208 Evolution and Adaptation 



— for instance, the hump on the male zebu cattle of India, 

 the tail of fat-tailed rams, the arched outline of the forehead 

 in the males of several breeds of sheep, and, lastly, the mane, 

 the long hairs on the hind-legs, and the dewlap of the male 

 of the Berbura goat." 



In these cases and in others that Darwin cites, which seem 

 clearly to indicate that some of these secondary sexual charac- 

 ters are not the result of sexual selection, he concludes, "that 

 they must be due to simple variability, together with sexually 

 limited inheritance. 



" Hence it appears reasonable to extend this same view to 

 all analogous cases with animals in a state of nature. Never- 

 theless I cannot persuade myself that it generally holds good, 

 as in the case of the extraordinary development of hair on 

 the throat and fore-legs of the male Ammotragus, or in 

 that of the immense beard of the male Pithecia. Such study 

 as I have been able to give to nature makes me believe that 

 parts or organs which are highly developed, were acquired 

 at some period for a special purpose. With those antelopes 

 in which the adult male is more strongly colored than the 

 female, and with those monkeys in which the hair on the 

 face is elegantly arranged and colored in a diversified 

 manner, it seems probable that the crests and tufts of hair 

 were gained as ornaments ; and this I know is the opinion of 

 some naturalists. If this be correct, there can be little doubt 

 that they were gained, or at least modified through sexual 

 selection ; but how far the same view may be extended to 

 other mammals is doubtful." 



The astonishing colors in some of the monkeys cannot 

 be passed over without comment. 



"In the beautiful Cercopitkecus diana, the head of the 

 adult male is of an intense black, whilst that of the "female 

 is dark gray ; in the former the fur between the thighs is of 

 an elegant fawn-color, in the latter it is paler. 



" In the Cercopitliecus cynosurns and griseoviridis one part 



