CHAPTER XXX 



HUMAN CROSSES 



Mankind consists of a single species; at least no races exist 

 so distinct 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 

 much in bodily conformation and temperament as do the 

 most diverse races of mankind. 



Offspring produced by crossing such races do not lack in 

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

 only qualities which we desire either our horses or our citi- 

 zens to possess. It is a particular combination of qualities 

 which makes a race horse useful, and a different combination 

 which makes a draft horse useful. Crossing the two will 

 produce neither one type nor the other. The progeny will 

 be useless 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 horse or the draft horse, and will be too heterogene- 

 ous in character to serve any single purpose well. For such 

 reasons as these, pure breeds of domesticated animals are 

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

 special needs and conditions. Even then many animals of 

 small value must be produced and discarded and this process 

 must be continued for generations before the new type can 

 be established. For such reasons wide racial crosses among 

 men seem on the whole undesirable. There is no question 

 about the physical vigor of the offspring, provided the 

 parents are free from disease. The statement is often made 

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

 because they are mixed, but because the specimens that mix 



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