SUPPLEMENTAL NOTE, 709 



SUPPLEMENTAL NOTE 



ON 



SEXUAL SELECTION IN RELATION TO MONKEYS. 



[Reprinted from Nature, November 2, 1876, p. 18.] 



In the discussion on sexual selection in my " Descent of 

 Man;" no case interested and perplexed me so much as the 

 brightly colored hinder ends and adjoining parts of certain 

 monkeys. As these parts are more brightly colored in one 

 sex than the other, and as they become more brilliant 

 during the season of love, I concluded that the colors had 

 been gained as a sexual attraction. I was well aware that 

 I thus laid myself open to ridicule; though in fact it is not 

 more surprising that a monkey should display his bright- 

 red hinder end than that a peacock should display his mag- 

 nificent tail. I had, however, at that time no evidence of 

 monkeys exhibiting this part of their bodies during their 

 courtship ; and such display in the case of birds 

 affords the best evidence that the ornaments of the 

 males are of service to them by attracting or 

 exciting the females. I have lately read an article 

 by Joh. von Fischer, of Gotha, published in '^Der 

 Zoologische Garten," April, 1876, on the expression of 

 monkeys under various emotions, which is well worthy of 

 study by any one interested in the subject, and which 

 shows that the author is a careful and acute observer. In 

 this article there is an account of the behavior of a young 

 male mandrill when he first beheld himself in a looking- 

 glass, and it is added that after a time he turned round 

 and presented his red hinder end to the glass. Accord- 

 ingly I wrote to Herr J. von Fischer to ask what he sup- 

 posed was the meaning of this strange action, and he has 

 sent me two long letters full of new and curious details, 

 which will, I hope, be hereafter published. He says that 



