98 EVOLUTION 



birds and mammals are the only warm- 

 blooded animals, and they show a great 

 heightening of brain-development; in all 

 mammals except a few primitive forms there 

 is an extremely important and usually pro- 

 longed intimate connection between the 

 mother and the unborn young. 



The Ascent of Man. — As this final 

 achievement of Vertebrate evolution will be 

 discussed by Dr. Arthur Keith in a special 

 volume of this Library, we need not do more 

 than refer to a few points of general evolu-, 

 tionary interest. 



The real distinctiveness of man from his^ 

 nearest allies depends on his power of build- 

 ing up general ideas and of controlling his 

 conduct in relation to ideals. He has many 

 structural peculiarities, it is true, but the 

 differentiating qualities are in language, 

 thought and conduct, and in the finer brain 

 associated with these. 



The "Descent of Man" is the expansion 

 of a chapter in the "Origin of Species." In 

 other words, the evidences of man's origin 

 from an ancestral type common to him and 

 to the higher apes, are the same as those used 

 to substantiate the general doctrine of de- 

 scent. As Owen allowed long ago, there is an 

 "all-pervading similitude of structure" be- 

 tween man and the anthropoid apes; the 



