another great authoi-ity in this class, Prof. Thorell of Upsala (' On 
Em-opean Spiders,' 1869-"70, part i. p. 205) speaks as if female spiders 
were generally commoner than the males. 

12 See, on this subject, Mr. Pickard-Cambridge, as quoted in ' Qua*, 
terly Journal of Science,' 1868, p. 429. 



Q 



Chap. VIII.] SEXUAL SELECTION. 307 

Some of the lower Crustaceans are able to propagate their 
kind asexually, and this will account for the extreme rarity of 
the males. "With some other forms (as with Tanis and Cypris) 
there is reason to believe, as Fritz Miiller informs me, that the 
male is much shorter-lived than the female, which, supposing 
the two sexes to be at lirst equal in number, would explain the 
scarcity of the males. On the other hand, this same naturalist 
has invariably taken, on the shores of Brazil, far more males 
than females of the Diastylids and of Cypridina ; thus, with a 
species in the latter genus, sixty-three specimens caught the 
same day, included fifty-seven males ; but he suggests that this 
preponderance may be due to some unknown difference in the 
habits of the two sexes. With one of the higher Brazilian crabs, 
namely, a Gelasimus, Fritz Muller found the males to be more 
numerous than the females. The reverse seems to be the case, 
according to the large experience of Mr. 0. Spence Bate, with six 
common British crabs, the names of which he has given me. 

On the Power of Natural Selection to regulate the pro- 
portional Numbers of the Sexes, and General Fertility. — 
In some peculiar cases, an excess in the number of one sex 
over the other might be a great advantage to a species, 
as with the sterile females of social insects, or with those 
animals in which more than one male is requisite to ferti- 
lize the female, as with certain cirripedes and perhaps 
certain fishes. An inequality between the sexes in these 
cases might have been acquired through natural selection, 
but from their rarity they need not here be further con- 
sidered. In all ordinary cases an inequality would be no 
advantage or disadvantage to certain individuals more 
than to others; and therefore it could hardly have re- 
sulted from natural selection. We must attribute the 
inequality to the direct action of those unknown condi- 
tions, which with mankind lead to the males being born 
in a somewhat larger excess in certain countries than in 
others, or which cause the proportion between the sexes 
to differ slightly in legitimate and illegitimate births. 



808 THE PRINCIPLES OF [Part II. 

Let us now take the case of a species producing, from 
the unknown causes just alluded to, an excess of one sex 
— we- will say of males — these being superfluous and use- 
less, or nearly useless. Could the sexes he equalized 
through natural selection ? We may feel sure, from all 
characters being variable, that certain pairs would pro- 
duce a somewhat less excess of males over females than 
other pairs. The former, supposing the actual number of 
the offspring to remain constant, would necessarily pro- 
duce more females, and would therefore be more pro- 
ductive. On the doctrine of chances a greater number of 
the offspring of the more productive pairs would survive ; 
and these would inherit a tendency to procreate fewer 
males and more females. Thus a tendency toward equali- 
zation of the sexes would be brought about. But our 
supposed species would by this process be rendered, as 
just remarked, more productive ; and this would in many 
cases be far from an advantage ; for, whenever the limit to 
the numbers which exist depends, not on destruction by 
enemies, but on the amount of food, increased fertility 
will lead to severer competition and to most of the sur- 
vivors being badly fed. In this case, if the sexes were 
equalized by an increase in the number of the females, a 
simultaneous decrease in the total number of the offspring 
would be beneficial, or even necessary, for the existence 
of the species ; and this, I believe, could be effected through 
natural selection in the manner hereafter to be described. 
The same train of reasoning is applicable in the above, as 
well as in the following case, if we assume that females 
instead of males are produced in excess, for such females 
from not uniting with males would be superfluous and 
useless. So it would be with polygamous species, if we 
assume the excess of females to be inordinately great. 

An excess of either sex, we will again say of the males, 
could, however, apparently be eliminated through natural 



Chap. VIII.] SEXUAL SELECTION. 309 

selection in another and indirect manner, namely, by an 
actual diminution of the males, without any increase of 
the females, and consequently without any increase in the 
productiveness of the species. From the variability of all 
characters, we may feel assured that some pairs, inhabit- 
ing any locality, would produce a rather smaller excess of 
superfluous males, but an equal number of productive 
females. When the offspring fr.om the more and the less 
male-productive parents were all mingled together, none 
would have any direct advantage over the others ; but 
those that produced few superfluous males would have 
one great indirect advantage, namely, that their ova or 
embryos would probably be larger and finer, or their 
young better nurtured in the womb and afterward. We 
see this principle illustrated with plants ; as those which 
bear a vast number of seed produce small ones ; while 
those which bear comparatively few seeds, often produce 
laro;e ones well-stocked with nutriment for the use of the 
seedlings. 73 Hence the offspring of the parents which had 
wasted least force in producing superfluous males would 
be the most likely to survive, and would inherit the same 
tendency not to produce superfluous males, while retain- 
ing their full fertility in the production of females. So it 
would be with the converse case of the female sex. Any 
slight excess, however, of either sex could hardly be 
checked in so indirect a manner. Nor indeed has a con- 
siderable inequality between the sexes been always pre- 
vented, as we have seen in some of the cases given in the 
previous discussion. In these cases the unknown causes 
which determine the sex of the embryo, and which under 
certain conditions lead to the production of one sex in 

73 I have often been struck with the fact that, in several species of 
Primula, the seeds in the capsules which contained' only a few were 
very much larger than the numerous seeds in the more productive cap- 
sules. 



3L0 



TEE PRINCIPLES OF 



[Part II. 



excess over the other, have not been mastered by the sur- 
vival of those varieties which were subjected to the least 
waste of organized matter and force by the production of 
superfluous individuals of either sex. Nevertheless we 
may conclude that natural selection will always tend, 
though sometimes inefficiently, to equalize the relative 
numbers of the two sexes. 

Having said this much on the equalization of the 
sexes, it may be well to add a few remarks on the regula- 
tion through natural selection of the ordinary fertility of 
species. Mr. Herbert Spencer has shown in an able dis- 
cussion 74 that with all organisms a ratio exists between 
what he calls individuation and genesis ; whence it follows 
that beings which consume much matter or force in their 
growth, complicated structure, or activity, or which pro- 
duce ova and embryos of large size, or which expend 
much energy in nurturing their young, cannot be so pro- 
ductive as beings of an opposite nature. Mr. Spencer 
further shows that minor differences in fertility will be 
regulated through natural selection. Thus the fertility of 
each species will tend to increase, from the more fertile 
pairs producing a larger number of offspring, and these 
from their mere number will have the best chance of sur- 
viving, and will transmit their tendency to greater fer- 
tility. The only check to a continued augmentation of 
fertility in each organism seems to be either the expendi- 
ture of more power and the greater risks run by the 
parents that produce a more numerous progeny, or the 
contingency of very numerous eggs and young being pro- 
duced of smaller size, or less vigorous, or subsequently 
not so well nurtured. To strike a balance in any case be- 
tween the disadvantages which follow from the production 
of a numerous progeny, and the advantages (such as the 



14 'Principles of Biology,' vol. ii. 1867, chaps. ii.-xL 



Chap. YIII.J SEXUAL SELECTION. 311 

escape of at least some individuals from various dangers) 
is quite beyond our power of judgment. 

When an organism has once been rendered extremely 
fertile, how its fertility can be reduced through natural 
selection is not so clear as how this capacity was first ac- 
quired. Yet it is obvious that if individuals of a species, 
from a decrease of their natural enemies, were habitually 
reared in larger numbers than could be supported, all the 
members would suffer. Nevertheless the offspring from 
the less fertile parents would have no direct advantage 
over the offspring from the more fertile parents, when all 
were mingled together in the same district. All the in- 
dividuals would mutually tend to starve each other. The 
offspring indeed of the less fertile parents would lie under 
one great disadvantage, for, from the simple fact of being 
produced in smaller numbers, they would be the most lia- 
ble to extermination. Indirectly, however, they would 
partake of one great advantage ; for, under the supposed 
condition of severe competition, when all were pressed for 
food, it is extremely probable that those individuals which 
from some variation in their constitution produced fewer 
eggs or young, would produce them of greater size or 
vigor; and the adults reared from such eggs or young 
would manifestly have the best chance of surviving, and 
would inherit a tendency toward lessened fertility. The 
parents, moreover, which had to nourish or provide for 
fewer offspring would themselves be exposed to a less se- 
vere strain in the struggle for existence, and would have 
a better chance of surviving. By these steps, and by no 
others as far as I can see, natural selection, under the 
above conditions of severe competition for food, would 
lead to the formation of a new race less fertile, but better 
adapted for survival, than the parent-race. 



312 



SEXUAL SELECTION 



[Fart II. 



CHAPTER IX. 

SECONDARY SEXUAL CHARACTERS IN THE LOWER CLASSES 

OP THE ANIMAL KINGDOM. 



These Characters absent in the Lowest Classes. — Brilliant Colors. — Mol- 
lusca. — Annelids. — Crustacea, Secondary Sexual Characters strongly 
developed; Dimorphism; Color; Characters not acquired before 
Maturity. — Spiders, Sexual Colors of; Stridulation by the Males. — 
Myriapoda. 

In the lowest classes the two sexes are not rarely 
imited in the same individual, and therefore secondary 
sexual characters cannot be developed. In many cases in 
which the two sexes are separate, both are permanently 
attached to some support, and the one cannot search or 
struggle for the other. Moreover, it is almost certain that 
these animals have too imperfect senses and much too low 
mental powers to feel mutual rivalry, or to appreciate each 
other's beauty or other attractions. 

Hence in these classes, such as the Protozoa, Ccelen- 
terata, Echinodermata, Scolecida, true secondary sexual 
characters do not occur; and this fact agrees with the 
belief that such characters in the higher classes have been 
acquired through sexual selection, which depends on the 
will, desires, and choice, of either sex. Nevertheless some 
few apparent exceptions occur ; thus, as I hear from Dr. 
Baird, the males of certain Entozoa, or internal parasitic 
worms, differ slightly in color from the females ; but we 



Chap. IX.] SEXUAL SELECTION. 313 

have no reason to suppose that such differences have been 
augmented through sexual selection. 

Many of the lower animals, whether hermaphrodites 
or with the sexes separate, are ornamented with the most 
brilliant tints, or are shaded and striped in an elegant 
manner. This is the case with many corals and sea-anem- 
ones (Actinia?), with some jelly-fish (Medusae, Porpita, 
etc.), with some Planarise, Ascidians, numerous Star-fishes, 
Echini, etc. ; but we may conclude, from the reasons al- 
ready indicated, namely, the union of the two sexes in 
some of these animals, the permanently affixed condition 
of others, and the low mental powers of all, that such col- 
ors do not serve as a sexual attraction, and have not been 
acquired through sexual selection. With the higher ani- 
mals the case is very different ; for with them when one 
sex is much more brilliantly or conspicuously colored than 
the other, and there is no difference in the habits of the 
two sexes which will account for this difference, we have 
reason to believe in the influence of sexual selection ; and 
this belief is strongly confirmed when the more ornament- 
ed individuals, which are almost always the males, dis- 
play their attractions before the other sex. We may also 
extend this conclusion to both sexes, when colored alike, 
if their colors are plainly analogous to those of one sex 
alone in certain other species of the same group. 

How, then, are we to account for the beautiful or even 
gorgeous colors of many animals in the lowest classes ? 
It appears very doubtful whether such colors usually serve 
as a protection ; but we are extremely liable to err in re- 
gard to characters of all kinds in relation to protection, as 
will be admitted by every one who has read Mr. Wal- 
lace's excellent essay on this subject. It would not, for 
instance, at first occur to any one that the perfect trans- 
parency of the Medusas, or jelly-fishes, was of the highest 
service to them as a protection ; but when we are remind- 



314 SEXUAL SELECTION. [Part TL 

ed by Hackel that not only the medusae hut many float- 
ing mollusca, crustaceans, and even small oceanic fishes 
partake of this same glass-like structure, we can hardly 
doubt that they thus escape the notice of pelagic birds and 
other enemies. 

Notwithstanding pur ignorance how far color in many 
cases serves as a protection, the most probable view in re- 
gard to the splendid tints of many of the lowest animals 
seems to be that their colors are the direct result either 
of the chemical nature or the minute structure of their 
tissues, independently of any benefit thus derived. Hard- 
ly any color is finer than that of arterial blood ; but there 
is no reason to suppose that the color of the blood is in 
itself any advantage ; and though it adds to the beauty 
of the maiden's cheek, no one will pretend that it has been 
acquired for this purpose. So again with many animals, 
especially the lower ones, the bile is richly colored ; thus 
the extreme beauty of the Eolidse (naked sea-slugs) is 
chiefly due, as I am informed by Mr. Hancock, to the 
biliary glands seen through the translucent integuments ; 
this beauty being probably of no service to these animals. 
The tints of the decaying leaves in an American forest are 
described by every one as gorgeous ; yet no one supposes 
that these tints are of the least advantage to the trees. 
Bearing in mind how many substances closely analogous 
to natural organic compounds have been recently formed 
by chemists, and which exhibit the most splendid colors, 
it would have been a strange fact if substances similarly 
colored had not often originated, independently of any 
useful end being thus gained, in the complex laboratory 
of living organisms. 

The sub-kingdom of the Mollusca. — Throughout this 
great division (taken in its largest acceptation) of the 
animal kingdom, secondary sexual characters, such as we 



Chap. IX.] MOLLUSRS. 315 

are here considering, never, as far as I can discover, occur. 
Nor could they be expected in the three lowest classes, 
namely, in the Ascidians, Polyzoa, and Brachiopods (con- 
stituting the Molluscoida of Huxley), for most of these 
animals are permanently affixed to a support or have their 
sexes united in the same individual. In the Lamellibran- 
chiata, or bivalve shells, hermaphroditism is not rare. In 
the next higher class of the Gasteropoda, or marine uni- 
valve shells, the sexes are either united or separate. But 
in this latter case the males never possess special organs 
for finding, securing, or charming the females, or for fight- 
ing with other males. The sole external difference be- 
tween the sexes consists, as I am informed by Mr. Gwyn 
Jeffreys, in the shell sometimes differing a little in form ; 
for instance, the shell of the male periwinkle {Littorlna 
littorea) is narrower and has a more elongated spire than 
that of the female. But differences of this nature, it may 
be presumed, are directly connected with the act of repro- 
duction or with the development of the ova. 

The Gasteropoda, though capable of locomotion and 
furnished with imperfect eyes, do not appear to be en- 
dowed with sufficient mental powers for the members of 
the same sex to struggle together in rivalry, and thus to 
acquire secondary sexual characters. Nevertheless with 
the pulmoniferous gasteropods, or land-snails, the pairing 
is preceded by courtship ; for these animals, though her- 
maphrodites, are compelled by their structure to pair to- 
gether. Agassiz remarks, 1 " Quiconque a eu l'occasion 
d'observer les amours des limacons, ne saurait mettre en 
doute la seduction deployee dans les mouvements et les 
allures qui preparent et accomplissent le double embrasse- 
ment de ces hermaphrodites." These animals appear also 
susceptible of some degree of permanent attachment : an 
accurate observer, Mr. Lonsdale, informs me that he placed 

1 'De l'Espece et de la Class.' etc., 1869, p. 106. 



316 SEXUAL SELECTION. [Part II. 

a pair of land-shells {Helix pomatia), one of which was 
weakly, into a small and ill-provided garden. After a 
short time the strong and healthy individual disappeared, 
and was traced by its track of slime over a wall into an 
adjoining well-stocked garden. Mr. Lonsdale concluded 
that it had deserted its sickly mate ; but after an absence 
of twenty-four hours it returned, and apparently commu- 
nicated the result of its successful exploration, for both 
then started along the same track and disappeared over 
the wall. 

Even in the highest class of the Mollusca, namely, the 
Cephalopoda or cuttle-fishes, in which the sexes are sepa- 
rate, secondary sexual characters of the kind which we 
are here considering do not, as far as I can discover, oc- 
cur. This is a surprising circumstance, as these animals 
possess highly-developed sense-organs and have consider- 
able mental powers, as will be admitted by every one 
who has watched their artful endeavors to escape from an 
enemy. 5 ! Certain Cephalopoda, however, are characterized 
by one extraordinary sexual character, namely, that the 
male element collects within one of the arms or tentacles, 
which is then cast off, and, clinging by its sucking-disks 
to the female, lives for a time an independent life. So 
completely does the cast-off arm resemble a separate ani- 
mal, that it was described by Cuvier as a parasitic worm 
under the name of Hectocotyle. But this marvellous 
structure may be classed as a primary rather than as a 
secondary sexual character. 

Although with the Mollusca sexual selection does not 
6eem to have come into play, yet many uniyalve and 
bivalve shells, such as volutes, cones, scallops, etc., are 
beautifully colored and shaped. The colors do not appear 
in most cases to be of any use as a protection ; they are 

3 See, for instance, the account which I have given in my ' Journal 
of Researches,' 1845, p. 7. 



Chap. IX. J MOLLUSKS AND ANNELIDS. 317 

probably the direct result, as in the lowest classes, of the 
nature of the tissues ; the patterns and the sculpture of the 
shell depending on its manner of growth. The amount 
of light seems to a certain extent to be influential ; for 
although, as repeatedly stated by Mr. Gwyn Jeffreys, 
the shells of some species living at a profound depth 
are brightly colored, yet we generally see the lower sur- 
faces and the parts covered by the mantle less highly 
colored than the upper and exposed surfaces. 9 In some 
cases, as with shells living among corals or brightly-tinted 
sea-weeds, the bright colors may serve as a protection. 
But many of the nudibranch mollusca, or sea-slugs, are 
as beautifully colored as any shells, as may be seen in 
Messrs. Alder and Hancock's magnificent work ; and from 
information kindly given me by Mr. Hancock, it is ex- 
tremely doubtful whether these colors usually serve as a 
protection. With some species this may be the case, as 
with one which lives on the green leaves of alga?, and is 
itself bright green. But many brightly-colored, white or 
otherwise conspicuous species, do not seek concealment ; 
while again some equally conspicuous species, as well as 
other dull-colored kinds, live under stones and in dark re- 
cesses. So that, with these nudibranch mollusks, color 
apparently does not stand in any close relation to the na- 
ture of the places which they inhabit. 

These naked sea-slugs are hermaphrodites, yet they 
pair together, as do land-snails, many of which have ex- 
tremely pretty shells. It is conceivable that two hermaph- 
rodites, attracted by each other's greater beauty, might 
unite and leave offspring which would inherit their par- 
ents' greater beauty. But with such lowly-organized 

8 I have given (' Geolog. Observations on Volcanic Islands,' 1844, p. 
63) a curious instance of the influence of light on the colors of a fron- 
descent incrustation, deposited by the surf on the coast-rocks of Ascen. 
eion, and formed by the solution of triturated sea-shells. 



318 SEXUAL SELECTION. [Part II. 

creatures this is extremely improbable. Nor is it at all 
obvious how the offspring from the more beautiful pairs 
of hermaphrodites would have any advantage, so as to in- 
crease in numbers, over the offspring of the less beautiful, 
unless indeed vigor and beauty generally coincided. We 
have not here a number of males becoming mature before 
the females, and the more beautiful ones selected by the 
more vigorous females. If, indeed, brilliant colors were 
beneficial to an hermaphrodite animal in relation to its 
general habits of life, the more brightly-tinted individuals 
would succeed best and would increase in number ; but 
this would be a case of natural and not of sexual selection. 

/Sub-kingdom of the Vermes or Annulosa : Class, An- 
nelida (or Sea-worms). — In this class, although the sexes 
(when separate) sometimes differ from each other in char- 
acters of such importance that they have been placed un- 
der distinct genera or even families, yet the differences do 
not seem of the kind which can be safely attributed to 
sexual selection. These animals, like those in the joreced- 
ing classes, apparently stand too low in the scale for the 
individuals of either sex to exert any choice in selecting 
a partner, or for the individuals of the same sex to strug- 
gle together in rivalry. 

Sub-kingdom of the Arthropoda : Class, Crustacea. — 
In this great class we first meet with undoubted second- 
ary sexual characters, often developed in a remarkable 
manner. Unfortunately, the habits of crustaceans are 
very imperfectly known, and we cannot explain the uses 
of many structures peculiar to one sex. With the lower 
parasitic species the males are of small size, and they 
alone are furnished with perfect swimming-legs, antenna? 
and sense-organs ; the females being destitute of these or- 
gans, with their bodies often consisting of a mere dis- 



Chap. IX.] CRUSTACEANS. 319 

torted mass. But these extraordinary differences between 
the two sexes are no doubt related to their widely-differ- 
ent habits of life, and consequently do not concern us. 
In various crustaceans, belonging to distinct families, the 
anterior antennae are furnished with peculiar thread-like 
bodies, which are believed to act as smelling-organs, and 
these are much more numerous in the males than in the 
females. As the males, without any unusual development 
of their olfactory organs, would almost certainly be able 
sooner or later to find the females, the increased number 
of the smelling - threads has probably been acquired 
through sexual selection, by the better provided males 
having been the most successful in finding partners and 
in leaving offspring. Fritz Mtlller has described a re- 
markable dimorphic species of Tanais, in which the male 
is represented by two distinct forms, never graduating 
into each other. In the one form the male is furnished 
with more numerous smelling-threads, and in the other 
form with more powerful and more elongated chelae or 
pincers which serve to hold the female. Fritz Muller sug- 
gests that these differences between the two male forms 
of the same species must have originated in certain indi- 
viduals having varied in the number of the smelling- 
threads, while other individuals varied in the shape and 
size of their chelae ; so that of the former, those which 
-were best able to find the female, and of the latter, those 
which were best able to hold her when found, have left 
the greater number of progeny to inherit their respective 
advantages. 4 

In some of the lower crustaceans, the right-hand an- 
terior antenna of the male differs greatly in structure 

4 ' Facts and Arguments for Darwin,' English translat. 1869, p. 20. 
See the previous discussion on the olfactory threads. Sars has described 
a somewhat analogous case (as quoted in 'Nature,' 1870, p. 455) in a 
Norwegian crustacean, the Ponioporeia affinis. 



