SELECTION OF MATES 199 



evident. There are many groups of animals in which 

 males are scarcer than females. In such cases direct 

 personal competition would be unlikely, and in fact 

 does not, so far as we know, regularly occur. But, 

 nevertheless, a severe though unseen test is applied. 

 Each family at first contains on the average an equal 

 number of the two sexes, and therefore for every 

 male that grows to maturity at least two must perish ; 

 that is, the action of natural causes is not the same 

 for both sexes, but falls with unequal emphasis upon 

 the young males. For such diverse creatures as cats, 

 plaice, and hermit-crabs this conclusion has been found 

 to hold good. 



The life of animals and of working men agree in 

 this, that, consciously or unconsciously, it is a strife 

 to give their children the best chance. Their response 

 to this spirit takes varied forms, but ultimately it is 

 an answer to the same stimulus, and though it seems to 

 arise within us, it is the spirit of a hive whose boundaries 

 are not limited by the seen or tangible. But the case 

 of animals is heightened by the strenuous selection of 

 mates by whom the welfare of the race can be best 

 advanced. And in this, animals and the lower races 

 of mankind exhibit meticulous care for physical 

 prowess, for on that alone is advance possible. 



If we think such considerations below us, the 

 whirligig of time brings in its revenges with cries of 

 deterioration; and we revert to the study of animal 

 life with wonder at the severity of the test and the 

 richness of the reward that such competition exhibits, 



