S6 THE INFANCY OF ANIMALS 



nearly approaching the ancestral state of things than is 

 found to commonly prevail among the creatures of which 

 we are at the moment speaking. 



Thus, then, in comparing young birds we describe 

 those which are of the precocious type as more primitive, 

 more generalised, than those of the helpless type, and 

 this because activity is the common characteristic of 

 young reptiles, the stock from which the birds have 

 descended. We have reason to believe, as has been 

 shown already in these pages, that the young of the 

 earliest known birds were of the precocious type, and any 

 departure from this in the direction of specialisation is a 

 departure from which return is impossible. 



Very well. Let us then begin our survey of the nursery 

 life, so to speak, of young birds by a review of that of 

 the precocious types. Since these enter the world in a 

 condition to pick up food for themselves within an hour 

 or so after birth the parents are saved an enormous 

 amount of labour and fatigue ; for the young accompany 

 them on their wanderings, and all feed together. Never- 

 theless Nature seems to put the welfare of the race above 

 that of the individual, for while the parents escape the 

 strain of foraging for food, with the attendant and almost 

 ceaseless journeyings to and from the nest, things which 

 have to be borne when the young are helpless, they 

 are at the same time in so far relieved of parental 

 responsibility. 



And thus it is that we find in many cases the care of 

 the family falls entirely on the shoulders of the female, 

 as, for example, among the polygamous gallinaceous 

 birds, and among the ducks, phalaropes and hemipodes, 

 or entirely on the male, as in the rhea and emu. In 

 either case this is a source of weakness to the family, 



