I 2G 



NATURE 



[September 26, 191: 



the mammalia, by a continuation of this process of 

 building-up the cerebral cortex, or, if you prefer it, 

 the structure of the mind, was eventually formed that 

 living creature which has attained the most extensive 

 powers of profiting by individual experience. 



The study of the brain and mind, therefore, should 

 have been the first care of the investigator of human 

 origins. Charles Darwin, with his usual perspicuity, 

 fully realised this ; but since his time the role of in- 

 telligence and its instruments has been almost wholly 

 Ignored in these discussions ; or when invoked at all 

 wholly irrelevant aspects of the problems have been 

 considered. 



There can be no doubt that this neglect of the 

 evidence which the comparative anatomy of the brain 

 supplies is in large measure due to the discredit cast 

 upon this branch of knowledge by the singularly futile 

 pretensions of some of the foremost anatomists who 

 opposed Darwin's views in the discussions which took 

 place at the meetings of the British Association and 

 elsewhere more than fortv years ago. 



Many of you no doubt are familiar with Charles 

 Kingsley's delightful ridicule of these learned discus- 

 sions in the pages of "Water Babies." The con- 

 troversy excited by Sir Richard Owen's contention 

 that the great distinctive feature of the human brain 

 was the possession of a structure that used to be 

 called the hippocampus minor was not unjustly the 

 marl^ of his scathing satire. 



"The professor had even got up at the British 

 Association and declared that apes had hippopotamus 

 majors in their brains, just as men have. Which was 

 a shocking thing to say; for, if it were so, what 

 would become of the faith, hope, and charity of 

 immortal millions? You may think that there are 

 other more important differences between you and an 

 ape, such asbeing able to speak, and make machines, 

 and know right from wrong, and say your prayers, 

 and other little matters of that kind; but that is only 

 a child's fancy, my dear. Nothing is to be depended 

 upon but the great hippopotamus test. If you have 

 a hippopotamus major in your brain you are no ape, 

 though you had four hands, no feet, "and were more 

 apeish tlian the apes of all aperies. Always remember 

 that the one true, certain, final, and all-important 

 difference between you and an ape is that you have 

 a hippopotamus major in your brain and it lias none. 

 If a hippopotamus was discovered in an ape's brain, 

 why, it would not be one, you l^now, but something 

 else." 



The measure of the futility of the contention thus 

 held up to scorn can be more justiv realised now ; 

 for some years ago I discovered that the feature 

 referred to in Kingsley's burlesque phrase, "hippo- 

 potamus major," which Owen claimed to be distinctive 

 of the human brain, and Huxley maintained was 

 present also in apes, is quite a primitive characteristic, 

 and the common property of the mammalia in general. 



This illustration of the nature of the discussions 

 which distracted attention from the real problems, 

 although the most notorious one, is unfortunately 

 characteristic of the state of affairs that prevailed 

 when prejudice blinded men's eyes to the obvious 

 facts that were calling so urgentlv for calm investiga- 

 tion. 



yinn's Pedigree. 



No one who is familiar with the anatomy of man 

 and the apes can refuse to admit that no hypothesis 

 other than that of close kinship affords a reasonable 

 or credible explanation of the extraordinarily exact 

 identity of structure that obtains in most parts of the 

 bodies of man and the gorilla. To deny the validity 

 of this evidence of near kinship is tantamount to a 

 confession of the utter uselessness nf the faels of 

 NO. 2239, VOL. 90] 



comparative anatomy as indications of genetic relation- 

 ships, and a reversion to the obscurantism of the dark 

 ages of biology. But if anyone still harbours an 

 honest doubt in the face of this overwhelming testimony 

 from mere structure, the reactions of the blood will 

 confirm the teaching of anatomy ; and the suscepti- 

 bility of the anthropoid apes to the infection of human 

 diseases, from which other apes and mammals in 

 general are immune, should complete and clinch the 

 proof for all who are willing to be convinced. 



Nor can anyone who, with an open mind, applies 

 similar tests to the gibbon refuse to admit that it is 

 a true, if very primitive, anthropoid ape, nearly related 

 to the common ancestor of man, the gorilla, and the 

 chimpanzee. Moreover, its structure reveals indubit- 

 able evidence of its derivation from some primitive Old 

 World or catarrhine monkey akin to the ancestor of 

 the langur, the sacred monkey of India. It is 

 equally certain that the catarrhine apes were derived 

 from some primitive platyrrhine ape, the other, less 

 modified, descendants of which we recognise in the South 

 American monkeys of the present day; and that the 

 common ancestor of all these primates was a lemuroid 

 nearly akin to the curious litie spectral tarsier, which 

 still haunts the forests of Borneo, Java, and the 

 neighbouring islands, and awakens in the minds of 

 the peoples of those lands a superstitious dread — a sort 

 of instinctive horror at the sight of the ghost-like 

 representative of their first primate ancestor. 



This much of man's pedigree will, I think, be 

 admitted by the great majority of zoologists who are 

 familiar with the facts ; but I believe we can push 

 the line of ancestry still further back, beyond the most 

 primitive primate into Haeckel's suborder Meno- 

 typhla, which most zoologists regard as constituting 

 two families of insectivora. I need not stop to give 

 the evidence for this opinion, for most of the data and 

 arguments in support of it have recently been sum- 

 marised most excellently by Dr. W. K. Gregorv.' 



This group includes the Oriental tree-shrews and 

 the .African jumping-shrews. The latter (Macrosceli- 

 didae), living in the original South .\frican home of 

 the mammalia, present extraordinarilv primitive 

 features linking them by close bonds of afifinitv to the 

 marsupials. The tree-shrews (Tupaiidae), however, 

 which range from India to Java, while presenting 

 very definite evidence of kinship to their humble 

 African cousins, also display in the structure of their 

 bodies positive evidence of relationship to the stem of 

 the aristocratic primate phylum. 



Quite apart from the striking similarities produced 

 by identical habits and habitats, there are many 

 structural identities in the tree-shrews and lemuroids, 

 not directly associated with such habits, which can 

 be interpreted only as evidences of affinity. 



The Neopalliiini and its Relation to the Ability of 

 Learning by Experience. 



Having now sketched the broad lines of man's 

 pedigree right back to the most primitive mammals, 

 let us next consider what were the outstanding factors 

 that determined the course of his ancestors' progres- 

 sive evolution. 



The class mammalia, to which man belongs, is 

 distinguished in structure from all other vertebrates 

 mainly by the size and high development of the brain, 

 and, as regards the behaviour of its members, by the 

 fact that thev are able, in immeasurably greater degree 

 than all other animals, not excluding even birds, to 

 profit by individual experience. The behaviour of 

 most, or perhaps it would be more correct to say all, 

 animals, however comple.x and nicely adapted to their 



5 "The Orders of M.inni.ils," Bull. Amer. Mus. Nat. Hist, vol. xxvii., 

 1910, p. 321. 



