508 THE CHANGING GENERATIONS 



some of the less progressive groups, it is certain that by the end of the 

 fourth glacial age this was the sole remaining species of man. 



We can be sure that mankind constitutes a single species, for all groups 

 of people living today are interfertile, and there are no morphological 

 distinctions by which we may sharply divide them. If all living people, 

 without exception, belong to the same species, one simple, clear fact 

 emerges: all peoples of earth are infinitely more alike than they are dif- 

 ferent. Krogman has put this dramatically by saying that, ignoring 

 cultural differences, we are 99.44 per cent alike and only 0.56 per cent 

 different. Whether the actual ratio of identities to differences be 98:2 

 or 95 : 5 or even 90 : 10, the identities overwhelmingly preponderate. In 

 terms of genetics, the genes which make us Homo sapiens far outnumber 

 and outweigh the genes which make us different kinds of people. 



THE DIVERSITY OF MANKIND 



Although people are basically all alike, they are also all different. 

 Except for monovular twins, it is probable that no two individuals in 

 the world have exactly the same set of genes. We recognize particular 

 persons by their individual peculiarities, and we are aware that large 

 groups of people resemble one another more closely than they do mem- 

 bers of other groups. In common parlance these distinguishable groups 

 are called races, though the physical anthropologist tends to restrict this 

 tierm to the subdivisions of the major groups. 



The meaning of "race." At this point we are certain to encounter 

 emotional reactions to the word "race" in many persons to whom this 

 !ias become a "bad word" that ought never to be mentioned. Such 

 connotations arise from the tensions that exist between certain groups of 

 people; most of all they come from the pseudoscientific "raciology" of 

 che late Nazi regime, in the name of which great crimes were committed. 

 Perhaps it would be better if there were some other term we could use to 

 designate the physically distinguishable groups of mankind, which do 

 exist and of which we must take account. Since race is the term in use, we 

 shall have to accept it, define what it means in science, and say what it 

 does not mean. 



The Biological Definition of Race. To the biologist race is a genetic 

 and anatomical concept. It has nothing to do with cultural differences — 

 with such things as language, religion, nationality, or social habits. We 

 may define it in genetic terms, as does Boyd: "A human race is a popula- 

 tion which differs significantly from other populations in regard to the 

 frequency of one or more of the genes it possesses." Or, since we do not 

 know very much about the genetics of man, we may use morphological 

 (phenotypic) differences for the recognition of races and say with Hooton 

 that a biological race is a great division of mankind, the members of which, 



