538 THE DESCENT OF MAN 



in the latter genus, 63 specimens caught the same day in- 

 cluded 57 males; but he suggests that this preponderance 

 may be due to some unknown difference in the habits of 

 the two sexes. With one of the higher Brazilian crabs, 

 namely, a Gelasimus, Fritz Miiller found the males to be 

 more numerous than the females. According to the large 

 experience of Mr. C. Spence Bate, the reverse seems to be 

 the case with six common British crabs, the names of which 

 he has given me. 



The Proportion of the Sexes in Relation to Natural Selection 



There is reason to suspect that in some cases man has by 

 selection indirectly influenced his own sex-producing powers. 

 Certain women tend to produce during their whole lives 

 more children of one sex than of the other; and the same 

 holds good of many animals, for instance, cows and horses; 

 thus Mr. Wright, of Yeldersley House, informs me that one 

 of his Arab mares, though put seven times to different 

 horses, produced seven fillies. Though I have very little 

 evidence on this head, analogy would lead to the belief 

 that the tendency to produce either sex would be inherited 

 like almost every other peculiarity, for instance, that of pro- 

 ducing twins; and concerning the above tendency a good 

 authority, Mr. J. Downing, has communicated to me facts 

 which seem to prove that this does occur in certain families 

 of short-horn cattle. Col. Marshall"' has recently found on 

 careful examination that the Todas, a hill-tribe of India, 

 consist of 112 males and 84 females of all ages — that is in a 

 ratio of 183.3 males to 100 females. The Todas, who are 

 polyandrous in their marriages, during former times invari- 

 ably practiced female infanticide; but this practice has now 

 been discontinued for a considerable period. Of the chil- 

 dren born within late years, the males are more numerous 

 than the females, in the proportion of 124 to 100. Col. 

 Marshall accounts for this fact in the following ingenious 



M "The Todas," 1873, pp. 100, 111, 194, 196. 



