SEXVAL SELECTION IN RELATION TO MAN 729 



and emasculation produces the same effect on him as oa 

 the lower animals, for it "arrests that prominent growth 

 of the thyroid, etc., which accompanies the elongation of 

 the cords." " With respect to the cause of this difference 

 between the sexes, I have nothing to add to the remarks in 

 the last chapter on the probable effects of the long-continued 

 use of the vocal organs by the male under the excitement of 

 ze ^ rage, and jealousy. According to Sir Duncan Gibb," 

 the voice and" the form of the iarynx differ in the different 

 races of mankind; but with the Tartars, Chinese, etc., the 

 voice of the male is said niot to differ so much from that 

 of the female as in most other races. 



The capacity and love for singing or music, though not 

 a sexual character in man, must not here be passed over. 

 Although the sounds emitted by animals of all kinds serve 

 many purposes, a strong case can be made out that the vocal 

 organs were primarily used and perfected in relation to the 

 propagation of the species. Insects and some few spiders 

 are the lowest animals which voluntarily produce any sound ; 

 and this is generally effected by the aid of beautifully con- 

 structed stridulating organs, which are often confined to 

 the males. The sounds thus produced consist, I believe 

 in all cases, of the same note, repeated rhythmically;*' and 

 this is sometimes pleasing even to the ears of man. The 

 chief and, in some cases, exclusive purpose appears to be 

 either to call or charm the opposite sex. 



The sounds produced by fishes are said in some cases 

 to be made only by the males during the breeding season. 

 All the air-breathing Vertebrata necessarily possess an ap- 

 paratus for inhaling and expelling air, with a pipe capable 

 of being closed at one end. Hence when the primeval 

 members of this class were strongly excited and their 

 muscles violently contracted, purposeless sounds would 



" Owen, "Anatomy of Vertebrates," vol. iii. p. 603. 

 w "Journal of the Anthropolog. Soc," April, 1869, pp. Ivii. and Ixvi 

 » Dr. Scudder. "Notes on Stridulatlon," in "Proa Boston Soe. of Nat 

 HiBt.," vol. si., April, 1868. 



