324 



THE CONTINUITY OF THE RACE 



controlled breeding that have produced our purebred strains of horses, 

 dogs, cattle, and crop plants, he, too, could be molded into a wide variety 

 of pure-breeding strains. Under this procedure, it would be entirely 

 possible to develop a human race that would be homozygous for many 

 desirable qualities and that would at the same time be free from many 

 of the inherited liabilities that now affect many otherwise superior stocks. 

 Actually, of course, this "if" is impossible, and it certainly would be 

 undesirable. The qualities needed in a human society are far more complex 

 and varied than those that are sought in any of the domestic breeds that 

 man has developed; and the very uniformity so characteristic and desir- 



Fig. 22.3. Inheritance of nose form. At least three or four genes are involved, affecting 

 different characteristics, of which two are here shown. Prominent nose dominates small 

 nose; wide nostrils dominate slim (compressed) nostrils. 



able in purebred races would probably be very undesirable in human 

 society. 



There are, however, many details and tendencies in human inherit- 

 ance that do appear capable of practical management and control. A 

 rather large number of human qualities or capacities that are known to 

 be inherited can be clearly evaluated as definitely good or bad, no matter 

 what the remainder of an individual's genotype may be. It is largely 

 with such qualities that eugenics is concerned. It seeks to recognize 

 and evaluate an increasing number of these qualities, to determine the 

 precise mode of their inheritance, to discover the various ways in which 

 they may affect the phenotype, and to weigh the practicability of the 

 application of this knowledge by the individual, the family, and the 

 state. Nearly every modern nation has its endowed or state-supported 

 eugenics foundation, devoted to the discovery, dissemination, and ulti- 

 mate application of the facts and principles of human genetics. Thus 

 far, the practical possibilities of eugenics have hardly been evaluated, 

 but within recent years new methods and statistical techniques have 

 made possible a much more rapid accumulation of accurate knowledge. 

 Here may be mentioned the increasing attention to human genetics in 

 medicine and the importance that a knowledge of the patient's inherited 



