THE WAY LIFE BEGINS 71 



swallowing. They are thus called upon suddenly at birth to 

 assume functions that have never before been tried. The 

 heart, the muscular and nervous systems have long been 

 active. With the prepared food of the mother, digestion does 

 not seem difficult. 



The Two Factors that Separate Man from the Animals 



We have referred repeatedly to the very close parallel in 

 the development of man and the mammals, and, at earlier 

 stages, of a similar parallel between the mammals and the 

 simpler animals. The purpose in doing so is not only to state 

 the facts, but to simplify, as far as possible, the task of un- 

 derstanding the nature of animal and human development. 



There is, however, a great difference between man and 

 the mammals. For most people, the differences far out- 

 weight the similarities. From the viewpoint of physical 

 development this cannot be true, but there are two factors 

 intimately related to man's sexual life which are decisive 

 advances upon anything found in the animal world. 



The first and most important of these is the lengthened 

 period of human infancy — a period measured before, as 

 well as after, birth. Although there have been greatly dif- 

 ferent rates of growth, there is, at the moment of birth, little 

 difference between the young of man, the mammals, and 

 many birds as far as helplessness is concerned. In a matter 

 of a few weeks, however, the mammal — the rabbit, for exam- 

 ple, is able to care for itself. For the child it is a question of 

 years, due to both its slow development, and, in the case of 

 the child born in civilization, to a complex and difficult envi- 

 ronment. The prolongation of infancy is unique for the human 

 species, for although the elephant, the slowest breeder among 

 animals, has fewer offspring than man and carries the young 

 longer in utero, there is a relatively shorter growth period 

 for the young after birth. This lengthened period of infancy 

 and early childhood has had much to do with the development 

 of family and communal life. * Probably family life has in 

 turn lengthened the period of development. 



1 Cf. John Fiske. Cosmic Philosophy, Vol. II, p. 344 et seq. 



