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CONTROLLED NATURAL SELECTION
AND VALUE MARKING

CONTROLLED
NATURAL SELECTION

AND VALUE MARKING

BY

J. C. MOTTRAM, M.B. LDN.

•

LONGMANS, GREEN AND CO.
39 PATERNOSTER ROW, LONDON

NEW YORK, BOMBAY, AND CALCUTTA
1914

All rights reserved

PREFACE AND INTRODUCTION

THIS small volume makes public a new
Theory. At the outset it is most important
to make clear that no attempt is made to
prove the Theory. For this reason it would
have been better perhaps to have called it
a New Hypothesis. Nevertheless, although
proof is not attempted, the numerous ex-
amples mentioned for purposes of illustration
are, in themselves, facts which the Theory
correlates, and therefore to some extent put
the Theory to test.

One reason why proof is not attempted,
is that many and important observations
which would best test the Theory, have
either not been made or records of them have
not been found. So much is this the case,
that one of the chief reasons in bringing for-
ward the Theory is to stimulate such research.
Another reason is that it supports Charles
Darwin's Causo-mechanical Theory of the
Origin of Species. A weak part in this great
Theory is and always has been the subsidiary

321924

vi CONTROLLED NATURAL SELECTION

Theory of Sexual Selection. If therefore it
could be shown that the origin of secondary
sexual characters does not require this second
Theory for their explanation, and if at the
same time it can be shown that the origin
of these characters is precisely similar to that
of all characters : then the greater Theory,
instead of being weakened by the Theory of
Sexual Selection, will be strengthened by
this widening of its capacity. This is the
endeavour of the new Theory.

It follows, therefore, that it has as a foun-
dation— Darwin's Theory of the Origin of
Species, and thus it has support : but it is also
open to all the many arguments which are
levelled against this foundation. The Theory
does not deal only with secondary sexual
characters, but also with very many others
which cause di- or poly-morphisms. The
Theory is described as much as possible in
simple language ; technical words are when-
ever possible avoided, in order that it may
be intelligible to naturalists and field ob-
servers, for it is their valuable work which
is required for its substantiation or the re-
verse. New terminologies are not introduced,
although for descriptive purposes they would
have been invaluable, because on account of

PREFACE AND INTRODUCTION vii

the hypothetical nature of the thesis, they
did not appear to be justified. Repetition
has been avoided as much as possible, even
at the expense of forward reference, so that
the whole volume must be read in order that
a clear understanding may be obtained. The
volume is divided in the following manner :
Chapter I states the Theory; Chapters II,
III, and IV deal at length with some facts
on which the Theory rests ; the remaining
chapters exemplify the Theory.

Exception will probably be taken to some
of the premises chosen, to some of the steps
in the arguments ; but entrance into this
most difficult subject is made only with great
diffidence. Nevertheless hope is entertained
that even if the Theory does not correlate a
good number of the facts to which it is applied,
it will at least explain a few. Even if it does
no more than lead other minds along new
lines of thought, the author will not be dis-
satisfied.

CONTENTS

CHAP. PAGE

PREFACE AND INTRODUCTION v

I. THE THEORY 1

II. CONSPICUOUSNESS IN NATURE . . .12

III. CONSPICUOUS COLOUR . 21

IV. THE SELECTING POWER OF ENEMIES . . 42
V. FAMILY INSTINCTS 62

VI. THE COPULATORY ATTITUDES OF THE PAIR . 67

VII. PRE-COPULATORY DISPLAYS .... 73

VIII. SEXUAL COLOUR 78

IX. PARENTAL COLOUR . ... 91

X. PARENTAL AND SEXUAL CHARACTERS . . 98

XI. CONSIDERATION OF BRITISH BIRDS . 107

XII. HUMAN AND OTHER SOCIETIES . .122

CONTROLLED NATURAL SELECTION
AND VALUE MARKING

CHAPTER I

THE THEORY

BEFORE statement of the Theory is given,
certain facts of Nature must be called atten-
tion to, upon which the Theory may be said
to rest.

Firstly, the individuals of a species are, in
very many cases, not all of equal value. In
the vast majority of sexually differentiated
species, males are less valuable than females,
for these reasons : — the soma carrying the
female germ cells, the female, does not dis-
charge its germ cells until they are fertilised,
and often partially developed into embryos.
Thus the female often is equivalent to male
and female, and when about to give birth to
young, to male and female in the form of
young, individuals of the next generation.

A

2, CONTROLLED NATURAL SELECTION

On the other hand, the soma carrying the
male germ cells, the male, discharges its
germ cells before fertilisation, and therefore
is at no time bisexual, as the female can be.
For another reason, males are less valuable
than females — because the male can fer-
tilise a number of females ; therefore fewer
males than females are required by a species.
Further, as the sexes at birth commonly are
approximately equal, and the environment
of a species is always limited, and a species
is best off when it fills its environment with
individuals capable of the greatest fer-
tility ... it follows that males, when in
excess of females, or when equalling them
in number, or perhaps even when somewhat
less numerous, must be less valuable than
females. Besides a difference in the value
of individuals according to sex, there is a
difference according to age.

A very old and sterile, or relatively sterile,
individual is not only valueless but harmful
to the species, in that it fills a place that a
fertile individual should occupy. Young are
more valuable than old, because they have
a longer life for reproduction before them.

There are other factors which give in-
dividuals of a species differences in value,

THE THEORY 3

but sex and age are by far the most im-
portant.

The next fact that attention is drawn to,
is that within a species individuals often differ
widely in structure and characters. Males
differ from females, young from old, in form,
colour, structure, habits, instincts, and in many
other characters apart from their sexual organs.

These differences within a species are ap-
parently often greater than the differences
which distinguish one species from another
(compare male and female pheasant with
House and Tree sparrows), and are infinitely
greater than the variations always to be found
in every species, and by means of which, ac-
cording to Darwin's theory of the Origin of
Species, evolution has taken place.

Attention to one other fact must be called,
— namely, that individuals of a species often
form themselves into societies : males and
females become mated and form pairs, which
keep together throughout the breeding season,
or it may be for life. Parents and young also
often keep together, forming families ; or
families may meet to form herds ; societies
which may be temporary or permanent. More
complicated societies are not unknown ; for
instance, the hive bees.

4 CONTROLLED NATURAL SELECTION

On these three facts the theory may be said
to rest :

1. Within a species, individuals differ in
value.

2. Within a species, individuals differ in
structure.

3. Within a species, individuals form socie-
ties.

Further, there is a correlation between these
facts, in that the differences in value are
associated with the differences in structure.
Females are more valuable than males ; females
differ in structure from males other than in
their sexual organs. Young are more valuable
than old, and they too are different in structure.
The third fact is also correlated, in that differ-
ence in structure between male and female
and between young and old are especially to
be found in those animals which are closely
united socially, either sexually or into families.

The theory can now be stated under four
headings :

1. Natural Selection appreciates the differ-
ences in character which distinguish male from
female, young from old.

2. Natural Selection must treat associations
of individuals as units, just as it does single
individuals.

THE THEORY 5

3. Natural Selection, just as it brings about
diversity of structure by acting on individuals,
so it must bring about diversity of structure
by acting upon associations of individuals.

4. These diversities of structure found in
the unequally valuable members of societies,
control Natural Selection in such a way that
the less valuable are more liable to destruction
than the more valuable.

1. If Darwin's theory of Natural Selection
accounts for the evolution of organic matter,
if Natural Selection appreciates the more or
less small, continuous, or discontinuous varia-
tions which occur among the individuals of a
species, or even if it cannot appreciate these
but only larger variations, mutations —
if Natural Selection can do this, it must
appreciate the relatively great differences
which frequently distinguish male from female,
old from young. If the scales of Natural
Selection can detect a small difference be-
tween two individuals, it must be able to
easily detect great differences.

If chance alone does not govern the selec-
tion of very similar individuals, it is unlikely
to do so when the individuals are very
different. If the chance of taking one bird
out of two hen birds is not half, because,

6 CONTROLLED NATURAL SELECTION

although apparently similar, they are in fact
not so ; then the chance of selecting one out
of male and female birds must also not be
half; and in this case, because the individuals
are markedly different in structure, it is likely
to be further removed from half than in the
case of the apparently similar hens.

Thus these great differences in structure
between male and female, young and old,
must cause the male and the old to be more
or less liable to be selected than the female
and the young. One cannot conceive these
individuals having an equal chance of survival
in the struggle for existence.

Continuing this conception further, a ques-
tion at once arises : May not these differ-
ences in structure between male and female,
young and old, be such, that the more valuable
females and young may have a better chance
of survival than the less valuable males and
old ? may not this be their purpose ? This
question, although asked now, is answered
under heading 4, and is best answered after
headings 2 and 3 have been discussed.

2. Natural Selection must treat associations
of individuals as units, just as it does indi-
viduals. If, within a species, owing to the
struggle for existence, the fittest individuals

THE THEORY 7

alone survive — if the law of the survival of
the fittest be true — then this law must also
apply to pairs, families, or other societies of
individuals, either temporary or permanent.

If a pair A is better able to fit the environ-
ment of the species than pair B, then pair A
will have a better chance of survival, and so
of reproducing themselves, than pair B. The
male of pair A may not be better than the
male of pair B, or the female of pair A than
the female of pair B ; it is the combination
that matters and not the individuals.

So with all societies. If a community of bees
A possess, as a variation, a character which
enables them to better resist their enemies
than a community B not possessing this varia-
tion, then community A will survive and
reproduce, whilst B will succumb. In fact,
directly individuals form themselves into socie-
ties, whatever be the bond, whether close or
very slight, then they at once cease to be
units re natural selection, re the survival of
the fittest ; the society, the pair or the family
at once becomes the unit. Males may be
perhaps compared with males, females with
females — this male may be said to be
fitter than that ; but as long as the association
lasts, an individual's mate is as much a part

8 CONTROLLED NATURAL SELECTION

of himself, as any of his personal characters,
re evolution.

Those structures or characters of the indi-
viduals forming the society, which are alike,
being common to all, can of course be con-
sidered as units if desirable ; but those struc-
tures or characters peculiar to, say, the male
of a pair or of a family, cannot and must not
be considered apart from the pair or the
family.

This conception has been carried thus far,
in order that the explanation of heading 3
may be more easily understood.

3. Natural Selection, dc. — If the fixation of
a useful variation in an individual is brought
about by heredity and Natural Selection, then
when a useful variation occurs in a society,
although it may be confined to only one class
of individuals and not be found in all the
classes of individuals forming the society, it
none the less will become fixed in a like
manner.

For instance, certain males of a species may
develop, as a variation, a certain character
which, although not beneficial to them, or it
may even be harmful to them, is, however,
useful to the pair, male and female ; enabling
the pair to survive in the struggle for exist-

THE THEORY 9

ence, and to reproduce itself, better than
other pairs whose males do not possess this
added character. Such a character, associated
in the first place with maleness, will be
handed down by the male to the pair's male
offspring. Such a character should be looked
upon as a character of the pair and not of
the male, although bound to him.

So with other societies, parents or young
may possess, as variations, characters which
enable the family to reproduce itself better
than other families. When these become
fixed they must be looked upon, not as
characters of old individuals or young, but
as family characters.

It is possible to now explain heading 4.

4. These Diversities, &c. — If pairs, families,
or other societies have characters, and if,
within these societies, there are individuals
of different value, then these societies must
possess characters which compel Natural
Selection to select the less valuable indi-
viduals rather than the more valuable.

Suppose a pair be subjected to selection,
and suppose the male has, as variations, a
character which causes the selecting agent to
destroy him, the less valuable, rather than the
female, the more valuable ; then this pair will

10 CONTROLLED NATURAL SELECTION

have an advantage over other pairs, in which
the chance of male and female surviving is
equal.

If the female be destroyed, the character of
the female and the male will not be repro-
duced ; at any rate the chance of his, the
male, reproducing himself is less than males
in general, for he must find another mate.

If the male be destroyed, it by no means
follows that the male characters will be de-
stroyed, for it is likely that he has already
fertilised the female, especially as the society,
a pair in the majority of animals, only occurs
during the breeding season.

Directly the percentage of males in the population
become much reduced polygamy results, and the value
of the male will rise until it equals that of the female :
directly this balance is struck, further evolution of the
male, making him more liable to be selected, will cease.
Similarly with any other society of unequally valuable
individuals, they will become marked according to their
value, and in such a way that Natural Selection will be
controlled and compelled to take the less valuable rather
than the more valuable.

A review of the exposition. Facts :

1. Individuals of a species not of equal
value : male and female, old and young.

2. Individuals form themselves into so-
cieties : pairs, families, herds, &c.

THE THEORY 11

3. Individuals differ widely in structure :
male from female, young from old.

4. Correlation of these three facts : unequal
value with difference of structure, and both
with the formation of societies.

Sequence of argument :

1. Natural Selection must appreciate differ-
ences in structure ;

2. Natural Selection must treat associations
as units ;

3. And bring about diversity of structure
in them ;

4. Which structures control Natural Selec-
tion, so that less valuable individuals are more
liable to be destroyed than more valuable.

Thus when male is found to be different
from female it is necessary to inquire whether
the difference be due to (1) a character of
the individual which fits a monosexual en-
vironment, or (2) a character of the pair, also
of cause an environmental character, that
controls Natural Selection. And so with all
structures occurring in sociable animals and
confined to particular individuals.

Thus it is as a working hypothesis that this
new theory is brought forward, in the hope
that it may possibly explain the origin and
use of some polymorphisms.

CHAPTER II

CONSPICUOUSNESS IN NATURE

BEFORE proceeding to exemplify the Theory,
it is necessary, as will appear later, to con-
sider the methods by which animals render
themselves purposely conspicuous. Many
ways are utilised ; they may be conveniently
described under the following headings : Move-
ment, Form, Position, Colour, Sound, Scent.

Conspicuous Movement. — It is freely ad-
mitted that, in Nature, moving animals are
more conspicuous than resting ones ; the more
perfect the rest, the less conspicuous is the
animal. The simulation of death by the sus-
pension of every movement is commonly
employed by animals for protection, and ex-
amples are to be found among every class
of animals.

The majority, the vast majority of animals,
must perform various movements for the ob-
taining of food, for reproduction and other
vital processes. These motions are necessary,

12

CONSPICUOUSNESS IN NATURE 13

in spite of the fact that animals thus render
themselves conspicuous to their enemies.
Means are usually taken to make them as
little conspicuous as possible ; they are carried
out under cover, or at night, or only after
inspection has proved the absence of any
enemy. At the slightest alarm they cease.

It is not to this kind of motion that at-
tention is now to be drawn, but to those
motions made by animals whose purpose is
to make themselves conspicuous. Motions of
this kind, purposely conspicuous, are made
chiefly for two reasons : (1) to signal to
friends ; (2) to signal to enemies. Signals
to friends give notice of danger, of security,
of the presence of a comrade, of the pre-
sence of a male or female, and of many other
things.