320 



SEXUAL SELECTION. 



[Part II. 



a 



from the left-hand one, the latter resembling in its sim- 
pie tapering joints the antenna? of the female. In the male 

the modified antenna is either 
swollen in the middle or angu- 
larly bent, or converted (fig. 3) 
into an elegant, and sometimes 
wonderfully complex, prehensile 
organ. 6 It serves, as I hear from 
Sir J. Lubbock, to hold the fe- 
male, and for this same purpose 
one of the two posterior legs (b) 
on the same side of the body is 
converted into a forceps. In an- 
other family the inferior or pos- 
terior antennae are " curiously zig- 
zagged " in the males alone. 

In the higher crustaceans the 
anterior legs form a pair of chelae 
or pincers, and these are gener- 
ally larger in the male than in 
the female. In many species the 
FlG ' 3 "7from i Lu C bbock) )arwinii cnelse on tne opposite sides of the 

a. Part of right-hand anterior body are of Unequal size, the right- 

antenna of male, forming a 1 ■* •■ T . n ■* 

prehensile organ. hand one being, as I am informed 

b. Posterior pair of the thoracic -i -»«- rv o t> n 

legs of male. by Mr. L>. fepence Bate, generally, 

though not invariably, the largest.* 
This inequality is often much greater in the male than in 
the female. The two chelae also often differ in structure 
(figs. 4, 5 and 6), the smaller one resembling those of the fe- 
male. What advantage is gained by their inequality in size 

5 See Sir J. Lubbock in 'Annals, and Mag. of Nat. Hist.' vol. xi. 1853, 
pis. i. and x. ; and vol. xii. (1853) pi. vii. See also Lubbock in ' Transact. 
Ent. Soc.' vol. iv. new series, 1856-1858, p. 8. With respect to the zig- 
zagged antennae mentioned below, see Fritz Muller, ' Facts and Argu- 
ments for Darwin,' 1869, p. 40, foot-note. 




Chap. IX.] 



CRUSTACEANS. 



321 



on the opposito sides of the body, and by the inequality be- 
ing much greater in the male than in the female ; and why, 




Fig. 4.— Anterior part of bodv of Callianassa (from Milne-Edwards), showing 
the unequal and differently-constructed right and left-hand chelae of the male. 

^ N.B.— The artist by mistake has reversed the drawing, and made the left- 
hand chela the largest. 





Fig. 5. 



Fig. 6. 



Fig. 5.— Second leg of male Orchestia Tucuratinga (from Fritz Muller). 
Fig. 6— Ditto of female. 



when they are of equal size, both are often much larger 
in the male than in the female, is not known. The ehela3 
are sometimes of such length and size that they cannot 
possibly be used, as I hear from Mr. Spence Bate, for car- 
rying food to the mouth. In the males of certain fresh- 
water prawns (Paltemon) the right leg is actually longer 



322 SEXUAL SELECTION. [Part II. 

than the whole body. 6 It is probable that the great size 
of one leg with its chelee may aid the male in fighting 
with his rivals ; but this use will not account for their in- 
equality in the female on the opposite sides of the body. 
In Gelasimus, according to a statement quoted by Milne- 
Edwards, 7 the male and female live in the same burrow, 
which is worth notice, as showing that they pair, and the 
male closes the mouth of the burrow with one of its chela?, 
which is enormously developed ; so that here it indirectly 
serves as a means of defence. Their main use, however, 
probably is to seize and to secure the female, and this in 
some instances, as with Gammarus, is known to be the 
case. The sexes, however, of the common shore-crab 
( Garcinus mcenas), as Mr. Spence Bate informs me, junite 
directly after the female has moulted her hard shell, and 
when she is so soft that she would be injured if seized by 
the strong pincers of the male ; but as she is caught and 
carried about by the male previously to the act of moult- 
ing, she could then be seized with impunity. 

Fritz Miiller states that certain species of Melita are 
distinguished from all other amphipods by the females 
having " the coxal lamellae of the penultimate pair of feet 
produced into hook-like processes, of which the males lay 
hold with the hands of the first pair." The development 
of these hook-like processes probably resulted from those 
females which were the most securely held during the act 
of reproduction having left the largest number of off- 
spring. Another Brazilian amphipod (Orchestia Dar- 
winii, fig. 7) is described, by Fritz Miiller, as presenting a 
case of dimorphism, like that of Tanais ; for there are two 

6 See a paper by Mr. C. Spence Bate, with figures, in ' Proc. Zoolog. 
Soc.' 1868, p. 363 ; and on the nomenclature of the genus, ibid. p. 585. 
I am greatly indebted to Mr. Spence Bate for nearly all the above state- 
ments with respect to the chelse of the higher crustaceans. 

7 ' Hist. Nat. des Crust.' torn. ii. 1837, p. 50. 



Chap. IX.] CRUSTACEANS. 323 

male forms, which differ in the structure of their chelae. 8 
As chelae of either shape would certainly have sufficed to 
hold the female, for both are now used for this purpose, 
the two male forms probably originated, by some having 
varied in one manner and some in another ; both forms 
having derived certain special but nearly equal advan- 
tages, from their differently-shaped organs. 

It is not known that male crustaceans fight together 
for the possession of the females, but this is probable ; for 
with most animals when the male is larger than the female, 
. he seems to have acquired his greater size by having con- 
quered during many generations other males. Now, Mr. 
Spence Bate informs me that in most of the crustacean 
orders, especially in the highest or the Brachyura, the 
male is larger than the female ; the parasitic genera, how- 
ever, in which the sexes follow different habits of life, and 
most of the Entomostraca must be excepted. The chelae 
of many crustaceans are weapons well adapted for fight- 
ing. Thus a Devil-crab {Portunus puber) was seen by a 
son of Mr. Bate fighting with a Carcinus mamas, and the 
latter was soon thrown on its back, and had every limb 
torn from its body. When several males of a Brazilian 
Gelasimus, a species furnished with immense pincers, were 
placed together by Fritz Miiller in a glass vessel, they 
mutilated and killed each other. Mr. Bate put a large 
male Carcinus mamas into a pan of water, inhabited by 
a female paired with a smaller male ; the latter was soon 
dispossessed, but, as Mr. Bate adds, " if they fought, the 
victory was a bloodless one, for I saw no wounds." This 
same naturalist separated a male sand-skipper (so common 
on our sea-shores), Gammarus marinus, from its female, 
both of which were imprisoned in the same vessel with 
many individuals of the same species. The female, being 
thus divorced, joined her comrades. After an interval the 

8 Fritz MUller, ' Facts and Arguments for Darwin,' 1869, pp. 25-28. 



324 



SEXUAL SELECTION. 



[Part II. 



male was again put into the same vessel and he then, after 
swimming about for a time, dashed into the crowd, and 
without any fighting at once took away his wife. This 





Fig. 7. — Orchestia Darwinii (from Fritz Miiller), showing the differently-con* 
structed chelae of the two male forms. 



fact shows that in the Amphipoda, an order low in the 
scale, the males and females recognize each other, and are 
mutually attached. 



Chap. IX.] CRUSTACEANS. 325 

The mental powers of the Crustacea are probably- 
higher than might have been expected. Any one who 
lias tried to catch one of the shore-crabs, so numerous on 
many tropical coasts, will have perceived how wary and 
alert they are. There is a large crab (JBirgus latro), found 
on coral islands, which makes at the bottom of a deep 
burrow a thick bed of the picked fibres of the cocoa-nut. 
It feeds on the fallen fruit of this tree by tearing off the 
husk, fibre by fibre ; and it always begins at that end 
where the three eye-like depressions are situated. It then 
breaks through one of these eyes by hammering with its 
heavy front pincers, and, turning round, extracts the al- 
buminous core with its narrow posterior pincers. But these 
actions are probably instinctive, so that they would be 
performed as well by a young as by an old animal. The 
following case, however, can hardly be so considered : A 
trustworthy naturalist, Mr. Gardner, 9 while watching a 
shore-crab (Gelasimus) making its burrow, threw some 
shells toward the hole. One rolled in, and three other 
shells remained within a few inches of the mouth. In 
about five minutes the crab brought out the shell which 
had fallen in, and carried it away to the distance of a 
foot ; it then saw the three other shells lying near, and 
evidently thinking that they might likewise roll in, carried 
them to the spot where it had laid the first. It would, I 
think, be diflicult to distinguish this act from one per- 
formed by man by the aid of reason. 

With respect to color which so often differs in the 
two sexes of animals belonging to the higher classes, Mr. 
Spence Bate does not know of any well-marked instances 
with our British crustaceans. In some cases, however, 
the male and female differ somewhat in tint, but Mr. Bate 

9 ' Travels in the Interior of Brazil,' 1846, p. 111. I have given, in 
my ' Journal of Researches,' p. 463, an account of the habits of the 
Birgos. 



326 SEXUAL SELECTION. [Part II. 

thinks not more than may be accounted for by their dif- 
ferent habits of life, such as by the male wandering 
more about and being thus more exposed to the light. 
In a curious Bornean crab, which inhabits sponges, Mr. 
Bate could always distinguish the sexes by the male not 
having the epidermis so much rubbed off. Dr. Power 
tried to distinguish by color the sexes of the species 
which inhabit the Mauritius, but always failed, except 
with one species of Squilla, proably the S. stylifera, the 
male of which is described as being " of a beautiful blu- 
ish-green," with some of the appendages cherry-red, while 
the female is clouded with brown and gray, "with the 
red about her much less vivid than in the male." 10 In this 
case, we may suspect the agency of sexual selection. With 
Saphirina (an oceanic genus of Entomostraca, and there- 
fore low in the scale) the males are furnished with minute 
shields or cell-like bodies, which exhibit beautiful chan- 
ging colors ; these being absent in the females, and in the 
case of one species in both sexes. 11 It would, however, be 
extremely rash to conclude that these curious organs serve 
merely to attract the females. In the female of a Brazil- 
ian species of Gelasimus, the whole body, as I am informed 
by Fritz Mtiller, is of a nearly uniform grayish-brown. 
In the male the posterior part of the cephalo-thorax is 
pure white, with the anterior part of a rich green, shading 
into dark brown ; and it is remarkable that these colors 
are liable to change in the course of a few minutes — the 
white becoming dirty-gray or even black, the green " los- 
ing much of its brilliancy." The males apparently are 
much more numerous than the females. It deserves es- 
pecial notice that they do not acquire their bright colors 
until they become mature. They differ also from the fe- 

10 Mr. Ch. Fraser, in 'Proc. Zoolog. Soc.' 1869, p. 3. I am indebted 
to Mr. Bate for the statement from Dr. Power. 

11 Claus, 'Die freilebenden Copepoden,' 1863, s. 35. 



Chap. IX] SPIDERS. 327 

males in the larger size of their chelae. In some species 
of the genus, probably in all, the sexes pair and inhabit 
the same burrow. They are also, as we have seen, highly- 
intelligent animals. From the various considerations it 
seems highly probable that the male in this species has be- 
come gayly ornamented in order to attract or excite the 
female. 

It has just been stated that the male Gelasimus does 
not acquire his conspicuous colors until mature and nearly 
ready to breed. This seems the general rule in the whole 
class with the many remarkable differences in structure 
between the two sexes. We shall hereafter find the same 
law prevailing throughout the great sub-kingdom of the 
Vertebrata, and in all cases it is eminently distinctive of 
characters which have been acquired through sexual se- 
lection. Fritz Miiller ia gives some striking instances of 
this law ; thus the male sand-hopper (Orchestia) does not 
acquire his large claspers, which are very differently con- 
structed from those of the female, until nearly full grown ; 
while young his claspers resemble those of the female. 
Thus, again, the male Brachyscelus possesses, like all other 
amphipods, a pair of posterior antennse ; the female, and 
this is a most extraordinary circumstance, is destitute of 
them, and so is the male as long as he remains immature. 

Class, Arachnida (Spiders). — The males are often 
darker, but sometimes lighter than the females, as may be 
seen in Mr. Black wall's magnificent work. 13 In some spe- 
cies the sexes differ conspicuously from each other in col- 
or ; thus the female of Sparassus smaragdalus is dullish 
green , while the adult male has the abdomen of a fine 
yellow, with three longitudinal stripes of rich red. In 

12 ' Facts and Arguments,' etc., p. 79. 

13 ' A History of the Spiders of Great Britain,' 1861-1864. For the 
following facts, see pp. 102, 77, 88. 



328 SEXUAL SELECTION. [Part IL 

some species of Thomisus the two sexes closely resemble 
each other ; in others they differ much ; thus in T. citreus 
the legs and body of the female are pale yellow or green, 
while the front legs of the male are reddish-brown : in T. 
Jloricolens, the legs of the female are pale-green, those of 
the male being ringed in a conspicuous manner with vari- 
ous tints. Numerous analogous cases could be given in the 
genera Epeira, Nephila, Philodromus, Theridion, Liny- 
phia, etc. It is often difficult to say which of the two 
sexes departs most from the ordinary coloration of the 
genus to which the species belong; but Mr. Blackwall 
thinks that, as a general rule, it is the male. Both sexes 
while young, as I am informed by the same author, usu- 
ally resemble each other ; and both often undergo great 
changes in color during their successive moults before ar- 
riving at maturity. In other cases the male alone appears 
to change color. Thus the male of the above-mentioned 
brightly-colored Sparassus at first resembles the female 
and acquires his peculiar tints only when nearly adult. 
Spiders are possessed of acute senses, and exhibit much 
intelligence. The females often show, as is well known, 
the strongest affection for their eggs, which they carry 
about enveloped in a silken web. On the whole, it ap- 
pears probable that well-marked differences in color be- 
tween the sexes have generally resulted from sexual se- 
lection, either on the male or female side. But doubts 
may be entertained on this head from the extreme varia- 
bility in color of some, species, for instance, of Theridion 
lineatum, the sexes of which differ when adult ; this great 
variability indicates that their colors have not been sub- 
jected to any form of selection. 

Mr. Blackwall does not remember to have seen the 
males of any species fighting together for the possession 
of the female. Nor, judging from analogy, is this proba- 
ble ; for the males are generally much smaller than the 



Chap. IX.] SPIDERS. 329 

females, sometimes to an extraordinary degree. 14 Had 
the males been in the habit of fighting together, they 
would, it is probable, have gradually acquired greater 
size and strength. Mr. Black-wall has sometimes seen 
two or more males on the same web with a single female ; 
but their courtship is too tedious and prolonged an affair 
to be easily observed. The male is extremely cautious in 
making his advances, as the female carries her coyness to 
a dangerous pitch. De Geer saw a male that " in the 
midst of his preparatory caresses was seized by the object 
of his attentions, enveloped by her in a web and then de- 
voured, a sight which, as he adds, filled him with horror 
and indignation." 16 

Westring has made the interesting discovery that the 
males of several species of TherMion 16 have the power of 
making a stridulating sound (like that made by many 
beetles and other insects, but feebler), while the females 
are quite mute. The apparatus consists of a serrated ridge 
at the base of the abdomen, against which the hard hinder 
part of the thorax is rubbed ; and of this structure not a 
trace could be detected in the females. From the analogy 
of the Orthoptera and Homoptera, to be described in the 
next chapter, we may feel almost sure that the stridulation 
serves, as Westring remarks, either to call or to excite 

14 Aug. Vinson (' Araneides des lies de la Reunion,' pi. vi. figs. 1 and 
2) gives a good instance of the small sfze of the male Epeira nigra. In 
this species, as I may add, the male is testaceous and the female black 
with legs banded with red. Other even more striking cases of inequality 
in size between the sexes have been recorded (' Quarterly Journal of 
Science,' 1868, July, p. 429); but I have not seen the original accounts. 

15 Kirby and Spence, ' Introduction to Entomology,' vol. i. 1818, p. 
280. 

16 Theridion (Asagena, Sund.) serratipes, 4-punctatum et guttatum ; 
see Westring, in Kroyer, 'Naturhist. Tidskrift,' vol. iv. 1842-1843, p. 
349 ; and vol. ii. 1846-1849, p. 342. See, also, for other species, ' Ara- 
nese Svecicae,' p. 184. 

15 



> 
830 SEXUAL SELECTION. [Part II. 

the female ; and this is the first case in the ascending scale 
of the animal kingdom, known to me, of sounds emitted 
for this purpose. 

Class, Myriapoda. — In neither of the two orders in 
this class, including the millipedes and centipedes, can I 
find any well-marked instances of sexual differences such 
as more particularly concern us. In Glomeris limbata, 
however., and perhaps in some few other species, the males 
differ slightly in color from the females ; but this Glomeris 
is a highly-variable species. In the males of the Diplo- 
poda, the .legs belonging to one of the anterior segments 
of the body, or to the posterior segment, are modified into 
prehensile hooks which serve to secure the female. In 
some species of lulus the tarsi of the male are furnished 
with membranous suckers for the same purpose. It is a 
much more unusual circumstance, as we shall see when we 
treat of Insects, that it is the female in Lithobius which is 
furnished with prehensile appendages at the extremity of 
the body for holding the male. 17 

17 Walckenaer et P. Gervais, ' Hist. Nat. des Insectes ; Apteres, torn. 
iv. 1847, pp. 11, 19, 68. 



Chap. X.) INSECTS. 381 



CHAPTER X. 

• SECONDARY SEXUAL CHARACTERS OF INSECTS. 

Diversified Structures possessed "by the Males for seizing the Females. — 
Differences "between the Sexes, of which the Meaning is not under- 
stood. — Difference in Size between the Sexes. — Thysanura. — Diptera. 
— Hemiptera. — Homoptera, Musical Powers possessed by the Males 
alone. — Orthoptera, Musical Instruments of the Males, much diversi- 
fied in Structure ; Pugnacity ; Colors. — Neuroptera, Sexual Differences 
in Color. — Hymenoptera, Pugnacity and Colors. — Cojeoptera, Colors ; 
furnished with Great Horns, apparently as an Ornament; Battles; 
Stridulating Organs generally common to Both Sexes. 

In the immense class of insects the sexes sometimes 
differ in their organs for locomotion, and often in their 
sense-organs, as in the pectinated and beautifully plumose 
antennae of the males of many species. In one of the 
Ephemera?, namely Chloeon, the male has great pillared 
eyes, of which the female is entirely destitute. 1 The ocelli 
are absent in the females of certain other insects, as in the 
Mutillida?, which are likewise destitute of wings. But we 
are chiefly concerned with structures by which one male is 
enabled to conquer another, either in battle or courtship, 
through his strength, pugnacity, ornaments, or music. 
The innumerable contrivances, therefore, by which the 
male is able to seize the female, may be briefly passed 
over. Besides the complex structures at the apex of the 

* ! Sir J. Lubbock, ' Transact. Linnean Soc.' vol. xxv. 1866, p. 484. 
With respect to the Mutillidae see Westwood, l Mod. Class, of Insects,' 
vol. ii. p. 213. 



P32 SEXUAL SELECTION. [Part II. 

abdomen, which ought perhaps to be ranked as primary 
organs, 2 "it is astonishing," as Mr. B. D. Walsh 3 has re- 
marked, "how many different organs are. worked in by 
Nature, for the seemingly insignificant object of enabling 
the male to grasp the female firmly." The mandibles or 
jaws are sometimes used for this purpose; thus the male 
Corydalis cornutus (a neuropterous insect in some degree 
allied to the Dragon-flies, etc.) has immense curved jaws, 
many times longer than those of the female ; and they are 
smooth instead of being toothed, by which means he is 
enabled to seize her without injury. 4 One of the stag- 
beetles of North America (Lucanus elaphus) uses his jaws, 
which are much larger than those of the female, for the 
same purpose, but probably likewise, for fighting. In one 
of the sand-wasps (Ammophila) the jaws in the two sexes 
are closely alike, but are used for widely-different pur- 
poses ; the males, as Prof. Westwood observes, " are ex- 
ceedingly ardent, seizing their partners round the neck 
with their sickle-shaped jaws;" 6 while the females use 

2 These organs in the male often differ in closely-allied species, and 
afford excellent specific characters. But their importance under a func- 
tional point of view, as Mr. R. MacLachlan has remarked to me, has 
probably been overrated. It has been suggested, that slight differences 
m these organs would suffice' to prevent the intercrossing of well-marked 
varieties or incipient species, and would thus aid in their development. 
That this can hardly be the case, we may infer from the many recorded 
eases (see, for instance, Bronn, 'Geschichte der Natur,' B. ii. 1843, s. 
164; and Westwood, 'Transact. Ent. Soc' vol. iii. 1842, p. 195) of dis- 
tinct species having been observed in union. Mr. MacLachlan informs 
me (vide 'Stett. Ent. Zeitung,' 1867, s. 155) that when several species of 
Phryganidae, which present strongly-pronounced differences of this kind, 
were confined together by Dr. Aug. Meyer, they coupled, and one pair 
produced fertile ova. . 

3 ' The Practical Entomologist,' Philadelphia, vol. ii. May, 1867, p. 88. 

4 Mr. Walsh, ibid. p. 107. # 

5 ' Modern Classification of Insects,' vol. ii. 1840, pp. 206, 205. Mr. 
Walsh, who called my attention to this double use of the jaws, says that 
he has repeatedly observed this fact. 



Chap. X.] 



INSECTS. 



333 




these organs for burrowing in sand-banks and making 
their nests. 

