342 The Study of Animal Life app. 



the arguments used to prove the origin of animal from animal were 

 adapted to rationalise the ascent of man. 



(a) Physiological. — The bodily life of man is like that of mon- 

 keys ; both are subject to the same diseases ; various human traits, 

 such as gestures and expressions, are paralleled among the " brutes " ; 

 and children born during famine or in disease are often sadly 

 ape-like. 



{b) Morphological. — The structure of man is like that of the 

 anthropoid apes, none of his distinctive characters except that of 

 a heavy brain being momentous, and there are about seventy 

 vestigial structures in the muscular, skeletal, and other systems. 



{f) Historical. — There is little certainty in regard to the fossil 

 remains of prehistoric man, but some of these suggest more primi- 

 tive skulls, while the facts known about ancient life show at least 

 that there has been progress along certain lines. Moreover, there 

 is the progress of each individual life, from the apparently simple 

 egg-cell to the minute embryo, which is fashioned within the womb 

 into the likeness of a child, and being bom grows from stage to 

 stage, all in a manner which it is hard to understand if man be 

 not the outcome of a natural evolution. 



3. Various Opinions about the Descent of Man.— But 



opinion in regard to the origin of man is by no means unanimous. 



(a) A few authorities, notably A. de Quatrefages, maintain a 

 conservative position, believing that the evolutionist's case has not 

 been sufficiently demonstrated. But the majority of naturalists 

 believe the reverse, and think that the insufficiencies of evidence in 

 regard to man are counterbalanced by the force of the argument 

 from analogy. 



(i) Alfred Russel Wallace has consistently maintained a position 

 which seems to many a very strong one. "I fully accept," he 

 says, " Mr. Darwin's conclusion as to the essential identity of man's 

 bodily structure with that of the higher mammalia, and his descent 

 from some ancestral form common to man and the anthropoid apes. 

 The evidence of such descent appears to me overwhelming and 

 conclusive. Again, as to the cause and method of such descent 

 and modification, we may admit, at all events provisionally, that 

 the laws of variation and natural selection, acting through the 

 struggle for existence and the continual need of more perfect 

 adaptation to the physical and biological environments, may have 

 brought about, first that perfection of bodily structure in which he 

 is so far above all other animals, and in co-ordination with it the 

 larger and more developed brain, by means of which he has been 

 able to utilise that structure in the more and more complete sub- 

 jection of the whole animal and vegetable kingdoms to his 

 service." 



