134 " The Descent of Man " 



indicate a common descent, and cannot be explained as phenomena 

 of convergence. 



I believe 1 have shown in the above sketch that a theory vehich 

 derives man directly from lower forms without regarding apes as 

 transition-types leads ad ahsurdwm. The close structural relation- 

 ship between man and monkeys can only be understood if both are 

 brought into the same line of evolution. To trace man's line of 

 descent directly back to the old Eocene mammals, alongside of, but 

 with no relation to these very similar forms, is to abandon the method 

 of exact comparison, which, as Darwin rightly recognised, alone 

 justifies us in drawing up genealogical trees on the basis of resem- 

 blances and ditterences. The farther down we go the more does the 

 ground slip fi-om beneath our feet. Even the Lemuridae show very 

 numerous divergent conditions, much more so the Eocene mammals 

 (Creodonta, Condylarthra), the chief resemblance of which to man 

 consists in the possession of pentadactylous hands and feet ! Thus 

 the farther course of the line of descent disappears in the darkness 

 of the ancestry of the mammals. With just as much reason we might 

 pass by the Vertebrates altogether, and go back to the lower Inverte- 

 brates, but in that case it would be much easier to say that man 

 has arisen independently, and has evolved, without relation to any 

 animals, from the lowest primitive form to his present isolated and 

 dominant position. But this would be to deny all value to classifica- 

 tion, which must after all be the ultimate basis of a genealogical tree. 

 We can, as Darwin rightly observed, only infer the line of descent 

 from the degree of resemblance between single forms. If we 

 regard man as directly derived from primitive forms very far back, 

 we have no way of explaining the many points of agreement between 

 him and the monkeys in general, and the anthropoid apes in par- 

 ticular. These must remain an inexplicable marvel. 



I have thus, I trust, shown that the first class of special theories 

 of descent, which assumes that man has developed, parallel with the 

 monkeys, but without relation to them, from very low primitive forms 

 cannot be upheld, because it fails to take into account the close 

 structural affinity of man and monkeys. I cannot but regard this hypo- 

 thesis as lamentably retrograde, for it makes impossible any application 

 of the facts that have been discovered in the course of the anatomical 

 and embryological study of man and monkeys, and indeed prejudges 

 investigations of that class as pointless. The whole method is per- 

 verted; an unjustifiable theory of descent is first formulated with the 

 aid of the imagination, and then we are asked to declare that all 

 structural relations between man and monkeys, and between the 

 different groups of the latter, are valueless, — the fact being that they 

 are the only true basis on which a genealogical tree can be constructed. 