The tarsi of the front-legs are dilated in many male 
beetles, or are furnished with broad cushions of hairs; 
and in many genera of water-beetles they are armed with 
a round flat sucker, so that the male may adhere to the 
slippery body of the female. 
It is a much more unusual cir- 
cumstance that the females of 
some water-beetles (Dytiscus) 
have their elytra deeply 
grooved, and in Acilius sul- 
catus thickly set with hairs, 
as an aid to the male. The 
females of some other water- 
beetles (Hydroporus) have 
their elytra punctured for the 
same object. 6 In the male of 
Crabro wibrarhis (fig. 8), it is 
the tibia which is dilated into 
a broad horny plate, with mi- 
nute membraneous dots, giv- 
ing to it a singular appearance 
like that of a riddle. 7 In the 
male of Penthe (a genus of 
beetles) a few of the middle joints of the antennae are 
dilated and furnished on the inferior surface with cushions 
of hair, exactly like those on the tarsi of the Carabidoe, 

6 We have here a curious and inexplicable case of dimorphisrh, for 
some of the females of four European species of Dytiscus, and of certain 
species of Hydroporus, have their elytra smooth ; and no intermediate 
gradations between sulcated or punctured and quite smooth elytra have 
been observed. See Dr. H. Schaum, as quoted in the ' Zoologist,' vol. 
v.-vi. 184'7-'48, p. 1896. Also Kirby and Spence, 'Introduction to En- 
tomology,' vol. iii. 1826, p. 305. 

7 Westwood, * Modern Class.' vol. ii. p. 193. The following statement 




Fig. 8. — Crabro cribrarius. Upper 
figure, mae ; lower figure, female. 



334 



SEXUAL SELECTION, 



[Part II. 




"and obviously for the same end." In male dragon-flies, 
" the appendages at the tip of the tail are modified in an 
almost infinite variety of curious patterns 
to enable them to embrace the neck of the 
female-" Lastly, in the males of many in- 
sects, the legs are furnished with peculiar 
spines, knobs, or spurs ; or the whole leg is 
bowed or thickened, but this is by no means 
invariably a sexual character ; or one pair, 
or all three pairs are elongated, sometimes 
to an extravagant length. 8 

In all the orders, the sexes of many 
species present differences, of which ' the 
meaning is not understood. One curious 
case is that of a beetle (fig. 9), the male of 
which has the left mandible much enlarged ; 
so that the mouth is greatly distorted. In 
another Carabidous beetle, the Eurygna- 
thus, 9 we have the unique case, as far as 
known to Mr. Wollaston, of the head of the 
female being much broader and larger, 
though in a variable degree, than that of 
the male. Any number of such cases could 
be given. They abound in the Lepidoptera : 
one of the most extraordinary is that cer- 
tain male butterflies have their fore-legs 

Fig 9 _ Taphro- more or l ess atrophied, with the tibise and 
deres distortus tarsi reduced to mere rudimentary knobs. 

(much enlarged). J 

Upper figure, The win^s, also, in the two sexes often differ 

male; lower fig- & > > 

ure, female. j n neuration, 10 and sometimes considerably 

about Pcnthe, and others in inverted commas, are taken from Mr. Walsh, 
1 Practical Entomologist,' Philadelphia, vol. ii. p. 88. 

8 Kirby and Spence, ' Introduct.' etc., vol. iii. pp. 332-336. 

9 'Insecta Maderensia,' 1854, p. 20. 

10 E. Doubleday, « Annals and Mag. of Nat. Hist.' vol. i. 1848, p. 379. 




Chap. X-l INSECTS. . 335 

in outline, as in the Aricoris epitus, which was shown to 
me in the British Museum by Mr. A. Butler. The males 
of certain South American butterflies have tufts of hair on 
the margins of the wings, and horny excrescences on the 
disks of the posterior pair. 11 In several British butterflies, 
the males alone, as shown by Mr. TVonfor, are in parts 
clothed with peculiar scales. 

The purpose of the luminosity in the female glow- 
worm is likewise not understood ; for it is very doubtful 
whether the primary use of the light is to guide the male 
to the female. It is no serious objection to this latter be- 
lief that the males emit a feeble light ; for secondary sexu- 
al characters proper to one sex are often developed in a 
slight degree in the other sex. It is a more valid objection 
that the larvae shine, and in some species brilliantly : Fritz 
Miiller informs me that the most luminous insect which he 
ever beheld in Brazil was the larva of some beetle. Both 
sexes of certain luminous species of Elater emit light. 
Kirby and Spence suspect that the phosphorescence serves 
to frighten and drive away enemies. 

- 

Difference in Size between the Sexes. — "With insects of 
all kinds the males are commonly smaller than the fe- 
males ; 12 and this difference can often be detected even in 
the larval state. So considerable is the difference between 
the male and female cocoons of the silk-moth (JBombyx 
mori), that in France they are separated by a particular 
mode of weighing:. 13 In the lower classes of the animal 

I may add that the wings in certain Hymenoptera (see Shuckard, ' Fosso 
rial Hymenop.' 1837, pp. 39-43) differ in neuration according to sex. 

11 H. W. Bates, in 'Journal of Proc. Linn. Soc' vol. vi. 1862, p. 74. 
Mr. Wonfor's observations are quoted in ' Popular Science Review,' 1868, 
p. 343. 

11 Kirby and Spence, ' Introduction to Entomology,' vol. iii. p. 299. 

' 3 Robinet, 'Vers a Sole,' 1848, p. 207. 



336 SEXUAL SELECTION. [Pakt II. 

kingdom, the greater size of the females seems generally 
to depend on their developing an enormous number of ova ; 
and this may to a certain extent hold good with insects. 
But Dr. Wallace has suggested a much more probable ex- 
planation. He finds, after carefully attending to the de- 
velopment of the caterpillars of JBombyx cynthia and 
yama-mai, and especially of some dwarfed caterpillars 
reared from a second brood on unnatural food, " that in 
proportion as the individual moth is finer, so is the time 
required for its metamorphosis longer ; and for this reason 
the female, which is the larger and heavier insect, from 
having to carry her numerous eggs, will be preceded by 
the male, which is smaller and has less to mature." 14 Now, 
as most insects are short-lived, and as they are exposed to 
many dangers, it would manifestly be advantageous to the 
female to be impregnated as soon as possible. This end 
would be gained by the males being first matured in large 
numbers ready for the advent of the females; and this 
again would naturally follow, as Mr. A. R. Wallace has 
remarked," through natural selection ; for the smaller 
males would be first matured, and thus would procreate a 
large number of offspring which would inherit the reduced 
size of their male parents, while the larger males from be- 
ing matured later would leave fewer offspring. 

There are, however, exceptions to the rule of male in- 
sects being smaller than the females ; and some of these 
exceptions are intelligible. Size and strength would be 
an advantage to the males, which fight for the possession 
of the female; and in these cases the males, as with the 
stag-beetle (Lucanus), are larger than the females. There 
are, however, other beetles which are not known to fight 
together, of which the males exceed the females in size • 
and the meaning of this fact is not known ; but in some 

14 ' Transact. Ent. Soc.' 3d series, vol. v. p. 486. 
16 'Journal of Proc. Ent. Soc.' Feb. 4, 1867, p. lxxi. 



Chap. X.] INSECTS. 337 

of these cases, as with the huge Dynastes and Megasoma, 
we can at least see that there would be no necessity for 
the males to be smaller than the females, in order to be 
matured before them, for these beetles are not short-lived, 
and there would be ample time for the pairing of the sexes. 
So, again, male dragon-flies (Libellulidse) are sometimes 
sensibly larger, and never smaller, than the females : 16 and 
they do not, as Mr. MacLachlan believes, generally pair 
with the females, until a week or fortnight has elapsed, and 
until they have assumed their proper masculine colors." 
But the most curious case, showing on what complex and 
easily-overlooked relations so trifling a character as a 
difference in size between the sexes may depend, is that of 
the aculeate Hymenoptera ; for Mr. F. Smith informs me 
that throughout nearly the whole of this large group the 
males, in accordance with the general rule, are smaller 
than the females and emerge about a week before them ; 
but among the Bees, the males of Apis mettifica, Anthi- 
dium manicatum and Anthophora acervorum, and among 
the Fossores, the males of the Methoca ichneumonides, 
are larger than the females. The explanation of this 
anomaly is that a marriage-flight is absolutely necessary 
with these species, and the males require great strength 
and size in order to carry the females through the air. In- 
creased size has here been acquired in opposition to the 
usual relation between size and the period of development, 
for the males, though larger, emerge before the smaller fe- 
males. 

We will now review the several Orders, selecting such 
facts as more particularly concern us. The Lepidoptera 
(Butterflies and Moths) will be retained for a separate 
chapter. 

16 For this and other statements on the size of the sexes, see Kirby 
and Spence, ibid, vol iii. p. 300 ; on the duration of life in insects, see 
p. 344. 



338 SEXUAL SELECTION. [Part Lu 

Order, Thysanura. — The members of this Order are 
lowly organized for their class. They are wingless, dull- 
colored, minute insects, with ugly, almost misshapen heads 
and bodies. The sexes do not differ ; but they offer one 
interesting fact, by showing that the males pay sedulous 
court to their females even low down in the animal scale. 
Sir J. Lubbock, 17 in describing the Smynthurus luteus, 
says : " It is very amusing to see these little creatures co- 
quetting together. The male, which is much smaller than 
the female, runs round her, and they butt one another, 
standing face to face, and moving backward and forward 
like two playful lambs. Then the female pretends to run 
away and the male runs after her with a queer appearance 
of anger, gets in front and stands facing her again ; then 
she turns coyly round, but he, quicker and more active, 
scuttles round too, and seems to whip her with his antennae ; 
then for a bit they stand face to face, play with their an- 
tennae, and seem to be all in all to one another." 

Order, Diptera (Flies). — The sexes differ little in color. 
The greatest difference, known to Mr. F. Walker, is in the 
genus Bibio, in which the males are blackish or quite 
black, and the females obscure brownish orange. The 
genus Elaphomyia, discovered by Mr. Wallace 18 in New 
Guinea, is highly remarkable, as the males are furnished 
with horns, of which the females are quite destitute. The 
horns spring from beneath the eyes, and curiously resemble 
those of stags, being either branched or palmated. They 
equal in length the whole of the body in one of the spe- 
cies. They might be thought to serve for fighting, but, as 
in one species they are of a beautiful pink-color, edged 
with black, with a pale central stripe, and as these insects 
have altogether a very elegant appearance, it is perhaps 

11 c Transact. Lmnean Soc' vol. xxvi. 1868, p. 296. 
1 The Malay Archipelago,' vol. ii. 1869, p. 313. 



Chap. X.] DIPTERA AND HEMIPTERA. 339 

more probable that the horns serve as ornaments. That 
the males of some Diptera fight together is certain ; for 
Prof. Westwood 19 has several times seen this with some 
species of Tipula or Harry-long-legs. Many observers 
believe that when gnats (Culicidse) dance in the air in a 
body, alternately rising and falling, the males are courting 
the females. The mental faculties of the Diptera are 
probably fairly well developed, for their nervous system 
is more highly developed than in most other Orders of in- 
sects. 20 

Order, Hemiptera (Field-Bugs). — Mr. J. W. Douglas, 
who has particularly attended to the British species, has 
kindly given me an account of their sexual differences. 
The males of some species are furnished with wings, 
while the females are wingless ; the sexes differ in the 
form of the body and elytra ; in the second joints of their 
antennae and in their tarsi ; but, as the signification of 
these differences- is quite unknown, they may be here 
passed over. The females . are generally larger and more 
robust than the males. With British, and, as far as Mr. 
Douglas knows, with exotic species, the sexes do not com- 
monly differ much in color ; but in about six British spe- 
cies the male is considerably darker than the female, and 
in about four other species the female is darker than the 
male. Both sexes of some species are beautifully marked 
with vermilion and black. It is doubtful whether these 
colors serve as a protection. If in any species the males 
had differed from the females in an analogous manner, we 
might hav.e been justified in attributing such conspicuous 
colors to sexual selection with transference to both sexes. 

Some species of ReduvidaB make a stridulating noise ; 

19 'Modem Classification of Insects,' vol. ii. 1840, p. 526. 
80 See Mr. B. T. Lowne's very interesting work, ' On the Anatomy of 
the Blow-Fly, Musca vomitoria,' 1870, p. 14. 



340 SEXUAL SELECTION. [Part IL 

and, in the case of Pirates stridulus, this is said 21 to he 
effected by the movement of the neck within the pro- 
thoracic cavity. According to Westring, Reduvius per- 
sonatus also stridulates. But I have not been able to 
learn any particulars about these insects ; nor have I any 
reason to suppose that they differ sexually in this respect. 

Order, Homoptera. — Every one who has wandered in 
a tropical forest must have been astonished at the din 
made by the male Cicadas. The females are mute ; as the 
Grecian poet Xenarchus says, " Happy the Cicadas live, 
since they all have voiceless wives." The noise thus made 
could be plainly heard on board the "Beagle," when 
anchored at a quarter of a mile from the shore of Brazil ; 
and Captain Hancock says it can be heard at the distance 
of a mile. The Greeks formerly kept, and the Chinese 
now keep, these insects in cages for the sake of their song, 
so that it must be pleasing to the ears. of some- men." 
The Cicadidas usually sing during the day ; while the 
Fulgoridse appear to be night-songsters. The sound, ac- 
cording to Landois, 23 who has recently studied the subject, 
is produced by the vibration of the lips of the spiracles, 
which are set into motion by a current of air emitted from 
,the tracheae. It is increased by a wonderfully complex 
resounding apparatus, consisting of two cavities covered 
by scales. Hence the sound may truly be called a voice. 
In the female the musical apparatus is present^ but very 
much less developed than in the male, and is never used 
for producing sound. 

With respect to the object of the music, Dr. Hartman, 

31 Westwood, ' Modern Class, of Insects,' vol. ii. p. 473. 

22 These particulars are taken from Westwood's ' Modern Class, of 
Insects,' vol. ii. 1840, p. 422. See, also, on the Fulgoridse, Kirby and 
Spence, ' Introduct.' vol. ii. p. 401. 

23 « Zeitschrift fur wissenschaft. Zoolog.' B. xvii. 1867, 8. 152-158. 



Chap. X.] HOMOPTERA. 341 

in speaking of the cicada septemdeeim of the United 
States, says : 24 " The drums are now (June 6th and 7th, 
1851) heard in all directions. This I believe to be the 
marital summons from the males. Standing in thick 
chestnut-sprouts about as high as my head, where hun- 
dreds were around me, I observed the females coming 
around the drumming males." He adds : " This season 
(August, 18G8) a dwarf pear-tree in my garden produced 
about fifty larvae of Cic. pruinosa ; and I several times 
noticed the females to alight near a male while he was ut- 
tering his clanging: notes." Fritz Muller writes to me 
from Southern Brazil that he has often listened to a musi- 
cal contest between two or three males of a Cicada, hav- 
ing a particularly loud voice, and seated at a considerable 
distance from each other. As soon as the first had fin- 
ished his song, a second immediately began ; and after he 
had concluded, another began, and so on. As there is so 
much rivalry between the males, it is probable that the 
females not only discover them by the sounds emitted, but 
that, like female birds, they are excited or allured by the 
male with the most attractive voice. 

I have not found any well-marked cases of ornamental 
differences between the sexes of the Honioptera. Mr. 
Douglas informs me that there are three British sj>ecies, 
in which the male is black or marked with black bands, 
while the females are pale-colored or obscure. 

Order, Orthoptera. — The males in the three saltatorial 
families belonging to this Order are remarkable for their 
musical powers, namely, the Achetidse or crickets, the 
Locustidae for which there is no exact equivalent name in 
English, and the Acridiidae or grasshoppers. The stridu- 
lation produced by some of the Locustidae is so loud that 

24 I am indebted to Mr. "Walsh for having sent me this extract from a 
' Journal of the Doings of Cicada septemdeeim,' by Dr. Hartman. 



342 



SEXUAL SELECTION. 



[Part II. 



it can be heard during the night at the distance of a 
mile • 25 and that made by certain species is not unmusical 
even to the human ear, so that the Indians on the Ama- 
zons keep them in wicker cages. All observers agree that 
the sounds serve either to call or excite the mute females. 
But it has been noticed 26 that the male migratory locust 
of Russia (one of the Acridiidae), while coupled with the 
female, stridulates from anger or jealousy when ap- 
proached by another male. The house-cricket when sur- 
prised at night uses its voice to warn its fellows. 27 In 
North America the Katy-did (Flatyphyllum concavum, 

one of the Locustidae) is 
described 28 as mounting 
on 'the upper branches of a 
tree, and in the evening be- 
ginning his noisy babble, 
while rival notes issue from 
the neighboring trees, and 
the groves resound with the 
call of Katy-did -she -did 
the live-long night." Mr. 
Bates, in speaking of the 
European field-cricket (one 
of the Achetidae), says: 
"The male has been ob- 

■ 

served to place itself in the 
evening at the entrance of 
its burrow, and stridulate 
until a female approaches, when the louder notes are 
succeeded by a more subdued tone, while the success- 
ful musician caresses with his antennae the mate he has 

25 1* Guilding, ' Transact. Linn. Soc.' vol. xv. p. 154. 
2,5 Koppen, as quoted in the 'Zoological Record,' for 1867, p. 460. 
27 Gilbert White, 'Nat. Hist, of Selborne,' vol. ii. 1825, p. 262. 
58 Harris, 'Insects of New England,' 1842, p. 128. 




Pig. 10.— Gryllus campestris (from Lan- 
dois). 

Eight-hand figure, under side of part of 
the wing-nervure, much magnified, 
showing the teeth, st. 

Left-hand figure, upper surface of wing- 
cover, with the projecting, smooth ner- 
vure, r, across which the teeth (st) are 
scraped. 



Chap. X.] ORTHOPTERA. 343 

won." " Dr. Scudcler was able to excite one of these in- 
sects to answer him, by rubbing on a file with a quill. 30 
In both sexes a remarkable auditory apparatus has been 
discovered by Von Siebold, situated in the front legs." 1 

In the three Families the so\mds are differently pro- 
duced. In the males of the Achetidse both wing-covers 
have the same structure ; and this in the field-cricket 
(Gryllus campestris, fig. 10) consists, as described by 
Landois, 32 of from 131 to 138 sharp, transverse ridges or 
teeth (st) on the under side of one of the nervures of the 
wing-cover. This toothed nervure is rapidly scraped 
across a projecting, smooth, hard nervure (r) on the upper 
surface of the opposite wing. First one 
wing is rubbed over the other, and then 
the movement is reversed. Both wings 
are raised a little at the same time, so 
as to increase the resonance. In some 
species the wing-covers of the males are 
furnished at the base with a talc-like 
plate. 33 I have here given a drawing (fig. 
11) of the teeth on the under side of the FlG n _ Teeth of 
nervure of another species of Gryllus, viz., ^Sticu^cfrom 

G. domesticus. Landois). 

In the Locustidas the opposite wing-covers differ in 
structure (fig. 12), and cannot, as in the last family, be in- 
differently used in a reversed manner. The left wing, 
which acts as the bow of the fiddle, lies over the right 

29 ' The Naturalist on the Amazons,' vol. i. 1863, p 252. Mr. Bates 
gives a very interesting discussion on the gradations in the musical appa- 
ratus of the three families. See also Westwood, ' Modern Class.' vol. ii. 
pp. 445, 453. 

30 « Proc. Boston Soc. of Nat. Hist.' vol. xi. April, 1868. 

31 ' Nouveau Manuel d'Anat. Comp.' (French translat.), torn. i. 1850, 
p. 567. 

32 ' Zeitschrift fur wissenschaft. Zoolog.' B. xvii. 1867, s. 117. 

33 Westwood, ' Modern Class, of Insects,' vol. i. p. 440. 




844 



SEXUAL SELECTION. 



[Part II. 



wins: which serves as the fiddle itself. One of the ner- 
vures (a) on the under surface of the former is finely ser- 
rated, and. is scraped across the prominent nervures on the 
upper surface of the opposite or right wing. In our Brit- 
ish Phasgonura viridisSima it appeared to me that the 
serrated nervure is rubbed against . the rounded hind 
corner of the opposite wing, the edge of which is thick- 
ened, colored brown, and very sharp. In the right wing, 
but not in the left, there is a little plate, as transparent as 
talc, surrounded by nervures, and called the speculum, 
In Ephippiger vitium, a member of this same family, we 
have a curious subordinate modification; for the wing- 
covers are greatly reduced in size, but " the posterior part 
of the pro-thorax is elevated into a kind of dome over the 




Fig. 12.— Chlorocoelus Tanana (from Bates), a. b. Lobes of opposite winjj-coyeis. 



Chap. X.] ORTHOPTERA. 345 

wing-covers, and which has probably the effect of increas- 
ing the sound." 34 

We thus see that the musical apparatus is more differ- 
entiated or specialized in the Locustidse, which includes, 
I believe, the most powerful performers in the Order, than 
in the Achetidse, in which both wing-covers have the 
same structure and the same function. 35 Landois, however, 
detected in one of the Locustidse, namely, in Decticus, 
a short and narrow row of small teeth, mere rudiments, on 
the inferior surface of the right wing-cover, which under- 
lies the other and is never used as the bow. I observed 
the same rudimentary structure on the under side of the 
right wing-cover in Phasgonara viridissima. Hence we 
may with confidence infer that the Locustidse are de- 
scended from a form, in which, as in the existing Ache- 
tidse, both wing-covers had serrated nervures on the under 
surface, and could be indifferently used as the bow ; but 
that in the Locustidae the two wing-covers gradually be- 
came differentiated and perfected, on the principle of the 
division of labor, the one to act exclusively as the bow 
and the other as the fiddle. By" what steps the more 
simple apparatus in the Achetidse originated, we do not 
know, but it is probable that the basal portions of the 
wing-covers overlapped each other formerly as at present, 
and that the friction of the nervures produced a grating 
sound, as I find is now the case with the wing-covers of 
the females. 36 A grating sound thus occasionally and ac- 
cidentally made by the males, if it served them ever so 
little as a love-call to the females, might readily have been 
intensified through sexual selection by fitting variations in 
the roughness of the nervures having been continually 
preserved. 

