182 WORLD-POWER AND EVOLUTION 



Jews appear to be closely analogous to those in the length of 

 body, tail, foot, and ear in white mice. They also appear to be 

 analogous to the changes in flies and other insects. We have 

 already seen that the changes in the bodily form of the Jews from 

 place to place in Europe can scarcely be due to racial mixture, 

 economic conditions, or climatic selection. Neither can the 

 changes in the bodily form of the children of immigrants in New 

 York be due to these causes. So far as I can see the one factor 

 that does differ from place to place in such a way as to produce 

 the observed results is the variability of the climate. This factor, 

 as we have seen, is extremely susceptible to variations not only 

 from place to place, but from year to year, and month to month. 

 While the mean temperature of a given month varies only a few 

 degrees from year to year, one month may have four or five times 

 as many cold waves and hot waves as another. The most marked 

 climatic difference between eastern and western Europe is the 

 greater monotony of the cold winter weather in the east. 

 Similarly the chief difference between Italy and Poland, for 

 example, is the monotony of the long Sicilian summer compared 

 with the relative variability of the same season farther north. 

 Finally the outstanding contrast between the eastern United 

 States and Europe is the much greater variability of the weather 

 here than there. 



From these facts it appears that when Jews or Gentiles from 

 eastern Europe come to New York they suffer one kind of climatic 

 change. When South Italians come they suffer another kind, but 

 in both cases the change is pronounced. When Scotch or English 

 come to New York, on the contrary, they certainly experience a 

 climatic change, but it is by no means so pronounced as that to 

 which the people from less stormy climates are subjected. Hence 

 the failure of Boas to find any measurable changes in Scotch 

 children is what we should expect. 



Turning now to the effects of climatic variations upon racial 

 characteristics, we have seen that even the slightest change of 



