Janlarv, 1929 



EVOLUTION 



Page Three 



tar closer than that of the tapir to the horse, and that the 

 separation of the first pair was a much later event than 

 the separation of the second pair. 



Those who oppose Darwin's conclusion that man is an 

 offshoot from the anthropoid stem must attribute to 

 "parallelism" the numerous resemblances between the 

 anthropoid dentition and that of man, notwithstanding 

 the fact that these resemblances persist in spite of the pro- 

 found differences in diet between the prevailingly frugi- 

 vorous apes and the prevailingly carnivorous-herbivorous 

 man. But if the very numerous detailed and fundamental 

 resemblances between anthropoid dentition and that of 

 man are due to parallelism, what warrant is there for 

 using quite similar dental resemblances and differences for 

 uniting and distinguishing the members of the families of 

 elephants and odd-toed hoofed animals ? 



In judging the interrelationships of the members of any 

 large group the evidence derived from the dentition should 

 of course be supplemented and checked wherever possible 



Fig. 1. — Skeleton of right fore limb of A, Tapir ; B, Horse; C. 

 Chimpanzee; D, Man {I'eddah). C and D after Sarasin. 



by the characters observed in other parts of the body, 

 especially the skeleton of the limbs and feet. Let us apply 

 this test to our inquiry as to whether chimpanzee and man 

 are more nearly allied in structure than tapir and horse. 

 Fig. 1 will enable the reader to compare the forearm and 

 hand of chimpanzee an^ man on the one hand and of 

 tapir and horse on the other. 



Is the difference in the forearm and hand of chimpan- 

 zee and man anywhere nearly so profound as that between 

 tapir and horse? Here the evidence suggests that even on 

 the assumption of equal changes in equal times, chimpan- 

 zee and man have not been separated nearly so long as 

 have tapir and horse, and again it will be noted that this 

 greater resemblance between chimpanzee and man ■ per- 

 sists in spite of the marked difference in their habits. 



The differences between the hind limbs and feet of 

 chimpanzee and man, while very conspicuous, are on the 

 whole not nearly so great as the differences between the 

 hind limbs and feet of tapir and horse (Fig. 2). Ac- 



cording to the well established principle of adaptive radia- 

 tion, atter the descendants of an ancient common stock 

 pass from the ancestral life-zone to a new one, their 

 whole locomotor skeleton becomes adapted to the new 

 mode of life. It is well known that these new adaptations 

 tend to cover-up and obscure the characters inherited from 

 the older environment and contrasting widely with each 

 other in their modes of locomotion, show the maximum 

 contrast in their mind limbs, whereas the horse and the 

 tapir, continuing to use their limbs in much the same 

 way as did their remote common ancestors, differ from 

 each other chiefly in the fact that in the horse tendencies 

 toward centralizing the axis of the foot, which are already 

 clearly visible in the tapir, have been carried to the ex- 

 treme. And it will be shown presently that in spite of 

 the striking difference of the human foot from that of 

 the chimpanzee, its origin is perfectly explicable on the 

 hypothesis that it has been derived from the foot of a 

 primitive anthropoid type by a definite change of function 

 involved in the abandonment of arboreal life and the as- 

 sumption of bipedal running habits. 



The striking difference between the foot of the an- 

 thropoids and that of man has led Sir Ray Lankester and 

 others to regard the evolutionary gap between anthropoids 

 and man as equally profound and has been the principal 

 objection to Darwin's theory of the origin of man. This 

 brings us to the very kernel of the whole question, namely, 

 was man's place in nature correctly determined by Dar- 

 win, Huxley and Haeckel; is he still definitely the next 

 of kin to the anthropoid stock, or does he represent an 

 entirely independent group of unknown origin and rela- 

 tionships? 



(Prof. Gregory's answer to this question will appear in 

 our next number). 



Fig. 2. — Skeleton of right hind limb of A, Tapir; B, Horse; C, 

 Chimpanzee; D. Man. 



