The Role of Sex in the Evolution of Mind 241 



gans in the same insects has doubtless been greatly 

 furthered through the evolution of these structures. 

 The primary function of the vocal apparatus of the 

 vertebrates was probably to furnish a sex call, as 

 is now its exclusive function in the Amphibia. Only 

 later and secondarily did the voice come to be em- 

 ployed in protecting and fostering the young, and 

 as a means of social communication. And the evo- 

 lution of the voice in vertebrates doubtless influ- 

 enced to a marked degree the evolution of the sense 

 of hearing. It is not improbable, therefore, that 

 the evolution of the voice, with all its tremendous 

 consequences in regard to the evolution of mind, is 

 an outgrowth of the differentiation of sex. 



In cases of degeneration through parasitism or 

 other causes the female often proceeds much farther 

 on the downward path than the male. In the scale 

 bugs, for instance, the females have lost their wings 

 and many other structures, while the adult male re- 

 mains an active and graceful winged insect. The 

 necessity for finding the female has kept the male 

 from undergoing the degeneration that has over- 

 taken the other sex. 



Much of the elaborate organization of the imago 

 state of insects has reference to activities directly 

 or indirectly concerned with mating and depositing 

 the eggs in the proper environment for the develop- 

 ment of the young larva?. There is a relatively 

 long nymphal or larval period chiefly devoted to the 

 vegetative functions of assimilating nutriment, 