It is not to these signals, but to the signals
to enemies, that attention is now directed.
Signals to enemies are of two kinds, and
made for two reasons : (1) Repellent, to repel
the enemy, to frighten it away ; (2) Attrac-
tive, to attract the enemy, to draw its attack.
Examples of these two kinds of signals by
motion are to be found widely distributed
throughout the animal kingdom. The majority
of animals at bay attempt to frighten away an

14 CONTROLLED NATURAL SELECTION

enemy by making some menacing movement ;
even quite small animals, insects for instance,
will then make threatening motions. Under
Eepellent motions would also be classed Warn-
ing motions ; those which presuppose know-
ledge on the part of the enemy, the attacker ;
a knowledge gained by previous association of
the motion with some unpleasantness. There
is considerable evidence that this kind of
motion is frequently mimicked.

These signals by movement are, as a rule,
associated with numerous other displays —
displays of position, attitude, colour, sound,
and scent ; for this reason they are difficult
to analyse. It is often difficult to decide
whether the motion is the essential or an
accessory of the signal.

(2) Attractive. — Motion signals, whose pur-
pose is to attract an enemy, although fre-
quently overlooked, are also common in
Nature. Amongst birds, as mentioned in
Chapters V and X under Family Instincts,
parents will frequently endeavour, by the
making of conspicuous movements, to attract
an enemy, to draw its attack. Numerous
other examples will be given when considera-
tion is made of Sexual Displays. Purposely
conspicuous movement is probably, therefore,

CONSPICUOUSNESS IN NATURE 15

an entity in Nature, and may be conveniently
classified thus :

1. Signals to friends.

Purposely
conspicuous
movements. I 2. Signals to

enemies.

(a) Repelling conspicuous move-
ment : to repel an enemy,
to frighten it away.

(&) Attracting conspicuous
movement : to attract an
enemy, to draw its attack.

Position. — Conspicuousness as the result
of position cannot properly be considered
apart from the animal's surroundings, their
form and colour. A moth resting on a tree-
trunk may be conspicuous or not, according
as its form and colour contrasts or harmonises
with that of the tree. However, there is
little doubt that some animals sometimes,
and others frequently, purposely take up
positions which render them conspicuous in
Nature. It is not always easy to decide
whether any given observed position of an
animal which is conspicuous is the result
of accident or purpose. Only by a thorough
knowledge of the habits of the animal, and
after many observations have been made,
can this be decided. For in every animal's
surroundings can be found that which will
render it, on the one hand, conspicuous, or

16 CONTROLLED NATURAL SELECTION

on the other, inconspicuous. The form,
colour, and habits of the animal may be such
that it is seldom or never found among sur-
roundings which render it inconspicuous ; or
its form, colour, and habits may produce the
opposite effect ; unfortunately our knowledge
of the habits of animals is so small (possibly
because our attention has been chiefly con-
centrated on the study of their other charac-
ters) that we are usually unable to decide
whether the observed position in Nature of
an animal is conspicuous or inconspicuous,
the result of accident or purpose.

Further analysis of this method will not
be gone into, especially as it must again be
frequently referred to when dealing with
other methods.

Form. — By form, animals can be and are
more readily recognised than by any other
attribute ; in fact, it is by the amount of
space they occupy that we know them. There
are, no doubt, species which are more easily
distinguished from closely allied species by
colour or some other character, because they
are alike in form and size ; but the mind,
unconsciously, first places them according to
their form.

A wasp is recognised, first by its shape,

CONSPICUOUSNESS IN NATURE 17

but afterwards the mind may decide what
species of wasp it is by its colour, or some
other character. For this reason, form per
se is a character which the majority of
animals endeavour to hide, because the
majority of animals wish to make themselves
inconspicuous in Nature. So much is this
so, that a study of protection is in truth a
study of the means used to obliterate form.
Nevertheless, some animals which are pur-
posely conspicuous in Nature take no pre-
cautions to obliterate form, but, in fact, rather
accentuate their shape ; these may be said
to possess purposely conspicuous form.

Thayer has shown that form is commonly rendered
inconspicuous by obliterative shading.

Absence of obliterative shading or anti-obliterative
shading, when found in animals whose form could be
concealed by obliterative shading, will be examples of
purposely conspicuous form.

Purposely conspicuous form may be classi-
fied like purposely conspicuous motion, ac-
cording as the signal is to friends or to
enemies.

Mention has already been made of con-
spicuousness, produced by the taking up of
particular positions ; this may be accentuated
by the assumption of some easily seen form in

B

18 CONTROLLED NATURAL SELECTION

that position. Animals in defence, in order to
beat off an enemy, will erect combs, feathers,
or hairs, will open mouths, stretch necks, take
up an upright position, and in many other
ways assume conspicuous attitudes ; these
may be called Eepelling Conspicuous Atti-
tudes. Just as there are attracting conspicuous
movements, so there are attracting conspicuous
attitudes. Many animals by thus making them-
selves conspicuous endeavour to draw an
enemy's attack, for instance, from their young.
Birds especially will erect combs, spread tails,
and assume all manner of conspicuous attitudes
for this purpose. A large number of pre-
copulatory displays consist in the assumption
of conspicuous attitudes.

Sound. — Sound is seldom used for ought
but signalling to friend or foe. Silence spells
concealment, sound conspicuousness.

Sound can be similarly classified :

Purposely

conspicuous ^

sounds.

1. Signals to ((«) Between the aex*

- . , i (o) Between members or other
I societies.

2. Signals to
enemies.

(a.) Repellent
sounds : to
enemy away.

(b) Attractive

(conspicuous)
frighten

an

(conspicuous)

sounds : to attract an enemy,
to draw its attack.

CONSPICUOUSNESS IN NATURE 19

Repellent sounds are very commonly used
to ward off a foe : sudden and therefore
startling sounds are especially used. Attract-
ing sounds, to draw an enemy's attack from
the young, are often difficult to distinguish
from the alarm notes made to warn the young
of danger ; it may be that sometimes the same
note is used for the two purposes. The cry
of the Plover or Curlew certainly causes the
young to take cover, and more than likely
distracts the enemy's attention from the young
to the screaming parents.

Evidence will be brought forward later to
show that the songs of birds are to protect
the female, by drawing the attention of
any near predatory animal to the singer,
the male.

It may be here mentioned that the drawing
of an enemy's attack is not in any way an
act of self-destruction. Predatory animals
usually take their victims by surprise, and
probably then stand as good a chance of
making a successful capture, as when the
victim is purposely exposing itself in order
to draw attack.

Scent. — Scent is used precisely like Sound.
Repellent scents are always unpleasant ; but
owing to the inferiority of our sense of smell,

20 CONTROLLED NATURAL SELECTION

knowledge of the subject is meagre, and prob-
ably untrustworthy. It may be that there
are pleasing scents, the purpose of which is to
attract enemies.

One other method, by means of which
animals render themselves conspicuous, re-
mains to be considered, namely colour. This
has been left to the last, because it is the
most important and because a previous con-
sideration of the other methods may render
its consideration more comprehensible. This
is dealt with in the next chapter.

CHAPTER III

CONSPICUOUS COLOUR

IT is not possible to conceive that the colour
of an animal, in Nature, is purposeless, indif-
ferent, the result of chance. The colour of
domesticated animals may be conceived to be
of such a nature, but if one believes in the
Origin of Species as expounded by Charles
Darwin, then the colour of animals in Nature
must be looked upon as purposeful ; and it
can have but two uses : (1) to make an animal
inconspicuous, (2) to make it conspicuous.
This it can only do by contrast ; to consider the
colour of an animal per se must be meaning-
less ; only the comparison of its colour with
that of its surroundings can be of any value.
Therefore when considering the colour of
animals, at least three factors must be taken
into account : (1) the colour of the animal,
(2) the colour of its environments, and (3) the
animal's habits. Without a knowledge of its
habits, it is impossible to decide whether an

21

22 CONTROLLED NATURAL SELECTION

animal is conspicuous or inconspicuous in
Nature, wherein all kinds of backgrounds are
to be found, backgrounds which will render
the most brilliantly coloured animal incon-
spicuous, and backgrounds which will make
the dullest easy to see. For this reason, the
animal's habits must be taken into account ;
it is necessary to know whether a given
animal is commonly or uncommonly seen
against obliterating backgrounds. It is also
necessary to know, for instance, in the case
of butterflies, what are the common back-
grounds found behind the insects on the one
hand when they have open wings, and on the
other, when they have closed.

Colour rarely is used for other purposes. Metabolic
processes may give rise to colours which are purposeless,
apart from metabolism. Waste products which have to
be got rid of, may be deposited on the surfaces of plants
and animals.

Colour may have other uses ; for instance, black for the
absorption of the sun's heat, white for its reflection : the
green chlorophyl of plants comes under this category.

Eeference will again be made to Habits,
when Thayer's theory (that all animals are
protectively coloured) is being criticised ; in
the meantime, apart from habits, certain
generalisations of colour in Nature can be
made.

CONSPICUOUS COLOUR 23

The face of our earth is, broadly speaking,
coloured with secondary colours, greens,
browns, and greys ; these colours are not
laid down in flat tints but in broken masses,
which run one into the other, and nowhere
have defined margins. Individual leaves and
single stones can only be distinguished at
close range, and are then seen never to be
homogeneously coloured.

Certain portions of the globe are not so
coloured. The Arctic regions, mountain tops,
and sub-arctic regions in the winter are
covered with an even cloak of white ; deserts
are evenly coloured light brown ; oceans grey
or blue ; sky blue.

Into these backgrounds many animals fade,
through similarity of colouring. Spotted coats
and barred plumes of brown, green, and grey
blend with the field and forest ; white animals
in the snow, sandy-coloured in the desert,
grey at sea, &c., are invisible from afar.

Against these backgrounds certain parts
of plants and many animals stand out in
marked contrast — how are they coloured ?
In an exactly opposite manner : instead of
being coloured with secondary colours, the
primary ones are used, red, yellow, blue, with
black and white ; and instead of the colour

24 CONTROLLED NATURAL SELECTION

being laid down in broken masses, it is
painted on in broad flat tints. In this way
the maximum contrast is obtained. Flowers
are purposely conspicuous, so that insects and
birds may see and visit them ; they are
coloured with even washes of the primary
colours and with white. White daisies, yellow
buttercups, blue cornflowers, red poppies,
are examples always to hand ; green, grey, or
brown flowers form a very small percentage
of the whole ; they as a rule do not desire
the visits of the hoipolloi of insects, but of
one particular insect which they attract by
scent or some other method, apart from
colour.

The efficiency of this method of making
themselves conspicuous in Nature is patent
to everyone who views wild flowers ; they
will not be passed by unseen ; on the other
hand, brown and green flowers require diligent
searching for, with a well- trained eye. The
same may be said of edible fruits which present
purposely conspicuous colouring ; they are
found to be coloured with the primary
colours and with black and white, laid down
evenly.

Turn now to animals. Many are undoubtedly
protectively coloured with mottled greens,

CONSPICUOUS COLOUR 25

greys, and browns ; but there are others which
are painted with broad masses of the primary
colours and with black and white. May not
these present, like fruit and flowers, seeing
that the same method is used, purposeful con-
spicuous colouring ?

A more detailed analysis of these colours
will now be made.

White. — In regions where snow, either tem-
porarily or permanently, covers the ground,
white is used cryptically or protectively. It
is used also on the under- sides of many
animals, to produce obliterative modelling, as
Thayer has shown. Thayer is of opinion,
too, that it may also be used to conceal an
animal against the sky ; but when a flat white
surface is held against the sky at different
angles, it will either appear much darker than,
or if the sun is out, much lighter than the
white of the sky and be very conspicuous ;
only within a very small angle will it be equal
in tone to the sky. Further, only a very
small portion of the sky can be thus matched,
away from the sun and not far above the
horizon. Thus it appears that only with care,
and in one particular position, can a FLAT
white surface be made to appear inconspicuous
against the sky : with a solid white object,

26 CONTROLLED NATURAL SELECTION

it is of course quite impossible. A swan, for
instance, must always be conspicuous against
the sky. White, therefore, except in snow
and to produce obliterative modelling, will
render an animal conspicuous in Nature.

Black. — As with white, it is possible to
conceive of a black animal being invisible,
for instance, against a black shadow : a rook
sitting in the innermost recess of a thick
forest would be difficult to see ; but black
shadows are almost unknown in Nature,
especially cold black, such as is found in many
animals. Shadows in Nature are invariably
warm, because the objects in them are lit by
the reflected light from surrounding warmly
coloured objects.

Animals coloured black, and especially cold
black, must therefore be looked upon as con-
spicuously coloured. Attention had again
better be called to the fact, that it is not
enough to study colour alone ; habits must also
be taken into account. A black animal, living
in dark forests and always shunning the light,
cannot be compared in conspicuousness with
a black animal which lives in open country,
e.g. the female Blackbird with the Starling
or Rook.

Black therefore must be looked upon as

CONSPICUOUS COLOUR 27

conspicuous, unless contradicted by the habits
of the animal.

Blue. — Blue, in Nature, is found in the sky
and in its reflection in water and snow. If
white animals are seldom, if ever, inconspicuous
against the white (light grey) of the sky, then
blue animals can never be in harmony with
the blue of the sky. The amount of blue
light coming from a blue sky is enormous
compared to the amount coming from an
object coloured even very light blue, and
placed in the brightest sunlight.

It is therefore impossible for a terrestrial
animal coloured blue (a blue butterfly for
instance) ever to be in harmony with a blue
sky. Blue, used protectively, is however
found in oceanic fishes inhabiting the surface
of the water ; as a rule their dorsal surfaces
are coloured blue, in harmony with the low-
toned blue of very deep water as it is seen
from above. Now the blue of these fish is
not less brilliant than the blue found in
terrestrial animals ; and as this blue harmonises
with the low-toned blue of the sea, it cannot,
in terrestrial animals, ever harmonise with the
intensely high-toned blue of the sky. It thus
appears that the blue of terrestrial animals is
not protective ; and if not protective, it must

28 CONTROLLED NATURAL SELECTION

be purposely conspicuous, as it cannot be
indifferent.

Yellow. — The primary colour, yellow, is a
very rare environment for animals, and so it
is very rarely used protectively. A few insects
which fly in the autumn are yellow, in harmony
with the yellow autumnal foliage. Sunlight
penetrating young green foliage is not a pure
colour but yellow-green ; this colour is found
on the breasts of a number of birds, the
Willow Wren (Phylloscopus trochilus) for in-
stance ; compare this with the yellow bar in
the Goldfinch's (Carduelis elegans) wing, and
with the yellow of the male Golden Oriole.

Red. — Above all others, animals coloured
red are the most conspicuous in Nature,
because it is never found in the surroundings.
The rising and setting sun sometimes colours
all things red, animals as well as their sur-
roimdings. Thayer is of opinion that some
scarlet animals, Flamingoes (Phoenicopterus
ruber} for instance, are coloured thus to
render them invisible against the red of the
setting sun ; that which has already been said
about sky protections, under White and Blue,
also applies to Red ; a red animal against the
setting sun, by contrast, looks not red but
black.

CONSPICUOUS COLOUR 29

Having analysed to some extent colour in
Nature, and shown that some colours cannot,
and others probably do not, render an animal
inconspicuous, and must therefore make it
conspicuous, it now becomes necessary to
consider the colour and habits of animals
conjointly. By means of examples it will be
shown that the colour and habits of animals
are correlated ; and that conspicuous colouring
in animals is a fact of Nature.

