MATTHEW, CL/.UATE AND EVOLI'TION 201 



regions. Whatever be the causes of evolution, we must expect tliem to 

 act with maximum force in some one region ; and so long as the evolution 

 is progressing steadily in one direction, we shouhl expect them to con- 

 tinue to act with maximum force in that region. This point then will 

 be the center of dispersal of the race. At any given period, the most 

 advanced and progressive species of the race will be those inhabiting 

 that region ; the most primitive and unjjrogressive species will be those 

 remote from this center. Tlie remoteness is, of course, not a matter of 

 geographic distance but of inaccessibility to invasion, conditioned by the 

 habitat and facilities for migration and dispersal. 



If the environmental conditions in the center of dispersal pass the 

 point of maximum advantage for the race-type that is being developed 

 and become unfavorable to its progress, we should find its highest types 

 arranged in a circle around a central region, which was the former point 

 of dispersal, and tlie more primitive types arranged in concentric ex- 

 ternal circles. The central region will be unoccupied, or inhabited by 

 specialized but not higher adaptations. 



It would appear obvious tliat the present geographic distribution of a 

 race must be interpreted in some such way as this by anyone who accepts 

 the modern doctrine of evolution. Yet there are many high authorities 

 on geographic distribution who proceed apparently upon a precisely op- 

 posite theory. According to these authors, the distribution center of a 

 race is determined by the habitat of its most primitive species, and the 

 highest and most specialized members of the race are most i-emote from 

 its center of dispersal. This principle may Ije true enough so far as 

 concerns the first appearance of a given race, i. e., provided the most 

 ))rimitive species are also the oldest geologically; but it appears to me 

 to be the direct reverse of fact as regards the present distribution, or the 

 distribution at any one epoch of the past. The only ground on which it 

 could be defended would be that the progress of the race is due to its 

 migi-ation, and those members which did not migrate did not progress. 

 But this involves the view that its progressiveness up to the time that 

 its geographical environment changed was due to staying at home, and 

 the same progress after its environment changed was due to not staying 

 at liome. It seems to me that the prevalence of this view must be due 

 to some fallacious notions about migration, unconsciously retained, in- 

 volving a concept of it as analogous to travel in the individual. The 

 successful business man, no doubt, may pack up his baggage and take to 

 traveling, leaving home and going elsewhere and ]:)rofiting much thereby. 

 Xations have done the same thing, likewise to their advantage. But 

 there is very little analog}- here to the zoogeograpliic migration of spe- 