34 "Westwood, ' Modern Class, of Insects,' vol. i. p. 453. 

» Landois, ibid. s. 121, 122. 

38 Mr. Walsh also informs me that he has noticed that the female of 



346 



SEXUAL SELECTION. 



[Part II. 




In the last and third Family, namely, the AcridiMae 
or grasshoppers, the stridulation is produced in a very 
different manner, and is not so shrill, according to Dr. 
Scudder as in the preceding Families. The inner surface 
of the femur (fig. 13, r) is furnished with a longitudinal 
row of minute, elegant, lancet-shaped, elastic teeth, from 
85 to 93 in number; 37 and these are scraped across the 
sharp, projecting nervures on the wing-covers, which are 
thus made to vibrate and resound. Harris 31 says that 

when one of the males 
begins to play, he first 
"bends the shank of 
the hind-leg beneath the 
thigh, Where it is lodged 
in a furrow designed to 
receive it, and then draws 
the leg briskly up and 
down. He does not play 
both fiddles together, but 
alternately first upon one 
and then on the other." 

Fig. 13.— Hind-!egof Stenobothrus pratoram: T n mnrlv <mpr>ip<i thp hnsp 
r, the Btridu&ting rid^e ; lower figure, in man y Species tne VdhV 

Sited (from lTuSLT ridge ' much mag " of the abdomen is hol- 
lowed out into a great 
cavity which is believed to act as a resounding-board. In 
Pneumora (fig. 14), a South African genus belonging to this 
same family, we meet with a new and remarkable modifi- 
cation : in the males a small notched ridge projects ob- 
liquely from each side of the abdomen, against which the 
hind femora are rubbed. 39 As the male is furnished with 

the Platyphyllum concavum, " when captured, makes a feeble grating 
noise by shuffling her wing-covers together." 
31 Landois, ibid. s. 113. 

38 'Insects of New England,' 1842, p. 133. 

39 Westwood, ' Modern Classification,' vol. i. p. 462. 




Chap. X.] 



ORTHOPTERA. 



347 



wings, the female being wingless, it is remarkable that 
the thighs are not rubbed in the usual manner against the 
wing-covers ; but this may perhaps be accounted for by 
the unusually small size of the hind-legs. I have not been 
able to examine the inner surface of the thighs, which, 
judging from analogy, would be finely serrated. The 
species of Pneumora have been more profoundly modified 
for the sake of stridulation than any other orthopterous 
insect ; for in the male the whole body has been converted 





Fig. 14.— Pnenmora (from specimens in the British Museum). Upper figure, 

male ; lower figure, female. 



348 SEXUAL SELECTION. [Pakt II. 

into a musical instrument, being distended with air, like a 
great pellucid bladder, so as to increase the resonance. 
Mr. Trimen informs me that at the Cape of Good Hope 
these insects make a wonderful noise during the night. 

There is one exception to the rule that the females in 
these three Families are destitute of an efficient musical 
apparatus ; for both sexes of Ephippiger (Locustida?) are 
said 40 to be thus provided. This case may be compared 
with that of the reindeer, in which species alone both 
sexes possess horns. Although the female orthoptera are 
thus almost invariably mute, yet Landois 41 found rudi- 
ments of the stridulating organs on the femora of the fe- 
male AcridiidaB, and similar rudiments on the under sur- 
face of the wing-covers of the female Achetidae ; but he 
failed to find any rudiments in the females of Decticus, 
one of the Locustidae. In the Homoptera, the mute fe- 
males of Cicada have the proper musical apparatus in an 
undeveloped state ; and we shall hereafter meet, in other 
divisions of the animal kingdom, with innumerable in- 
stances of structures proper to the male being present in 
a rudimentary condition in the female. Such cases appear 
at first sight to indicate that both sexes were primordially 
constructed in the same manner, but that certain organs 
were subsequently lost by the females. It is, however, a 
more probable view, as previously explained, that the or- 
gans in question were acquired by the males and partially 
transferred to the females. 

Landois has observed another interesting fact, namely, 
that, in the females of the Acridiidse, the stridulating teeth 
on the femora remain throughout life in the same condition 
in which they first appear in both sexes during the larval 
state. In the males, on the other hand, they become 
fully developed and acquire their perfect structure at 

^•Westwood, ibid. vol. i. p. 453. 

« Landois, ibid. s. 115, 116, 120, 122. 



Chap. X.] ORTHOPTERA. 349 

the last moult, when the insect is mature and ready to 
breed. 

From the facts now given, we see that the means by 
which the males produce their sounds are extremely di- 
versified in the Orthoptera, and are altogether different 
from those employed by the Homoptera. But throughout 
the animal kingdom we incessantly find the same object 
gained by the most diversified means ; this being due to 
the whole organization undergoing in the course of ages 
multifarious changes ; and, as part after part varies, differ- 
ent variations are taken advantage of for the same gen- 
eral purpose. The diversification of the means for pro- 
ducing sound, in the three families of the Orthoptera and 
in the Homoptera, impresses the mind with the high im- 
portance of these structures to the males, for the sake of 
calling or alluring the females. We need feel no surprise 
at the amount of modification which the Orthoptera have 
undergone in this respect, as we now know, from Dr. 
Scudder's remarkable discovery, 42 that there has been 
more than ample time. This naturalist has lately found a 
fossil insect in the Devonian formation of New -Bruns- 
wick, which is furnished with " the well-known tympanum 
or stridulating apparatus of the male Locustidae." This 
insect, though in most respects related to the Neuroptera, 
appears to connect, as is so often the case with very an- 
cient forms, the two Orders of the Neuroptera and Or- 
thoptera which are now generally ranked as quite distinct. 

I have but little more to say on the Orthoptera. Some 
of the species are very pugnacious : when two male field- 
crickets (GrylZus campestris) are confined together, they 
fight till one kills the other ; and the species of Nantis are 
described as manoeuvring with their sword-like front-limbs, 
like hussars with their sabres. The Chinese keep these 

42 ' Transact. Ent. Soc.' 3d series, vol. ii. (' Journal of Proceedings,' 
p. 1 17.) 



350 SEXUAL SELECTION. [Part IL 

insects in little bamboo cages and match them like game- 
cocks. 43 "With respect to color, some exotic locusts are 
beautifully ornamented ; the posterior wings being marked 
with red, blue, and black ; but, as throughout the Order 
the two sexes rarely differ much in color, it is doubtful 
whether they owe these bright tints to sexual selection. 
Conspicuous colors may be of use to these insects as a 
protection, on the principle to be explained in the next 
chapter, by giving notice to their enemies that they are 
unpalatable. Thus it has been observed 44 that an Indian 
brightly-colored locust was invariably rejected when of- 
fered to birds and lizards. Some cases, however, of sex- 
ual differences in color in this Order are known. The 
male of an American cricket 45 is described as being as 
white as ivory, while the female varies from almost white 
to greenish yellow or dusky. Mr. "Walsh informs me 
that the adult male of Spectrum femoratum (one of 
the Phasmidse) " is of a shining brownish-yellow color ; 
the adult female being of a dull, opaque, cinereous brown ; 
the young of both sexes being green." Lastly, I may 
mention that the male of one curious kind of cricket 46 is 
furnished with "a long membranous appendage, which 
falls over the face like a veil ; " but whether this serves 
as an ornament is not known. 

Order, Neuroptera. — Little need here be said, except 
in regard to color. In the Ephemeridse the sexes often 
differ slightly in their obscure tints ; 47 but it is not prob- 

43 Westwood, c Modern Class, of Insects,' vol. i. p. 427 ; for crickets, 
p. 445. 

44 Mr. Ch. Home, in 'Proc. Ent. Soc.' May 3, 1869, p. xii. 

45 Jhe Oecanthus nivalis. Harris, ' Insects of New England,' 1842, 
p. 124. 

46 Platyblemnus : Westwood, ' Modern Class.' vol. i. p. 447. 

47 B. D. Walsh, the Pseudo-neuroptera of Illinois, in ' Proc. .Ent. Soc. 
of Philadelphia,' 1862, p. 361. 



Chap. X.] NEUROPTERA. 351 

able that the males are thus rendered attractive to the 
females. The Libellulidse or dragon-flies are ornamented 
with splendid green, blue, yellow, and vermilion metallic 
tints ; and the sexes often differ. Thus, the males of some 
of the Agrionidoe, as Prof. Westwood remarks, 48 " are of 
a rich blue with black wings, while the females are fine 
green with colorle'ss wings." But in Agrion Mamburii 
these colors are exactly reversed in the two sexes. 49 In the 
extensive North American genus of Hetserina, the males 
alone have a beautiful carmine spot at the base of each 
wing. In Anax Junius the basal part of the abdomen in 
the male is a vivid ultra-marine blue, and in the female 
grass-green. In the allied genus Gomphus, on the other 
hand, and in some other genera, the sexes differ but little 
in color. Throughout the animal kingdom, similar cases 
of the sexes of closely-allied forms either differing greatly, 
or very little, or not at all, are of frequent occurrence. 
Although with many Libellulidae there is so wide" a differ- 
ence in color between the sexes, it is often difficult to say 
which is the most brilliant ; and the ordinary coloration 
of the two sexes is exactly reversed, as we have just seen, 
in one species of Agrion. It is not probable that their 
colors in any case have been gained as a protection. As 
Mr. MacLachlan, who has closely attended to this family, 
writes to me, dragon-flies — the tyrants of the insect-world 
— are the least liable of any insect to be attacked by birds 
or other enemies. He believes that their bright colors 
serve as a sexual attraction. It deserves notice, as bearing 
on this subject, that certain dragon-flies appear to be at- 
tracted by particular colors : Mr. Patterson observed B0 that 
the species of Agrionida?, of which the males are blue, 

48 ' Modern Class.' vol. ii. p. 37. 

49 Walsh, ibid. p. 381. I am indebted to this naturalist for the follow, 
ing facts on Hetaerina, Anax, and Gomphus. 

60 'Transact. Ent. Soc' vol. i. 1836, p. lxxxL 



352 SEXUAL SELECTION. [Part 1L 

settled in numbers on the blue float of a fishing-line ; while 
two other species were attracted by shining white colors. 

It is an interesting fact, first observed by Schelver, 
that the males, in several genera belonging to two sub- 
families, when they first emerge from the pupal state are 
colored exactly like the females ; but that their bodies in 
a short time assume a conspicuous milky-blue tint, owing 
to the exudation of a kind of oil, soluble in ether and alco- 
hol. Mr. MacLachlan believes that in the male of Libel- 
licla depressa this change of color does not occur until 
nearly a fortnight* after the metamorphosis, when the sexes 
are ready to pair. 

Certain species of Neurothemis present, according to 
Brauer, 61 a curious case of dimorphism, some of the females 
having their wings netted in the usual manner; while 
other females have them " very richly netted as in the 
males of the same species." Brauer " explains the phe- 
nomenon on Darwinian principles by the supposition that 
the close netting of the veins is a secondary sexual char- 
acter in the males." This latter character is generally de- 
veloped in the males alone, but being, like every other 
masculine character, latent in the female, is occasionally 
developed in them. We have here an illustration of the 
manner in which the two sexes of many animals have 
probably come to resemble each other, namely, by varia- 
tions first appearing in the males, being preserved in 
them, and then transmitted to and developed in the fe- 
males ; but in this particular genus a complete transference 
is occasionally and abruptly effected. Mr. MacLachlan 
informs me of another case of dimorphism occurring in 
several species of Agrion in which a certain number of 
individuals are found of an orange-color, and these are in- 
variably females. This is probably a case of reversion, 
for in the true Libellulae, when the sexes differ in color, 

61 See abstract in the 'Zoological Record' for 1867, p. 450 



Chap. X.] HYMEXOPTERA. 353 

the females are always orange or yellow, so that, supposing 
Agrion to be descended from some primordial form hav- 
ing the characteristic sexual colors of the typical Libelluhe, 
it would not be surprising that a tendency to vary in this 
manner should occur in the females alone. 

Although many dragon-flies are such large, powerful, 
and fierce insects, the males have not been observed by 
Mr. MacLachlan to fight together, except, as he believes, 
in the case of some of the smaller species of Agrion. In 
another very distinct group in this Order, namely, in the 
Termites or white ants, both sexes at the time of swarm- 
ing may be seen running about, " the male after the fe- 
male, sometimes two chasing one female, and contending 
with great eagerness who shall win the prize. 1 



?5 52 



Order, Hymenoptera. — That inimitable observer M. 
Fabre, 63 in describing the habits of Cerceris, a wasp-like 
insect, remarks that " fights frequently ensue between the 
males for the possession of some particular female, who 
sits an apparently unconcerned beholder of the struggle 
for supremacy, and, when the victory is decided,, quietly 
flies away in company with the conqueror." Westwood" 
says that the males of one of the saw-flies (Tenthredinse) 
" have been found fighting together, with their mandibles 
locked." As M. Fabre speaks of the males of Cerceris 
striving to obtain a particular female, it may be well to 
bear in mind that insects belonging to this Order have the 
power of recognizing each other after long intervals of 
time, and are deeply attached. For instance, Pierre Huber, 
whose accuracy no one doubts, separated some ants, and 
when after an interval of four months they met others 

62 Kirby and Spence, 'Introduct. to Entomology,' vol. ii. 1818, p. 35. 

53 See an interesting article, " The Writings of Fabre," in ' Nat. Hist. 
Review,' April, 1862, p. 122. 

54 ' Journal of Proc. of Entomolog. Soc.' Sept. 7, 1863, p. 169. 

16 



354 SEXUAL SELECTION. [Part II. 

which had formerly belonged to the same community, 
they mutually recognized and caressed each other with 
their antennae. Had they been strangers they would have 
fought together. Again, when two communities engage 
in a battle, the ants on the same side in the general confu* 
sion sometimes attack each other, but they soon perceive 
their mistake, and the one ant soothes the other. 66 

In this order slight differences in color, according to 
sex, are common, but conspicuous differences are rare ex- 
cept in the family of Bees ; yet both sexes of certain 
groups are so brilliantly colored — for instance, in Chrysis, 
in which vermilion and metallic greens prevail — that we 
are tempted to attribute the result to sexual selection. In 
the Ichneumonidae, according to Mr. Walsh, 66 the males 
are almost universally lighter colored than the females. 
On the other hand, in the Tenthredinidse the males are 
generally darker than the females. In the Siricidae the 
sexes frequently differ : thus the male of Sirexjuvencus is 
banded with orange, while the female is dark purple ; but 
it is difficult to say which sex is the most ornamented. 
In Tremex colwmboe the female is much brighter colored 
than the male. With ants, as I am informed by Mr. F. 
Smith, the males of several species are black, the females 
being testaceous. In the family of Bees, especially in 
the solitary species, as I hear from the same distinguished 
entomologist, the sexes often differ in color. The males 
are generally the brightest, and, in Bombus as well as in 
Apathus, much more variable in color than the females. 
In Anthophora retusa the male is of a rich fulvous brown, 
while the female is quite black : so are the females of sev- 
eral species of Xylocopa, the males being bright yellow. 
In an Australian bee (Lestis bombylans), the female is of 

55 P. Huber, ' Recherches sur les Moeurs des Fourmis,' 1810, pp. 
150, 165. 

M 'Proc. Entomolog. Soc. of Philadelphia,' 1866, pp. 238, 239. 



Chap. X.] HYMEXOPTERA.— COLEOPTERA. 355 

an extremely brilliant steel-blue, sometimes tinted with 
vivid green; the male being of a bright brassy color 
clothed with rich fulvous pubescence. As in this group 
the females are provided with excellent defensive weap* 
ons in their stings, it is not probable that they have come 
to differ in color from the males for the sake of protection. 
Mutilla Europcea emits a stridulating noise ; and ac- 
cording to Goureau " both sexes have this power. He 
attributes the sound to the friction of the third and pre- 
ceding abdominal segments; and I find that these sur- 
faces are marked with very fine concentric ridges, but so 
is the projecting thoracic collar, on which the head artic- 
ulates ; and this collar, when scratched with the point of 
a needle, emits the proper sound. It is rather surprising 
that both sexes should have the power of stridulating, as 
the male is winged and the female wingless. It is notori- 
ous that Bees express certain emotions, as of anger, by the 
tone of their humming, as do some dipterous insects ; but 
I have not referred to these sounds, as they are not known 
to be in any way connected with the act of courtship. 

Order, Coleoptera (Beetles). — Many beetles are col- 
ored so as to resemble the surfaces which they habitually 
frequent. Other species are ornamented with gorgeous 
metallic tints — for instance, many Carabida?, which live 
on the ground and have the power of defending them- 
selves by an intensely acrid secretion — the splendid dia- 
mond-beetles which are protected by an extremely hard 
covering — many species of Chrysomela, such as G. cere- 
alls, a large species beautifully striped with various col- 
ors, and in Britain confined to the bare summit of Snow- 
don — and a host of other species. These splendid colors, 
which are often arranged in stripes, spots, crosses, and 
other elegant patterns, can hardly be beneficial, as a pro* 

67 Quoted by "Westwood, ' Modern Class, of Insects,' vol. ii. p. 214. 



356 SEXUAL SELECTION. [Past II. 

tection, except in the case of some flower-feeding species ; 
and we cannot believe that they are purposeless. Hence 
the suspicion arises that they serve as a sexual attrac- 
tion ; but we have no evidence on this head, for the sexes 
rarely differ in color. Blind beetles, which cannot of 
course behold each other's beauty, never exhibit, as I hear 
from Mr. Waterhouse, Jr., bright colors, though they 
often have polished coats : but the explanation of their 
obscurity may be that blind insects inhabit caves and 
other obscure stations. 

Some Longicorns, however, especially certain Prioni- 
da3, offer an exception to the common rule that the sexes 
of beetles do not differ in color. Most of these insects are 
large and splendidly colored. The males in the genus 
Pyrodes, 58 as I saw in Mr. Bates's collection, are generally 
redder but rather duller than the females, the latter being 
colored of a more or less splendid golden green. On the 
other hand, in one species the male is golden green, the 
female being richly tinted with red and purple. In the 
genus Esmeralda the sexes differ so greatly in color that 
they have been ranked as distinct species : in one species 
both are of a beautiful shining green, but the male has a 

68 Pyrodes pulcherrimus, in which the sexes differ conspicuously, has 
been described by Mr. Bates in ' Transact. Ent. Soc.' 1869, p. 50. I will 
specify the few other cases in which I have heard of a difference in color 
between the sexes of beetles. Kirby and Spence (' Introduct. to Ento- 
mology,' vol. iii. p. 301) mention a Cantharis, Meloe, Rhagium, and the 
Leptura testacea ; the male of the latter being testaceous, with a black 
thorax, and the female of a dull red all over. These two latter beetles 
belong to the Order of Longicorns. Messrs. R. Trimen and Waterhouse, 
Jr., inform me of two Lamellicorns, viz., a Peritrichia and Trichius, the 
male of the latter being more obscurely colored than the female. In 
Tillus elongatus the male is black, and the female always, as it is believed, 
of a dark-blue color with a red thorax. The male, also, of Orsodacna 
ztra, as I hear from Mr. Walsh, is black, the female (the so-called 
0. ruficollis) having a rufous thorax, 



Chap. X.] 



COLEOPTERA. 



357 



red thorax. On the whole, as far as I could judge, the 
females of those Prionidse, in which the sexes differ, are 
colored more richly than the males ; and this does not ac- 
cord with the common rule in regard to color when ac- 
quired through sexual selection. 





Fig. 15.— Chalcosoma atlas. Upper ficmre. male (reduced) ; lower figure, female 

(natural size). 



A most remarkable distinction between the sexes of 
many beetles is presented by the great horns which rise 
from the head, thorax, or clypeus of the males; and in 
some few cases from the under surface of the body. These 
horns, in the great family of the Lamellicorns, resemble 
those of various quadrupeds, such as stags, rhinoceroses, 
etc., and are wonderful both from their size and diversi- 
fied shapes. Instead of describing them, I have given 
figures of the males and females of some of the more re- 
markable forms. (Figs. 15 to 19.) The females gen- 



358 



SEXUAL SELECTION. 



[Part II. 




Fig. 16.— Copris isidis. (Left-hand figures, males.) 





Fig. 17.— Phanaeus faunus. 




Fig. 18.— Dipelicus cantori. 




Fig. 19.— Onthophagus rangifer, enlarged. 




Chap. X.] COLEOPTERA. 359 

erally exhibit rudiments of the horns in the form of small 
knobs or ridges ; but some are destitute of even a rudi- 
ment. On the other hand, the horns are nearly as well 
developed in the female as in thfc male of JPhanceus Ian- 
cifer; and only a little less well developed in the females 
of some other species of the same genus and of Copris. 
In the several subdivisions of the family, the differences 
in structure of the horns do not run parallel, as I am in- 
formed by Mr. Bates, with their more important and 
characteristic differences ; thus, within the same natural 
section of the genus Onthophagus, there are species which 
have either a single cephalic horn, or two distinct horns. 

In almost all cases, . the horns are remarkable from 
their excessive variability ; so that a graduated series 
can be formed, from the most highly-developed males to 
others so degenerate that they can barely be distinguished 
from the females. Mr. Walsh 69 found that in Phanmus 
carnifex the horns were thrice as long in some males as 
in others. Mr. Bates, after examining above a hundred 
males of Onthophagus rangifer (fig. 19), thought that he 
had at last discovered a species in which the horns did 
not vary ; but further research proved the contrary. 