The Sheldrake (Tadorna cornuta) will be
the first example : the sexes are nearly similar,
coloured with large masses of black, white,
and red ; it lives in estuaries, on mud flats
and sand banks, it nests in sand hills ; among
these surroundings, no matter at what angle
it is viewed, it is an object visible from afar,
often at a distance of several miles. It is
possible to conceive of a background, of
boulders for instance, or of different coloured
seaweeds on white sand, against which the
bird would not be conspicuous : just as it
is easy to conceive of a background against
which it would be conspicuous : but ask the
wild-fowler or longshoreman which is the
most conspicuous bird on the shore, and
he will say— the Sheldrake. Systematically
watch the birds over a long period of time

30 CONTROLLED NATURAL SELECTION

and from different heights, from the tops of
cliffs as well as from the bases, not once in a
day will they become difficult to see.

If the Sheldrake is protectively coloured,
and this is the only alternative, then why does
it utilise a different colouring from the other
shore birds, which are undoubtedly protec-
tively coloured — the Waders, &c. ? If, on
the other hand, it is conspicuously coloured,
how does it manage to hold its own against
hawks and other predatory animals ? By
living always in open country where it cannot
be approached unawares, by always being
close to water where it can seek safety by
diving.

Why is it conspicuously coloured ?

Although to show the raison d'etre of con-
spicuous colouring would add much to the
above argument, this must be reserved for a
future chapter, in order to prevent confusion
and overlapping of the subject.

The next example chosen is the >Stonechat
(Pratincola Rubicola), a bird presenting a very
similar colour to the Sheldrake — black, red,
and white. These are its habits. It lives
and breeds on open commons, always a con-
spicuous bird from its habit of constantly
perching on the topmost branches of the

CONSPICUOUS COLOUR 31

furze bushes. Stonechats have been observed
for many hours at a stretch and from all
angles, but only on very rare occasions are
they difficult to see, as when they have dropped
down for a moment on to broken ground after
some insect food. They never depart far from
their undergrowth of furze or briar, so have
constantly at hand a secure refuge in case of
attack, and thus do not require protective
coloration. The usual background of this
bird is the sky and dark bushes, not broken
ground.

Consider the Rook (C. Frugilegus). In the
early morning the flock leave the woods, to
spend the whole day in the open country,
where they are a mark for miles around,
especially on a day of sun, for then the flashes
of light from their glossy plumages will reveal
their presence three or four miles away. In
a tree the bird is equally visible as a dark
mass against the sky. When it is possible
to look down on a colony of their nests, the
sitting birds stand out blue-black in marked
contrast to the broken brown of the nests.
The Eook is a social bird : there is safety in
numbers : it will be an advantage to a single
lost bird to be able to see the flock from
afar.

32 CONTROLLED NATURAL SELECTION

The Soldier Beetle (Telephones) is con-
spicuous in Nature, not entirely because it
is coloured black and red, but because it
chooses to spend its days on the surfaces of
white umbelliferous flowers, whence it can
be seen from afar and is at the mercy of any
bird who cares to feed upon it.

The Black Beetle (Pimarcha Icevigata) is
coloured an intense, cold, blue-black. It is
a beetle which is at large during the day,
crawling slugglishly and clumsily about and
taking no pains to conceal itself : a very con-
spicuous object. If given to birds, they will
either not take them, or having picked at
them will spend many minutes scraping their
beaks, obviously in an endeavour to get rid
of a very unpleasant flavour ; they will seldom
swallow these beetles. The Soldier Beetle is
similarly treated.

The Cinnabar Moth (Euchelia Jacobcece).
Coloured black and vivid red : it flies by day :
it is a slow flier and would fall an easy victim
to any enemy : it never takes any pains to
conceal itself, as other insects do when dis-
turbed : it does not bury itself in the grasses :
it does not seek safety in flight.

The Large White Butterfly (P. brassicce).
A slow flier — it can be seen at least 500 yards

CONSPICUOUS COLOUR 33

away — it would fall an easy victim to any bird.
In London, where the Sparrows have had
little experience of White Butterflies, I have
on several occasions (four) seen Sparrows
(P. domesticus) take them on the wing, but
always, after pecking them and killing them,
they have left them. Apparently they are
relatively unpalatable.

The Red Admiral Butterfly (Pyrameis
Atalanta) spends many hours of the day,
with outstretched wings, on flowers : flat
flowers are especially chosen ; here it is always
a conspicuous object, no matter how viewed.
It depends for its safety on quickness of sight
and rapidity of flight. When sleeping, it
closes its wings, displaying the under surfaces
only, which are not conspicuously coloured ;
and it chooses to rest among surroundings
which render it inconspicuous — among dead
leaves or on the barks of trees, &c. If
disturbed whilst thus resting, it does not fly
away, but relies for escape entirely on its pro-
tective colouring, and the simulation of an
inanimate object.

These habits associated in the same insect,
with exposure of the bright upper surfaces
of the wings on the one hand, and with the
dull under surfaces on the other, indicate,

c

34 CONTROLLED NATURAL SELECTION

without doubt, that the upper surfaces are
conspicuous in Nature and the under ones
inconspicuous.

It is probably an advantage for Admiral
butterflies to be able to see other Admiral
butterflies on flowers, from a distance ; and
thus to find good food and mates, &c.

The Tadpole (Rana Temporaries), when
very young, is coloured uniformly black. At
this stage, they keep together in colonies,
forming black wriggling masses, as noticeable
from under water as from above, and make,
when disturbed, no effort at concealment.

It is noteworthy that the black of the young
tadpole, like the black of the frog's ovum,
may be for the purpose of absorbing the sun's
heat.

Experiments have shown that young tad-
poles are unpalatable to both birds and fish ;
it seems, therefore, that they can with safety
render themselves conspicuous, and utilise
the beneficial heat-absorbing property of
blackness.

Sufficient examples, and they could be
multiplied almost indefinitely, have now been
given, to show that many animals are con-
spicuous in Nature and make no attempt to
conceal themselves.

CONSPICUOUS COLOUR 35

It appears, therefore, that Thayer's theory,
that all animals are protectively coloured, does
not correctly describe the facts. An artist's
eye will note, or his hand be able to depict,
the most brilliant animals among surround-
ings which render them inconspicuous ; but
if the animals are rarely found among these
surroundings, then such observations and such
illustrations appertain to exceptions and not
to the rule, and thereby hide the truth.

Certain broad conclusions may now be
made :

1. Animals which are coloured with the
primary colours and with black and white,
and on which these colours are laid down in
large and distinct areas, MAY or may NOT
present conspicuous colouring : a close study
of their habits and surroundings can alone
decide how they must be classed.

2. Animals which are coloured with the
secondary colours, or with the primary colours
much broken into small masses, one into
the other, are almost invariably protectively
coloured. But in these also, habits must be
taken into account. One is now in a position
to classify colour ; as before mentioned, it
must first be divided into Purposely Con-
spicuous and Purposely Inconspicuous. These

36 CONTROLLED NATURAL SELECTION

may be again sub-divided as in the following
table :

<

COLOUR

inconspicuous

to enemies

protective = procryptic.

to food

aggressive = anticryptic.

(to friends)

(? valueless.)

conspicuous

to signal to
enemies

to attract enemies =
attracting colour.

to repel enemies
= Aposematic.
= Pseudo-sematic.

to signal to
friends

Recognition marks
= Episematic.

to signal to
food

to attract food (as in
Mantidae)
= Pseudo-episematic.
= alluring colour.

The colour of an animal can, however, never
be considered as a unit. Some of the coloured
parts will be used for one purpose, others for
another. For instance, in many animals and
especially in birds, parts are conspicuously
coloured which are usually concealed, and
which are only displayed on definite occa-
sions and for definite purposes : thus, too, the
Red Admiral butterfly can, at will, display

CONSPICUOUS COLOUR 37

the upper surface of its wings, or the under
ones. No general statement, therefore, can be
made of its coloration, but its upper and
under surfaces must be separately labelled.
Further, it is readily conceived that additional
knowledge of its habits might necessitate
qualifications of these labellings : for instance,
the black might prove to be a signal to
enemies, and the red bar a social signal.

Here, however, colour must be considered
only in so far as it is purposely conspicuous, and
especially with regard to signals to enemies.

Signals to enemies are of two kinds only :
(a) in order to repel enemies ; (6) in order to
attract enemies.

Examples of repelling conspicuous colouring
(conspicuous colouring associated with un-
palatableness) are afforded by animals which
have warning coloration : it is unnecessary to
give examples, but it may be mentioned that,
in the opinion of many, protection is not
obtained, in the vast majority of these cases,
by an association in the minds of predatory
animals, of unpleasantness with a particular
species ; but with a particular class of animals,
coloured similarly.

For instance, a bird will pass by a black
beetle, not because it has tasted that particular

38 CONTROLLED NATURAL SELECTION

species, but because it is coloured black like
another species, whose flavour it has sampled ;
indeed the first beetle may in reality be palat-
able. Thus have been accounted for many
cases of mimicry, and their origin, by fortuitous
variations of palatable insects resembling un-
palatable.

To describe a colour as a warning colour,
is to describe it from the point of view of an
enemy ; it is a description of purpose rather
than of effect. The following table, given in
Professor Poulton's book, is a classification of
colour for the most part from this point of
view. Attracting colour has not been intro-
duced : it would fall under B after some
modification. The terminologies here used
have been placed in their appropriate places
in the table given on p. 36.

A. Apatetic Colours = colours resembling some part of

environment.

(1) Cryptic (a) procryptic = protective resemblance.

(b) anticryptic = aggressive resemblance.

(2) Pseudo-sematic = false signalling.

(a) pseudo-sematic = protective mimicry.

(b) pseudo-episematic = aggressive mimi-

cry or alluring.

B. Sematic Colours = signalling colours.

(1) Aposematic = warning.

(2) Episematic = recognition marks.
[(3) 1 = attracting colour.]

CONSPICUOUS COLOUR 39

Eeturning to Table I, Repelling Conspicu-
ous Colouring is also exemplified by Alarm-
ing Coloration ; many birds will frighten
away an enemy by suddenly displaying vivid
colour — the distention of scarlet bladders,
or erection of bright plumes. Insects also
utilise this method of scaring enemies ; organs
coloured with the primary colours are suddenly
disclosed or protruded.

Attracting Conspicuous Colouring, it will be
shown, is possibly much commoner in Nature
than is generally supposed ; accepted examples
are as yet uncommon. The bright under-
wings of many insects are supposed to be
of this nature, that predatory animals may
seize them, rather than more vulnerable
parts.

Parent birds, when protecting their young,
will display their brightest plumes, in order
to attract the enemy's attention, to draw
its attack ; and many examples are given in
Chapter VIII.

In the meantime, mention may be made of
certain colour marks, here called attraction
marks.

The eye-spots found in insects are con-
sidered to be for the purpose of attracting
an enemy's attention to them in order that

40 CONTROLLED NATURAL SELECTION

it may be induced to strike them rather than
more vulnerable parts, which have not eye-
spots. Other marks and colourings serve
the same purpose ; for instance, the brilliant
under- wings of many moths.

Here are examples of purposely conspicuous
characters whose function is to attract enemies.
Whenever conspicuous colouring is found on
invulnerable parts, the question must be asked,
Is this an attracting mark ? There is some
evidence that these marks are by no means
uncommon. In birds, for instance, the con-
spicuous marks and bars on wings and tail
may be of this nature. As is often the case in
insects, they are concealed when at rest and
displayed during flight, and may cause enemies
to strike at tail or wing and thus not injure
vital parts.

It is noteworthy that although young as
a rule do not present conspicuous colouring,
they do usually have these attraction marks.
(For examples see Chapter IX.)

It will be well to review the conclusions
which have been arrived at in the last two
chapters :

1. Purposeful conspicuousness of animals
is a fact of Nature.

2. It is produced in animals by means of

CONSPICUOUS COLOUR 41

movement, form, position, sound, scent, and
colour ; and probably in other ways.

3. It is used for three purposes : A, to
signal to friends ; B, to signal to enemies ;
and C, rarely, to signal to food.

4. The signals to enemies are of two kinds :
A, to repel them ; B, to attract them.

CHAPTEE IV

THE SELECTING POWER OF ENEMIES

IT is impossible to conceive of an environ-
ment, without also calling to mind that which
is invested. A biological environment is the
sum of many factors which, added together,
permit of life. A study of these factors
shows that they are not homogeneous, but
that each of them is made up of a continuous
series of diversities. Many obviously have
this constitution, such as temperature, alti-
tude above sea-level, the relation of the differ-
ent points on a tree-trunk to the points of the
compass. Others seem to form a discontin-
uity, but in these cases steps are probably not
absent, only crowded together.

Just as environment cannot be conceived
alone, so living matter cannot : the two are
inextricably mingled. The structure of living
matter is bound to its function : and function
is action on environment. Without environ-
ment, living matter could not be recognised.

The Environment of a Unit of Living

THE SELECTING POWER OF ENEMIES 43

Matter. — Here, a unit of living matter is
used in the sense of a single individual, one of
many which, collectively, form a species. If
examination be made of its environment, no
matter which factor be chosen for observation,
it will be found to be definitely bounded, in
spite of the factor not being homogeneous.

During a definite time — this must be taken
into account — a plant occupies a definite quan-
tity of space, it takes from the soil a definite
quantity of mineral matter and receives a
definite amount of sunlight.

A single animal wandering on a mountain-
side, climbs up and down to definite heights
above sea-level.

This power of being able to adapt itself to
the diversities of its environment, within limits,
is a property of all living matter.

The Environment of a Species. — If the en-
vironment of a unit is defined, then the en-
vironment of a collection of units, a species,
must be definite.

In the case of sexual dimorphism and other di- and
poly-morphisms, the environment of the species would be
the environments of the several types of individuals added
together : the defined environment of the male added to
the defined environment of the female, &c. This addition
is necessary because the environment of the several types
of individuals is not identical, although each is defined.

44 CONTROLLED NATURAL SELECTION

Fig. 1 is a pictorial representation of this
conception ; ~EV E2, E3, &c., are the factors
of the environment, shaded, to show their
serial nature ; the area enclosed by dark lines
is the environment of the species. Fig. 2 is
a simplified illustration. The environment of

E.i.

E.2.

E.3.

E.4.

E.s.
E.e.

FIG. 1.

FIG. 2.

a species can be classified into common and
specific. The common environment is shared
with other species (many animals breathe air
and drink water) ; its specific environment it
occupies, solus.

If, as has been considered, structure means

THE SELECTING POWER OF ENEMIES 45

environment, it is impossible to conceive of
two species occupying the same environment :
because one cannot conceive of two species
which, being different in structure, are yet
similar in function ; which is the same as
having similar relations to the same environ-
ment. Different structures, different functions,
different environments — here is an analogy ;
but in different structures, similar functions,
and the same environment — there is none.

Allied species, or a species and an estab-
lished variety of it, may occupy neighbouring
environments, but never the same. If allied
species do not, distant species probably cannot.
Thus a species must be alone in its specific
environment, and never the subject of com-
petition with other species. On account of the
absence of competition and because a species
increases in geometrical progression, the
species must always completely fill its specific
environment ; except when it has been unable
to keep pace with an increase in quantity of
its specific environment. A species is rare or
common, according to whether its specific
environment is restricted or unconfined. As
will be shown later, it is not possible to
conceive of a restricted common environment,
and a surplus of specific environment.

