78 EVOLUTION AND ANIMAL LIFE 



female never, perhaps, sees the male which fertilizes her dropped 

 eggs? In many fishes the spring ornamentation of the males is 

 just as marked and just as brilliant as in the birds or other 

 animals of much higher intelligence and corresponding power of 

 choice. Witness the horned dace, chubs, and stone rollers in 

 any brook in spring. 



Choice on a basis of ornament and attractiveness implies a 

 high degree of aesthetic development on the part of the females 

 of animals of whose development in this line we have no other 

 proof. Indeed, this choice demands aesthetic recognition among 

 animals to which we distinctly deny such a development, as 

 the butterflies and other insects in which secondary sexual 

 characters of color, etc., are abundant and conspicuous. Sim- 

 ilarly with practically all invertebrate animals. Further, in 

 those groups of higher animals where aesthetic choice may be 

 presumed possible, we have repeated evidence that preferences 

 vary with individuals. Certainly they do with men, the animal 

 species in which such preferences certainly and most conspicu- 

 ously exist. 



In some human races hair on the face is thought beautiful; 

 in others, ugly. Besides even if we may attribute fairly a cer- 

 tain amount of aesthetic feeling to such animals as mammals and 

 birds, is this feeling so keen as to lead the female to have 

 preference among only slightly differing patterns or songs? 

 Yet this assumption is necessary if the development of ornament 

 and other attracting and exciting organs is to be explained by 

 the selection and gradual accumulation through generations of 

 slight fortuitously appearing fluctuating variations in the males. 



There are actually very few recorded cases in which the ob- 

 server believes that he has noted an actual choice by a female. 

 Darwin records eight cases among birds. Since Darwin, not 

 more than half a dozen other cases, all doubtful, have been 

 noted. Also a few instances, all more illustrative of sexual 

 excitation of females resulting from the perception of odor or 

 actions, than any degree of choice on their part, have been 

 listed. 



In numerous cases the so-called attractive characters of the 

 males, described usually from preserved (museum) specimens, 

 have been found, in actual life, to be of such a character that 

 they cannot be noted by the female. For example, the brilliant 

 colors and curious horns of the males of the dung beetles are, in 



