96 AFRICAN POLITICAL SYSTEMS
based on descent in nearly every case. Chieftainships were limited to one clan, as we have seen; some of the councillorships (i.e. the bakabilo) are confined to a few of the older clans; and head-manships, though they may be won through the chiefs favour, tend to become hereditary in their turn. All priestly offices are hereditary without exception, as is natural where an ancestral cult of this type is practised. Magico-economic specialists, particularly those in charge of fishing villages, usually acquire their powers by descent also, as do some of the doctors and diviners (yangd). In each case the supernatural powers almost invariably correlated with political authority in this area are conferred by a rite, of great complexity, in the case of the succession of a chief, known as ukypyanika. For these reasons it is essential to study the dogma of descent by which these powers are believed to be transferred from one generation to another, and the legal rules of succession by which status and office are passed from one man to another.
(a) The Dogma of Descent. By dogma of descent I mean, first, those theories of procreation1 which express a people's beliefs as to the physical contribution of the father and mother to the formation of the child, and hence the traditional conception of the physical continuity between one generation and the next; and next their beliefs as to the influence of the dead members of each social group over the living, and hence the social identification2 of a man with the line of his dead ancestors.
Among the Bemba it is believed that a child is made from the blood of a woman which she is able to transmit to her male and female children. A man can possess this blood in his veins, but cannot pass it on to his children, who belong to a different clan. Physiological paternity is recognized. Children are often described as being like their fathers, and are expected to give the latter affection and respect although they have no legal obligations to them under the matrilineal system. 'We take our fathers' presents because they begot us,' they say. But it is nevertheless the physical
1 This term was first introduced by Malinowski, who showed how the rules of matrilineal descent among the Trobriand islanders are buttressed by beliefs that the father makes no physical contribution to the birth of his child. Similar material published by Rattray from the Ashanti area shows a belief in a double contribution of blood from the mother and spirit from the father correlated with a bilateral emphasis on descent.
2 To use a term employed in a very stimulating manner by RadclifFe Browne.