Chap. VIII. SEXUAL SELECTION. 275 



led to the much more frequent development of secon- 

 dary sexual characters in the male than in the female. 

 But the development of such characters will have been 

 much aided, if the conclusion at which I arrived after 

 studying domesticated animals, can be trusted, namely, 

 that the male is more liable to vary than the female. 

 I am aware how difficult it is to verify a conclusion of 

 this kind. Some slight evidence, however, can be gained 

 by comparing the two sexes in mankind, as man has 

 been more carefully observed than any other animal. 

 During the Novara Expedition 15 a vast number of mea- 

 surements of various parts of the body in different races 

 were made, and the men were found in almost every 

 case to present a greater range of variation than the 

 women ; but I shall have to recur to this subject in 

 a future chapter. Mr. J. Wood, 16 who has carefully 

 attended to the variation of the muscles in man, puts 

 in italics the conclusion that " the greatest number of 

 " abnormalities in each subject is found in the males." 

 He had previously remarked that "altogether in 102 

 " subjects the varieties of redundancy were found to 

 " be half as many again as in females, contrasting 

 " widely with thft greater frequency of deficiency in 

 " females before described." Professor Macalister like- 

 wise remarks 17 that variations in the muscles "are 

 " probably more common in males than females." 

 Certain muscles which are not normally present in man- 

 kind are also more frequently developed in the male 

 than in the female sex, although exceptions to this rule 



15 'Reise der Novara: Anthropolog. Tlieil,"* 1867, s. 21G-2G9. TJie 

 results were calculated by Dr. Weisbach from measurements made by 

 Drs. K. Scherzer and Schwarz. On the greater variability of the males 

 of domesticated animals, see my ' Variation of Animals and Plants 

 under Domestication,' vol. ii. 1868, p-. 75. 



16 'Proceedings Royal Soc.' vol. xvi. July, 18GS, p. :">19 and 524. 



17 < Proc. Royal Irish Academy,' vol. x. 1868, p. 123. 



rti •) 