46 CONTROLLED NATURAL SELECTION

The Relation of Species to Species. — The
environment of one species may form that
of another — beneath forest trees, tree-ferns
thrive ; on the stems of tree-ferns, filmy ferns
find suitable homes. The cat feeds on the
mouse, whose enemy the cat is. Thus, one
species can, through its environment, affect
that of another ; but a species, per se, cannot
affect another species because action implies
something acted upon, and anything upon
which a species acts is its environment.
Species may occupy a common environment,
but, as will be shown, in so doing, neither
each other nor their specific environments
are affected.

fc». The Species and its Environment. Their
Relations. — So far, the following conceptions
have been arrived at. Structure equals en-
vironment. The boundaries of the specific
environment of a species are defined. Each
species has its own specific environment. A
species completely fills its specific environ-
ment. A species can only be acted upon
by physical and biological forces, through its
environment.

Further consideration must now be made
of the selecting agent, the Environment. It
has been shown not to be homogeneous, but

THE SELECTING POWER OF ENEMIES 47

that all of its factors are parts of a continuous
series. Therefore the selecting power of the
environment will not be homogeneous but
will be arranged through the environment, in
the form of a continuous series. And as the
individuals that go to form a species are not
identical, but differ more or less from each,
it follows that these variations of a species,

E.

i.

E.

2.

E.

3.

E.

4.

E.

3.

- ^- jj _

V.

i.

V.

2.

V.

3.

V.

4.

V.
8.

_ V.

1 " J ^* IK

FIG. 3.

whether continuous or discontinuous, will
TEND to become serially arranged through the
specific environment, according to the serial
arrangement of the selecting power of the
environment : as is shown in Fig. 3, Vv V2,
V3-Vn perfectly fitting Ep E2, E3-En. If
discontinuous there will be gaps.

In Nature, this is prevented by inter-
crossing (and migration). If the species were

48 CONTROLLED NATURAL SELECTION

distributed over an unlimited space, then the
environment would be differentiated; but
because, in Nature, space is always limited,
this environmental classification only occurs
to a limited extent ; when a species is dis-
tributed over a wide area, when the environ-
mental gradient is very slight, then this
establishment of varieties and sub-species may
take place locally.

The above use of such words as SPACE,
LOCALLY, AREA, &c. may give the impression
that distribution through space is alone
alluded to : these words are used with refer-
ence to the environmental gradient, whatever
be the factors of its composition.

SPACE is chosen for illustration, for clear-
ness' sake.

Varieties and sub-species may thus become
established by environmental differentiation,
and, it may be, evoluted into distinct species.
Thus, without the help of any outside force,
new species may arise within the enclosure of
a specific environment, as in Fig. 4. In a
similar way, the environment may become
sexually differentiated when the sexes are
separate, as in Fig. 5. Males often differ widely
in structure from females, and occupy an
entirely different environment. This sexual

THE SELECTING POWER OF ENEMIES 49

differentiation of the specific environment is
the only possible cause of secondary sexual
characters, as this volume attempts to show.
Although other theories, as for instance
Darwin's theory of Sexual Selection, attempt
to account for these structural differences
in other ways. Also, in polymorphic species,
the environment becomes similarly split up.

!'

•

I

I.

1

,

LI,

FIG. 4.

O.

FIG. 5.

It has been seen that the specific environ-
ment is curtailed by the limit of the ability
of the species to adapt itself to the diversities
of the factors which form its environment.
This property is common to all living matter,
and without it Life, as we know it, could not
exist. If living matter could not thus accom-
modate itself but could only occupy a homo-

D

50 CONTROLLED NATURAL SELECTION

geneous environment, then living matter would
assume an infinite number of different forms,
corresponding to the infinite number of the
diversities of its environment ; and each form
would be infinitely restricted (see Fig. 3).
Associated with this adaptation must be
structural alteration ; function and structure
are inseparable — these are acquired char-
acters.

Nevertheless, in spite of this power of adap-
tation, one cannot conceive a variation of a
species, whatever its nature, displacing another
species from its specific environment, which
it completely fills and perfectly fits ; to accom-
plish this, the variation would have to differ
from the parent in a great number of struc-
tures, be a great mutation and would have
at the same time to fit perfectly a new
environment, in fact more perfectly than the
former occupier, which itself is a perfect fit ;
can such a correlation come about through
Chance ?

Change in Environment. — Change in en-
vironment may be quantitative ; the specific
environment may increase, decrease, or dis-
appear entirely, in which case the species will
becomejcommon, rare, or extinct. The change
may be qualitative, and consist in the addi-

THE SELECTING POWER OF ENEMIES 51

tion or subtraction of one or more factors
to or from the specific environment.

The subtraction of a factor may lead to
extinction of the species ; a food supply may
fail. Or if the species continues to thrive,
then those structures which were related to
the lost factor will degenerate. Those indi-
viduals who waste the least nourishment or
sustenance on a useless organ will have an
advantage over others in which this organ
is more developed. Degenerated organs are
found in species occupying degenerated en-
vironments. Degenerate structures will be
found to vary most because of the absence of
the fixing power of environmental selection.

If a factor be subtracted locally, then a
local degenerate variety or sub-species will
be found.

The addition of a new factor to the specific
environments may produce extinction. Short
of extinction, an added factor will prevent
a species fitting its environment perfectly ;
but sooner or later, as the result of variation
of the species and environmental selection,
new structures will arise which will enable
the species to perfectly fit the new environ-
ment. Further addition of factors will be
followed by the addition of new structures ;

52 CONTROLLED NATURAL SELECTION

in this way, there will be evolution. Highly
evolved species will be found in highly com-
plex and often restricted environments ; such
species will be found to vary very little.
High specialisation demands great fixity of
structure. The local addition of a factor
will produce local evolution and the estab-
lishment of a sub-species.

Reasons have been given why one cannot
conceive of a species being displaced from its
specific environment by the variety of another :
for similar reasons, one cannot conceive of a
variation of a species being able either to
occupy an environment rendered vacant by
the extinction of a species, or to discover an
entirely new environment. Evolution equals
environmental differentiation, the better ap-
preciation by organic matter of the diversities
of its environment. The question of com-
petition yet remains to be considered. As
has already been shown, this can only occur
within a common environment, and then
only when the common environment is not
sufficient to accommodate the two or more
species which share it. Suppose (see Fig. 6)
Sx and S2 are two species, El and E2
are their specific environments, and E3 a
common environment, where competition is

THE SELECTING POWER OF ENEMIES 53

going on. Then the common environment
will be a selecting agent and will select either
Sj or S2 ; one or other must be selected, for
they cannot both be alike re the environment.
The selected one will then include the common
environment in its specific environment, as
in Fig. 7. If they are very similar, then
different parts of the environment having
slightly different selecting powers, because of
its diversity, will select, some S1? some S2.

FIG. 6.

The common environment will become divided,
one part joining the specific environment of
Sx; the other part, the specific environment
of S2, as shown in Fig. 8. In neither
case will the species be in any way changed.

This competition with the common environ-
ment cannot cause the origin of a new species,
but it may possibly lead to the extinction
of one.

Attention must here be drawn to the dif-
ference between competition occurring within

54 CONTROLLED NATURAL SELECTION

a species, and competition between two or
more species ; to the difference between intra-
and inter-specific struggles.

In intra-specific struggles, because the indi-
viduals are very similar, the struggle will be
prolonged : very small differences will decide

I

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I

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.1.

!

11

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E.g

1

1

"7"

s.,

i

As.

FIG. 7.

1

1
1

\

II

E.1
!

1

I

1
]

i

1

T

E

a

1

I

I

I

5

1

E

i

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i

FIG. 8.

life and death. Under these conditions evolu-
tion will proceed.

In inter-specific struggles, which take place
within common environments (when they be-
come overcrowded) because the individuals
are not similar in structure, the struggle will
be soon over. One species is bound to be
vastly more fit than the other, and will there-
fore quickly displace it. Can a struggle be

THE SELECTING POWER OF ENEMIES 55

long protracted between individuals as dif-
ferent in structure as are two species? If
it cannot, then such a struggle can have no
effect as regards evolution, because a rela-
tively long period of time is required both for
the origin and fixation of variations.

Two caterpillars, A and B, feed upon a
certain tree ; the tree becomes rare ; competi-
tion between A and B at once begins. In a
few years A will displace and render B
extinct, or vice versa ; because one must pos-
sess certain characters, structures, and habits
which give it a very decided advantage in
the struggle ; or A will be able to turn out B,
for instance, from the young leaves, and B
turn out A from the old leaves ; A will be
found feeding only on young leaves, B on
old — there will be splitting of the common
environment.

In neither case can this competition in a
common environment be a factor in evolution.

Before proceeding further it is necessary to
review the conclusions that have been made.

1. The boundaries of the environment of a
species are definite.

2. The competition between species and
species leads to either extinction of one or
the splitting of the common environment into

56 CONTROLLED NATURAL SELECTION

two specific environments. Species generally
occupy common environments without com-
petition because there is no crowding there.
Common environments do not give rise to
specific structures.

3. New species are formed by differentiation
of their specific environments.

4. The environment becomes similarly sexu-
ally and socially differentiated.

5. Change in environment will produce
either evolution or degeneration. If ontogeny
and phylogeny give the history of a species,
they should also give the history of its en-
vironment.

The earliest forms of life were probably all aquatic.
The embryos of nearly all vertebrates and invertebrates
have some characters and structures which indicate that
their distant ancestors lived in water.

The conceptions or confessions of faith
embodied in most of the above arguments are
of course not new ; they have been recalled
because they lead the way to the subject
under consideration, namely, the power of
enemies as selecting agents.

Particular attention is directed to con-
clusions Nos. 2 and 3, which state that
common environments do not give rise to
specific structures, or in other words, the

THE SELECTING POWER OF ENEMIES 57

selection of common environments is, re
evolution and the origin of species, of much
less importance than the selection of specific
environments.

Specific environments can often be recog-
nised by their being usually restricted. The
environment which restricts a species is a
part of its specific environment. This will
be found to be in the vast majority of cases
either food supply or enemies. Food supply
and enemies are closely connected ; if one is im-
portant, both must be. A is the food supply
of B : B is the enemy of A. The greatest
disturbances which man has made in Nature
have been due to alterations in one of these
two factors. The two most efficient ways of
either exterminating a species or controlling
it are the destruction of its food supply or the
increase of its enemies. In Nature's balance
the weights are these two factors.

Isolation is probably the greatest deter-
mining factor in the preservation of species.
It ensures protection from fresh enemies.
Migration the greatest determining factor in
the destruction of species. It introduces new
enemies. Species with many enemies are the
least variable. Protection from enemies causes
species to vary, as in domesticated animals.

58 CONTROLLED NATURAL SELECTION

It is possible to arrive at the same con-
clusion in other ways. There is evidence
that the destruction of wild animals is in
many respects similar to that observed in
man : and that an animal life-table is very
like a human one. Many are born to die
almost at once : some die before reaching
maturity ; others become adults ; and a few
only reach old age. It has therefore been said
that Natural Selection acts chiefly upon the
young, and therefore must be most effective
before the assumption of adult characters :
and thus cannot be a powerful force in Evo-
lution. But this is a false argument, apart
from consideration of juvenile characters.
Consider one thousand individuals, and sup-
pose that ten of these become reproductively
mature ; then it is obvious that the death of
one of these ten will be equivalent to the
destruction of one hundred newly born in-
dividuals ; which means that the power of
Natural Selection, re Evolution, when adults
are operated upon, is a hundred times as great
as when newly born individuals are dealt with,
and still greater when the adults are about
to reproduce. It follows, therefore, that the
factors which decide life or death of adults
are very important ones of Natural Selection.

THE SELECTING POWER OF ENEMIES 59

Evidence will now be brought forward that
the most important of the selecting factors,
the one always at work, is the species'
enemies.

Consider temperature ; a severe winter kills
off those with poor resisting power to cold ;
then summer's drought comes, and another
batch is destroyed. The following winter is
mild, so the next generation are not subjected
to selection by cold. A very hot summer
destroys many of these, perhaps just those
which are able to best resist cold : so that any
advance in ability to resist cold, as a result
of the first selection, will be lost, on account
of the inconstancy of the selecting agent and
the swamping effects of the other agents. But
with enemies, the case is different ; they are
always present, destroying through all the
year ; and their action will be accumulative.

There is a property of enemies that requires
to be especially mentioned. They destroy
suddenly. There is no time for the species
to protect itself by means of acquired char-
acters. This power which enables organic
matter to adapt itself to diversities of en-
vironment is valueless in respect of enemies :
only hereditary characters can be used for this
purpose. Therefore, as hereditary characters

60 CONTROLLED NATURAL SELECTION

usually form specific characters and acquired
characters do not, it follows that the char-
acters to do with protection from enemies are
likely to be very important ones.

Much criticism has been levelled against natural selec-
tion from a mathematical point of view, and especially as
regards the swamping effects of chance. If chance kills
off 950 of a 1000 individuals, then natural selection has
50 instead of 1000 to work with. However, the effect
must be the same, except that longer time will be re-
quired for the origin of favourable variations. When,
however, after perhaps many generations the favourable
variation does arise and escape the hands of chance, then
it will be one amongst 50 instead of one in 1000, and
therefore less likely to be swamped.

False examples of chance are often cited. The stepping
of a horse on an ant's nest is a typical one. The action
of the horse may be the result of chance. But what can
be said about the position of the nest ? The mother ant
in the past chose this particular spot for her nest. Other
mothers chose in some cases no doubt places where horses
are not likely to walk. Will not such mothers therefore
be thus selected to carry on the race?

In conclusion it may be said that, although
the subject has been approached from several
standpoints, reasoning has led in each case to
the same two conclusions :

1. Specific environments are more impor-
tant than common environments as selecting
agents.

2. Species' enemies are very important

THE SELECTING POWER OF ENEMIES 61

factors of specific environments : and must
be powerful selecting agents calling forth
important corresponding structures.

One other conclusion that has been arrived at may here
be mentioned.

As has been truly pointed out, the welfare of a species
is almost of as much importance to the species' enemy as
to the species itself. In spite of this, some naturalists
expect to find highly protectively coloured animals almost
free from enemies. Were this so, then there would be
no selection, there would be nothing to maintain this
specialisation, which according to present-day arguments
would at once begin to degenerate until its efficacy failed,
permitting the enemy to again destroy.

It seems, therefore, that the most efficient protective
coloration can only be maintained by a severe selection
by enemies. So only can be produced and maintained
other highly specialised characters such as warning
coloration.

One must therefore expect to observe that animals
which present a high degree of protective or warning
coloration, frequently form food for their predaceous
enemies.

CHAPTER V

FAMILY INSTINCTS

IT may appear strange that instincts are first
chosen to illustrate this Theory, for of all
characters they are the least known or under-
stood, and only in recent years have they been
systematically studied, and been given an im-
portant place among characters as a whole.

They have been chosen because, as family
characters, they well and clearly illustrate the
Theory.

The vast majority of parents have an in-
stinct which compels them to sacrifice them-
selves for the sake of their young ; this
sacrificing instinct is present in both sexes,
and varies according to the age of the young.
When the progeny is very young it is strongest,
and as it grows older so the instinct becomes
less strong : finally, when the progeny is full
grown, it entirely ceases, and in many cases is
replaced by another instinct, which compels
the parents to drive away their progeny. The

FAMILY INSTINCTS 63

possession of this parental instinct has an
effect on the selection of enemies within the
family : the likelihood of their selecting young
is much reduced. As has been shown, young
are more valuable to the species than old;
therefore the species controls Natural Selec-
tion in such a way, that more valuable young
are preserved at the expense of less valuable
parents. Families having this character are
more likely to bring their young to maturity,
and to thus reproduce themselves, than families
in which this parental character is faint or
absent.

