180 WORLD-POWER AND EVOLUTION 



ment between the results of Fishberg in his study of European 

 Jews and of Boas in his study of immigrants. I emphasize the 

 importance of this because the strength of any conclusion is much 

 more than doubled when it is based upon two independent lines 

 of evidence. Moreover, although Fishberg and Boas assisted one 

 another, Boas, whose work was done later, does not appear to 

 have recognized the remarkable way in which his results are sup- 

 ported by those of Fishberg. This arises partly from the fact 

 that Boas, in accordance with long habit, is prone to attribute 

 as much as possible to purely economic causes and to events which 

 happen in accordance with man's own artificial surroundings, 

 while Fishberg, in accordance with the well-established usage of 

 ethnology and anthropology, is inclined to attribute as much as 

 possible to racial mixture. 



Since racial mixture obviously has nothing to do with Boas' 

 results, and since it probably has only the slightest influence 

 upon the facts described by Fishberg, we seem forced to conclude 

 that the differences between American-born and foreign-born 

 children of immigrants are due to environment. The question 

 then is. What particular features of the environment are respon- 

 sible ? Boas, as I have said, seems inclined to attribute the changes 

 to the urban environment. He shows that Ammon in Baden and 

 Livi in Italy have found evidence that on the whole the people 

 of the cities have slightly longer heads than those of the country 

 districts around them. These authors, however, believe that this 

 is merely because the cities that they investigated lie in regions 

 where the average length of the people's heads is less than in the 

 more remote districts whence many of the people of the city were 

 originally drawn. Hence the presence of people from a distance 

 increases the average length of the city heads. Boas accepts this 

 idea, but tries also to show that in Italy this factor is not enough 

 to account for the observed differences. His argument is interest- 

 ing, but unlike his study of immigrants in New York, it is based 

 largely on assumptions, and hence is not conclusive. 



