278 HUMAN BIOLOGY 



polyandrous peoples are the Todas of India, among whom 

 the males are markedly in excess of the females. These are 

 fair samples of the data available and what we observe 

 is that polygyny may flourish in an excess male population 

 as well as in the reverse condition. But even should the 

 correlation be regular, we should hesitate to regard the 

 sex ratio as the determiner of the marriage system, since by 

 infanticide and other means the community may so regulate 

 the survival sex ratio as to conform to the marriage ideal. 



The studies of Pitt-Rivers indicate no direct relation 

 between the sex ratio and the form of marriage, but show 

 that a declining population, regardless of the form of mar- 

 riage, is accompanied by an excess of male survivals, and 

 an increasing population by parity, or an excess in females. 

 In the cases cited, the populations in the New Hebrides 

 and that of the Toda country are declining, and that of 

 the Navajo increasing, which is consistent with the con- 

 clusions of Pitt-Rivers. While it may be wise to reserve 

 decision as to the general validity of this theory, it is clear 

 that the sex ratio can no longer be considered an important 

 initial factor in determining the form of marriage. 



PROMISCUITY AND THE BIRTH RATE 



Having shown that the sex ratio has in itself no claim as a 

 determiner of the marriage form, we may consider the 

 relation between birth rate and marriage. It is conceivable 

 that if a form of marriage is highly unfavorable to a parity 

 of the sexes, the groups practicing it will either die out, or 

 be socially demoralized, and that in this way it should come 

 about that one or two of the possible forms of marriage 

 would dominate. Thus, it has been said that polyandry 

 leads to extinction because the birth rate is low; but many 

 groups of primitive people having other forms of marriage 

 are dying out equally fast. Further, data upon the birth 

 rate of primitive peoples are scarcely obtainable because 

 mothers do not accurately recall the number of children 

 they have borne. The attempts recently made to check 

 up on the birth rates for Eskimo and American Indians are 

 not conclusive, but as far as they go, indicate a birth rate 

 as high as that of White Americans in colonial days. This 



