PROPORTION OF THE SEXES. 255 



From the ncveral foregoing cases we have some reason to 

 believe that infanticide practiced in the manner above explained, 

 tends to make a male-producing race; but I am far from sup- 

 posing that this practice In the case of man, or some analogous 

 process with other species, has been the sole determining cause 

 of an excess of males. There may be some unknown law leading 

 to this result in decreasing races, which have already become 

 somewhat infertile. Besides the several causes previously al- 

 luded to, the greater facility of parturition amongst savages, 

 and the less consequent injury to their male infants, would 

 tend to increase the proportion of live-born males to females. 

 There does not, however, seem to be any necessary connection 

 between savage life and a marked excess of males; that is if we 

 may judge by the character of the scanty offspring of the lately 

 existing Tasmanians and of the crossed offspring of the Tahi- 

 tians now inhabiting Norfolk Island. 



As the males and females of many animals differ somewhat in 

 habits and are exposed in different degrees to danger, it is 

 probable that in many cases, more of one sex than of the other 

 are habitually destroyed. But as far as I can trace out the com- 

 plication of causes, an indiscriminate though large destruction 

 of either sex would not tend to modify the sex-producing power 

 of the species. With strictly social animals, such as bees or ants, 

 which produce a vast number of sterile and fertile females in 

 comparison with the males, and to whom this preponderance is 

 of paramount importance, we can see that those communities 

 would flourish best which contained females having a strong 

 inherited tendency to produce more and more females; and in 

 such cases an unequal sex-producing tendency would be ulti- 

 mately gained through natural selection. With animals living 

 in herds or troops, in which the males come to the front and 

 defend the herd, as with the bisons of North America and certain 



greyhounds, many more female puppies are destroyed than males, 

 just as with the Toda infants. Mr. Cupples assures me that this is 

 usual with Scotch deer-hounds. Unfortunately, I know nothing of 

 the proportion of the sexes In any breed, excepting greyhounds, and 

 there the male births are to the female as 110.1 to 100. Now from In- 

 quiries made from many breeders, It seems that the females are In 

 some respects more esteemed, though otherwise troublesome; and it 

 does not appear that the female puppies of the best-bred dogs are 

 systematically destroyed more than the males, though this does some- 

 times taka place to a limited extent. Therefore I am unable to de- 

 cide whether we can, on the above principles, account for the pre- 

 ponderance of male births In greyhounds. On the other hand, we 

 have seen that with horses, cattle, and sheep, which are too valuable 

 for the young of either sex to be destroyed, if there Is any difference, 

 the females are slightly In excess. 



