ASSORTATIVE MATING FOR COLOR IN AMERICAN NEGRO 



127 



using this division, is .34. The coefficient of contingency for the various 

 types of N, NNW, NW, and NWW matings is .37. Thus it appears that 

 Negroes tend on the average to marry Negroes of approximately the same 

 color, but that the relationship is curvilinear, i.e., light wives marry hus- 

 bands darker than themselves, and dark wives marry husbands lighter than 

 themselves. 



What is the significance of this type of mating for the variability of the 

 offspring? Fraternal variability would be increased if mating were entirely 

 random as regards pigmentation, and lessened to the extent that there was 

 selective mating of darks with darks and lights with lights. Table 3 shows 

 for various types of genealogical crosses the actual number of matings of 

 given types, and the number of matings that would have been expected 



TABLE 3 



Actual and theoretical number of matings according to genealogical class of father and mother 



on the basis of random selection. There is a proportion greater than chance 

 for N X N, N X NNW, NW X NWW, and NWW X NWW matings, and 

 less than chance for the other types of crosses. The fraternal variability 

 of the offspring of these 218 matings was 5.87. If we assume that the 

 actual fraternal variability for each type of cross is the true variability of the 

 universe, and then weight its importance in determining the variability 

 of the 218 crosses according to the theoretical number of crosses of that 

 type there would have been if mating were random, the fraternal variability 

 of the 218 families would have been 6.19. 



Similarly, the fraternal variability of the offspring of the 95 families in 

 which the parents were within 6 per cent of the same pigmentation reading 

 was 5.04; the fraternal variability of the 228 families classified according to 



