784 THE DESCENT OF MAN 



We thus learn that man is descended from a hairy, tailed 

 quadruped, probably arboreal in its habits, and an inhabi- 

 tant of the Old World. This creature, if its whole structure 

 had been examined by a naturalist, would have been classed 

 among the Quadrumana, as surely as the still more ancient 

 progenitor of the Old and New World monkeys. The Quad- 

 rumana and all the higher mammals are probably derived 

 from an ancient marsupial animal, and this through a long 

 line of diversified forms, front some amphibian-like creat- 

 ure, and this again from some fish-like animal. In the dim 

 obscurity of the past we can see that the early progenitor 

 of all the Vertebrata must have been an aquatic animal, 

 provided with branchiae, with the two sexes united in the 

 same individual, and with the most important organs of 

 the body (such as the brain and heart) imperfectly or not 

 at all developed. This animal seems to have been more 

 like the larvae of the existing marine Ascidians than any 

 other known form. 



The high standard of our intellectual powers and moral 

 disposition is the greatest difficulty which presents itself, 

 after we have been driven to this conclusion on the origin 

 of man. But every one who admits the principle of evolu- 

 tion must see that the mental powers of the higher animals, 

 which are the same in kind with those of man, though so 

 different in degree, are capable of advancement. Thus the 

 interval between the mental powers of one of the higher 

 apes and of a fish, or between those of an ant and scale- 

 insect, is immense; yet their development does not offer 

 any special difficulty; for, with our domesticated animals, 

 the mental faculties are certainly variable, and the varia- 

 tions are inherited. No one doubts that they are of the 

 utmost importance to animals in a state of nature. There- 

 fore the conditions are favorable for their development 

 through natural selection. The same conclusion may be 

 extended to man; the intellect must have been all-impor- 

 tant to him, even at a very remote period, as enabling him 



