II 



THE EVOLUTION OF PARENTAL CARE 



TNSTINCTS for the care of young extend far 

 -"-down in the animal kingdom and their origin 

 therefore dates back to an early period in the history 

 of the earth. The important role which these in- 

 stincts have played in the evolution of animal life, — 

 a role which has increased in importance as animals 

 have become more highly evolved, — renders the sub- 

 ject of their origin and course of evolution one of 

 especial interest to the comparative psychologist. 

 With a full realization of the fact that phylogeny is 

 a treacherous field I have nevertheless ventured in 

 the following account to outline the probable way in 

 which animals came to care for their offspring, and 

 to point out briefly how parental care has been in- 

 strumental in shaping the more advanced stages of 

 the evolutionary process. 



In several respects, notably in relation to social 

 and ethical evolution, the institution of parental care 

 has formed the foundation for higher stages of de- 

 velopment. Organized societies in animals generally 

 have their beginning in the expansion of the family. 

 In some insects, for instance, such as the ants, bees, 

 and social wasps, various gradations may be traced 



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