Thus, the FAMILY comes to possess this
character which has arisen as a variation and
has been preserved through heredity : just as
within the individual, particular forms, struc-
tures, or colours or other character having
been born, becomes fixed.

Natural Selection, dealing with families,
produces family characters whose function is
to preserve the more valuable members of the
family, at the expense of the less valuable.

To return to parental instincts, closely allied
to the sacrificing instinct is a combative one.
Parents will attack an enemy of their young.
If they prove victorious, the instinct which
directed their actions may be called combative ;

64 CONTROLLED NATURAL SELECTION

if they are beaten in the fight, it will be called
sacrificing.

There is another parental instinct, commonly
found in birds, which may be called an attract-
ing instinct. It consists of unusual and con-
spicuous movements whose object is to distract
an enemy from their young and entice it to
attack the parents ; these are often described
as feints because the birds appear to pretend
to have broken legs or wings, or to be other-
wise wounded and crippled. By these attract-
ing instincts the parents draw an enemy's
attack, and having accomplished this, then
make good their own escape. During these
feints, several ways of making themselves
conspicuous are utilised : bright colours are
displayed ; wings, wherein are bright bars, are
opened ; tails containing white feathers are
spread ; breasts or backs are turned, according
as they are brightly coloured, towards the
enemy. Strange forms are assumed ; combs
are erected, tails spread, wings opened and
necks thrown out ; and conspicuous sounds
are made. By these and other methods,
parents make themselves conspicuous.

When pre-copulatory displays are considered, it will be
shown what a close similarity there is between these
parental displays, these attracting instincts, and the dis-

FAMILY INSTINCTS 65

plays made before copulation, which are usually called the
displays of courtship. It will be further shown that,
whereas the parental displays are to protect the young,
the sexual displays of the male are to protect the female.

Whilst the parents are responding to these
instincts, the young are behaving quite dif-
ferently. Eeacting to a warning of danger,
given (either vocally or by other ways) to
them by the parents, they instinctively make
themselves as inconspicuous as possible : they
at once squat or seek cover. This family
character possessed by the young must con-
trol Natural Selection within the family, just
as the parental instincts do. The young of
a family who instinctively seek cover, when
warned by the parents, have a better chance
of surviving and of reproducing themselves,
than the young who do not thus respond to
their parents' call.

In like manner can be accounted for very
many of the instincts found confined to parents,
and those possessed solely by the young.
Further, as will be shown later, many of the
characters found confined to either parent or
young, no matter what their nature, either
structure, form, or colour, can be similarly
explained.

Instincts have been chosen first for con-

E

66 CONTROLLED NATURAL SELECTION

sideration because they are self-evidently a
means whereby Natural Selection within a
family is controlled.

Many account for the parental sacrificing
instinct by concluding that the young and
the juvenile, because they are helpless and
inexperienced in defence, require protection
of their parents. But such an argument is
not sound. They require protection because
they are valuable to the species : their help-
lessness adds nothing to their value. How-
ever, apart from this question : the origin
of these characters as variations confined to
particular members of a society and their
fixation, must have been through Natural
Selection dealing with families, and not with
individuals ; and further, these characters
must control Natural Selection in such a way
that one set of individuals, the young, is
rendered more liable to be selected for sur-
vival than the other, the parents.

CHAPTER VI

THE COPULATORY ATTITUDES OF THE PAIR

ANIMALS form themselves into a number of
different societies. In the last chapter, the
society of a family was considered in respect
of one of its characters, its instincts ; another
society has now to occupy the mind — the
pair, the associated male and female. There
is probably no society in Nature more close
than the copulating pair. And because the
pair thus united are especially open to at-
tack, Natural Selection will probably leave
its mark on these two individuals. As has
been clearly proved, females are more valuable
than males ; search should therefore reveal
the presence of characters in the pair, which
control Natural Selection in such a way that
during copulation females will be preserved
at the expense of males.

At present, only one character of the
copulating pair will be dealt with — the at-
titudes they assume during copulation. A

67

68 CONTROLLED NATURAL SELECTION

hasty consideration might lead to the expres-
sion of opinion that copulatory attitudes
depended on the position, structure, and
mechanism of the copulatory organs : but the
facts of Nature lead one to argue that she
does not mould organs and then leave the
individual to fit them as best he can ; instead,
one is encouraged to believe that organs are
made for use in a particular way. The ques-
tion that is now asked is — Do the copula-
tory attitudes assumed by animals, in any way
assist in the preservation of the female at the
expense of the male ?

In mammals and birds, the position of the
male above and behind the female must un-
doubtedly render him, in the event of an
attack by an enemy, far more liable to be
killed. A couple are especially liable to be
successfully attacked from behind ; a frontal
attack would be in their full view and likely
to fail. A hawk stooping at a pair of birds,
must strike the male. In mammals, the male,
standing on his hind legs, is helpless compared
to the female, who, standing on all four, is
able to spring aside on the instant. Further,
experience has taught predatory animals that
it is unwise to leave a stricken victim until
it is certainly dead; for this reason, seldom

THE COPULATORY ATTITUDES 69

more than one of a pair is likely to be killed
in an attack. The male's death is nothing to
the species, for he probably has already ferti-
lised the female, if not during the last copula-
tion, at a former one ; her death would be
a great loss to the species, the loss of very
valuable fertilised ova.

The length of time taken by the copula-
tory act varies with the species, and among
mammals is longest in the predatory ones ;
compare, in this respect, the Felidae Canidae
and Mustelidae with the Suidae, Cervidae
Equidae or Muridae and Leporidae.

Among birds, I am aware of only one ex-
ception to the rule that the male mounts the
hen — Swans (Cygnus olor), which copulate
breast to breast, and so will apparently be
equally liable to be killed if then attacked.
It is noteworthy, that of all birds, Swans are
probably the least liable to attack, because of
their pugnacity and great strength.

In the majority of insects, the copulatory
period is often prolonged for many hours or
even days ; during this long period the pairs
are in a helpless condition, able only to make
feeble attempts to escape from danger. In
many species, the male rests on top of the
female, as it were guarding her and often

70 CONTROLLED NATURAL SELECTION

carrying her in flight. In other species, the
pairs unite end to end ; in these cases, other
methods encouraging the taking of the male
are utilised, as will be shown later. But
although it seems that when thus united, an
enemy would chance to take male and female
equally, in many cases, owing to the position
in space occupied by the copulating pair, this
is not so ; for instance, in some cases the male
clings to a grass stem or other support, whilst
the female dangles below ; a bird taking such
a pair will strike first where the insect joins
the grass, having learnt by experience that
of insects, this, the head end, is the most
vulnerable part ; the bird will seize the male,
the female becoming unjoined will be likely
to escape. In such ways as this, by the
assumption of a particular position on the
part of the pair, will the taking of males rather
than females be encouraged. «

When copulating insects are given to birds, it has been
observed that when one has been seized, the other is
apparently mistaken by the bird for some foreign object,
which the bird endeavours to and does get rid of by
rapidly shaking its head : those insects which are firmly
joined together and only with difficulty parted will thus
be disconnected.

The copulating habits of the Common

THE COPULATORY ATTITUDES 71

Sparrow (Passer domesticus) are worthy of
mention. Whilst the successful male is per-
forming the act, the pair are usually closely
surrounded by a number of chattering males.
If this company of birds be attacked, it is not
likely that the female will be taken, but rather
one of the many males. I have twice seen a
Hawk take a Sparrow under these conditions,
and on each occasion it was a male. These
two observations of course prove nothing,
but, at the same time, it appeared to me to be
impossible for the hawk to chance to take the
female ; a chance greater than the relative
number of males to females.

So with certain insects, in which, during
copulation, the pairs are surrounded by a
host of males, these must protect the female,
whether this be the aim of such a gathering
or no. The above applies to many Diptera,
the Bees (Apiarice), Termidae, and others.

Lastly, in bisexual or hermaphrodite animals,
there is no difference in the relative position
of the two individuals as would be expected
according to the Theory, for they are of the
same value. During copulation, they always
make a symmetrical figure.

Thus in conclusion it may, I think, be fairly
stated that the position assumed by the pair

72 CONTROLLED NATURAL SELECTION

during copulation renders males more liable
to destruction than females. In this way the
species may be said to control Natural Selec-
tion, so that valueless males may be destroyed
rather than valuable females.

CHAPTER VII

PRE-COPTJLATORY DISPLAYS

BEFORE copulation, the male commonly makes
some display; such are often called the dis-
plays of courtship, implying an association
with mating ; but as many animals mate only
once in a lifetime or in a season, whilst these
displays are made before each copulation, they
are better described by being called Pre-
copulatory Displays. A study of them shows
that they undoubtedly render the male con-
spicuous and purposely so. All the methods
mentioned in Chapters II and III are em-
ployed : movements are made, forms assumed,
attitudes struck, sounds produced, scents
secreted and vivid colours are laid bare,
all of which make the male conspicuous in
Nature. The female, during this display of
the male, remains silent and motionless, and
usually more or less concealed.

Here, then, is material to which the Theory
can be applied : Two individuals, male and

73

74 CONTROLLED NATURAL SELECTION

female, unequal in value, associated together,
and at a time when the difference in their
values is greatest, i.e. during the breeding
season ; the male, the less valuable, renders
himself conspicuous in many ways ; the female
keeps more or less concealed. Here are two
associated individuals of different value, pre-
senting different characters. According to
the Theory, these characters, or at least some
of them, should control Natural Selection in
such a way that the less valuable male will
be taken, rather than the more valuable female.
Further, at this time, the pair are especially
liable to be successfully attacked, because
their attention is fully occupied with sexual
affairs ; so that some provision for the selec-
tion of the male may be expected. Therefore
may it not be, that the male renders himself
conspicuous in order that, in the event of the
pair being attacked by an enemy, he may be
destroyed rather than the female ? The Hawk
will stoop, the Cat will spring, at the more
easily seen bird. It does not follow that
one of the two must in every case perish ;
the display of the male will draw the attack
of any neighbouring enemy and thus, as
it were, clear the air, so that dangerous
copulation may be accomplished in safety.

PRE-COPULATORY DISPLAYS 75

This, in fact, is the meaning of such display,
its purpose.

Direct evidence of this is, and possibly must
always be, wanting.

The period of destruction of an animal
forms so minute a portion of its whole life,
that a single person, even if constantly observ-
ing, could record only a few deaths, and of
these only a small percentage would be deaths
of either male or female during sexual display.
Experiments could be arranged to test the
theory. Pairs of animals could be subjected
to their enemies.

Although direct evidence is wanting, some
indirect evidence appears to give support.
To the vast majority of animals man is
an enemy. His presence causes them to
stop doing the affair of the day, and to
seek cover. But his presence often does
not cause the cessation of pre-copulatory
displays ; on the other hand it may cause
them to be more vigorously performed.
In fact his presence calls forth this male
reaction as powerfully as the presence of
the female. Numerous examples have been
recorded of display in the absence of the
female, and when only man or an enemy
is at hand.

76 CONTROLLED NATURAL SELECTION

Another favouring fact is that animals, not
liable to be attacked, either make no pre-
copulatory displays or only poor ones. It is
also noteworthy that the displays made by
the parents for the protection of their young
during the attack of an enemy, are very
similar to and sometimes exactly like pre-
copulatory displays. In one case an enemy
is the stimulating agent ; may it not be so in
both?

Just as there is no direct evidence in favour
of this conception, so there is none against
it. Other theories have been propounded to
account for the facts ; these will be discussed
under Sexual Colour (Chapter VIII) ; and
what contrary indirect evidence there is will
be also then considered.

Some have likened these displays to car-
esses, and have supposed that by them
the male overcomes a coyness of the
female. Females appear to be coy be-
cause they take no notice of the male's
display; for this reason, when the male's
display appears to be kindly in nature to-
wards the female, it is called a caress ; and
no heed is taken of the many cases in
which the male's display appears quite brutal.
Further, much coyness on the part of the

PRE-COPULATORY DISPLAYS 77

female must, one would think, be harmful
to the species.

This explanation therefore appears unsatis-
factory, even for the small number of displays
which it could account for.

CHAPTEE VIII

SEXUAL COLOUR

MALES and females are frequently coloured
differently. With comparatively few excep-
tions, the males are more brightly coloured,
especially during the breeding season. These
characters are widely distributed throughout
the animal kingdom, and this universality
indicates that the cause must be of a world-
wide nature. In some cases it has been
observed that the sexes occupy either entirely,
or somewhat different, environments, hence
their colour differences.

But in other cases, environmental differ-
ences, corresponding to these colour and
other structural differences, have not been
found. For this reason other theories have
been propounded to account for them.

Darwin's sexual selection is the most gener-
ally accepted theory. This states that females
select males which have characters pleasing
to them, bright colours for instance. Assume

78

SEXUAL COLOUR 79

that this is so and that males in this way
become altered in character. Such a male
character must be either beneficial or detri-
mental to the species as a whole ; it cannot
be neutral. If detrimental, the species must
either become extinct, or Natural Selection
will remove the offending character ; if bene-
ficial, then Natural Selection would have
fixed the male's useful variation without the
assistance of female selection. Characters,
confined to the male, can be fixed by Natural
Selection alone, and thus selection on the part
of the female is not necessary to explain
their origin. In order that females, by selec-
tion, may alter the characters of males, two
monosexual variations (one in the male, the
other in the female) must arise simultaneously,
and further, these must be related. For in-
stance, a bright colour must arise as a varia-
tion in the male, and at the same time there
must be born in the female as a variation,
an instinct which compels her to prefer this
bright-coloured male. To conceive of this is
difficult.

On the other hand, Natural Selection would
require only one variation to arise. If a
beneficial character arises, it will become
fixed, although the variation be confined to

80 CONTROLLED NATURAL SELECTION

one sex; this conception is easier. Such a
variation would be correlated with the sexual
determinant ; variations not so correlated or
bound to a sexual determinant cannot, one
would conceive, be made to do so by Natural
Selection : for instance, favour their fixation
in the male, and their eradication in the
female.

Sexual Selection, if it explains the origin
of extra sexual characters, does not explain
their use, yet, as has just been shown, they
must be useful, or otherwise Natural Selec-
tion would remove them.

Beside this argument, there are many facts
that sexual selection fails to correlate and
which it ought to correlate. They mostly
come under the following headings :

1. Sex selection accounts for the brilliant
colours of males, but fails to account for
equally brilliant colours which are frequently
found in both sexes.

2. Sexual selection, if it has been observed,
has not been observed to be especially asso-
ciated with animals which show the greatest
sexual differences in characters. Birds, for
instance, in which the sexes are similar, do
not show less selection by the female of
the male, than birds whose males are of

SEXUAL COLOUR 81

the most brilliant colour compared to their
females.

3. If females select then, there must be
either more males than females or polygamy :
but in many insects which present marked
sexual differences, males and females are
equal in number. Further, very few examples
of selection by females have been recorded ;
whereas many experiments have been carried
out that conclusively show that females do
not select.