The extraordinary size of the horns, and their widely- 
different structure in closely-allied forms, indicate that 
they have been formed for some important purpose ; but 
their excessive variability in the males of the same species 
leads to the inference that this purpose cannot be of a 
definite nature. The horns do not show marks of fric- 
tion, as if used for any ordinary work. Some authors 
suppose 60 that as the males wander much more than the 
females, they require horns as a defence against their 
enemies ; but in many cases the horns do not seem well 
adapted for defence, as they are not sharp. The most 

59 'Proa Entomolog. Soc. of Philadelphia,' 1864, p. 228. 

60 Kirby and Spence, ' Introduct. Entomolog.' vol. iii. p. 300. 



360 SEXUAL SELECTION. [Part II. 

obvious conjecture is that they are used by the males for 
fighting together ; but they have never been observed to 
fight ; nor could Mr. Bates, after a careful examination of 
numerous species, find jany sufficient evidence, in their 
mutilated or broken condition, of their having been thus 
used. If the males had been habitual fighters, their size 
would probably have been increased through sexual selec- 
tion, so as to have exceeded that of the female ; but Mr. 
Bates, after comparing the two sexes in above a hundred 
species of the Copridae, does not find in well-developed in- 
dividuals any marked difference in this respect. There is, 
moreover, one beetle, belonging to the same great divis- 
ion of the Lamellicorns, namely, Lethrus, the males of 
which are known to fight, but they are not provided with 
horns, though their mandibles are much larger than those 
of the female. 

The conclusion, which best agrees with the fact of the 
horns having been so immensely yet not fixedly devel- 
oped — as shown by their extreme variability in the same 
species and by their extreme diversity in closely-allied 
species — is that they have been acquired as ornaments. 

This view will at first appear extremely 
improbable ; but we shall hereafter find 
with many animals, standing much higher 
in the scale, namely, fishes, amphibians, 
reptiles, and birds, that various kinds of 
crests, knobs, horns, and combs, have 
been developed apparently for this sole 
purpose. 

Fig. 20. — Onitis far- The males of Onitis furcifer (fig. 20) 
from beneath. V1BWe are furnished with singular projections 
on their anterior femora, and with a great 
fork or pair of horns on the lower surface of the thorax. 
This situation seems extremely ill-adapted for the display 
of these projections, and they may be of some real service ; 




Chap. X.] COLEOPTERA. 3 6 1 

but no use can at present be assigned to them. It is a 
highly-remarkable fact, that although the males do not ex- 
hibit even a trace of horns on the upper surface of the 
body, yet in the females a rudiment of a single horn on the 
head (fig. 21, a), and of a crest (b) on the thorax, are plainly 
visible. That the slightest thoracic crest in the female 





Fig. 21.— Left-hand figure, male of Onitis fureifer, viewed laterally. Ri«ht-hand 
figure, female, a. Rudiment of cephalic horn. b. Trace of thoracic horn or 
crest. 

is a rudiment of a projection proper to the male, though 
entirely absent in the male of this particular species, is 
clear : for the female of JBubas bison (a form which comes 
next to Onitis) has a similar slight crest on the thorax, 
and the male has in the same situation a great projection. 
So again there can be no doubt that the little point (a) 
on the head of the female Onitis fureifer, as well of the 
females of two or three allied species, is a rudimentary 
rej^resentative of the cephalic horn, which is common to 
the males of so many lamellicorn beetles, as in Phanseus, 
fig. 17. The males, indeed, of some unnamed beetles in 
the British Museum, which are believed actually to be- 
long to the genus Onitis, are furnished with a similar 
horn. The remarkable nature of this case will be best 
perceived by an illustration : the Ruminant quadrupeds 
run parallel with the lamellicorn beetles, in some females 
possessing horns as large as those of the male, in others 
having tjiem much smaller, or existing as mere rudiments 
(though this is as rare with ruminants as it is common 



362 SEXUAL SELECTION [Part II. 

with Lamelli corns), or in having none at all. Now, if a 
new species of deer or sheep were discovered with the 
female bearing distinct rudiments of horns, while the 
head of the male was absolutely smooth, we should have 
a case like that of Onitis furcifer. 

In this case the old belief of rudiments having been 
created to complete the scheme of Nature is so far from 
holding good, that all ordinary rules are completely 
broken through. The view which seems the most proba- 
ble is that some early progenitor of Onitis acquired, like 
other Lamellicorns, horns on the head and thorax, and then 
transferred them, in a rudimentary condition, as with so 
many existing species, to the female, by whom they have 
ever since been retained. The subsequent loss of the 
horns by the male may have resulted through the prin- 
ciple of compensation from the development of the pro- 
jections on the lower surface, while the female has not 
been thus affected, as she is not furnished with these pro- 
jections, and consequently has retained the rudiments of 
the horns on the upper surface. Although this view is 
supported by the case of Bledius immediately to be given, 
yet the projections on the lower surface differ greatly in 
structure and development in the males of the several spe- 
cies of Onitis, and are even rudimentary in some ; never- 
theless the upper surface in all these species is quite desti- 
tute of horns. As secondary sexual characters are so emi- 
nently variable, it is possible that the projections on the 
lower surface may have been first acquired by some pro- 
genitor of Onitis and produced their effect through com 
pensation, and then have been in certain cases almost 
completely lost. 

All the cases hitherto given refer to the Lamellicorns, 
but the remains of some few other beetles, belonging to 
two widely-distinct groups, namely, the Curculionidse and 
Otaphylinidoe, are furnished with horns — in the former on 



Chap. X.] COLEOPTERA. 363 

the lower surface of the body, 61 in the latter on the upper 
surface of the head and thorax. In the Staphylinidae the 
horns of the males in the same species are extraordinarily 
variable, just as we have seen with the Lamellicorns. In 





£, $ 



Fig. 22.— Bledius taurus, magnified. Left-hand figure, male ; right-hand figure, 

female. 

Siagonium we have a case of dimorphism, for the males 
can be divided into two sets, differing greatly in the size 
of their bodies, and in the development of their horns, 
without any intermediate gradations. In a species of 
Bledius (fig. 22), also belonging to the Staphylinidae, male 
specimens can be found in the same locality, as Prof. 
Westwood states, "in which the central horn of the tho- 
rax is very large, but the horns of the head quite rudi- 
mental; and others, in which the thoracic horn is much 
shorter, while the protuberances on the head are long." 6a 
Here, then, we apparently have an instance of compensa- 
tion of growth, which throws light on the curious case 
just given of the loss of the upper horns by the males of 
Onitis farcifer. 

Law of Battle, — Some male beetles, which seem ill 
fitted for fighting, nevertheless engage in conflicts for the 
possession of the females. Mr. Wallace 63 saw two males 
of Leptorhynchiis angustatus, a linear beetle with a much 

61 Kirby and Spence, ibid. vol. iii. p. 329. 

62 ' Modern Classification of Insects,' vol. i. p. 172. On the same page 
there is an account of Siagonium. In the British Museum I noticed one 
male specimen of Siagonium in an intermediate condition, so that the 
dimorphism is not strict. 

63 ' The Malay Archipelago,' vol. ii. 1869, p. 276. 



364 SEXUAL SELECTION. [Part II. 

elongated rostrum, " fighting for a female, who stood close 
by busy at her boring. They pushed at each other with 
their rostra, and clawed and thumped apparently in the 
greatest rage." The smaller male, however, " soon ran 
away, acknowledging himself vanquished." In some few 
cases the males are well adapted for fighting, by possess- 
ing great toothed mandibles, much larger than those of the 
females. This is the case with the common stag-beetle 
(Lucanus cervus), the males of which emerge from the 
pupal state about a week before the other sex, so tha 4 
several may often be seen pursuing the same female. At 
this period they engage in fierce conflicts. When Mr. A. 
H. Davis 64 enclosed two males with one female in a box, 
the larger male severely pinched the smaller one, until he 
resigned his pretensions. A friend informs me that when 
a boy he often put the males together to see them fight, 
and he noticed that they were much bolder and fiercer 
than the females, as is well known to be the case with the 
higher animals. The males would seize hold of his finger, 
if held in front, but not so the females. With many 
of the Lucanidce, as well as with the above-mentioned 
Leptorhynchus, the males are larger and more powerful 
insects than the females. The two sexes of Lethrus 
cephalotes (one of the Lamellicorns) inhabit the same bur- 
row ; and the male has larger mandibles than the female. 
If, during the breeding-season, a strange male attempts to 
enter the burrow, he is attacked ; the female does not re- 
main passive, but closes the mouth of the burrow, and en 
courages her mate by continually pushing him on from 
behind. The action does not cease until the aggressor ia 
killed or runs away. 65 The two sexes of another lamelli- 

64 ' Entomological Magazine,' vol. i. 1833, p. 82. See also, on the con- 
flicts of this species, Kirby and Spence, ibid. vol. iii. p. 314 ; and West- 
wood, ibid. vol. i. p. 187. 

65 Quoted from Fischer, in ' Diet. Class. d'Hist. Nat.' torn. x. p. 324. 



Chap. X.] COLEOPTERA. 365 

corn beetle, the Ateuchus cicatricosus, live in pairs, and 
seem much attached to each other ; the male excites the 
female to roll the balls of dung in which the ova are de- 
posited ; and, if she is removed, he becomes much agita- 
ted. If the male is removed, the female ceases all work, 
and, as M. Brulerie 66 believes, would remain on the spot 
until she died. 

The great mandibles of the male Lucanidse are ex- 
tremely variable both in size and structure, and in this 
respect resemble the horns on the head and thorax of 
many male Lamellicorns and Staphylinidae. A perfect 
series can be formed from the best-provided to the worst- 
provided or degenerate males. Although the mandibles 
of the common stag-beetle, and probably of many other 
species, are used as efficient weapons for fighting, it is 
doubtful whether their great size can thus be accounted 
for. We have seen that with the I/ucanus elaphus of 
North America they are used for seizing the female. As 
they are so conspicuous and so elegantly branched, the 
suspicion has sometimes crossed my mind that they may 
be serviceable to the males as an ornament, in the same 
manner as the horns on the head and thorax of the 
various above-described species. The male Chiasognathus 
grant ii of South Chili — a splendid beetle belonging to the 
same family — has enormously-developed mandibles (fig. 
23) ; he is bold and pugnacious; when threatend on any 
side he faces round, opening his great jaws, and at the 
same time stridulating loudly; but the mandibles were 
not strong enough to pinch my finger so as to cause 
actual pain. 

Sexual selection, which implies the possession of con- 
siderable perceptive powers and of strong passions, seems 
to have been more effective with the Lamellicorns than 

66 'Ann. Soc. Entomolog. France,' 1866, as quoted in ' Journal of 
Travel,' by A. Murray, i868, p. 135. 



SG6 



SEXUAL SELECTION. 



[Part II. 



with any other family of theColeoptera or beetles. With 

some species the males are provided 
with weapons for lighting ; some live 
in pairs and show mutual affection • 
many have the power of stridulating 
when excited; many are furnished 
with the most extraordinary horns, 
apparently for the sake of ornament ; 
some which are diurnal in their hab- 
its are gorgeously colored ; and, last- 
ly, several of the largest beetles in 
the world belong to this family, which 
was placed by Linnaeus and Fabri- 
cius at the head of the Order of the 
Coleoptera. 67 




Fig. 23. — Chiasoenathus 
grant ii, reduced 
figure, male ; lower figure, 
female. 



Stridulating organs. — Beetles 
belonging to many and widely-dis- 
tinct families possess these organs. 
The sound can sometimes be heard 
at the distance of several feet or even 
yards, 68 but is not comparable with 
that produced by the Orthoptera. 
The part which may be called the 
rasp generally consists of a narrow 
slightly-raised surface, crossed by 
very fine, parallel ribs, sometimes so 
fine as to cause iridescent colors, and 
having a very elegant appearance 
under the microscope. In some cases, 
Upper for instance, with Typhceus, it could 
be plainly seen that extremely mi- 



67 Westwood, ' Modern Class.' vol. i. p. 184. 

es Wollaston, On certain musical Curculionidae, ' Annals and Mag. of 
Nat. Hist.' vol. vi. 1860, p. 14. 



Chap. X.] 



COLEOPTERA. 






nute, bristly, scale-like prominences, which cover the 
whole surrounding surface in approximately parallel lines, 
give rise to the ribs of the rasp by becoming confluent 
and straight, and at the same time more prominent and 
smooth. A hard ridge on any adjoining part of the body 
which in some cases is specially modified for the pur- 
pose, serves as the scraper for the rasp. The scraper is 
rapidly moved across the rasp, or conversely the rasp 
across the scraper. 

These organs are situated in widely-different positions. 
In the carrion-beetles (Necrophorus) two parallel rasps (r, 
fig. 24) stand on the dorsal surface of the fifth abdominal 





Fig. 24.— Necrophorus (from Landois) r. The two rasps. Left-hand figure, part 

of the rasp highly magnified. 

segment, each rasp being crossed, as described by Lan- 
dois, 69 by from 126 to 140 fine ribs. These ribs are 
scraped by the posterior margins of the elytra, a small 
portion of which projects beyond the general outline. In 
many Crioceridoe, and in Chjthra 4-jnoictata (one of the 
Chrysomelidse), and in some Tenebrionidie, etc., 70 the rasp 

69 'Zeitsehrift fur wiss. Zoolog.' B. xvii. 1867, s. 127. 

70 1 am greatly indebted to Mr. G. R. Crotch for having sent me nu- 
merous prepared specimens of various beetles belonging to these three 
families and others, as well as for valuable information of all kinds. He 
believes that the power of stridulation in the Clythra has not been pre- 
viously observed. I am also much indebted to Mr. E. "W. Janson, for 
information and specimens. I may add that my son, Mr. F. Darwin, finds 



368 SEXUAL SELECTION. [Part II. 

is seated on the dorsal apex of the abdomen, on the py- 
gidium or pro-pygidium, and is scraped as above by the 
elytra. In Heterocerus, which belongs to another family, 
the rasps are placed on the sides of the first abdominal 
segment, and are scraped by ridges on the femora. 71 In 
certain Curculionidse and Carabidse, 72 the parts are com- 
pletely reversed in position, for the rasps are seated on the 
inferior surface of the elytra, near their apices, or along 
their outer margins, and the edges of the abdominal seg- 
ments serve as the scrapers. In JPelobius hermanni (one 
of Dytiscidse or water-beetles) a strong ridge runs parallel 
and near to the sutural margin of the elytra, and is 
crossed by ribs, coarse in the middle part, but becoming 
gradually finer at both ends, especially at the upper end ; 
when this insect is held under water or in the air, a strid- 
ulating noise is produced by scraping the extreme horny 
margin of the abdomen against the rasp. In a great num- 
ber of long-horned beetles (Longicornia) the organs are 
altogether differently situated, the rasp being on the 
meso-thorax, which is rubbed against the pro-thorax; 
Landois counted 238 very fine ribs on the rasp of Ceram- 
byx heros. 

Many Lamellicorns have the power of stridulating, 
and the organs differ greatly in position. Some species 
stridulate very loudly, so that when Mr. F. Smith caught 

that Dermestes murinus stridulates, but he searched in vain for the appa 
ratus. Scolytus has lately been described by Mr. Algen as a stridulator 
in the 'Edinburgh Monthly Magazine,' 1869, Nov., p. 130. 

71 Schiodte, translated in 'Annals and Mag. of Nat. Hist.' vol. xx. 
1867, p. 37. 

72 Westringhas described (Kroyer, 'Naturhist. Tidskrift,' B. ii. 1848- 
'49, p. 334) the stridulating organs in these two, as well as in other fam- 
ilies. In the Carabidae I have examined Elaphrus uliginosus and Blethisa, 
multipunctata, sent to me by Mr. Crotch. In Blethisa the transverse 
ridges on the furrowed border of the abdominal segment do not come 
aito play, as far as I could judge, in scraping the rasps on the elytra. 



CnAP. X.] 



COLEOPTERA, 



369 



a Trox sabulosus, a gamekeeper who stood by thought that 
he had caught a mouse ; but I failed to discover the proper 
organs in this beetle. In Geotrupes and Typhams a nar- 
now ridge runs obliquely across (r, fig. 25) the coxa of 
each hind-leg, having in G. stercorarius eighty-four ribs, 
which are scraped by a specially projecting 
part of one of the abdominal segments. In 
the nearly-allied Gopris lunaris, an exces- 
sively narrow fine rasp runs along the sutu- 
ral margin of the elytra, with another short 
' rasp near the basal outer margin ; but in 
some other Coprini the rasp is seated, ac- 
cording: to Leconte, 73 on the dorsal surface of 
the abdomen. In Oryctes it is seated on 
the pro-pygidium, and in some other Dy- 
nastini, according to the same entomolo- 
gist, on the under surface of the elytra. 8 

Lastly, Westringr states that in Omaloplia Fig. 25.— Hind-leg 

.. ° . _ of Geotrupes ster- 

brunnea the rasp is placed on the pro- corarius (from 




Landois). 

r. Rasp, c. Coxa. 
/. Femur, t. Tibia. 
tr. Tarsi. 



sternum, and the scraper on the meta- 
sternum, the parts thus occupying the 
under surface of the body, instead of the 
upper surface as in the Longicorns. 

We thus see that the stridulating organs in the differ- 
ent coleopterous families are wonderfully diversified in 
position, but not much in structure. Within the same 
family some species are provided with these organs, and 
some are quite destitute of them. This diversity is intelli- 
gible, if we suppose that originally various species made 
a shuffling or hissing noise by the rubbing together of the 
hard and rough parts of their bodies which were in con- 
tact; and that, from the noise thus produced being in 
some way useful, the rough surfaces were gradually de- 

73 I am indebted to Mr. Walsh, of Illinois, for having sent me extracts 
from Leconte's ' Introduction to Entomology,' pp. 101, 143. 



3 TO SEXUAL SELECTION. [Part II. 

velopcd into regular stridulating organs. Some beetles, as 
they move, now produce, either intentionally or uninten- 
tionally, a shuffling noise, without possessing any proper 
organs for the purpose. Mr. Wallace informs me that the 
JEuchirus longimanus (a Lamellicorn, with the anterior 
legs wonderfully elongated in the male) "makes, while 
moving, a low hissing sound by the protrusion and con- 
traction of the abdomen ; and when seized it produces a 
grating sound by rubbing its hind-legs against the edges 
of the elytra." The hissing sound is clearly due to a 
narrow rasp running along the sutural margin of each 
elytron ; and I could likewise make the grating sound by 
rubbing the shagreened surface of the femur against the 
granulated margin of the corresponding elytron; but I 
could not here detect any proper rasp ; nor is it likely 
that I could have overlooked it in so large an insect. 
After examining Cychrus and reading what Westring has 
written in his two papers about this beetle, it seems very 
doubtful whether it possesses any true rasp, though it has 
the power of emitting a sound. 

From the analogy of the Orthoj)tera and Homoptera, 
I expected to find that the stridulating organs in the 
Coleoptera differed according to sex ; but Landois, who 
has carefully examined several species, observed no such 
difference ; nor did Westring ; nor did Mr. G. R. Crotch 
in preparing the numerous specimens which he had the 
kindness to send me for examination. Any slight sexual 
difference, however, would be difficult to detect, on ac- 
count of the great variability of these organs. Thus, in 
the first pair of the JSTecropliorus humator and of the 
Pelohius which I examined, the rasp was considerably 
larger in the male than in the female ; but not so with 
succeeding specimens. In Geotrupes stercorarius the rasp 
appeared to me thicker, opaquer, and more prominent in 
three males than in the same number of females ; conse- 



Chap. X.] COLEOPTERA. 371 

quently my son, Mr. F. Darwin, in order to discover 
whether the sexes differed in their power of stridalating, 
collected fifty-seven living specimens, which he separated 
into two lots, according as thev made, when held in the 
6ame manner, a greater or lesser, noise. He then examined 
their sexes, but found that the males were very nearly in 
the same proportion to the- females in both lots. Mr. F. 
Smith has kept alive numerous specimens of Mononychns 
pseudacori (Curculionidoe), and is satisfied that both sexes 
stridulate, and apparently in an equal degree. 

Nevertheless the power of stridulating is certainly a 
sexual character in some few Coleoptera. Mr. Crotch has 
discovered that the males alone of two species of Helio- 
pathes (Tenebrionidoe) possess stridulating organs. I ex- 
amined five males of H. gibbus, and in all these there wao 
a well-developed rasp, partially divided into two, on the 
dorsal surface of the terminal abdominal segment ; while 
in the same number of females there was not even a rudi- 
ment of the rasp, the membrane of this segment being 
transparent and much thinner than in the male. In H. 
cribratostriatus the male has a similar rasp, excepting 
that it is not partially divided into two portions, and the 
female is completely destitute of this organ ; but in addi- 
tion the male has on the apical margins of the elytra, on 
each side of the suture, three or four short longitudinal 
ridges, which are crossed by extremely fine ribs, parallel 
to and resembling those on the abdominal rasp ; whether 
these ridges serve as an independent rasp, or as a scraper 
for the abdominal rasp, I could not decide : the female 
exhibits no trace of this latter structure. 

Again, in three species of the Lamellicorn genus 
Oryctes, we have a nearly parallel case. In the females 
of 0. gryphus and nasicornis the ribs on the rasp of the 
pro-pygidium are less continuous and less distinct than in 
the males ; but the chief difference is that the whole upper 



372 SEXUAL SELECTION. [Part II. 

surface of this segment, when held in the proper light, is 
seen to be clothed with hairs, which are absent or are rep- 
resented by excessively fine down in the males. It should 
be noticed that, in all Coleoptera, the effective part of the 
rasp is destitute of hairs. In 0. senegalensis the differ- 
ence between the sexes is more strongly marked, and this 
is best seen when the proper segment is cleaned and 
viewed as a transparent object. In the female the whole 
surface is covered with little separate crests, bearing 
spines ; while in the male these crests become, in proceed- 
ing toward the apex, more and more confluent, regular, 
and naked ; so that three-fourths of the segment is covered 
with extremely fine parallel ribs, which are quite absent 
in the female. In the females, however, of all three spe- 
cies of Oryctes, when the abdomen of a softened specimen 
is pushed backward and forward, a slight grating or stim- 
ulating sound can be produced. 

