8 MAN, THE ANIMAL 



familiar — but none of these eight extinct races is 

 definitely known to have been the immediate 

 progenitor of modern man. In all of these in- 

 vestigations, the great majority of opinion is 

 clearly in favor of regarding these various fossils 

 as distinctively human. There do not appear to 

 be any clear transition types between primitive 

 man and the higher mammals though we are led 

 to believe that there must have been since man 

 appeared on the earth after other forms of life 

 became established and since he has more that is 

 common with the animals than is different from 

 them. 



This is the type of problem that has perplexed 

 the layman most often. It is the one that we are 

 asked most frequently to explain. Possibly an 

 illustration or two will make it clear that the con- 

 ditions which surrounded fossil and recent man 

 were not limited to man. Again we take our main 

 facts from the biologist's intimate friend, the 

 paleontologist. He has given a great deal of time 

 to the question of the origin of the horse. Much 

 is known of its history and the gradual loss of all 

 but one toe which became greatly lengthened and 

 constitutes the main part of the leg in modern 

 horses. But our interest should be fixed on that 

 period in the evolution of the horse when there 

 were a large number of species that roamed the 

 mid-western prairies of North America. No less 