4. In many animals, the male undoubtedly
selects the female, and yet the male is the
more brightly coloured.

5. The displays of courtship are not to do
with mating, but, as has been shown, are
pre-copulatory displays ; they therefore do
not play the r61e in sexual selection which
is assigned to them.

6. Further, these displays are not made
only by animals which present secondary
sexual differences in characters, but are also
made by animals whose sexes are similar.

7. Sexual selection does not explain the
absence of conspicuous male colouring in
predatory and night animals ; or rather they
form unexplained exceptions.

Of course there must be many facts which

F

82 CONTROLLED NATURAL SELECTION

the theory of sexual selection explains or
correlates, else it could never have been con-
ceived. Nevertheless much has been written
against sexual selection, especially in Germany
and America, and a general demand made for
another explanation.1 There are other theories.
Wallace explains the dull dresses of female
birds and insects by supposing that the young-
producing females require better protection
than the males. But one would think that if
dull plumes are an advantage to the female
they would also be of use to the male, and
that therefore he would don them too. This
theory of Wallace apparently comes very near
to the one under description, but in reality it
is almost the converse. The new theory states
that the male becomes brilliant in colour in
order that he may be more likely to be
destroyed : and thus the dull-coloured female
gain protection. In Wallace's theory the
female becomes altered for her sake, in this
theory the male for the female's sake. Wallace

1 The author's theory is not, strictly speaking, antagonistic to
Sexual Selection, but only in so far that such selection cannot
be for the purpose of gratifying the female's sense of beauty.
The new theory is quite able to embrace female selection
provided they instinctively select males which will be more
attractive to enemies than males in general ; for instance, con-
spicuously coloured males as against beautiful males.

SEXUAL COLOUR 83

explains the dull colour of females but not
the brilliant colour of males.

Emery's theory of the origin of secondary
sexual characters as mono-sexual sports may
explain their origin, although there appears
to be little evidence of this, but makes no
attempt to define the cause of these differ-
ences ; or assumes that the sport is retained
because and when it fits the environment
better than the old type.

Those who believe in the transmission of ac-
quired characters look upon secondary sexual
characters as adaptations and due to the
stimulation of parts through use. Controlled
natural selection accounts for both the origin
and purpose of secondary sexual characters
in the following way. Males are more con-
spicuous in nature than females : males are
less valuable than females. Males and females
are associated together during life, and especi-
ally during the breeding season when the
difference in colour is greatest, and when their
difference in value is highest : therefore accord-
ing to the theory, the conspicuous colour of
the male serves to control natural selection
in such a way that the less valuable male
will be killed in preference to the more
valuable female.

84 CONTROLLED NATURAL SELECTION

The occurrence of only a single variation is
necessary for this conception. Because females
who happen to choose the most conspicuous
males, will be more liable to escape destruc-
tion than females who happen to be mated
with less conspicuous males : and the former
females will therefore be more likely to hand
on this male character than the latter females.
This applies to all the purposely conspicuous
characters of males.

Stolzmann in 1885 put forward a theory to
account for the secondary sexual characters
of birds, which in some respects resembles
this theory.

Having observed that males are often more
numerous than females, he justly concluded
that the species' food supply was being wasted
on them and that this excess of males was
harmful to the species ; more especially be-
cause he believed that the paired females
during the breeding season were harried by
celibate males, with injurious results. He
therefore conceived that the brilliant colours
of the males arose in order that they might
easily be seen by enemies and their ranks
thus thinned.

This theory was very short-lived, because
it was speedily pointed out, that if males

SEXUAL COLOUR 85

become conspicuous in order to be killed,
only less conspicuous ones will be left to
carry on the species, and conspicuousness
will thus be quickly eradicated by Natural
Selection.

It is obvious that this criticism cannot be
levelled at the author's theory, which in some
respects is not unlike Stolzmann's. The
author's theory deals with the pair, male and
female associated together at the breeding
season or during copulation ; under these con-
ditions the destruction of a conspicuous male
by no means precludes that his characters will
not be handed down to the next generation.
He most probably will have already fertilised
the female either partially or entirely. It
may here be noted that secondary sexual
characters are at their highest development
at the time when the female is ready to be
fertilised ; male birds, for instance, are in their
most brilliant plumage, not during their nest-
ing season, but at a considerable time before
this, in either the last of winter or the first
of spring.

The relative proportion of males to females
is, as Stolzmann concludes, a most important
factor in the welfare of the species. Accord-
ing to the theory, great excess of males

86 CONTROLLED NATURAL SELECTION

should be associated with great secondary
sexual difference, and vice versa.

In some animals, an excess of males is pro-
duced by special methods, e.g. ants and bees.
It appears not so much to ensure the fertili-
sation of all females, as to render the chance
of their destruction small. It is noteworthy
that polygamy is usually associated with great
secondary sexual differences ; these latter, ac-
cording to the theory, give rise to great
destruction of males, hence the association,
as in the peacock. In predatory animals,
polygamy is very rare ; as are also great
secondary sexual differences.

If, as some maintain, the purpose of eye-spots in insects
is to entice enemies to strike them, rather than more
vulnerable parts : may not the eye-spots on the peacock's
(Pavo Cristatus) tail be to entice an enemy away from the
female, to draw its attack?

When considering the parental colouring
of birds, it will be noted that confinement of
conspicuous colouring to the male is asso-
ciated with open-nesting habits. It is possible
that, among birds, conspicuous colouring con-
fined to the male arose in this way (Wallace),
and that afterwards it has become greatly
evoluted by Natural Selection working with
pairs. There is some evidence that open-

SEXUAL COLOUR 87

nesting cannot alone account for such great
differentiation, for when males incubate,
females are never more than slightly more
conspicuously coloured. It appears, there-
fore, that the difference in value between the
sexes, or some other factor, must be looked
for to explain this.

As with parental colour, so with sexual
colour — conspicuous colours among preda-
tory animals, or among night animals, would
not be anticipated, nor is it found.

So also sexual dimorphism should, accord-
ing to the theory, not be found in aposematic
animals, nor is it at all common ; because,
having few enemies, they are not very liable to
attack. Sometimes secondary sexual char-
acters occur before sexual maturity, as in the
upland Goose (Chloephaga Magellanica). In
this case one would conclude that the society
feels the great value of the female even at
this early stage.

Worthy of note and favouring the theory is
the fact that in mimicry it is often only the
female which seeks protection in this way;
the male, it would seem, purposely refraining
from doing so, in order that, should the pair
be attacked during mating or copulation, he
will be destroyed at the saving of the female.

88 CONTROLLED NATURAL SELECTION

Finally, it will be well to classify secondary
sexual characters in the light of this new
theory.

MONO-SEXUAL CHARACTERS :

1. Characters that are adaptations to a mono-
sexual environment ; for instance, associated
with a food supply confined to one sex, with
copulation, with the rearing of young, with
the recognition or finding of one sex by the
other, &c.

2. Characters whose purpose is to control
Natural Selection within the pair, value marks;
for instance, attracting colour, sound, scent,
&c. confined to the male.

It must be clearly understood that the second
cause of mono-sexual characters is, like the
first, an environmental character. It is the
result of selection by enemies, which selec-
tion has been shown to be one of the most
important factors of a species' specific en-
vironment. For this reason it should not,
theoretically, be given a major heading in
the classification of the causes of mono-sexual
characters. There is, however, a side issue
which to some extent justifies this arrange-
ment ; for the species behaves towards enemies
in a particular manner.

It adjusts this selection by enemies so that,

SEXUAL COLOUR 89

when the members of a species are not all
of equal value, the less valuable will be more
likely to be destroyed than the more valuable.

It is as if the species, realising that it must
form the food supply of another species and
that certain of its members must be destroyed,
conserved its valuable members, by casting
its valueless ones to satisfy the enemy.

This it does, not actively but passively, by
so clothing the valueless that they will be
more easily seen by the enemy and thus more
liable to be attacked.

As before mentioned, it does not follow that
in every case they will be destroyed, they may
make good their escape ; but by drawing the
attack, the valuable will be preserved from
attack.

Further, it is obvious that there will be a
limit to this value marking : as, for instance,
when males become less numerous than
females, so their relative value will increase ;
they are not entirely valueless.

When they thus become of equal value as
the female, further alteration in structure will
cease.

The limit to which this differentiation will
proceed, will depend on the number of females
a single male is able to fertilise, or his initial

90 CONTROLLED NATURAL SELECTION

value to the species in other respects. The
greater the polygamy the greater the sexual
difference, should be the rule. This, I think,
most will agree, is borne out in Nature. Thus
it appears that sexual differentiation is fre-
quently an expression of selection by enemies.

CHAPTER IX

PARENTAL COLOUR

A COMPARISON of the colour of parents and
young shows, that whereas young are almost
invariably protectively coloured, parents are
not uncommonly conspicuously coloured.
This difference in colour is explained by some,
who say that the protective colouring of young
animals is the colour of their ancestors, which
they must assume ^during development, be-
cause development reproduces the ancestry
of the species : and who say that protective
colouring must therefore be assumed, whether
beneficial or not : and who look upon the
conspicuous colouring of many adults as a
more recent added character.

There is no doubt that an animal, during
development, does reproduce its ancestry, but
then there is no evidence that it must do so.
Not all the characters of its ancestors are
retained, but only a few : and of the few, many
do not attain to as high a development as

92 CONTROLLED NATURAL SELECTION

was present in the ancestors. Is it not reason-
able to suppose that only those characters are
retained which are useful, or that of a given
character only so much as is useful : or else
why are so many completely lost ?

The Tadpole (Rana temporaries) has first
external gills, then internal gills, and finally
lungs, all of which are put to use : so too it
is possible that the gill clefts or their rudi-
ments found in the human embryo then serve
some useful purpose. Natural Selection must
deal with ova, embryos, juveniles, as it does
with adults, and produce embryonic or juvenile
characters. Ova and embryos, like adults,
have environments to which they must adapt
themselves.

We are accustomed to 'study chiefly adult
characters and to forget that adult is but a
stage, merging on the one side into youth, and
on the other, old age ; each of which have
important characters. Some of the characters
of old age may be looked upon as means by
which the species rids itself of an individual
which has shed all its germ cells.

Selection must occur with reference to a
character, at the time of, or after, the appear-
ance of the character, and not before. Thus
the characters that go to form an embryo or

PARENTAL COLOUR 93

young animal, or an adult, are of two kinds —
(1) structures, or parts of structures, which
their ancestors possessed, and which have
been retained because they are useful ; (2)
added structures, which their distant ancestors
never possessed, to fit some new environment ;
these may be added at any stage of develop-
ment from the egg to the complete adult.
Therefore the hereditary explanation of the
difference of colour between young and adult
is not sufficient. That this is so is also proved
by the whole of experimental embryology, and
also by the fact that examples can be found
of young animals not presenting protective
colouring, and almost certainly not having the
colour of their ancestors. One must conclude,
therefore, that young animals are as a rule
protectively coloured, and adults often con-
spicuously coloured, for a purpose.

An examination of the species which present
protectively coloured young and conspicuously
coloured adults, reveals the fact that in the
vast majority of cases young and parents are
associated together during a portion of their
lives ; and further, that it is whilst thus
associated that the difference is most marked
— e.g. parents are most brilliant during the
breeding season. Examples of conspicuously

94 CONTROLLED NATURAL SELECTION

coloured parents and protectively coloured
young are to be found widely distributed in
the animal kingdom. In fact, it is exceptional
to find parents, bringing up young, which do
not show this difference in colour or other
character. Thus are brought together the
three factors with which Controlled Natural
Selection can work :

(1) A society of animals

(2) Of different value, and

(3) Having different characters.

During Natural Selection the less valuable
and conspicuous parents will be taken, at the
saving of the more valuable and inconspicuous
young. The predatory animal will take the
conspicuous parents that it can best see, and
leave the young that are only seen with
difficulty.

When dealing with Parental Instincts, men-
tion was made of the displays of colour that
are made by the parent when the family is
attacked; they will show their brightest plumes
to the enemy and endeavour to draw its
attack ; they will display bright colours which
are otherwise concealed in wings and tail (see
Concealed Conspicuous Colours, Chapter III).

Predatory animals, because they have no
enemies, should not present conspicuous colour-

PARENTAL COLOUR 95

ing, neither do they ; they are almost always
protectively coloured.

For instance, of the Falconidae, only the
small insectivorous species that are liable to
be attacked by the more powerful kinds show
conspicuous colouring. For similar reasons,
no night birds should present, nor do they,
conspicuous colouring. There are, however,
many birds which present conspicuous colour-
ing only in the male : with very few exceptions
these are found to make open nests, which
require the female to be protectively coloured ;
for this reason, only the male is conspicuously
coloured (when males incubate, females are
the more conspicuous). There still remain
many which are neither predatory nor night
birds, and which, nevertheless, are protectively
coloured in both sexes ; it is among these
birds that conspicuous displays are seen best,
and most marked. The position these birds
will take up, the motion they will make in an
endeavour thus to protect their young, are
remarkable — the Meadow-pipit (Anthus pra-
tensis), the Reed-bunting (Emberiza schceni-
clus), and the Partridge (Perdix cinerea) are
well-known examples. Only by the collection
of a large number of facts such as these can
the theory become a law. As before mentioned,

96 CONTROLLED NATURAL SELECTION

it is now only being introduced as a working
hypothesis. It will probably not explain all
cases of conspicuous colouring among parents,
for it has been shown that conspicuous colour-
ing may be used for other purposes.

Attraction marks (see page 40, Chapter III)
may be especially mentioned, for although
they are conspicuous they are found in both
parents and young. The rule appears to be :
(1) vital parts that are conspicuously coloured
in parents are protectively coloured in young,
and (2) non-vital parts conspicuously coloured
in parents are similarly coloured in young.

A few examples are necessary: (1) The
Goldfinch (Carduelis elegans) : yellow bar
across the wing, found in both parents and
young; other conspicuous colours on vital
parts of parents are not found in young,
which are protectively coloured ; (2) Wheat-
ear (Saxicola cenanthe) : white rump present
in both parents and young ; (3) Wood-pigeon
(Columba palumbus) : white patch on side of
neck in parent, and because on a vital part,
not present in young; (4) Mallard (Anasbascus):
speculum on wing found in young and old, in
all plumages.

It appears, therefore, that some of the differ-
ences in colour between parents and young,

PARENTAL COLOUR 97

like the differences between male and female,
may be due to the selection of enemies work-
ing on individuals of different value ; may in
fact be on one hand value marks, and on the
other adaptation to enemies.

CHAPTER X

PARENTAL AND SEXUAL CHARACTERS

MENTION has been made that among birds,
for instance, there are many which do not
present conspicuous colouring, in either sex.
It has also been shown (under parental
instincts) how these birds protect their
young by making themselves conspicuous
other than by means of colour ; similarly
it has been noted that female protection
is accomplished in these birds by pre-copu-
latory displays on the part of the male,
quite apart from colour. In these crypti-
cally coloured birds, another male character
is also possibly used for female protection,
namely — Song.

The production of sounds during pre-
copulatory displays are obviously a part of
the display. But the songs of birds cannot
be thus classed.

