102 HUMAN FECUNDITY 



and in some cases upon fertility ; for though fertility is not, 

 properly speaking, considered in this chapter, it is convenient to 

 deal with certain matters here. 



To polygamy has often been attributed a decrease in the 

 number of children born to a woman. Whether it is supposed 

 that the practice of polygamy in some way decreases fecundity 

 or has an influence upon fertility is not clear. In any case there is 

 no evidence that it has any influence either upon fecundity or 

 upon fertility. There is no reason to think that polygamy is 

 attended b}^ any structural or physiological changes such as would 

 influence fecundity, and the statistical evidence does not show 

 any difference in the average number of children born, whether 

 monogamy or polygamy is practised. Theal investigated this 

 question as far as marriages among Bantu women are concerned. 

 He collected a number of returns and sums up the returns as follows. 

 ' Altogether these returns embraced 393, the wives or widows 

 of monogamists, mostly professing Christians, and 591 women, 

 the wives or widows of polygamists. In a few instances it was 

 noted that the women might not have passed the age of child- 

 bearing. The 393 women, wives of monogamists, had borne 

 2,223 children, that is on an average 5-65 children to a woman. 

 The 591 women, wives of polygamists, had borne 3,298 children, 

 that is on an average 5-58 children to each woman. Thus mono- 

 gamy made hardly any appreciable difference in the birth-rate.' ^ 



The question of the influence of lactation on fecundity is of 

 considerable importance, but unfortunately no very definite 

 conclusions can be drawn from the facts known. There is a con- 

 siderable amount of evidence to the effect that the continuance 

 of lactation to some extent inhibits heat in animals and menstrua- 

 tion in women. Though the effect of continued lactation is 

 doubtless in this direction, it cannot be said to be of any very 

 definite strength. It is stated that mares giving suck are liable to 

 miss a season."^ ' There can be no doubt that in the case of sows 

 early weaning is conducive to a more frequent recurrence of 

 oestrous and an increased number of htters.' ^ ' The return of 

 menstruation during lactation in women has been dealt with 

 recently by Heil and Dingwall Fordyce. Heil, who has studied 

 the conditions of 200 nursing mothers, expresses the belief that 



1 Theal, Yellotv- and Dark-Skinned People of Africa, p. 348. " Heape, 



Joe. cit. , p. 43. * Marshall, loc. cit., p. 400. 



