252 INTRODUCTION TO EVOLUTION 



Most persons think first of skin color when they think of racial differ- 

 ences. But here also there is great variability in amount of skin pigment 

 present in different members of a single racial group. There is also great 

 similarity in this respect among members of some diverse racial groups. 

 Some inhabitants of India, for example, have darker skins than do some 

 inhabitants of Africa. And again, variability in skin color occurs inde- 

 pendently of variability in blood groups, tasting ability, and so on. Even 

 hair form (straight, wavy, curly, kinky) is independent of skin color in 

 inheritance, and most importantly, there is no correlation between any of 

 these characteristics and such attributes as mental ability. 



In bodily proportions variability within racial groups resembles variabil- 

 ity between racial groups, and there is no correlation with blood groups, 

 skin color, hair form, tasting ability, and so on. Thus we think of Scandi- 

 navians as tall and long-headed (dolichocephalic) although not all of 

 them are, by any means. Exceptionally tall and long-headed are the Wa- 

 tusi tribe in eastern Africa, while their "next-door neighbors," the Pygmies, 

 form a marked contrast in both respects. 



Space permitting, we might add to the list indefinitely. The point we wish 

 to make will be evident from these few examples, however: In the mat- 

 ter of genetic difTerence a race is only a "constellation of characters," in 

 Boyd's phrase (1950). Races present mosaics of characteristics varying in- 

 dependently in their distribution. A population is called a race if it differs 

 from some other population in relative frequencies of blood group genes, 

 in proportion of individuals possessing the "taster" gene, in frequency of 

 the genes controlling skin color, of the genes controlling hair form, of those 

 controlling eye color, of those controlling stature, of those controlling head 

 shape, and so on. Populations within a single race differ in these same 

 ways. Thus races blend imperceptibly into each other and no sharp lines 

 can be drawn between them. As Dobzhansky (1950) stated, "It is most im- 

 portant to realize that the differences between the 'major' human races 

 are fundamentally of the same nature as the relatively minute differences 

 between the inhabitants of adjacent towns and villages." 



Accordingly we note that races are populations characterized by cer- 

 tain frequencies of the genes. Contrary to older ideas, there is no such 

 thing as a racial "type" which all members of a race tend to approximate. 

 The "typical Negro" or "typical Mongolian" has no more actual existence 

 than does the "average man" about whom we sometimes read. No individ- 

 ual ever is "average"; each individual differs from every other in some re- 

 spects ("identical" twins most closely approach an exception to this state- 

 ment). We find the same situation when we attempt to classify individuals 