Singing birds are conspicuous in nature,

PARENTAL AND SEXUAL CHARACTERS 99

and there is considerable evidence that they
always sing for this purpose. When perform-
ing, the males invariably take up prominent
positions, the tops of trees, high in the air, on
the summits of rocks, &c., whence they may
easily be seen from all around. Further, many
of them sing when disturbed or frightened
by an enemy ; a stone cast into a reed-bed or
thicket will at once start the warblers in full
chorus. They sing in the morning and evening
when predatory animals are feeding. They
sing when a hawk or weasel shows itself in
the copse. They do not sing to their females,
who may be out of hearing, and who take no
notice of the song, but proceed with the affairs
of the day, unaffected. May not this male
character be brought into the line which many
other male characters have been considered
to take, namely, that its purpose is to attract
possible enemies, so that comparatively value-
less males may perish, rather than their valu-
able females, or at least draw the enemy's
attack ?

The instrumentation of the males of insects
may also be, in many cases, for this purpose.
Sound -producing males are most commonly
found in palatable insects.

Scent may similarly be used for female

100 CONTROLLED NATURAL SELECTION

protection ; the absence of scent in many
hen birds which nest on the ground, in-
dicates that scent plays a greater part in
Nature than our feeble sense organ would
lead us to imagine.

The pleasant perfume which some male
insects have, may be to draw an enemy's
attention to them, during copulation, rather
than to the female. In offensively scented
insects, the sexes are usually similar, and
the character is probably of a warning
nature.

This concludes the majority of the char-
acters of conspicuousness which distinguish
parents from young, male from female : in
the one case, young as protected at the ex-
pense of parents ; in the other, females at
the expense of males. The following table
indicates how precisely similar are the
methods used ; examples are given from
among birds :

PARENTAL AND SEXUAL CH£.ftA'CTERS

TABLE I
PROTECTION OF YOUNG BY PARENTS

Position.

Form.

Movement.

Sound.

Scent.

Colour.

display

PAEENTS

take up
promi-
nent
positions :

erect
plumes,
spread
tails and
wings.

simulate
injury,
flutter,
&c.

make
various
noises —
the cack-
ling hen.

(no ex-
amples
found.)

their
bright
plumes
and have
bright

colours.

remain

iTOUNG

lie low,
squat.

conceal
their
form.

quite
motion-
less or

remain
silent.

(no ex-
amples
found.)

are cryp-
tically
coloured.

retreat.

PROTECTION OF FEMALE BY MALE

does not

M

1

pre-copu-
latory
attitudes.

pre-copu-

latory
erection
of plumes,

many
curious
pre-copu-
latory
move-

pre-copu-
latory
sounds,
also

lose
scent :
in many
insects

has at-
tracting
colour.

&c.

songs.

sweet-

scented.

FEMALE

remains
for the
most part
con-
cealed.

hides
form.

quiescent.

quiet.

scentless
during
breeding
season.

is crypti-
cally
coloured.

If, as some will be willing to admit, the
parents use these various ways for the pro-

102 CONTROLLED NATURAL SELECTION

tection of their young (instinctively), why
should not similar performances and exhibi-
tions on the part of the male, be to protect
the female ? A more detailed comparison of
the means the parent uses to protect the
young, with the pre-copulatory displays of the
male, shows how strikingly similar are not
only the methods used, but the actual move-
ments, positions, and sounds, &c., made. In
one case a given stimulus, the presence of an
enemy coupled with possession of young,
causes the parent to instinctively react ; in
the other a given stimulus, the presence of
an enemy, either real or assumed, coupled
with the sexual possession of a female, causes
the male to react in a similar manner. And
just as attracting instincts in both sexes serve
to protect the young, and in the male to
protect the female, so the attracting colour
of parents and males will have the same
effect.

Further, these displays, pre-copulatory and
for young protection, are often made when
neither females nor young are present, but at
the approach of an enemy; they are then
called expressions of fear, instead of reactions
to a stimulus. May not this be the stimulus
always, no matter when they are displayed ?

PARENTAL AND SEXUAL CHARACTERS 103

For each species a table can be drawn up,
like the above table of generalities ; for in-
stance, in the case of a blackbird (Turdus
merula) the following table results :

TABLE II
PROTECTION OF YOUNG BY PARENTS

Position.

Form.

Movement.

Sound.

Scent.

Colour.

PARENTS

show
them-
selves
promi-
nently in
the hedge
row.

droop
wings,
spread
tails.

hop and
flutter
from
branch
to
branch.

loud
cackling
noises.

nil.

male
attract-
ing
colour.

YOUNG

remain
con-
cealed.

remain
con-
cealed.

remain

still.

silent.

nil.

young
crypti-
cally
coloured.

PROTECTION OF FEMALE BY MALE

•
3
H

takes up
promi-
nent
positions
on trees,
&c.

droops
wings,
and
spreads
tail.

hops and
flutters
from
branch
to
branch.

incessant,
loud
cackling,
and
song.

nil.

has at-
tracting
colour
(black).

FEMALE

does not
do so.

does not
alter
form.

remains
still.

silent.

nil.

crypti-
cally
coloured.

104 CONTROLLED NATURAL SELECTION

To this must be added the sacrificing and
combative instincts which are used by the
parents for the protection of the young, and
by the male for the protection of the female.
Female protection by this method is not very
common in Nature ; the best examples are to
be found in the higher animals, and especi-
ally those which live together in societies :
herds are often thus protected by the males.

All possible combinations, of attracting and
protecting colorations, will now be briefly
considered.

(7= conspicuous or attracting coloration.
/= inconspicuous or cryptically coloured.
P= parents.
Y= young.

P C Very common, especially in species
Y 1 which form themselves in societies of
families ; but also rarely in other species
in which the parents do not look after
the young. To protect the more valu-
able young, in the latter case, in the
absence of the formation of a society.

P I Almost unknown, and forming ex-

Y C ceptions to the rule. Examples can

often be explained; for instance, the

young frog, the tadpole, when black

and conspicuous, is not palatable.

PARENTAL AND SEXUAL CHARACTERS 105

PC By no means uncommon ; in the vast

Y C majority of these cases the conspicuous

characters of the young are like those

of the parents, and, like them, are of

a warning nature.

P I A common condition when the species
Y I does not form itself into the society or
family ; but when families are found,
some conspicuous character is almost
always found in the parents, which is
not present in the young.

$ C Is very common in all mono-sexual
£ / animals : to protect the more valuable
female.

$ I Very rare and form exceptions to the
4 C theory ; can sometimes be explained by
their having unusual habits, as in the
Phalaropes ; or by their being pro-
tectively coloured to different environ-
ments, although not at first sight
obviously so.

$ C Not uncommon, and almost always
4 C the conspicuous characters are warning.

$ I Not uncommon ; colour or form may
4 / be similar in the two sexes and pro-
tective, but they are seldom entirely

106 CONTROLLED NATURAL SELECTION

alike ; usually the male will be found
to be conspicuous in one or more char-
acters, as in song birds.

In conclusion it may be said that many, if
not the majority of those characters which
distinguish males from females, are similar
to the differences found between parents and
young.

Males equal females plus some other char-
acters, females equal young plus some char-
acters. In each case the added characters
are alike, and according to the theory serve
the same purpose.

CHAPTER XI

CONSIDERATION OF BRITISH BIRDS

IN order to demonstrate, in still more detail,
the applicability of the theory, it will now be
applied to the colour of adult British Birds
during the breeding season. This material
is chosen because it is better to treat a small
amount of material exhaustively, than to pick
out from a large quantity (aves) only favour-
able examples ; and because the habits and
colours of British Birds are very well and
widely known : also because birds, as a whole,
are thus by no means badly exemplified ; and
birds well exemplify the theory. They are
classified in the following way, and will be
considered accordingly :

II. Birds of prey.
2. Night birds.
3. Song birds.
4. Other birds.

2. Female attracting ( 5. Open nests.
Male attracting \ 6. Closed nests.

3. Female cryptic ( 7. Open nests.
Male attracting \ 8. Closed nests.

4. Female attracting f 9. Open nests (2 birds).
Male cryptic \ 10. Closed nests (nil).

107

108 CONTROLLED NATURAL SELECTION

The following method of placing the birds
in the tables is employed. Birds presenting
defined, unconcealed, flat areas of red, blue,
yellow, black or white are placed under "at-
tracting " ; the rest under " cryptic." In a
few cases difficulties arise ; for instance, the
Ring Dove (C. palumbus) has a small white
patch on either side of the neck, and should
therefore have been placed under "attract-
ing " : but because the area of white is, com-
pared to the bird, very small, and the bird
otherwise undoubtedly cryptically coloured,
it has been placed under " cryptic."

DIVISION I

Birds of Prey. — See Table I.

Without exception, none of these birds
present conspicuous colouring because they
are not liable to be attacked. They require to
be cryptically coloured so as to be able to
approach their prey unobserved. The sexes
are similar, therefore males are not espe-
cially destroyed, and polygamy does not
occur.

Night Birds.— See Table II.

These are, without exception, cryptically
coloured ; attracting colour for the protection

CONSIDERATION OF BRITISH BIRDS 109

of females and young would be useless, because
at night it would be invisible to enemies.

Birds of Song. — See Table III.

In these birds, female protection is accom-
plished by means of the attracting songs of
the males. The young are protected by the
parents rendering themselves conspicuous in
other ways ; among these birds, the best
examples of sacrificing and combative instincts
and attracting motions and sounds, for the
protection of young, are to be found.

Other Birds.— See Table IV.

The absence of conspicuous colouring in
these birds cannot in all cases be explained.
In the Divers, protection of young is not
necessary, as these birds have always a re-
treat at their feet — the water. Others are in
reality birds of song, although not so placed,
i.e. the Curlew, the Whimbrel, Redshank,
Common Sandpiper, Greenshank, the Doves,
and the Wryneck. Some inhabit thick under-
growths, where conspicuous colours would
not tell — Corncrake, Water-rail, and Hedge
Sparrow.

In the Partridge, the young are protected
by attracting movements of the parents, which
in this bird are remarkable ; but there seems
to be no provision for the protection of the

110 CONTROLLED NATURAL SELECTION

female, except perhaps the habit the male
has of always rising first, when the pair is
flushed. In this bird, pre-copulatory displays
are by no means wanting. There yet remain
to be accounted for, the Greylag Goose, Sand-
martin, Tree Sparrow, and Tree-creeper; some-
thing might be said of each, but controversial
and therefore doubtful facts would have to
be utilised.

DIVISION II

This division includes birds presenting
bi- sexual attracting coloration for the pro-
tection of their cryptically, or much less
brilliantly coloured young.

Many of these birds have a seasonal moult :
in the winter, when they do not possess young,
they don a cryptic dress. In some the change
from juvenile to adult plumage is slow, and
extends over several years : usually these
full-grown but not maturely coloured birds
do not breed, and therefore do not require
attracting coloration for protection of young.
Further, adult and immature birds often keep
together, in companies, for several seasons,
in which case the gradual change from juvenile
to adult plumage would be a prolonged ad-

CONSIDERATION OF BRITISH BIRDS 111

vantage, in that young would be constantly
protected, as in the Gannet.

Although both the males and females of
these birds are conspicuously coloured, the
males are usually more conspicuous. This
would make the males more powerful attrac-
ting agents than females. Other methods
are of course also utilised.

There is evidence that some of these birds present
warning coloration ; for instance, powerful birds (Swan,
Cormorant, &c.), and ill-flavoured birds (Petrels and
Kingfisher).

DIVISION III

Comprises birds having purposely con-
spicuous or attracting coloration confined
to the male. The vast majority of these birds
(Table VII) make open nests, a habit that
possibly causes the female to be cryptically
coloured. Thus the male only has attractive
coloration for the purpose of protecting the
young. Arising in this way, this coloration
is also used during the breeding season, for
the protection of the female.

In the analidae, the males usually take no
part in the bringing up of the young, and yet
the males are very conspicuously coloured
during the breeding season ; moreover, directly

CONTROLLED NATURAL SELECTION

the males desert the females, they become,
by a post-nuptial moult, cryptically coloured.
It appears probable, therefore, that the male
coloration during the breeding season is for
the purpose of protecting the female. In the
other birds, the males assist in the rearing of
the young and do not lose this conspicuous
plumage, by means of a post-nuptial moult.

The following conceptions are thus arrived
at:

1. The females are cryptically coloured be-
cause of the open-nesting habits.

2. The males retain attracting coloration
for the purpose of protecting the young.

3. The difference in colour between the
sexes thus arising, is also used during the
breeding season, for the purpose of protecting
the female.

Three birds which present sexual differences
in colour, nest in closed nests : the Stonechat,
Whinchat, and House Sparrow (Table VIII).
In the case of the Stonechat and the Whin-
chat, it is probable that this nesting habit is
a recent acquisition, for they lay blue and
blue-green eggs, characteristic of open-nesting
birds, and not the white eggs usually laid by
closed-nesting birds ; further, although these
nests are domed, the covering is frequently

CONSIDERATION OF BRITISH BIRDS 113

scanty ; and in the case of the Sparrow, may
be entirely absent. The dome of the Sparrow's
nest is never well-made nor very complete.

It is necessary now to return to DIVISION II :
" Birds having Conspicuous Colouring in Both
Sexes."

As would be expected, the majority of these
make closed nests. There are, however, some
which make open ones but whose females are
not cryptically coloured (see Table V) ; in some
of these the conspicuous colouring is concealed
whilst the hen is sitting (Table V, * birds) ;
others are powerful birds, or birds which nest
in colonies and whose females are not liable
to be attacked whilst sitting (Table V, birds
marked f).

Four birds, the Water-hen and the Coot,
the Red- and Black- throated Divers, are able
to leave their nests unobserved, and do so at
the least alarm, so that it is very difficult to
view these birds sitting.

In two birds, the Lapwing and the Oyster-
catcher, the male keeps guard over the sitting
female and warns her on the approach of
danger ; she is thus able to leave the nest
when the enemy is far distant. Without opera
glasses, it is difficult to view these birds
whilst sitting.

H

CONTROLLED NATURAL SELECTION

For these several reasons, it is not necessary
for the females of the above birds, although
making open nests, to be cryptically coloured.
This completes the list of British Birds, with
the exception of the Phalaropes and Dotterel,
in which the female sex is the more brightly
coloured one. In these birds, the male in-
cubates the eggs in an open nest, and so only
the female retains the conspicuous colouring
that is used for the protection of young.

One other fact is of some interest: many cases have
been observed of females assuming male plumage; this
change of plumage has been found to be associated with
sterility ; whatever the mechanism by which this is
brought about, it is clearly, according to the theory, an
advantage to the species. Males are more conspicuous
than females because they are less valuable, therefore a
sterile female, because she is less valuable than a fertile
one, becomes conspicuous.

It will be well to review the facts which
the theory correlates regarding the colour of
British Birds : it accounts for

1. The presence of conspicuous colouring
in both sexes.

2. The more conspicuous colouring of the
male in these birds.

3. The presence of conspicuous colouring
in the male only.

CONSIDERATION OF BRITISH BIRDS 115

4. The absence of conspicuous colouring in
preying birds.

5. The absence of conspicuous colouring in
night birds.

6. The association of open- nesting with
conspicuous males.

7. The post-nuptial change of plumage in
the analidse and its absence in other epigamic
coloured birds.

8. The brighter colouring of the female in
the Phalaropes and Dotterel.

9. The presence of cryptic colouring in
females and young birds.

10. The older the bird, the more brightly
coloured it is, as in the Gannet.

11. The female assuming male plumage, when rendered
sterile by disease.

Thus can this hypothesis be applied to any
selected material. In birds, it seems that
protection of young is the most important
factor in causing colour-differentiation in the
society ; had insects been chosen, the protec-
tion of females would have been seen to be a
most important factor in sexual differentiation
of colour.

