COURTSHIP AND SEX 199 



Now it is plain that forceful competition among rival 

 males for the possession of a female or of several females 

 does not differ in kind from the ordinary struggle for food 

 and foothold, except that it is strictly intra-specific. Darwin 

 pointed out indeed (p. 349) that sexual selection is less 

 rigorous than natural selection ; that it is less of a life-and- 

 death affair ; that it operates through the unsuccessful 

 males having fewer, less vigorous, or no offspring ; and that 

 it is not limited by the general conditions of life ; but there 

 is in all this no departure from the natural selection position. 

 This part of the theory, therefore, remains valid to those who 

 regard natural selection as a vera causa, 



(B) Darwin went on to those characters that are useful in 

 the recognition and capture of the females. When a male 

 excels his neighbours in his capacities for finding, pursuing, 

 and catching the female, sexual selection, he said, again 

 comes into action (" Descent of Man," p. 324). The male 

 moth often finds his mate by the olfactory acuteness of his 

 large antennae ; some small crustaceans recognise the other 

 sex almost instantaneously when there is chance contact in 

 the water ; in some fishes, recognition depends on colour 

 and on behaviour ; many experiments led Goltz to believe 

 that the male frog distinguishes the female by touch ; in 

 birds, visual and auditory impressions count for most ; in 

 mammals, the scent is often of chief importance (see 

 S. J. Holmes, " Studies in Animal Behaviour," Boston, 

 1916, pp. 219-328). 



Since correct recognition of the one sex by the other is 

 often of essential importance to the race, it is not surprising 

 to find Darwin saying (" Descent of Man," p. 324) : " But 

 in most cases of this kind it is impossible to distinguish 

 between the effects of natural and sexual selection." This 

 part of the theory also remains valid, if one believes in 

 selection at all. 



(C) Darwin primarily used the term sexual selection for 

 all cases where sifting occurs in relation not to ordinary 

 nutrition and self-preservation, but to pairing. It was only 

 secondarily that he laid emphasis on the " choice " that the 



