178 EVOLUTION, GENETICS, AND EUGENICS 



workshops of the north," and the balance is in favour of Asia as the 

 cradle of modern mammals. 



Is it an idle dream to think of the future ? A survey of the past 

 reveals the vanishing of whole faunas from extensive countries, which 

 were then repeopled by other forms from elsewhere. What has 

 happened before, may happen in times to come. Countless groups, 

 once flourishing, are no more ; many others have had their day and are 

 now on the decline, whilst others are flourishing now, are even in the 

 increase and seem to have a future before them. Such favoured 

 assemblies are the toads and frogs, lizards and snakes, Passerine birds 

 and rodents, mostly the small-sized members of their tribes; the days 

 of giants are past. All this has happened in the natural course of 

 events, without the influence of man, who only within most recent 

 times has become the most potent and destructive factor to the ancient 

 faunas of the world. 



SUMMARY OF THE ARGUMENT FOR EVOLUTION AS BASED ON 

 GEOGRAPHIC DISTRIBUTION 



On the hypothesis of special creation or on any other hypothesis 

 except evolution that has even been suggested, the extremely intricate 

 patchwork of animal and plant distribution remains an unsolvable 

 picture puzzle, without rhyme or reason. When this puzzle is attacked 

 with the aid of the evolutionary idea, the key to the whole maze is 

 furnished and the difficulties clear up with remarkable ease. The 

 whole hodgepodge makes sense and we can understand many pre- 

 viously irreconcilable facts. In no field does the working hypothesis 

 of evolution work to such advantage as in this field. 



On the basis that a species arises at one place, spreads out over 

 large areas, becoming modified as it goes, that new species are formed 

 from old through modification after isolation from the parent-stock, 

 how do the facts of distribution look when examined in detail ? 



i. Cosmopolitan groups, those with the widest distribution, are 

 those to whom no barriers are sufficient to check migration, e.g., 

 strong fliers, Man, earthworms carried by Man. 



2. Restricted groups are usually those to which barriers are 

 readily set up and are frequently the last remnants of a formerly 

 successful fauna or flora, which continue to survive only in some 

 restricted area where the conditions are rather more favorable than 

 elsewhere. 