In the case of the Heliopathes and Oryctes there can 
hardly be a doubt that the males stridulate in order to 
call or to excite the females ; but with most beetles the 
stridulation apparently serves both sexes as a mutual call. 
This view is not rendered improbable from beetles stridu- 
lating under various emotions ; we know that birds use 
their voices for many purposes besides singing to their 
mates. The great Chiasognathus stridulates in anger or 
defiance ; many species do the same from distress or fear 
when held so that they cannot escape : Messrs. Wollaston 
and Crotch were able, by striking the hollow stems of 
trees in the Canary Islands, to discover the presence of 
beetles belonging to the genus Acalles by their stridula- 
tion. Lastly, the male Ateuchus stridulates to encourage 
the female in her work, and from distress when she is re- 
moved. 71 Some naturalists believe that beetles make this 

74 M. P. de la Brulerie, as quoted in ' Journal of Travel,' A. Murray, 
vol. i. 1808, p. 135. 



Chap. X.j COLEOPTERA. 273 

noise to frighten away their enemies ; but I cannot think 
that the quadrupeds and birds which are able to devour 
the larger beetles, with their extremely hard coats, would 
be frightened by so slight a grating sound. The belief 
that the stridulation serves as a sexual call is supported 
by the fact that death-ticks (Anobiwn tessellatum) are well 
known to answer each other's ticking, or, as I have my- 
self observed, a tapping noise artificially made ; and Mr. 
Doubleday informs me that he has twice or thrice ob- 
served a female ticking, 76 and in the course of an hour or 
two has found her united with a male, and on one occa- 
sion surrounded by several males. Finally, it seems 
probable that the two sexes of many kinds of beetles were 
.at first enabled to find each other by the slight shuffling 
noise produced by the rubbing together of the adjoining 
parts of their hard bodies ; and that as the males or 
females which made the greatest noise succeeded best in 
finding partners, the rugosities on various parts of their 
bodies were gradually developed by means of sexual se- 
lection into true stridulating organs. 

75 Mr. Doubleday informs me that " the noise is produced by the in- 
sect raising itself on its legs as high as it can, and then striking its thorax 
five or six times, in rapid succession, against the substance upon which 
it is sitting." For references on this subject see Landois, ' Zeitschrift 
fur wissen. Zoolog.' B. xvii. s. 131. Olivier says (as quoted by Kirby and 
Spence, ' Introduct.' vol. ii. p. 395) that the female of Fimelia striata 
produces a rather loud sound by striking her abdomen against any hard 
substance, " and that the male, obedient to this call, soon attends her, 
and they pair." 



374 SEXUAL SELECTION. [Part IL 



CHAPTER XI. 

insects, continued. — order lepidoptera. 

Courtship of Butterflies. — Battles. — Ticking Noise. — Colors common to 
Both Sexes, or more brilliant in the Males. — Examples.— Not due to 
the Direct Action of the Conditions of Life. — Colors adapted for Pro- 
tection. — Colors of Moths. — Display. — Perceptive Powers of the Lepi-^ 
doptera. — Variability. — Causes of the Difference in Color between 
the Males and Females. — Mimicry, Female Butterflies more brilliantly 
colored than the Males. — Bright Colors of Caterpillars. — Summary 
and Concluding Remarks on the Secondary Sexual Characters of In- 
sects. — Birds and Insects compared. 

In this great Order the most interesting point for us is 
the difference in color between the sexes of the same spe- 
cies, and between the distinct species of the same genus. 
Nearly the whole of the following chapter will be devoted 
to this subject ; but I will first make a few remarks on one 
or two other points. Several males may often be seen 
pursuing and crowding round the same female. Their 
courtship appears to be a prolonged affair, for I have fre- 
quently watched one or more males pirouetting round a 
female until I became tired, without seeing the end of the 
courtship. Although butterflies are such weak and fragile 
creatures, they are pugnacious, and an Emperor butterfly ■ 
has been captured with the tips of its wings broken from 

1 Apatura Iris : ' The Entomologist's "Weekly Intelligencer,' 1859, p. 
139. For the Bornean Butterflies, see C. Collingwood, 'Rambles of a 
Naturalist,' 1868, p. 183. 



Chap. XL] BUTTERFLIES AND MOTHS. 375 

a conflict with another male. Mr. Collingwood, in speak- 
ing of the frequent battles between the butterflies of Bor- 
neo, says, " They whirl round each other with the greatest 
rapidity, and appear to be incited by the greatest ferocity." 
One case is known of a butterfly, namely, the Ageronia 
feronia, which makes a noise like that produced by a 
toothed wheel passing under a spring-catch, and which 
could be heard at the distance of several yards. At Rio de 
Janeiro this sound was noticed by me, only when two 
were chasing each other in an irregular course, so that it is 
probably made during the courtship of the sexes ; but I 
neglected to attend to this point. 2 

Every one has admired the extreme beauty of many 
butterflies and of some moths ; and we are led to ask, How 
has this beauty been acquired? Have their colors and 
diversified patterns simply resulted from the direct action 
of the physical conditions to which these insects have been 
exposed, without any benefit being thus derived? Or 
have successive variations been accumulated and deter- 
mined either as a protection or for some unknown purpose, 
or that one sex might be rendered attractive to the other ? 
And, again, what is the meaning of the colors being wide- 
ly different in the males and females of certain species, 
and alike in the two sexes of other species ? Before at- 
tempting to answer these questions a body of facts must 
be given. 

With most of our English butterflies, both those which 
are beautiful, such as the admiral, peacock, and painted 
lady (Vanessse), and those which are plain-colored, such 
as the meadow-browns (Hipparchise), the sexes are alike. 
This is also the case with the magnificent Heliconidae and 

2 See my 'Journal of Researches,' 1845, p. 33. Mr. Doubleday has 
detected ('Proc. Ent. Soc' March 3, 1845, p. 123) a peculiar mem- 
branous sac at the base of the front wings, which is probably connected 
with the production of the sound. 



376 SEXUAL SELECTION. [Part II. 

Danaidne of the tropics. But in certain other tropical 
groups, and with some of our English butterflies, as the 
purple emperor, orange-tip, etc. {Apatura Iris and An- 
thocharis cardamines), the sexes differ either greatly or 
slightly in color. Nq language suffices to describe the 
splendor of the males of some tropical species. Even 
within the same genus we often find species presenting an 
extraordinary difference between the sexes, while others 
have their sexes closely alike. Thus in the South Ameri- 
can genus Epicalia, Mr. Bates, to whom I am much in- 
debted for most of the following. facts and for looking over 
this whole discussion, informs me that he knows twelve 
species, the two sexes of which haunt the same stations 
(and this is not always the case with butterflies), and 
therefore cannot have been differently affected by external 
conditions. 3 In nine of these species the males rank among 
the most brilliant of all butterflies, and differ so greatly 
from the comparatively plain females that they were for- 
merly placed in distinct genera. — The females of these 
nine species resemble each other in their general type of 
coloration, and likewise resemble both sexes in several 
allied genera, found in various parts of the world. Hence, 
in accordance with the descent-theory, we may infer that 
these nine species, and probably all the others of the genus, 
are descended from an ancestral form which was colored 
in nearly the same manner. In the tenth species the fe- 
male still retains the same general coloring, but the male 
resembles her, so that he is colored in a much less gaudy 
and. contrasted manner than the males of the previous 
species. In the eleventh and twelfth species, the females 
depart from the type of coloring which is usual with 
their sex in this genus, for they are gayly decorated in 

8 See also Mr. Bates's paper in ' Proc. Ent. Soc. of Philadelphia,' 
1865, p. 206. Also Mr. Wallace on the same subject, in regard to Dia- 
dema, in 'Transact. Entomolog. Soc. of London,' 1869, p. 278. 



Chap. XI.] BUTTERFLIES AND MOTHS. 377 

nearly the same manner as the males, but in a somewhat 
less degree. Hence in these two species the bright colors 
of the males seem to have been transferred to the females ; 
while the male of the tenth species has either retained, or 
recovered the plain colors of the female as well as of the 
parent-form of the genus ; the two sexes being thus ren- 
dered, in both cases, though in an opposite manner, nearly 
alike. In the allied genus Eubagis, both sexes of some of 
the species are plain-colored and nearly alike ; while with 
the Greater number the males are decorated w T ith beauti- 
ful metallic tints, in a diversified manner, and differ much 
from their females. The females throughout the genus re- 
tain the same general style of coloring, so that they com- 
monly resemble each other much more closely than they 
resemble their own proper males. 

In the genus Papilio, all the species of the iEneas 
group are remarkable for their conspicuous and strongly- 
contrasted colors, and they illustrate the frequent ten- 
dency to gradation in the amount of difference between 
the sexes. In a few species, for instance, in P. ascanius, 
the males and females are alike ; in others the males are 
a little or very much more superbly colored than the fe- 
males. The genus Junonia, allied to our Vanessa?, offers a 
nearly parallel case, for although the sexes of most of the 
species resemble each other and are destitute of rich col- 
ors, yet in certain species, as in J. cenone, the male is 
rather more brightly colored than the female, and in a few 
(for instance, J. andremiaja) the male is so different from 
the female that he might be mistaken for an entirely dis- 
tinct species. 

Another striking case was pointed out to me in the 

British Museum by Mr. A. Butler, namely, one of the 

Tropical American Theclae, in which both sexes are nearly 

alike and wonderfully splendid; in another, the male is 

colored in a similarly gorgeous manner, while the whole 
17 



378 SEXUAL SELECTION. [Par r II. 

upper surface of the female is of a dull uniform brown. 
Our common little English blue butterflies, of the genus 
Lycama, illustrate the various differences in color between 
the sexes, almost as well, though not in so striking a man- 
ner, as the above exotic genera. In JOyccena agestis both 
sexes have wings of a brown color, bordered with small 
ocellated orange spots, and are consequently alike. In L. 
cegon the wings of the male are of a fine blue, bordered 
with black ; while the wings of the female are brown, with 
a similar border, and closely resemble those of JO. agestis. 
Lastly, in JO. avion both sexes are of a blue color and 
nearly alike, though in the female the edges of the wings 
are rather duskier, with the black spots plainer ; and in a 
bright-blue Indian species both sexes are still more closely 
alike. 

I have given the foregoing cases in some detail, in 
order to show, in the first place, that, when the sexes of 
butterflies differ, the male as a general rule is the most 
beautiful, and departs most from the usual type of color- 
ing of the group to which the species belongs. Hence in 
most groups the females of the several species resemble 
each other much more closely than do the males. In 
some exceptional cases, however, to which I shall here- 
after allude, the females are colored more splendidly than 
the males. In the second place, these cases have been 
given to bring clearly before the mind that, within the 
same genus, the two sexes frequently present every gra- 
dation from no difference in color to so great a difference 
that it was long before the two were placed by entomolo- 
gists in the same genus. In the third place, we have seen 
that, when the sexes nearly resemble each other, this ap- 
parently may be due either to the male having transferred 
his colors to the female, or to the male having retained, 
or perhaps recovered, the primordial colors of the genus 
to which the species belongs. It also deserves notice that 



Chap. XL] BUTTERFLIES AND MOTHS. 379 

in those groups in which the sexes present any difference 
of color, the females usually resemble the males to a cer- 
tain extent, so that, when the males are beautiful to an ex- 
traordinary degree, the females almost invariably exhibit 
some degree of beauty. From the numerous cases of gra- 
dation in the amount of difference between the sexes, and 
from the prevalence of the same general type of coloration 
throughout the whole of the same group, we may con- 
clude that the causes, whatever they may be, which have 
determined the brilliant coloring of the males alone of 
some species, and of both sexes in a more or less equal 
degree of other species, have generally been the same. 

As so many gorgeous butterflies inhabit the tropics, it 
has often been supposed that they owe their colors to the 
Q*reat heat and moisture of these zones ; but Mr. Bates 4 
has shown, by the comparison of various closely-allied 
groups of insects from the temperate and tropical regions, 
that this view cannot be maintained ; and the evidence 
becomes conclusive when brilliantly-colored males and 
plain-colored females of the same species inhabit the same 
district, feed on the same food, and follow exactly the 
same habits of life. Even when the sexes resemble each 
other, we can hardlv believe that their brilliant and beau- 
tifully-arranged colors are the purposeless result of the 
nature of the tissues, and the action of the surrounding 
conditions. 

With animals of all kinds, whenever color has been 
modified for some special purpose, this has been, as far as 
we can judge, either for protection or as an attraction be- 
tween the sexes. With many species of butterflies the 
upper surfaces of the wings" are obscurely colored, and 
this in all probability leads to their escaping observation 
and danger. But butterflies when at rest would be par- 
ticularly liable to be attacked by their enemies ; and al- 

4 ' The Naturalist on the Amazons,' vol. i. 1863, p. 19. 



880 SEXUAL SELECTION. [Part II. 

most all' the kinds when resting raise their wings verti- 
cally over their backs, so that the lower sides alone are 
exposed to view. Hence it is this side which in many 
cases is obviously colored so as to imitate the surfaces on 
which these insects commonly rest. Dr. Rossler, I be- 
lieve, first noticed the similarity of the closed wings of 
certain Vanessa? and other butterflies to the bark of trees. 
Many analogous and striking facts could be given. The 
most interesting one is that recorded by Mr. Wallace 6 
of a common Indian and Sumatran butterfly (Kallima), 
which disappears like magic when it settles in a bush ; 
for it hides its head and antenna? between its closed 
wings, and these, in form, color, and veining, cannot be 
distinguished from a withered leaf together with the foot- 
stalk. In some other cases the lower surfaces of the 
wings are brilliantly colored, and yet are protective ; thus 
in Thecla riibi the win^s when closed are of an emerald 
green and resemble the young leaves of the bramble, on 
which this butterfly in the spring may often be seen 
seated. 

Although the obscure tints of the upper or under sur- 
face of many butterflies no doubt serve to conceal them, 
yet we cannot possibly extend this view to the brilliant 
and conspicuous colors of many kinds, such as our admiral 
and peacock Vanessa?, our white cabbage-butterflies (Pie- 
ris), or the great swallow-tail Papilio which haunts the 
open fens — for these butterflies are thus rendered visible 
to every living creature. With these species both sexes 
are alike; but in the common brimstone butterfly (Go- 
nepteryx rhamni) the male is of an intense yellow, while 
the female is much paler ; and in the orange-tip (Antho- 
*ihari$ cardamines) the males alone have the bright 

6 See the interesting article in the c Westminster Eeview,' July, 1867, 
p. 10. A woodcut-of the Kallima is given by Mr. Wallace in 4 Hard- 
wicke's Science Gossip,' Sept., 1867, p. 196. 



Chap. XI.] BUTTERFLIES AND MOTHS. 381 

orange tips to their wings. In these cases the males and 
females are equally conspicuous, and it is not credible 
that their difference in color stands in any relation to or- 
dinary protection. Nevertheless, it is possible that the 
conspicuous colors of many species may be in an indirect 
manner beneficial, as will hereafter be explained, by lead- 
ing their enemies at once to recognize them as unpala- 
table. Even in this case it does not certainly follow that 
their bright colors and beautiful patterns were acquired 
for this special purpose. In some other remarkable cases, 
beauty has been gained for the sake of protection, through 
the imitation of other beautiful species, which inhabit the 
same district and enjoy an immunity from attack by be- 
ing in some way offensive to their enemies. 

The female of our orange-tip butterfly, above referred 
to, and of an American species (Anth. genutia) probably 
show us, as Mr. Walsh has remarked to me, the primordial 
colors of the parent-species of the genus ; for both sexes 
of four or five widely-distributed species are colored in 
nearly the same manner. We may infer here, as in several 
previous cases, that it is the males of Anth. cardamines 
ard genutia which have departed from the usual type of 
coloring of their genus. In the Anth. sara from California, 
the orange-tips have become partially developed in the fe- 
male ; for her wings are tipped with reddish orange, but 
paler than in the male, and slightly different in some other 
respects. In an allied Indian form, the Iphlas glaucippe, 
the orange-tips are fully developed in both sexes. In this 
Iphias the under surface of the wings marvellously resem- 
bles, as pointed out to me by Mr. A. Butler, a pale-col* 
ored leaf; and, in our English orange-tip, the under surface 
resembles the flower-head of the wild-parsley, on which it 
may be seen going to rest at night. 8 The same reasoning 

8 See the interesting observations by Mr. T. "W". "Wood, ' The Stu- 
dent,' Sept. 1868, p. 81. 



382 SEXUAL SELECTION. [Part II. 

power which compels us to believe that the lower surfaces 
have here been colored for the sake of protection, leads us 
to deny that the wings have been tipped, especially when 
this character is confined to the males, with bright orange 
for the same purpose. 

Turning now to Moths : most of these rest motionless 
with their wings depressed during the whole or greater 
part of the day ; and the upper surfaces of their wings 
are often shaded and colored in an admirable manner, as 
Mr. Wallace has remarked, for escaping detection. With 
most of the Bombycidas and Noctuidte, 7 when at rest, the 
front-wings overlap and conceal the hind-wings ; so that 
the latter might be brightly colored without much risk ; 
and they are thus colored in many species of both families. 
During the act of flight, moths would often be able to es- 
cape from their enemies ; nevertheless, as the hind-wings 
are then fully exposed to view, their bright colors must 
generally have been acquired at the cost of some little 
risk. But the following fact shows us how cautious we 
ought to be in drawing conclusions on this head. The 
common yellow under-wings (Triphaena) often fly about 
during the day or early evening, and are then conspicuous 
from the color of their hind-wings. It would naturally 
be tli ought that this would be a* source of danger ; but 
Mr. J. Jenner Weir believes that it actually serves them 
as a means of escape, for birds strike at these brightly- 
colored and fragile surfaces, instead of at the body. For 
instance, Mr. Weir turned into his aviary a vigorous spe- 
cimen of Triphaena pronuba, which was instantly pur- 
sued by a robin ; but, the bird's attention being caught 
by the colored wings, the moth was not captured until 
*fter about fifty attempts, and small portions of the wings 
were repeatedly broken oiF. He tried the same expert 

7 Mr. Wallace in ' Hardwicke's Science Gossip,' Sept. 1867, p. 193. 



£hap. XL] BUTTERFLIES AND MOTHS. 383 

rnent, in the open air, with a T. fimbria and swallow; 
but the large size of this moth probably interfered with 
its capture. 8 "We are thus reminded of a statement made 
by Mr. Wallace, 9 namely, that, in the Brazilian forests and 
Malayan islands, many common and highly-decorated but- 
terflies are weak flyers, though furnished with a broad ex- 
panse of wings ; and they " are often captured with pierced 
and broken wings, as if they had been seized by birds, 
from which they had escaped : if the wings had been much 
smaller in proportion to the body, it seems probable that 
the insect would more frequently have been struck or 
pierced in a vital part, and thus the increased expanse of 
the wings may have been indirectly beneficial." 

Display. — The bright colors of butterflies and of some 
moths are specially arranged for display, whether or not 
they serve in addition as a protection. Bright colors 
would not be visible during; the nicdit: and there can be 
no doubt that moths, taken as a body, are much less gayly 
decorated than butterflies, all of which are diurnal in their 
habits. But the moths in certain families, such as the 
Zygaenidse, various Sphingidae, Uraniidae, some Arctiiche 
and Saturniidse, fly about during the day or early evening, 
and many of these are extremely beautiful, being far more 
brightly colored than the strictly nocturnal kinds. A few 
exceptional cases, however, of brightly-colored nocturnal 
species have been recorded. 10 

There is evidence of another kind in regard to display. 

« See also, on this subject, Mr. Weir's paper in ' Transact. Ent Soc' 
1869, p. 23. 

9 'Westminster Review,' July, 1867, p. 16. 

19 For instance, Lithosia ; but Prof. Wesiwood {* Modern Class, of 
Insects,' toL iL p. S90) seems surprised at this case. On the relative 
"colors of diurnal and nocturnal Lepidoptera, see ibid. pp. 333, 392 ; also 
Harris, ' Treatise on the Insects of New England,' 1842, p. 315. 



384 SEXUAL SELECTION". [Part IL 

Butterflies, as before remarked, elevate their wings when 
at rest, and while basking in the sunshine often alternately 
raise and depress them, thus exposing to full view both 
surfaces ; and, although the lower surface is often colored 
in an obscure manner as a protection, yet in many species 
it is as highly colored as the upper surface, and sometimes 
in a very different manner. In some tropical species the 
lower surface is even more brilliantly colored than the 
upper. 11 In one English fritillary, the Argynnis aglaia, 
the lower surface alone is ornamented with shining silver 
disks. Nevertheless, as a general rule, the upper surface, 
which is probably the most fully exposed, is colored more 
brightly and in a more diversified manner than the lower. 
Hence the lower surface generally affords to entomologists 
the most useful character for detecting the affinities of 
the various species. 

Now if we turn to the enormous group of moths, which 
do not habitually expose to full view the under surface of 
their wings, this side is very rarely, as I hear from Mr. 
Stainton, colored more brightly than the upper side, or 
even with equal brightness. Some exceptions to the rule, 
either real or apparent, must be noticed, as that of Hypo- 
pyra, specified by Mr. Wormald." Mr. R. Trimen informs 
me that, in Guenee's great work, three moths are figured, 
in which the under surface is much the most brilliant. 
For instance, in the Australian Gastrophora the upper 
surface of the fore-wing is pale grayish-ochreous, while 
the lower surface is magnificently ornamented by an ocel- 
lus of cobalt-blue, placed in the midst of a black mark, 
surrounded by orange-yellow, and this by bluish-white. 

