1024 LIFE : OUTLINES OF GENERAL BIOLOGY 



with related neighbour-species. (See Karl Pearson, Grammar of 

 Science, 2nd ed., 1900, p. 418.) 



At this point attention may be directed to the important contri- 

 butions to the Natural History of mating to be found in H. Eliot 

 Howard's monumental British Warblers (1907-15). We venture 

 to think that this acute and sympathetic observer exaggerates 

 what most naturalists call the "instinctive" at the expense of the 

 "intelligent" element in the behaviour of birds, and that he is 

 unnecessarily antagonistic to Darwin's theory of sexual selection, 

 but his work is a rich treasure-house of reliable data. It is of great 

 interest, for instance, to realise 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 advanta- 

 geous, or, to the several individuals, most pleasing "territories" for 

 nesting. Not less important is the evidence that the soberly coloured 

 warblers do not fall behind brilliantly coloured birds in the elaborate- 

 ness and abandon of their display attitudes and poses. We have 

 referred in the section on courtship to Howard's observations and 

 reflections on the courting behaviour of such birds as the yellow- 

 hammer. 



CRITICISMS OF DARWIN'S THEORY OF SEX SELECTION. 



Darwin was weU 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 tastej 

 on the part of the female which at first appear extremely improb-J 

 able". (Descent of Man, p. 326.) The first very serious criticism! 

 came from Wallace in 1871, and was restated in his Darwinism in 

 1889. The most elaborate criticism as yet is surely to be found h 

 T. H. Morgan's Evolution and Adaptation (1903), where no fewei 

 than twenty-four reasons are given for rejecting the theory.] 

 Within our narrow limits we must confine our attention to the three 

 criticisms which seem most important. 



{a) There is, in the first place, an admitted difficulty in th( 

 scarcity of direct evidence that some of the males are actually dis- 

 qualified and left unmated. If all the males get mates sooner 01 

 later, then no discriminate elimination is effected. Prof. Karl 

 Pearson has given statistical evidence of preferential mating inj 

 mankind, but this is hardly procurable in the animal world.] 

 Darwin met the objection in various ways. He pointed out that inj 

 some species the males outnumber 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 evolutionar] 

 movement will be determined by them, and not by the handicappe( 



