32 SOCIAL EVOLUTION 



securing mates, or at any rate less robust mates, would 

 have fewer progeny and eventually their line would die 

 out. There were also combats between rival males for 

 the possession of females as well as the preferential 

 mating where the female chooses or seems to choose. 

 There is little reason to doubt the effect of selection 

 where there is combat among males. For when the 

 younger or weaker candidates are killed, or expelled 

 from the herd, or left unmated, there is discriminate 

 elimination, the progeny inherit the strong constitutions 

 of their parents. But as to preferential mating, the 

 theory has broken down rather badly under criticism 

 since Darwin's time. 7 



There is one other point of considerable importance 

 which must be discussed before we can understand the 

 real significance of natural selection. It is the alleged 

 inheritance of acquired characters. The athlete has 

 larger and more developed muscles than the average 

 man. Do his children inherit larger and more developed 

 muscles? Many years ago the naturalist Lamarck ad- 

 vanced a theory that modifications induced in the struc- 

 ture of the parent by adaptation to its surroundings 

 were inherited by the offspring. His classic illustration 

 of this theory was the giraffe. The entire frame of the 

 giraffe has been adapted to support an enormously long 

 neck which is of use to the animal in reaching the foliage 

 of trees. Lamarck thought that the ancestors of the 

 giraffe had ordinary necks but had increased the length 

 of them through many successive generations by con- 

 stantly stretching to reach high foliage. Moreover, when 

 the neck became so long as to require for its support 

 special changes in the general form of the animal, these 



7 Thomson & Geddes, op. cit., p. 172. 