11 Such differences between the upper and lower surfaces of the wiugg 
of several species of Papilio may be seen in the beautiful plates to Mr. 
Wallace's Memoir on the Papilionidae of the Malayan Region, in ' Trans- 
act. Linn. Soc' vol. xxv. part i. 1865. 

12 « Proc. Ent. Soc' March 2, 1868. 



Ciup. XI.] BUTTERFLIES AND MOTHS. 385 

But the habits of these three moths are unknown ; so that 
no explanation can be given of their unusual style of col- 
oring. Mr. Trimen also informs me that the lower sur- 
face of the wings in certain other Geometrse 13 and quadri- 
fid Nocture is either more variegated or more brightly 
colored than the upper surface ; but some of these species 
have the habit of " holding their wings quite erect over 
their backs, retaining them in this position for a consider- 
able time," and thus exposing to view the under surface. 
Other species, when settled on the ground or herbage, 
have the habit of now and then suddenly and slightly 
lifting up their wings. Hence, the lower surface of the 
wings being more brightly colored than the upper surface, 
in certain moths, is not so anomalous a circumstance as it 
at first appears. The Saturniidae include some of the 
most beautiful of all moths, their wings being decorated, 
as in our British Emperor moth, with fine ocelli ; and Mr. 
T. W. Wood 14 observes that they resemble butterflies in 
some of their movements ; " for instance, in the gentle 
waving up and # down of the wings, as if for display, which 
is more characteristic of diurnal than of nocturnal Lepi- 
doptera." 

It is a singular fact that no British moths, nor, as far 
as I can discover, hardly any foreign species, which are 
brilliantly colored, differ much in color according to sex ; 
though this is the case with many brilliant butterflies. 
The male, however, of one American moth, the Satumia 
Jo, is described as having its fore-wings deep yellow, 
curiously marked with purplish-red spots ; while the wings 
of the female are purple-brown, marked with gray lines. 16 
The British moths which differ sexually in color are all 

13 See also an account of the South American genus Erateina (one of 
the Geometry) in ' Transact Ent. Soc' new series, vol. v. pis. xv., xvi. 

14 'Proc. Ent. Soc. of London,' July 6, 1868, p. xxvii. 

,s Harris, ' Treatise,' etc., edited by Flint, 1862, p. 399. 



3S6 SEXUAL SELECTION. [Part II. 

brown, or various tints of dull yellow, or nearly white. 
In several species the males are much darker than the 
females, 16 and these belong to groups which generally fly 
about during the afternoon. On the other hand, in many 
genera, as Mr. Stainton informs me, the males have the 
hind-wings whiter than those of the female — of which fact 
Agrotis exclamationis offers a good instance. The males 
are thus rendered more conspicuous than the females, 
while flying about in the dusk. In the Ghost Moth (He- 
pialus humuli) the difference is more strongly marked ; 
the males being white, and the females yellow, with 
darker markings. It is difficult to conjecture what the 
meaning: can be of these differences between the sexes in 
the shades .of darkness or lightness ; but we can hardly 
suppose that they are the result of mere variability with 
sexually-limited inheritance, independently of any benefit 
thus derived. 

From the foregoing statements it is impossible to ad- 
mit that the brilliant colors of butterflies and of some few 
moths have commonly been acquired for the sake of pro- 
tection. We have seen that their colors and elegant pat- 
terns are arranged and exhibited as if for display. Hence 
I am led to suppose that the females generally prefer, or 

16 For instance, I observe in my son's cabinet that the males are 
darker than the females in the Lasiocampa qucrcus, Odonestis potatoria y 
Hypogymna dispar, DasycMra pudibunda, and Cycnia mendica. In this 
latter species the difference in color between the two sexes is strongly 
marked ; and Mr. Wallace informs me that we here have, as he believes, 
an instance of protective mimicry confined to one sex, as will hereafter 
be more fully explained. The white female of the Cycnia resembles the 
very common Spilonoma menthrasti, both sexes of which are white ; and 
Mr. Stainton observed that this latter moth was rejected with utter dis- 
gust by a whole brood of young turkeys, which were fond of eating other 
moths ; so that, if the Cycnia was commonly mistaken by British birda 
for the Spilosoma, it would escape being devoured, and its white decep- 
tive color would thus be highly beneficial. 



Chap. XI.] BUTTERFLIES AND MOTHS. 387 

are most excited by the more brilliant males ; for on any- 
other supposition the males would be ornamented, as far 
as we can see, for no purpose. "We know that ants and 
certain lamellicorn beetles are capable of feeling an at- 
tachment for each other, and that ants recognize their fel- 
lows after an interval of several months* Hence there is 
no abstract improbability in the Lepidoptera, which prob- 
ably stand nearly or quite as high in the scale as these 
insects, having sufficient mental capacity to admire bright 
colors. They certainly discover flowers by color, and, as 
I have elsewhere shown, the plants which are fertilized 
exclusively by the wind never have a conspicuously-col- 
ored corolla. The Humming-bird Sphinx may often be 
seen to swoop down from a distance on a bunch of flowers ' 
in the midst of green foliage ; and I have been assured 
by a friend that these moths repeatedly visited flowers 
painted on the walls of a room in the south of France. 
The common white butterfly, as I hear from Mr. Double- 
day, often flies down to a bit of paper on the ground, no 
doubt mistaking it for one of its own species. Mr. Col- 
lingwood, 17 in speaking of the difficulty of collecting cer- 
tain butterflies in the Malay Archipelago, states that "a 
dead specimen pinned upon a conspicuous twig will often 
arrest an insect of the same species in its headlong flight 
and bring it down within easy reach of the net, especially 
it" it be of the opposite sex." 

The courtship of butterflies is a prolonged affair. 
The males sometimes fight together in rivalry ; and many 
may be seen pursuing or crowding round the same female. 
If, then, the females do not prefer one male to another, 
the pairing must be left to mere chance, and this does 
not appear to me a probable event. If, on the other hand, 
the females habitually, or even occasionally, prefer the 
more beautiful males, the colors of the latter will have 

17 ' Rambles of a Naturalist in the Chinese Seas,' 1868, p. 182. 



3S8 SEXUAL SELECTION. [Part II 

been rendered brighter by degrees, and will have been 
transmitted to both sexes or to one sex, according to 
which law of inheritance prevailed. The process of sexual 
selection will have been much facilitated, if the conclu- 
sions arrived at from various kinds of evidence in the sup- 
plement to the ninth chapter can be trusted ; namely, that 
the males of many Lepidoptera, at least in the imago 
state, greatly exceed in number the females. 

Some facts, however, are opposed to the belief that 
female butterflies prefer the more beautiful males ; thus, 
as I have been assured by several observers, fresh females 
may frequently be seen paired with battered, faded, or 
dingy males ; but this is a circumstance which could hard- 
ly fail often to follow from the males emerging from their 
cocoons earlier than the females. With moths of the 
family of the Bombycidae, the sexes pair immediately after 
assuming the imago state; for they cannot feed, owing to 
the rudimentary condition of their mouths. The females, 
as several entomologists have remarked to me, lie in an 
almost torpid state, and appear not to evince the least 
choice in regard to their partners. This is the case with 
the common silk-moth [JB. mori), as I have been told by 
some Continental and English breeders. Dr. Wallace, 
who has had such immense experience in breeding Bom- 
byx cynthia, is convinced that the females evince no choice 
or preference. He has kept above 300 of these moths liv- 
ing together, and has often found the most vigorous fe- 
males mated with stunted males. The reverse apparently 
seldom occurs ; for, as he believes, the more vigorous 
males pass over the weakly females, being attracted by 
those endowed with most vitality. Although we have 
been indirectly induced to believe that the females of 
many species prefer the more beautiful males, I have no 
reason to suspect, either with moths or butterflies, that 
the males are attracted by the beauty of the females. If 



Chap. XL] BUTTERFLIES AND MOTHS. 389 

the more beautiful females had been continually preferred, 
it is almost certain, from the colors of butterflies being so 
frequently transmitted to one Sex alone, that the females 
would often have been rendered more beautiful than their 
male partners. But this does not occur except in a few 
instances; and these can be explained, as we shall pres- 
ently see, on the principle of mimicry and protection. 

As sexual selection primarily depends on variability, a 
few words must be added on this subject. In respect to 
color there is no difliculty, as any number of highly-varia- 
ble Lepidoptera could be named. One good instance will 
suffice : Mr. Bates showed me a whole series of specimens 
of Papillo sesostris and childrence y in the latter the males 
varied much in the extent of the beautifully-enamelled 
green patch on the fore-wings, and in the size of the white 
mark, as well as of the splendid crimson stripe on the 
hind-wings; so that there was a great contrast between 
the most and least gaudy males. The male of Papillo 
sesostris, though a beautiful insect, is much less so than 
P. childrence. It likewise varies a little in the size of the 
green patch on the fore-wings, and in the occasional ap- 
pearance of a small crimson stripe on the hind-wings, bor- 
rowed, as it would seem, from its own female ; for the fe- 
males of this and of many other species in the iEneas 
group possess this crimson stripe. Hence, between the 
brightest specimens of P. sesostris and the least bright of 
P. childrence, there was but a small interval; and it was 
evident that, as far as mere variability is concerned, there 
would be no difficulty in permanently increasing, by means 
of selection, the beauty of either species. The variability 
is here almost confined to the male sex ; but Mr. Wallace 
and Mr. Bates have shown 18 that the females of some 

18 Wallace on the Papilionida? of the Malayan Region, in ' Transact. 
Linn. Soc.' vol. xxv. 1865, pp. 8, 36. A striking case of a rare variety, 



590 SEXUAL SELECTION. [Part IL 

other species are extremely variable, the males being 
nearly constant. As I have before mentioned the Ghost 
Moth {Ilepialus humuli) as one of the best instances in 
Britain of a difference in color between the sexes of 
moths, it may be worth adding 19 that, in the Shetland 
Islands, males are frequently found which closely resem- 
ble the females. In a future chapter I shall have occasion 
to show that the beautiful eye-like spots or ocelli, so com- 
mon on the wings of- many Lepidoptera, are eminently 
variable. 

On the whole, althouga many serious objections may 
be urged, it seems probable that most of the species of 
Lepidoptera which are brilliantly colored, owe their col- 
ors to sexual selection, excepting in certain cases, pres- 
ently to be mentioned, in which conspicuous colors are 
beneficial as a protection. From the ardor of the male 
throughout the animal kingdom, he is generally willing to 
accept any female ; and it is the female which usually ex- 
erts a choice. Hence, if sexual selection has here acted, 
the male, when the sexes differ, ought to be the most 
brilliantly colored ; and this undoubtedly is the ordinary 
rule. When the sexes are brilliantly colored and resem- 
ble each other, the characters acquired by the males ap- 
pear to have been transmitted to both sexes. But will 
this explanation of the similarity and dissimilarity *n 
color between the sexes suffice ? 

The males and females of the same species of butterfly 
are known 20 in several cases to inhabit different stations, 

strictly intermediate between two other well-marked female varieties, is 
given by Mr. Wallace. See also Mr. Bates, in c Proc. Entomolog. Soc. 
Nov. 19, 1866, p. xl. 

19 Mr. R. MacLachlan, ' Transact. Ent. Soc' vol. ii. part 6th, 3d series, 
1866, p. 459. 

20 H. W. Bates, 'The Naturalist on the Amazons,' vol. ii. 1863, p. 
228. A. R. Wallace, in ' Transact. Linn. Soc' vol. xxv. 1865, p. 10. 



Chap. XL] BUTTERFLIES AND MOTHS. 391 

the former commonly basking in the sunshine, the latter 
haunting gloomy forests. It is therefore possible that 
different conditions of life may have acted directly on the 
two sexes ; but this is not probable, 31 as in the adult state 
they are exposed during a very short period to different 
conditions ; and the larvse of both are exposed to the same 
conditions. Mr. Wallace believes that the less brilliant 
colors of the female have been specially gained in all or 
almost all cases for the sake of protection. On the con- 
trary, it seems to me more probable that the males alone, 
in the large majority of cases, have acquired their bright 
colors through sexual selection, the females having been 
but little modified. Consequently the females of distinct 
but allied species ought to resemble each other much 
more closely than do the males of the same species ; and 
this is the general rule. The females thus approximately 
show us the primordial coloring of the parent-species of 
the group to which they belong. They have, however, 
almost always been modified to a certain extent by some 
of the successive steps of variation, through the accumula- 
tion of which the males were rendered beautiful, having 
been transferred to them. The males and females of allied 
though distinct species will also generally have been ex- 
posed during their prolonged larval state to different con- 
ditions, and may have been thus indirectly affected ; 
though with the males any slight change of color thus 
caused will often have been completely masked by the 
brilliant tints gained through sexual selection. When we 
treat of Birds, I shall have to discuss the whole question 
whether the differences in color between the males and 
females have been in part specially gained by the latter 
as a protection ; so that I will here # only give unavoidable 
details. 

81 On this whole subject, see ' The Variation of Animals and Plants 
under Domestication,' vol. ii. 1868, chap, xxiii. 



592 SEXUAL SELECTION. [Pabt II 

In all cases when the more common form of equal in- 
heritance by both sexes has prevailed, the selection of 
bright-colored males would tend to make the females 
bright-colored ; and the selection of dull-colored females 
would tend to make the males dull. If both processeB 
were carried on simultaneously, they would tend to neu- 
tralize each other. As far as I can see, it would be ex- 
tremely difficult to change through selection the one form 
of inheritance into the other. But, by the selection of suc- 
cessive variations, which were from the first sexually lim- 
ited in their transmission, there would not be the slightest 
difficulty in giving bright colors to the males alone, and 
at the same time, or subsequently, dull colors to the fe- 
males alone. In this latter manner female butterflies and 
moths may, as I fully admit, have been rendered incon- 
spicuous for the sake of protection, and widely different 
from their males. 

Mr. Wallace 22 has argued with much force in favor of 
his view that, when the sexes differ, the female has been 
specially modified for the sake of protection; and that 
has been effected by one form of inheritance, namely, the 
transmission of characters to both sexes, having been 
changed through the agency of natural selection into the 
other form, namely, transmission to one sex. I was at 
first strongly inclined to accept this view; but, the more I 
have studied the various classes throughout the animal 
kingdom, the less probable it has appeared. Mr. Wallace 
urges that both sexes of the Heliconidce, Dana idee, Acra- 
eidce, are equally brilliant because both are protected 
from the attacks of birds and other enemies, by their of- 
fensive odor; but that in other groups, which do not 
possess this immunity, the females have been rendered 

22 A. R. Wallace, in 'The Journal of Travel,' vol. i. 1868, p. 88. 
•Westminster Review/ July, 186*7, p. 37. See also Messrs. Wallace and 
Bates in 'Proc. Ent. Soc*.' Nov. 19, 1866, p. xxxix. 



Chap. XL] BUTTERFLIES AND MOTHS. 393 

inconspicuous, from having more need of protection than 
the males. This supposed difference in the " need of pro- 
tection by the two sexes " is rather deceptive, and requires 
some discussion. It is obvious that brightly-colored indi- 
viduals, whether males or females, would equally attract, 
and obscurely-colored individuals equally escape, the at- 
tention of their enemies. But we are concerned with the 
effects of the destruction or preservation of certain indi- 
viduals, of either sex, on the character of the race. With 
insects, after the male has fertilized the female, and after 
the latter has laid her eggs, the greater or less immunity 
from danger of either sex could not possibly have any 
effect on the offspring. Before the sexes have performed 
their proper functions, if they existed in equal numbers 
and if they strictly paired (all other circumstances being 
the same), the preservation of the males and females 
would be equally important for the existence of the spe- 
cies and for the character of the offspring. But with 
most animals, as is known to be the case with the do- 
mestic silk-moth, the male can fertilize two or three 
females ; so that the destruction of the males would not 
be so injurious to the species as that of the females. On 
the other hand, Dr. Wallace believes that with moths the 
progeny from a second or third fertilization is apt to 
be weakly, and therefore would not have so good chance 
of surviving. When the males exist in much greater 
numbers than the females, no doubt many males might 
be destroyed with impunity to the species ; but I cannot 
see that the results of ordinary selection for the sake of 
protection would be influenced by the sexes existing in 
unequal numbers; for the same proportion of the more 
conspicuous individuals, whether males or females, would 
probably be destroyed. If, indeed, the males presented a 
greater range of variation in color, the result would be 
different ; but we peed not here follow out such complex 



394 • SEXUAL SELECTION. [Part II. 

details. On the whole, I cannot perceive that an ine- 
quality in the numbers of the two sexes would influence 
in any marked manner the effects of ordinary selection on 
the character of the offspring. 

Female Lepidoptera require, as Mr. Wallace insists, 
some days to deposit their fertilized ova and to search 
for a proper place ; during this period (while the life of 
the male was of no importance) the brighter-colored fe- 
males would be exposed to danger and would be liable to 
be destroyed. The duller-colored females, on the other 
hand, would survive, and thus would influence, it might be 
thought, in a marked manner the character of the species 
■ — either of both sexes or of one sex, according to which 
form of inheritance prevailed. But it must not be for- 
gotten that the males emerge from the cocoon-state some 
days before the females, and during this period, while 
the unborn females were safe, the brighter-colored males 
would be exposed to danger; so that ultimately both 
sexes would probably be exposed during a nearly equal 
length of time to danger, and the elimination of conspicu- 
ous colors would not be much more effective in the one 
than the other sex. 

It is a more important consideration that female Le- 
pidoptera, as Mr. Wallace remarks, and as is known to 
every collector, *are generally slower flyers than the males. 
Consequently the latter, if exposed to greater danger 
from being conspicuously colored, might be able to escape 
from their enemies, while the similarly-colored females 
would be destroyed ; and thus the females would have the 
most influence in modifying the color of their progeny. 

There is one other consideration: bright colors, as far 
as sexual selection is concerned, are commonly of no ser- 
vice to the females ; so that if the latter varied in bright- 
ness, and the variations were sexually limited in their 
transmission, it would depend on mere chance whether 



Chap. XI.] BUTTERFLIES AND MOTHS. 395 

the females had their bright colors increased; and this 
would tend throughout the Order to diminish the number 
of species with brightly-colored females in comparison 
with the species having brightly-colored males. On the 
other hand, as bright colors are supposed to be highly ser- 
viceable to the males in their love-struggles, the brighter 
males (as we shall see in the chapter on Birds) although 
exposed to rather greater danger, would on an average 
procreate a greater number of offspring than the duller 
males. In this case, if the variations were limited in their 
transmission to the male sex, the males alone would be 
rendered more brilliantly colored; but if the variations 
were not thus limited, the preservation and augmentation 
of such variations would depend on whether more evil 
was caused to the species by the females being rendered 
conspicuous, than good to the males by certain individuals 
being successful over their rivals. 

As there can hardly be a doubt that both sexes of 
many butterflies and moths have been rendered dull-col- 
ored for the sake of protection, so it may have been with 
the females alone of some species in which successive 
variations toward dulness first appeared in the female sex, 
and were from the first limited in their transmission to 
the same sex. If not thus limited, both sexes would be- 
come dull-colored. We shall immediately see, when we 
treat of mimicry, that the females alone of certain but- 
terflies have been rendered extremely beautiful for the 
sake of protection, without any of the successive protec- 
tive variations having been transferred to the male, to 
whom they could not possibly have been in the least de- 
gree injurious, and therefore could not have been elimi- 
nated through natural selection. Whether in each par- 
ticular species, in which the sexes differ in color, it is the 
female Avhich has been specially modified for the sake of 
protection; or whether it is the male which has been spe- 



396 SEXUAL SELECTION. [Part II. 

cially modified for the sake of sexual attraction, the fe- 
male having retained her primordial coloring only slightly 
changed through the agencies before alluded to; or 
whether again both sexes have been modified, the fe- 
male for protection and the male for sexual attraction, can 
only be definitely decided when we know the life-history 
of each species. 

Without distinct evidence, I am unwilling to admit 
that a double process of selection has long been going on 
with a multitude of species — the males having been ren- 
dered more brilliant by beating their rivals ; and the fe- 
males more dull-colored by having escaped from their 
enemies. We may take as an instance the common brim- 
stone butterfly (Gonepteryx), which appears early in the 
spring before any other kind. The male of this species is 
of a far more intense yellow than the female, though she 
is almost equally conspicuous ; and in this case it does 
not seem probable that she specially acquired her pale 
tints as a protection, though it is probable that the male 
acquired his bright colors as a sexual attraction. The fe- 
male of Anthocaris cardamines does not possess the beau- 
tiful orange tips to her wings with which the male is or- 
namented ; consequently she closely resembles the white 
butterflies (Pieris) so common in our gardens ; but we 
have no evidence that this resemblance is beneficial. On 
the contrary, as she resembles both sexes of several spe- 
cies of the same genus inhabiting various quarters of the 
world, it is more probable that she has simply retained to 
a large extent her primordial colors. 

Various facts support the conclusion that, with the 
greater number of brilliantly-colored Lepidoptera, it is the 
male which has been modified; the two sexes having 
come to differ from each other, or to resemble each other, 
according to which form of inheritance has prevailed. In- 
heritance is governed by so many unknown laws or con- 



Chap. XI.] BUTTERFLIES AND MOTHS. . 397 

clitions, that they seem to us to be most capricious in their 
action ; 23 and we can so far understand how it is that with 
closely-allied species the sexes of some differ to an aston- 
ishing degree, while the sexes of others are identical in 
color. As the successive steps in the process of variation 
are necessarily all transmitted through the female, a 
greater or less number of such steps might readily become 
developed in her ; and thus we can understand the fre- 
quent gradations from an extreme difference to no differ- 
ence at all between the sexes of the species within the 
same group. These cases of gradation are much too com- 
mon to favor the supposition that we here see females ac- 
tually undergoing the process of transition and losing 
their brightness for the sake of protection ; for we have 
every reason to conclude that at any one time the greater 
number of species are in a fixed condition. "With respect 
to the differences between the females of the species in 
the same genus or family, we can perceive that they de- 
pend, at least in part, on the females partaking of the col- 
ors of their respective males. This is well illustrated in 
those groups in which the males are ornamented to an ex- 
traordinary degree ; for the females in these groups gener- 
ally partake to a certain extent of the splendor of their 
male partners. Lastly, we continually find, as already 
remarked, that the females of almost all the species in the 
same genus, or even family, resemble each other much 
more closely in color than do the males ; and this indi- 
cates that the males have undergone a greater amount of 
modification than the females. 

