178 WORLD-POWER AND EVOLUTION 



country are longer and narrower than those of similar children 

 born abroad. This causes the cephalic index to be lower by about 

 three points. The difference is not great, but it is remarkably 

 systematic so that its reality can scarcely be doubted. Among 

 the Bohemians and other non-Jewish peoples from east central 

 Europe both the length and the width of the head decrease, but 

 as the width decreases more than the length, the heads become a 

 little narrower. Hence the cephalic index drops a little, but not 

 so much as in the case of the Jews. Here we have essential unity 

 between the Jews and the people who live around them. If we 

 suppose that the environment causes the changes in head-form we 

 at once find the explanation of the fact that in Europe the cephalic 

 index of the Jews everywhere approaches so closely to that of 

 the other races in the same region. Turning now to the Italians 

 we find that among them the form of the head changes, but not 

 in the same fashion as among the more northern people. In both 

 Italian groups the length of the head decreases and the width 

 increases, so that the cephalic index, contrary to that of the 

 Jews, shows an increase. 



In estimating the importance of the work of Boas, it is highly 

 significant that the most systematic difference between children 

 born abroad and in New York is in the shape of the head. 

 Stature may be influenced by economic conditions, but in the 

 head we have an organ whose form apparently has nothing to 

 do with such conditions. The objector may say that there are 

 other possible causes of changes in the head-form. Boas has 

 carefully investigated this. For instance, he considers the kind 

 of pillows on which children lie, and the practice of swaddling 

 infants which prevails largely in Europe but is soon given up on 

 coming to this country. There seems no reason, however, to think 

 that the changes in the shape of the children's heads are due to 

 any such mechanical causes. Another possible objection is that 

 it is unreasonable that the same environment should act in one 

 way on the Italians and in another on the people from farther 



