HUMAN FECUNDITY 97 



possibly the third factor may have varied in the same direction. 

 It has also been noted that similar changes have been observed 

 to take place in animals which have been subject to better con- 

 ditions. The fact that human conditions have certainly been 

 bettered suggests that the same cause may have been at work 

 in the case of man. There is, however, no doubt that changes in 

 the case of man are not wholly explicable in this way. In 

 part the differences are racial differences, and to the degree 

 in which the differences are racial they cannot be attributed to 

 the direct effect of the surroundings. 



8. Additional support to the view that fecundity has increased 

 with civilization is given by certain other types of evidence. In 

 the first place it appears to be a fact that the reproductive organs 

 of the more primitive races of mankind are smaller and in all 

 respects less well-developed than those of civilized races. 1 It is 

 not meant that the organs differ qualitatively in any way ; they 

 are merely smaller relatively to the other organs than among 

 civilized races. It is doubtful how we should interpret these facts ; 

 but it does not seem unreasonable to assume a connexion between 

 a lesser development of the reproductive organs and a lower degree 

 of fecundity. 



Secondly, we have a considerable body of evidence with respect 

 to the strength of sexual desire among these races. 2 Many 

 observers have recorded their opinion that the members of these 

 more primitive races do not experience sexual excitement to the 

 same degree as do the members of the more civilized races. There 

 are other observations which record the difficulty experienced in 

 obtaining sexual erethism. It seems reasonable to associate these 

 observations with a lower degree of fecundity than that found 

 among civilized races. 



In this connexion the fact that lack of sexual excitement 

 renders fertilization less likely is relevant. As fertilization has 

 been achieved with the female in a condition of narcosis, 3 it is 

 clear that sexual excitement is not necessary. Nevertheless, if the 



1 The evidence is summarized by Ploss and Bartels, loc. cit., vol. i, ch. vi. 



2 See Ploss and Bartels, loc. cit., vol. i, ch. xix, and Havelock Ellis, ' Studies in 

 the Psychology of Sex', Analysis of the Sexual Impulse, p. 209. The fact is com- 

 mented upon by Ratzel, History of Mankind, vol. ii, p. 17. As examples of the 

 evidence for particular races see, for the Malays, Stevens, Zeit. fur Eth., Bd. xxviii, 

 1896, p. 180; for the Fuegians, Hyades et Deniker, Mission scientifique du Cap 

 Horn, Tome vii, p. 187; for the Andamanese, Portman, ./ A. L, vol. xxv, p. 369. 



3 Mayer, loc. cit., p. 409. 

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