460 DIRECTIVE FACTORS IN EVOLUTION: 



of reliable data. * It is of great interest, for instance, to 

 discover how much competition there is among the male 

 warblers, before the females arrive on the scene, in the way 

 of discovering and securely holding the most advantageous 

 territories for nesting. ISTot less important is the evidence 

 that the soberly coloured warblers do not fall behind bril- 

 liantly coloured birds in the elaborateness and abandon of 

 their display attitudes and poses. 



(g) Darwin was well aware of many of the difficulties 

 besetting his theory. With his wonted candour he anticipated 

 various objections, e.g., that the theory '^ implies powers 

 of discrimination and taste on the part of the female which 

 at first appear extremely improbable '' (Descent of Man, 

 p. 326). The first very serious criticism came from Wal- 

 lace in 1871, and was restated in his Darwinism in 1889. 

 The most elaborate criticism as yet is surely to be found 

 in T. H. Morgan's Evolution and Adaptation (1903), where 

 no fewer than 24 reasons are given for rejecting the theory. 

 Within our narrow limits we must confine our attention to 

 the three criticisms which seem most important. 



There is, in the first place, an admitted difficulty in the 

 scarcity of direct evidence that some of the males are actually 

 disqualified and left unmated. If all the males get mates 

 sooner or later, then no discriminate elimination is effected. 

 Prof. Karl Pearson has given statistical evidence of prefer- 

 ential mating in mankind, but this is hardly procurable in 

 the animal world. Darwin met the objection in various 

 ways. He pointed out that in some species the males out- 

 number the females, and that in some other species there is 

 polygamy. If the more attractive males have in such cases 

 an advantage in mating, the direction of evolutionary move- 

 ment will be determined by them, and not by the handicapped 



