CHAPTEE XV 



HOMES AND DOMESTIC HABITS 



142. Importance of care of the young. The nest-building 

 and domestic habits of animals are adaptations, but adapta- 

 tions of behavior or habit rather than of structure, and are 

 based on instinct, intelligence, and reason. These instincts 

 and habits are among the most important shown by animals, 

 because on them depends largely the continuance of the 

 species. Of primary importance in the perpetuation of the 

 species is the possession by animals of adaptations of struc- 

 ture and behavior, which help the individual live long enough 

 to attain full development and to leave offspring. But in 

 the case of many animals a successful start in life on the 

 part of the offspring depends on the existence in the par- 

 ents of certain domestic habits concerned with the care and 

 protection of their young. The young of many animals de- 

 pend absolutely, for a part of their lifetime, on this parental 

 care. In these cases it is quite as necessary for the continued 

 existence of the species that the habits that afford this care 

 be successful as that the parent should come successfully to 

 mature development and to the production of offspring. 



143. Care of the young, and communal life. The nest- 

 building or home-making habits and the continued per- 

 sonal care of the young for a part of their lifetime are most 

 highly developed and widespread among the birds, mam- 

 mals, and insects ; and it is both among the insects and 

 the higher vertebrates that we find most developed those 

 social and communal habits discussed in Chapter IX. The 

 principal activities of an animal community have to do 



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