Chapter XXII 



SOME ASPECTS OF THE BIOLOGY OF 

 HUMAN POPULATIONS 



Raymond Pearl 



A POPULATION may be defined as an aggregation of 

 individual organisms of the same species, living 

 together in a hmited and defined universe. In the case 

 of human beings the limits of the "universe" of a particular 

 population are commonly defined either geographically or 

 politically. We thus speak intelligibly of the "population of 

 the United States," meaning the aggregation of human beings 

 Hving together within the geographical boundaries of the 

 United States of America. 



The problems presented by human populations are many 

 and diverse. The economic conditions prevaifing within any 

 particular population, its social organization, its racial 

 composition, and so on, all suggest many questions to which 

 the answers are generally either not known at all, or only 

 vaguely and imperfectly. But underlying all such questions 

 are still more basic ones, which have to do with the biology of 

 human populations. Man is an animal. However civihzed 

 he is or may become, what it is that after all keeps him 

 present and voting, as the phrase goes, is the basic fact that 

 he is an organism, which, in the aggregate, must be nourished, 

 must reproduce, and must finally die. The fundamental 

 characteristics of those groups of human beings that we call 

 populations necessarily depend upon these basic biological 

 attributes and actions of the individuals which compose 

 them. But recent research has demonstrated that a complete 

 account of the biology of a population will require something 

 more than an examination of the biology of each separate 

 individual composing it. The group behaves biologically in 

 certain ways as a whole. For the adequate study of such 

 phenomena there is rapidly developing a separate division 

 of science, which is called "group biology," or the biology of 

 populations. It is to the discussions of the biology of human 

 populations that this chapter will be chiefly devoted. 



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