When material is considered in this way,
that is, exhaustively, discourse is confined
almost entirely to exceptions. A wrong im-

116 CONTROLLED NATURAL SELECTION

pression of the utility of the theory is thereby
obtained, because it appears necessary to so
frequently strain it. Theories are usually
substantiated by chosen facts. It is well,
therefore, to state that 173 birds have been
considered, and only a few have required to
be reviewed.

TABLE I.— BIRDS OF PREY

Falconidae -

Marsh Harrier . .
Hen Harrier . .
Montague's Harrier
Buzzard ....
Golden Eagle . .
White-tailed Eagle
*Sparrow Hawk .
Osprey ....
Peregrine Falcon .
Merlin ....
Kestrel ....

~, .. f Richardson's Skua

Stercorarimae \ ~

I Common JSkua

Heron .

Circus seruginosus
C. cyaneus
C. cineraceus
Buteo vulgaris
Aquila chrysartus
Haliartus albicilla
Accipiter nisus
Pandion palisetus
Falco peregrinus
F. sesalon

Tinnunculus alaudarius
S. crepidatus
S. catarrhactes
Ardea cinerea

[* Mimicked by cuckoo, Cuculus canorus.]

TABLE II.— NIGHT BIRDS

f Barn Owl . .

Long-eared Owl

Strigidse I Short-eared Owl

Tawny Owl . .

v Little Owl

Strix flammea
Asio otus
A. brachyotus
Syrnium aluco
Athene noctua

CONSIDERATION OF BRITISH BIRDS 117

Snipe .
Woodcock .
Stone Curlew
Nightjar
Bittern

Gallinago caelestis
Scolopax rusticulus
(Edicnemus scolopax
Caprimulgus europceus
Botaurus stellar is

TABLE III.— SONG BIRDS

Missel Thrush .
Song Thrush
Nightingale
Whitethroat . .
Lesser Whitethroat
Garden Warbler .
Dartford Warbler
Chiffchaff .
Willow Wren
Wood Wren
Reed Warbler .
Sedge Warbler .
Grasshopper Warbler .
Wren ....
Meadow Pipit
Tree Pipit .
Rock Pipit .
Skylark
Woodlark .
Corn Bunting

Turdus viscivorus
T. musicus
Daulias luscinia
Sylvia cinerea
S. curruca
S. hortensis
Melizophilus undatus
Phylloscopus rufus
P. trochilus
P. sibilatrix
Acrocephalus streperus
A. phragmitis
Locustella nsevia
Proglodytes parvulus
Anthus pratensis
A. trivialis
A. obscurus
Alauda arvensis
A. arborea
Emberiza miliaria

TABLE IV.— OTHER BIRDS

Hedge Sparrow .
Spotted Flycatcher
Sand Martin
Tree Sparrow

Accentor modularis
Muscicapa grisol
Cotili riparia
Passer montanus

118 CONTROLLED NATURAL SELECTION

Tree Creeper

Wood Pigeon

Stock Dove .

Rock Dove .

Turtle Dove

Whimbrel . . .

Curlew

Common Sandpiper

Redshank .

Greenshank

Great Crested Grebe .

Little Grebe

Common Guillemot

Greylag Goose

Wryneck

Corncrake .

Partridge .

Red Grouse

Ptarmigan .

Water-rail .

Certhia familiaris
Columba palumbus
C. oenas
C. livia

Turtur communis
Numenius phceopus
N. arquata

Tringoides hypoleucus
Totanus calidris
T. canescens
Podiceps cristatus
Tachybaptes fluviatilis
Lomvia triole
Anser cinerrus
lynx torquilla
Crex pratensis
Perdix cinerea
Tetrao scoticus
T. mutus
Rallus Aquaticus

TABLE V

*Red-legged Partridge .

*Dunlin

*Golden Plover .

*Ringed Plover

*Rlng Ouzel .

*Kentish Plover .

Lapwing

Water-hen .

Oyster Catcher .

Coot .

Black-throated Diver .

Red-throated Diver

Caccabio rufa
Tringa alpina
Charadrius fluvialis
-<3Egialitis hiaticula
Turdus torquatus
A. cantiana
Vanellus vulgaris
Gallinula chloropus
Hsematopus ostralegus
Fulica atra
Colymbus arcticus
C. Septemtrionalis

CONSIDERATION OF BRITISH BIRDS 119

Goldfinch .
f Hawfinch .
f Cormorant .
fShag .
fGannet
fSwan .

fSix Species of Gulls
fFive Species of Terns .
fRazor Bill .
t Five Species of Corvidae
f Black Guillemot .

Carduelis elegans
Coccothrauster vulgaris
Phalacrocorax carbo
P. graculus
Sula bassana
Cygnus (olor)
Laridae
Laridae
Alea torda

Uria grylle

TABLE VI

Hirundo rustica
Chelidon urbica
Muscieapa atricapilla
Cinclus aquaticus
Ruticilla pho3nicurus
Erithacus rubecula
Montacilla lugubris
Saxicola oananthe

Swallow
House Martin
Pied Flycatcher .
Dipper-
Redstart

Robin ....
Pied Wagtail
Wheatear .
Five Species of Parinae
Gold Crest Wren
Nuthatch .
Starling
Three Species of Corvidae
Swift .... Cypselus apus
Three Species of Picidae
Kingfisher .
Merganser .
Goosander .
Sheldrake

Regulus cristatus
Sitta caesia
Sturnus vulgaris

Alcedo ispida
Mergus serrator
M. merganser
Padorna cornuta

Four Species of Turbinaris

Pufiln.

Fratercula artica

120 CONTROLLED NATURAL SELECTION

TABLE VII

Eider Duck .

Mallard

Shoveller

Teal .

Pochard

Golden Eye

Gadwell

Garganey .

Tufted Duck

Widgeon

Pheasant

Capercaille .

Black Grouse

Greenfinch .

Siskin .

Chaffinch .

Linnet

Twite .

Lesser Redpoll .

Bullfinch .

Yellow Bunting .

Crossbill

Reed Bunting

Blackbird .

Cirl Bunting

Bearded Tit

Blackcap

Grey Wagtail

Red-backed Shrike

Yellow Wagtail .

Somateria mollissima
Anas boscas
Spatula clypeata
Querquedula discors
Fuligula perina
F. clangula

Chaulelasmus streperus
Q. cercia
F. cristata
Mareca penelope
Phasianus colchicus
Tetrao urogallus
T. tetrix

Ligurinus chloris
Chrysometris spinus
Fringilla co3lebs
Linola cannabina
F. flavirostris
L. rufescens
Pyrrhula Europcea
Emberiza citrinella
Loxia curvirostra
E. schcaniclus
Turdus merula
E. cirlus

Panurus biamicus
Sylvia atricapilla
Motacilla melanope
Lanius collurio
M. rayii

CONSIDERATION OF BRITISH BIRDS 121

TABLE VIII

Stonechat . . . Pratincola rubicola
Whinchat . . .P. rubetra
House Sparrow . . Passer domesticus

TABLE IX

Phalarope and Dotterel

CHAPTER XII

HUMAN AND OTHER SOCIETIES

AT present only two societies have been dealt
with, the Pair and the Family. Before, how-
ever, passing on to others, a few remarks
will be made relevant to the Pair among
insects.

In many insects the period of copulation
extends over several hours and often over
days. Moreover they are, during this period,
quite defenceless and are able to utilise but
poor means of escape. Therefore one would
expect to find them exhibiting characters which
would entice enemies to take males rather
than females ; especially as the unnatural dis-
joining of pairs, even a short time after copu-
lation has begun, does not result in an entirely
infertile female, but in a more or less com-
pletely fertilised one.

In some cases the separating of the pair
takes place immediately either male or female
are seized, and especially the male ; in others

HUMAN AND OTHER SOCIETIES

separation appears to be difficult or to require
some time.

Observations show that unpalatable insects especially
have this habit, but too few have been made to justify
a definite statement. If this prove to be a fact, its
meaning is clear — they do not require this method for
the escape of either male or female, because they are not
so liable to attack.

In this connection some observations, which
have been made when birds are given copu-
lating insects as food, have a bearing — one of
the two copulating individuals is seized, but
instead of both being at once swallowed, the
bird for some reason almost always shakes or
scrapes off the other. The impression gained
is that the bird mistakes the second insect
for an adherent foreign body.

It appears, therefore, that were the male
of a copulating pair to be seized by a pre-
datory animal, there would be considerable
chance of the female escaping.

The following are methods of self-advertise-
ment whereby male insects draw the attack
of enemies :

1. Position. — Males rest on the top of the
female and are therefore more likely to be
seized. In many cases the males are very
much larger than the females and completely

CONTROLLED NATURAL SELECTION
enclose them during copulation (the Cow-dung

Fly).

In 'other cases, although not on top of the
female, the males are more ready to hand
because the pair takes up a particular position
in space ; for instance, the female may hang
pendent from the male, this will encourage
an enemy to seize the male : the bird would
consider the point of suspension to be the
head- end, and therefore seize this as being
the most valuable part.

2. Movement. — When attempts at escape
are made, it is almost invariably the rule that
the male flies or runs carrying the female ; in
order to prevent escape, the bird will invari-
ably strike at the moving parts, the male :
where there is movement there is vulnerability
(many lepidoptera). Even when actual escape
is not attempted, the male will often make
attracting flutterings of his wings when dis-
turbed; this is a very common character
(most noctuce).

3. Colour. — Attracting colour in the male
is common ; when both sexes are conspicuous
the colour is usually " warning."

4. Mimicry. — It is common to find only
females mimicking and thereby gaining pro-
tection. The absence of mimicry on the part

HUMAN AND OTHER SOCIETIES

of the males renders them liable to be
attacked.

5. Sound. — Males make sounds during copu-
lation, especially when disturbed or captured.

6. Scent. — When both males and females
are scented, the odour which they exhale is
usually obnoxious and either advertises un-
palatableness or renders them unpalatable.
When males alone are scented they are per-
fumed ; this renders them especially attractive
rather than repulsive.

7. Dances are often made by males, who
thus render themselves open to attack. The
females do not leave cover except for a
moment to join the males and be fertilised.
These are pre-copulatory displays similar to
those found in birds. Will not the dances of
the Bower Birds, the running in and out of
the bower, the display of bright objects on
the ground around the bower, draw the attack
of enemies and clear the air for copulation ?

8. Males seek the females, thereby expos-
ing themselves to enemies more than females.
It seems, therefore, that the Theory is able to
explain the vast number of secondary sexual
characters of insects.

Other societies must now be considered, and
first the Herd. Here, no new kind of indi-

126 CONTROLLED NATURAL SELECTION

vidual is found but a combination of sexually
mature males and females, and young. This
society differs from the Family, in that the
onset of a breeding season does not break up
the family formed at the previous breeding
season.

In this society, males are always much less
numerous than females, and thus the inferior
value of the male is demonstrated.

Herd A, in which there are few males, is
better off 'than Herd B, in which males and
females are equal in number, because Herd
A will require less of a limited food supply
and yet have the same reproductive power.

Now, probably in all vertebrate animals,
the sexes are more or less equal at birth :
the question therefore arises — How does the
species rid itself of these males in excess
of the number required, which are not only
useless but positively harmful ? In the follow-
ing ways :

1. By fighting among the males, the more
powerful males destroy the less powerful.
Herd A, whose males possess this instinct,
will have an advantage over Herd B, whose
males do not fight.

2. By the expulsion of males from the herd.
The more powerful males, instead of destroy-

HUMAN AND OTHER SOCIETIES 127

ing the less powerful, are sometimes satisfied
by their banishment ; the females may assist
after a battle has declared the victors. The
expelled males, without the protection of the
herd, probably quickly fall victims to preda-
tory animals.

3. By the destruction of males by females :
this is not unknown.

4. By enemies more frequently destroying
males than females because of their possessing
"attracting" characters. When a herd is
attacked the males, because they possess com-
bative and sacrificing instincts, usually protect
the young and the females, and must often
thus themselves be destroyed.

If males and females were alike both in
characters and instincts, as many females
would be killed as males.

By these methods, Natural Selection within
the herd is controlled. The adult male pos-
sesses special secondary sexual characters
for purposes of offence and defence ; the
young males are like the females and do not
present these characters, these offensive and
defensive instincts, until sexually mature —
this because young males are more valuable
than old ones.

The attracting colour of male birds, which

128 CONTROLLED NATURAL SELECTION

live together in flocks, is not attained some-
times for several years.

Males, when at the zenith of their power,
become monarchs of the herd for a season or
two, and are then thrown out to die. Poor
males never become monarchs. The per-
centage of males cannot be dangerously
reduced by these methods, because the per-
centage of males to females at birth remains
always the same.

In certain species of insects, especially in
the Hymenoptera, another kind of society is
found, composed of males, females, young and
neuters or asexual females. In these societies,
the actual production of males is controlled
by the females and neuters ; males are pro-
duced only when required, and after they have
fertilised the young females they either die or
are destroyed, the females and neuters alone
remaining to carry on the species. (The males
of these insects are not provided with weapons
of offence — stings, &c.) Here, then, pro-
visions are made not only for the destruction
of males but for the limitation of their pro-
duction.

Asexual reproduction in invertebrates,
which is by no means rare, appears to be

HUMAN AND OTHER SOCIETIES 129

for the same purpose, namely, in order that
valuable food material may not be wasted
on comparatively invaluable males. It seems
that it is only owing to the necessity of
occasional cross-fertilisation, that males are
born at all.

Finally, Human Society may be briefly
examined in the light of the new Theory.
The fighting instincts of the male are perhaps
better developed in man than in any lower
animal. Primitive races were perpetually at
war and valuable females were the prizes of
war. Races were prosperous or otherwise,
according as they were good fighters or not ;
this resulted in polygamy and great power of
reproduction. To-day, the more civilised
races do not fight and are therefore not
polygamous. The reproductive power of the
races of to-day is therefore much curtailed
and the relative value of the female very
much increased.

Besides the fighting instinct, the male has
a strong instinct to protect females even at
the expense of his life, and both males and
females have a similar instinct with regard to
their children. The habit which the males of
savage races have of rendering themselves
conspicuous by paint and feathers, may be in

i

130 CONTROLLED NATURAL SELECTION

order to make themselves easily visible to
their enemies, other tribes. It must be re-
membered that savage man delighted in fight-
ing; he did not seek always to take his
enemy unawares, but rather desired to meet
him in fair and open battle.

There appears to be little in civilisation,
to which this Theory can be applied. The
present-day demand of the female for some
recognition of her great value to the race,
may possibly be a cry of Nature, a call from
out the past.

Human society illustrates the conclusions
which were arrived at in Chapter IV by show-
ing that competition does not lead to advance-
ment, which is best gained by environmental
differentiation or specialisation.

Finally, it may be said that species rid them-
selves of males in the following ways :

1. Sacrifice them to enemies.

2. Cause them to destroy one another.

3. Themselves destroy them.

4. Or control their production.

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