CHAPTER XXXI 



THE HUMAN SPECIES 



We have considered man as a self-maintaining individual, as a member 

 of a hereditary sequence, and as a product of evolution. Our account 

 would be seriously incomplete if we failed to treat of mankind as an 

 existing species, variable, racially diverse, and unusual in many respects. 



To begin with, man is a single species, Homo sapiens. This species is 

 complex both in origin and in composition and is unique among organisms 

 in possessing a social heritage called culture. Culture, a product of the 

 human mind, has evolved independently of man's biological evolution and 

 at a rate which has lately become very rapid. It now so permeates the 

 human environment and so modifies the behavior and appearance of 

 individuals and groups that we find it hard to distinguish differences due 

 to heredity from those produced by culture. 



The human species comprises more than two billion individuals and 

 is rapidly increasing. It occupies and dominates the earth to an extent 

 never remotely approached by any other animal. Man's dominance and 

 abundance are, however, of recent date and constitute an unprecedented 

 situation to which he is far from adjusted. The sudden rise of Homo 

 sapiens has profoundly affected not only the world environment, but 

 even the trends of physical and cultural evolution within our species. 



THE UNITY OF MANKIND 



We have seen that the family Hominidae split off from the other 

 primates during or before the Pliocene and that several different kinds 

 of men existed during the first half of the Pleistocene epoch. It is now 

 quite generally agreed that all these men are properly referable to the 

 genus Homo, to which we also belong, though we continue to call them by 

 such time-honored names as Pithecanthropus erectus and Sinanthropus 

 pekinensis. It is also agreed that from one or more of the branches of the 

 Java-Peking stock came the various types of Neanderthaloid men, 

 specifically or subspecifically distinct from one another. Some of these 

 persisted with but slight change until late in the Pleistocene. One group 

 of Neanderthaloids must have changed more rapidly, for by mid-Pleis- 

 tocene it had evolved into Homo sapiens. Whether or not it absorbed 



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