462 ON OUR PRESENT KNOWLEDGE OF THE ORIGIN OF MAN. 



was, fifty years later, to be the most important basis of the work upon 

 which he was to spend his life, the most secure support of that doctrine 

 of descent which was founded by Lamarck in the very year ot Darwin's 

 birth, and which was at that time received with warm approbation by 

 his grandfather, Erasmus Darwin. 



Of all the naturalists of the nineteenth century Charles Darwin has 

 certainly had the greatest success and the most powerful influence. 

 We often, indeed, call the last forty years the " Darwinian age." And 

 if we investigate more closely the causes of this unexampled success we 

 will see, as I have repeatedly said, that they depend upon three impor- 

 tant services rendered: (1) The total reform of the theory of descent or 

 doctrine of Lamarck; (2) the founding of the new theory of natural 

 selection, the special Darwinian theory; and (3) the development of the 

 science of the evolution of man, that most important deduction from 

 the theory of descent, which far exceeds in significance all other prob- 

 lems of the doctrine of evolution. 



I shall to-day, before this zoological congress, speak only of the last- 

 named service of Darwin, and do this for the especial purpose of showing 

 critically the certainty to which we have attained in our present knowl- 

 edge of the origin of man and of the various branches of his genealogical 

 tree. That this is one of the most important of all scientific questions 

 is to-day no longer disputed. For all other problems which the human 

 mind can investigate and understand are conditioned chiefly by the 

 psychological theory of perception, and this again depends upon the 

 animal nature of man, upon his origin, his development, and his mental 

 powers. With good reason, then, did the greatest zoologist of our 

 century, Thomas Huxley, characterize this problem as the "question of 

 questions for mankind," as the "problem which underlies all others and 

 is more deeply interesting than any other." This was done in 1863 in 

 the second of those three masterly essays which for the first time 

 thoroughly examined the " Evidence as to man's place in nature" in 

 the light of the Darwinian theory; the first, treating of the anthropoid 

 apes, the second of the relations of man to the next lower animals, the 

 third of some fossil human' remains. Darwin himself, in 1859, in his 

 principal work, On the Origin of Species, had purposely avoided referring 

 to these consequences of his doctrine except in a brief, significant, 

 passing allusion that, by its means, light would be thrown on the origin 

 of man and his history. Later (1871) in his famous work on The Descent 

 of Man, and Selection in Eelation to Sex, Darwin brought forward in a 

 most able manner, both the morphological and the historical as well as 

 the physiological and psychological side of this problem. 



I had myself, in 1886, in my Generelle Morphologie, estimated the 

 importance of the "history of the development of organisms as bearing 

 upon anthropology," and especially remarked that the fundamental 

 biogenetic law held good for man also; with him, as with all other 

 organisms, there is the most intimate causal connection between 



