CHAPTER XXX 



HUMAN CROSSES 



Mi^^NKiND consists of a single species; at least no races exist 

 so c^istinct that when they are crossed sterile progeny are pro- 

 duced. The widest possible human crosses are comparable 

 with the crossing of geographical varieties of a wild species 

 of animal, or with the crossing of distinct breeds of domesti- 

 cated animals. The race horse and the draft horse differ as 

 muph in bodily conformation and temperament as do the 

 Dio^^t diverse races of mankind. 



0/fspring produced by crossing such races do not lack in 

 vigor, size or reproductive capacity. But these are not the 

 only qualities w^hich we desire either our horses or our citi- 

 zens ^ to possess. It is a particular combination of qualities 

 whic:}! makes a race horse useful, and a different combination 

 whicl|i makes a draft horse useful. Crossing the two will 

 produ^ce neither one type nor the other. The progeny will 

 be use.jess as race horses and they will not make good draft 

 horses. A second generation of offspring will be more vari- 

 able but will rarely approach the specialized type of either 

 the race hvr)rse or the draft horse, and will be too heterogene- 

 ous in chan^cter to serve any single purpose well. For such 

 reasons as Lhese, pure breeds of domesticated animals are 

 rarely crossed unless a new type of animal is desired to meet 

 special needs i^^^nd conditions. Even then many animals of 

 small value musi'^ be produced and discarded and this process 

 must be continue! i for generations before the new type can 

 be established. For such reasons wide racial crosses among 

 men seem on the whoJe undesirable. There is no question 

 about the physical vigeor of the offspring, provided the 

 parents are free from disea^se. The statement is often made 

 that mixed races are feeble, btut if this is ever true it is not 

 because they are mixed, but beca-use the specimens that mix 



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