SEXUAL SELECTION, ASSORTATIVE MATING, ETC. 223 



the male in meeting the hazards of battle. The brilliant plumage 

 of male birds, their powers of song and their instincts for display- 

 ing their charms during courtship would probably long ago have 

 been eliminated by natural selection had it not been for their 

 appeal to the aesthetic appreciation of the females. 



It is the part of Darwin's theory of sexual selection which 

 implies the potency of female choice which has incurred the 

 greatest amount of adverse criticism. It is undeniable that in 

 man, who is the only creature we are directly concerned with at 

 present, female selection is capable of operating much as Darwin 

 supposed it to act among less highly developed animals. How far 

 this fact suffices to account for the differences in the appear- 

 ance of the two sexes is a difficult problem. Some of these, such 

 as the greater size and strength of man, his broader shoulders and 

 the greater development of his pugnacious instincts may be in 

 part the result of the "law of battle" during the early stages of his 

 evolution, though they may be in part also the outcome of strug- 

 gles which had no direct relation to mating. That sexual selection 

 in the sense of preferential mating has played any important 

 part in producing the relatively hairless condition of the human 

 body or the development of beards in the male sex is open to grave 

 doubt. In fact, it would be hazardous to assert that any particu- 

 lar feature of either sex owes its existence wholly or even mainly 

 to sexual selection. Nevertheless this factor can scarcely fail to 

 have exerted some influence on racial development at all periods 

 of human history. It is perhaps safe to say that unattractive 

 women have always been at a discount, and that, notwithstanding 

 their subordinate position among primitive peoples, women have 

 in one way or another exercised a certain degree of choice in the 

 selection of their mates. Undoubtedly the rigidity of tribal 

 custom has greatly restricted the operation of sexual selection by 

 women, and in many cases practically eliminated it altogether. 

 Darwin, however, cites many illustrations of the fact that "with 

 savages the women are not in quite so abject a state in relation to 

 marriage as has often been supposed. They can tempt the men 

 whom they prefer, and can sometimes reject those whom they 