Mimicry. — This principle was first made clear in an ad- 
mirable paper by Mr. Bates, 24 who thus threw a flood of 

83 ' The Variation of Animals and Plants under Domestication,' yoL ii 
chap. xii. p. 17. 

* 4 • Transact. Linn. Soc.' vol. xxiii. 1862, p. 495. 



398 SEXUAL SELECTION. [Paut II. 

light on many obscure problems. It had previously been 
observed that certain butterflies in South America, belong- 
ing to quite distinct families, resembled the Heliconi- 
das so closely, in every stripe and shade of color, that 
they could not be distinguished except by an experi- 
enced entomologist. As the Heliconidge are colored in 
their usual manner, while the others depart from the usual 
coloring of the groups to which they belong, it is clear 
that the latter are the imitators, and the Heliconidae the 
imitated. Mr. Bates further observed that the imitating 
species are comparatively rare, while the imitated swarm 
in large numbers; the two sets living mingled togeth- 
er. From the fact of the HelieonidaB being conspicuous 
and beautiful insects, yet so numerous in individuals and 
species, he concluded that they must be protected from 
the attacks of birds by some secretion or odor ; and this 
hypothesis has now been confirmed by a considerable 
body of curious evidence. 26 From these considerations 
Mr. Bates inferred that the butterflies which imitate the 
protected species had acquired their present marvellously 
deceptive appearance through variation and natural se- 
lection, in order to be mistaken for the protected kinds 
and thus to escape being devoured. No explanation is 
here attempted of the brilliant colors of the imitated, but 
only of the imitating butterflies. We must account for the 
colors of the former in the same general manner as in 
the cases previously discussed in this chapter. Since 
the publication of Mr. Bates's paper, similar and equally 
striking facts have been observed by Mr. Wallace 26 in the 
Malayan region, and by Mr. Trimen in South Africa. 
As some writers 27 have felt much difficulty in under- 

25 'Proc. Ent. Soc' Dec. 3, 1866, p. xiv 

96 ' Transact. Linn. Soc' vol. xxv. 1865, p. 1; also { Transact. Ent. 
Soc.' vol. iv. (3d series), 1867, p. 301. 

91 See an ingenious article entitled -" Difficulties of the Theory of Nat- 



Chap. XL] BUTTERFLIES AND MOTHS. 399 

standing how the first steps in the process of mimicry 
could have been effected through natural selection, it may 
be well to remark that the process probably has never 
commenced with forms widely dissimilar in color. But, 
with two species moderately like each other, the closest 
resemblance, if beneficial to either form, could readily be 
thus gained ; and, if the imitated form was subsequently 
and gradually modified through sexual selection or any 
other means, the imitating form would be led along the 
same track, and thus be modified to almost any extent, so 
that it might ultimately assume an appearance or coloring 
wholly unlike that of the other members of the group to 
which it belonged. As extremely slight variations in col- 
or would not in many cases suffice to render a species so 
like another protected species as to lead to its preserva- 
tion, it should be remembered that many species of Lepi- 
doptera are liable to considerable and abrupt variations in 
color. A few instances have been given in this chapter ; 
but under this point of view Mr.. Bates's original paper 
on mimicry, as well as Mr. Wallace's papers, should be 
consulted. 

In the foregoing cases both sexes of the imitating spe- 
cies resemble the imitated; but occasionally the female 
alone mocks a brilliantly-colored and protected species 
inhabiting the same district. Consequently the female 
differs in color from her own male, and, which is a rare and 
anomalous circumstance, is the more brightly-colored of the 
two. In all the few species of Pieridse, in which the female 
is more conspicuously colored than the male, she imitates, 

ural Selection," in the ' Month,' 1869. The writer strangely supposes 
that I attribute the variations in color of the Lepidoptera, by which cer- 
tain species belonging to distinct families have come to resemble others, 
to reversion to a common progenitor ; but there is no more reason to 
attribute these variations to reversion than in the case of any ordinary 
variation. 



tOO SEXUAL SELECTION. [Part II. 

as I am informed by Mr. Wallace, some protected species 
inhabiting the same region. The female of Diadema 
anomala is rich purple-brown with almost the whole 
surface glossed with satiny blue, and she closely imitates 
the Euploea midamus, " one of the commonest butter- 
flies of the East ; " while the male is bronzy or olive- 
brown, with only a slight blue gloss on the outer parts 
of the wings. 28 Both sexes of this Diadema and of D, 
bolina follow the same habits of life, so that the differ- 
ences in color between the sexes cannot be accounted 
for by exposure to different conditions ; 29 even if this ex- 
planation were admissible in other instances. 30 

The above cases, of female butterflies which are more 
brightly-colored than the males, show us, firstly, that 
variations have arisen in a state of nature in the female 
sex, and have been transmitted exclusively, or almost ex- 
clusively, to the same sex ; and, secondly, that this form 
of inheritance has not been determined through natural 
selection. For, if we assume that the females, before they 
became brightly colored in imitation of some protected 
kind, were exposed during each season for a longer period 
to danger than the males, or if we assume that they 
could not escape so swiftly from their enemies, we can 
understand how they alone might originally have acquired 
through natural selection and sexually-limited inheritance 
their present protective colors. But, except on the prin- 
ciple of these variations having been transmitted exclu* 
sively to the female offspring, we cannot understand why 
the males should have remained dull-colored; for it would 

28 Wallace, " Notes on Eastern Butterflies," ' Transact. Ent. Soc' 
1869, p. 287. 

"Wallace, in 'Westminster Review,' July, 1867, p. 37; and in 
♦Journal of Travel and Nat. Hist.' vol. i. 1868, p. 88. 

80 See remarks by Messrs. Bates and Wallace, in ' Proc. Ent Soc.' 
Nov. 19, 1866, p. xxxix. 



Chap. XI.] BUTTERFLIES AND MOTHS. 401 

surely not have been in any way injurious to each indi- 
vidual male to have partaken by inheritance of the pro- 
tective colors of the female, and thus to have had a better 
chance of escaping destruction. In a group in which 
brilliant colors are so common as with butterflies, it can- 
not be supposed that the males have been kept dull-col- 
ored through sexual selection by the females rejecting the 
individuals which were rendered as beautiful as them- 
selves. We may, therefore, conclude that in these cases 
inheritance by one sex is not due to the modification 
through natural selection of a tendency to equal inherit- 
ance by both sexes. 

It may be well here to give an analogous case in an- 
other Order, of characters acquired only by the female, 
though not in the least injurious, as far as we can judge, 
to the male. Among the Phasmidae, or spectre-insects, 
Mr. Wallace states that it is often the females alone that 
so strikingly resemble leaves, while the males show only 
a rude approximation." Now, whatever may be the hab- 
its of these insects, it is highly improbable that it could 
be disadvantageous to the males to escape detection by 
resembling leaves. 81 Hence we may conclude that the 

31 See Mr. Wallace in 'Westminster Review,' Julyj 1867, pp. 11, 3*7. 
The male of no butterfly, as Mr. "Wallace informs me, is known to differ in 
color, as a protection, from the female ; and he asks me how I can ex- 
plain this fact on the principle that one sex alone has varied and has 
transmitted its variations exclusively to the same sex, without the aid of 
selection to check the variations being inherited by the other sex. No 
doubt, if it could be shown that the females of very many species had been 
rendered beautiful through protective mimicry, but that this has never 
occurred with the males, it would be a serious difficulty. But the number 
of cases as yet known hardly suffices for fair judgment. We can sec 
that the males, from having the power of flying more swiftly, and thus 
escaping danger, would not be so likely as the females to have had their 
colors modified for the sake of protection ; but this would not in the 
least have interfered with their receiving protective colors through in- 

18 



402 SEXUAL SELECTION. PPart IL 

females alone in this latter as in the previous cases origi- 
nally varied in certain characters ; these characters hav- 
ing been preserved and augmented through ordinary se- 
lection for the sake of protection, an 1 from the first trans- 
mitted to the female offspring alone. 

Bright Colors of Caterpillars. — While reflecting on 
the beauty of many butterflies, it occurred to me that 
some caterpillars were splendidly colored, and as sexual 
selection could not possibly have here acted, it appeared 
rash to attribute the beauty of the mature insect to this 
agency, unless the bright colors of their larvce could be in 
some manner explained. In the first place, it may be ob- 
served that the colors of caterpillars do not stand in any 
close correlation with those of the mature insect. Sec- 
ondly, their bright colors do not serve in any ordinary 
manner as a protection. As an instance of this, Mr. Bates 
informs me that the most conspicuous caterpillar which he 
ever beheld (that of a Sphinx) lived on the large green 
leaves of a tree on the open llanos of South America ; it 
was about four inches in length, transversely banded with 
black and yellow, and with its head, legs, and tail of a 
bright red. Hence it caught the eye of any man who 

heritance from the females. In the second place, it is probable that 
sexual selection would actually tend to prevent a beautiful male from 
becoming obscure, for the less brilliant individuals would be less attrac- 
tive to the females. Supposing that the beauty of the male of any species 
had been mainly acquired through sexual selection, yet if this beauty 
likewise served as a protection, the acquisition would have been aided 
by natural selection. But it would be quite beyond our power to dis- 
tinguish between the two processes of sexual and ordinary selection 
Hence it is not likely that we should be able to adduce cases of the malea 
having been rendered brilliant exclusively through protective mimicry, 
though this is comparatively easy with the females, which have rarely or 
never been rendered beautiful, as far as we can judge, for the sake of 
sexual attraction, although they have often received beauty through in- 
heritance from their male parents. 



Chap. XL] BUTTERFLIES AND MOTHS. 403 

passed by at the distance of many yards, and no doubt of 
every passing bird. 

I then applied to Mr. Wallace, who has an innate 
genius for solving difficulties. After some consideration 
he replied : " Most caterpillars require protection, as may 
be inferred from some kinds being furnished with sjunes 
or irritating hairs, and from many being colored green like 
the leaves on which they feed, or curiously like the twigs 
of the trees on which they live." I may add as another 
instance of protection, that there is a caterpillar of a moth, 
as I am informed by Mr. J. Mansel Weale, which lives on 
the mimosas in South Africa, and fabricates for itself a 
case, quite undistinguishable from the surrounding thorns. 
From such consideration Mr. Wallace thought it probable 
that conspicuously-colored caterpillars were protected by 
having a nauseous taste ; but as their skin is extremely 
tender, and as their intestines readily protrude from a 
wound, a slight peck from the beak of a bird would be as 
fatal to them as if they had been devoured. Hence, as 
Mr. Wallace remarks, " distastefulness alone would be in- 
sufficient to protect a caterpillar unless some outward sign 
indicated to its would-be destroyer that its prey was a dis- 
gusting morsel." Under these circumstances it would 
be highly advantageous to a caterpillar to be instanta- 
neously and certainly recognized as unpalatable by all 
birds and other animals. Thus the most gaudy colors 
would be serviceable, and might have been gained by 
variation and the survival of the most easily-recognized 
individuals. 

This hypothesis appears at first sight very bold ; but 
when it was brought before the Entomological Society sa 
it was supported by various statements ; and Mr. J. Jen- 
ner Weir, who keeps a large number of birds in an aviary, 

32 'Proc. Eutomolog. Soc.' Dec. 3, 1SG6, p. xlv., and March 4, 1867, 

p. liXX. 



404 SEXUAL SELECTION. [Part II. 

has made, as he informs me, numerous trials, and finds no 
exception to the rule, that all caterpillars of nocturnal and 
retiring habits with smooth skins, all of a green color, and 
all which imitate twigs, are greedily devoured by his birds. 
The hairy and spinose kinds are invariably rejected, as 
were four conspicuously-colored species. When the birds 
rejected a caterpillar, they plainly showed, by shaking 
their heads and cleansing their beaks, that they were dis- 
gusted by the taste. 33 Three conspicuous kinds of caterpil- 
lars and moths were also given by Mr. A. Butler to some 
lizards and frogs, and were rejected ; though other kinds 
were eagerly eaten. Thus the probable truth of Mr. Wal- 
lace's view is confirmed, namely, that certain caterpillars 
have been made conspicuous for their own good, so as to 
be easily recognized by their enemies, on nearly the same 
principle that certain poisons are colored by druggists for 
the good of man. This view will, it is probable, be here- 
after extended to many animals, which are colored in a 
conspicuous manner. 

Summary and Concluding Remarks on Insects. — 
Looking back to the several Orders, we have seen that 
the sexes often differ in various characters, the meaning 
of which is not understood. The sexes, also, often differ 
in their organs of sense or locomotion, so that the males 
may quickly discover or reach the females, and still oftener 
in the males possessing diversified contrivances for retain- 
ing the females when found. But we are not here much 
concerned with sexual differences of these kinds. 

In almost all the Orders, the males of some species, 
even of weak and delicate kinds, are known to be highly 
pugnacious ; and some few are furnished with special weap- 
ons for fighting with their rivals. But the law of battle 

33 See Mr. J. Jenner Weir's paper on insects and insectivorous birds, 
in 'Transact. Ent. Soc' 1869, p. 21 ; also Mr. Butler's paper, ibid. p. 2T. 



Chap. XL] SUMMARY ON INSECTS. 405 

does not prevail nearly so widely with insects as with the 
higher animals. Hence probably it is that the males have 
not often been rendered larger and stronger than the fe- 
males. On the contrary, they are usually smaller, in order 
that they may be developed within a shorter time, so as to 
be ready in large numbers for the emergence of the 
females. 

In two families of the Homoptera the males alone pos- 
sess, in an efficient state, organs which may be called vo- 
cal ; and in three families of the Orthoptera the males alone 
possess stridulating organs. In both cases these organs 
are incessantly used during the breeding-season, not only 
for calling the females, but for charming or exciting them 
in rivalry with other males. No one, who admits the agen- 
cy of natural selection, will dispute that these musical 
instruments have been acquired through sexual selection. 
In four other Orders the members of one sex, or more 
commonly of both sexes, are provided with organs for 
producing various sounds, which apparently serve merely 
as call-notes. Even when both sexes are thus provided, 
the individuals which were able to make the loudest or 
most continuous noise would gain partners before those 
which were less noisy, so that their organs have probably 
been gained through sexual selection. It is instructive to 
reflect on the wonderful diversity of the means for produ- 
cing sound, possessed by the males alone or by both sexes 
in no less tha^n six Orders, and which were possessed by at 
least one insect at an extremely remote geological epoch. 
We thus learn how effectual sexual selection has been in 
leading to modifications of structure, which sometimes, as 
with the Homoptera, are of an important nature. 

For the reasons assigned in the last chapter, it is prob- 
able that the great horns of the males of many lamellicorn, 
and some other beetles, have been acquired as ornaments. 
So perhaps it may be with certain other peculiarities con- 



406 SEXUAL SELECTION. [Part II. 

fined to the male sex. From the small size of insects, we 
are apt to undervalue their appearance. If we could im- 
agine a male Chalcosoma (fig. 15) with its polished, bronzed 
coat-of-mail, and vast complex horns, magnified to the 
size of a horse or even of a dog, it would be one of the 
most imposing animals in the world. 

The coloring of insects is a complex and obscure sub- 
ject. When the male differs slightly from the female, 
and neither is brilliantly colored, it is probable that the 
two sexes have varied in a slightly different manner, with 
the variations transmitted to the same sex, without any 
benefit having been thus derived or evil suffered. When 
the male is brilliantly colored and differs conspicuously 
from the female, as with some dragon-flies and many but- 
terflies, it is probable that he alone has been modified, and 
that he owes his colors to sexual selection ; while the fe- 
male has retained a primordial or very ancient type of 
coloring, slightly modified by the agencies before explained, 
and has therefore not been rendered obscure, at least in 
most cases, for the sake of protection. But the female 
alone has sometimes been colored brilliantly so as to imi- 
tate other protected species inhabiting the same district. 
When the sexes resemble each other and both are obscure- 
ly colored, there is no doubt that they have been in a 
multitude of cases colored for the sake of protection. So 
it is in some instances when both are brightly colored, 
causing them to resemble surrounding objects such as 
flowers, or other protected species, or indirectly by giving 
notice to their enemies that they are of an unpalatable 
nature. In many other cases in which the sexes resemble 
each other and are brilliantly colored, especially when the 
colors are arranged for display, we may conclude that they 
have been gained by the male sex as an attraction, and 
have been transferred to both sexes. We are more es- 
pecially led to this conclusion whenever the same type of 



> 



Chap. XI.] SUMMARY ON INSECTS. 40? 

coloration prevails throughout a group, aud we find that 
the males of some species differ widely in color from the 
females, while both sexes of other species are quite alike, 
with intermediate gradations connecting these extreme 
states. 

In the same manner as bright colors have often been 
partially transferred from the males to the females, so it 
has been with the extraordinary horns of many lamellicom 
and some other beetles. So, again, the vocal or instru- 
mental organs proper to the males of the Homoptera and 
Orthoptera have generally been transferred in a rudimen- 
tary, or even in a nearly perfect condition to the females ; 
yet not sufficiently perfect to be used for producing sound. 
It is also an interesting fact, as bearing on sexual selec- 
tion, that the stridulating organs of certain male Orthop- 
tera are not fully developed until the last moult ; and that 
the colors of certain male dragon-flies are not fully devel- 
oped until some little time after their emergence from the 
pupal state, and when they are ready to breed. 

Sexual selection implies that the more attractive indi- 
viduals are preferred by the opposite sex ; and as with in- 
sects, when the sexes differ, it is the male which, with 
rare exceptions, is the most ornamented and departs most 
from the type to which the species belongs, and as it is 
the male which searches eagerly for the female, we must 
suppose that the females habitually or occasionally prefer 
the more beautiful males, and that these have thus ac- 
. quired their beauty. That in most or all the orders the 
females have the power of rejecting any particular male, 
we may safely infer from the many singular contrivances 
possessed by the males, such as great jaws, adhesive 
cushions, spines, elongated legs, etc., for seizing the 
female ; for these contrivances show that there is some 
difficulty in the act. In the case of unions between dis- 
tinct species, of which many instances have been recorded, 



408 SEXUAL SELECTION. [Part IL 

the female must have been a consenting party. Judging 
from what we know of the perceptive powers and affec- 
tions of various insects, there is no antecedent improba- 
bility in sexual selection having come largely into action ; 
but we have as yet no direct evidence on this head, and 
some facts are opposed to the belief. Nevertheless, when 
we see many males pursuing the same female, we can 
hardly believe that the pairing is left to blind chance — ■ 
that the female exerts no choice, and is not influenced by 
the gorgeous colors or other ornaments with which the 
male alone is decorated. 

If we admit that the females of the Homoptera and 
Orthoptera appreciate the musical tones emitted by their 
male partners, and that the various instruments for this 
purpose have been perfected through sexual selection, 
there is little improbability in the females of other insects 
appreciating beauty in form or color, and consequently in 
such characters having been thus gained by the males. 
But, from the circumstance of color being so variable, and 
from its having been so often modified for the sake of pro- 
tection, it is extremely difficult to decide in how large a 
proportion of cases sexual selection has come into play. 
This is more especially difficult in those Orders such as the 
Orthoptera, Hymenoptera, and Coleoptera, in which the 
two sexes rarely differ much in color ; for we are thus cut 
off from our best evidence of some relation between the 
reproduction of the species and color. With the Coleop- 
tera, however, as before remarked, it is in the great lamel- 
licorn group, placed by some authors at the head of the 
Order, and in which we sometimes see a mutual attach- 
ment between the sexes, that we find the males of some 
species possessing weapons for sexual strife, others fur- 
nished with wonderful horns, many with stridulating or- 
gans, and others ornamented with splendid metallic tints. 
Hence it seems probable that all these characters have 



Chap. XI.] SUMMARY OX IXSECTS. 409 

been gained though the same means, namely, sexual selec- 
tion. 

When we treat of Birds, we shall see that they pre- 
sent in their secondary sexual characters the closest anal- 
ogy with insects. Thus, many male birds are highly pug- 
nacious, and some are furnished with special weapons for 
fighting with their rivals. They possess organs which are 
used during the breeding-season for producing vocal and 
instrumental music. They are frequently ornamented 
with combs, horns, wattles, and plumes, of the most diver- 
sified kinds, and are decorated with beautiful colors, all 
evidently for the sake of display. We shall find that, as 
with insects, both sexes, in certain groups, are equally 
beautiful, and are equally provided with ornaments which 
are usually confined to the male sex. In other groups 
both sexes are equally plain-colored and unornamented. 
Lastly, in some few anomalous cases, the females are more 
beautiful than the males. We shall often find, in the 
same group of birds, every gradation from no difference 
between the sexes to an extreme difference. In the latter 
case we shall see that the females, like female insects, often 
possess more or less plain traces of the characters which 
properly belong to the males. The analogy, indeed, in all 
these respects, between birds and insects, is curiously 
close. Whatever explanation applies to the one class 
probably applies to the other ; and this explanation, as we 
shall hereafter attempt to show, is almost certainly sexual 
selection. 



END OF VOL. I. 



NEW WORK BY MR. DARWIN. 



I^ow ready. I vol. Thick i2mo. With Illustrations. $3.50. 

The Expression of the Emotions 
in Man and Animals. 

By CHARLES DARWIN, F. R. S., Author of the "Origin of Species," etc., etc. 

"Whatever one thinks of Mr. Darwin's theory, it must be admitted that his great 
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