RELATIONS OF BARRIERS TO HUMAN BREEDING 



In the period before our Civil War, while men were 

 looking for an excuse if not a justification for slavery the 

 subject of the unity of man's species was much discussed. 

 In these later days, removed from the passions of politics, 

 as a purely academic question the inquiry has been reopened. 

 Ideas have changed much in the intervening fifty or sixty 

 years and now we have to define all over again what is 

 meant by species or race. 



In connection with the new ideas of heredity we have 

 gained a new conception of species and race. We now 

 apply the terms indifferently and say a species, or race, is 

 an intergenerating group of individuals distinguished by 

 the possession of one or more unit-characters. As we look 

 over mankind we note at once the groups that have always 

 been distinguished : the Negroes with black skin and woolly 

 hair; the oriental race with olive or yellow skin and (typi- 

 cally) narrow eyes; the American Indian with brown-red 

 skin and long straight hair, and the Caucasians with white 

 skin and high cephalic index. This naive classification 

 may have sufficed for the dawn of anthropology, but today 

 we recognize its insufficiency. In the group of Caucasians 

 are hundreds of distinctive characters upon each of which 

 a race might be founded. There are the brunette skin and 



1 Much of the present chapter is reprinted from the author's book, Heredity 

 in Relation to Eugenics, and it appears here through the courtesy of the publishers 

 of that book, Messrs. Henry Holt & Co. 



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