December 23, 1922] 



NA TURE 



835 



the ancient alphabet of the teeth, particularly as regards 

 the teeth of primate forms, Dr. Gregory is our most 

 highly trained expert. The survey he has now issued 

 embraces not only the American tarsioid and lemuroid 

 fossil -forms, lying in or near the basal phylum which 

 has given us our modern apes and lemurs, but also in- 

 cludes an examination of the corresponding fossil forms 

 found in Europe. He deals minutely with the fossil 

 remains of apes found in the Oligocene deposits of 

 Egypt, the anthropoid remains found in the Miocene 

 and Pliocene deposits of Europe and of India — 

 particularly those described in 1915 by Dr. G. E. 

 Pilgrim, of the Indian Geological Survey, — and the 

 various discoveries which have been made of fossil 

 human remains. 



Although the routes chosen by Dr. Gregory and by 

 the reviewer have been different they have led to 

 exactly the same goal — namely, that the gorilla, 

 chimpanzee, and man are twigs growing from the 

 same branch of the great primate stem. " Taken as 

 a whole," writes Dr. Gregory, " the testimony of 

 comparative anatomy affords cumulative evidence for 

 Darwin's inference that some ancient member of the 

 anthropomorphous sub-group gave birth to man. The 

 detailed studies of the dentition in Part IV. of this 

 work leads me to the conclusion that the ancient 

 member of the anthropomorphous sub-group was closely 

 allied to, or even identical with Sivapithecus or 

 Drvopithecus of the Miocene Simiinae." 



The reviewer agrees with Dr. Gregory that, on 

 comparing the structural " make-up " of man with 

 that of the great anthropoid apes, " the resemblances 

 are far more numerous, detailed, and fundamental 

 than the differences " ; the reviewer would go further 

 and say that in any theory of human lineage the 

 common origin of man, the gorilla, chimpanzee, and 

 orang, must be regarded as a " fixed point " in framing 

 all our speculations. At this early stage in our search 

 for man's pedigree, with only fragmentary documents 

 at our disposal, and with yawning gaps in our book 

 of evidence, complete unanimity between any two 

 investigators cannot be expected. 



In Dr. Gregory's opinion mankind is, in a geological 

 sense, a recent product. So late as mid-Miocene 

 times — about a million of years ago if we accept 

 Dr. Gregory's rough estimate — he believes that our 

 ancestry was represented by such fossil forms as 

 Sivapithecus or Drvopithecus — which, so far as we 

 yet know them, must be regarded as true anthropoid 

 apes, not very different from the chimpanzee and 

 gorilla. There is no ground for supposing that in 

 foot or in brain the}- possessed any trace of the adapta- 

 tions which have become so pronounced features of 

 the human body. The life-periods and the rate of 



NO. 2773, VOL. I io] 



reproduction of this ancestral stock must have been 

 of the anthropoid order, namely, about seven genera- 

 tions to the century. 



In the period postulated by Dr. Gregory for man's 

 differentiation there would have been some 70,000 

 generations. The representatives of mankind we 

 encounter by mid-Pleistocene times have already a 

 brain which has three times the volume of the chim- 

 panzee brain. Is it pos ible to con eive a brain like 

 that of the chimpanzee, although constituted upon 

 the same structural and functional plan as is the 

 human organ, attaining a human standard in the 

 course of 70,000 generations ? It is true that the 

 discoveries of Dr. Ariens Rappers- have shown that 

 the countless myriads of nerve units which make up 

 the human brain are, during the period of development, 

 controlled and grouped by a mechanism the nature 

 of which we can only gu ss at as yet. Making all 

 allowances on this score, the reviewer cannot conceive 

 the possibility of the extreme structural and functional 

 complexity of the human brain having been evolved 

 from an anthropoid stage in the course of 70,000 

 generations. While Dr. Gregory is inclined to accept 

 our present knowledge of the geological record at its 

 face value and trace man's origin from an anthropoid 

 of the mid-Miocene period, the reviewer would make 

 allowances for the great blanks in our geological 

 record, which further discoveries will make good, and 

 assume a pre-Miocene date for the divergence of the 

 phvla of man and great anthropoids. It is very 

 difficult to believe that the human brain arose as 

 mushroom-like growth. 



Those who have made systematic attempts to 

 determine the evolutionary relationship of one animal 

 form to another know well that it cannot be settled 

 on the evidence of one set of organs ; all the structural 

 systems of the body have to be taken into account. 

 Often the evidence of one system — such as that of 

 the teeth, which go with the alimentary system — will 

 seem to clash with or contradict the evidence of other 

 systems. Dr. Gregory is too experienced an evolutionist 

 to make a mistake in this respect ; whenever possible 

 he supports or modifies the conclusions reached on 

 dental evidence by appealing to testimony afforded 

 by other systems of the body. Even when this is 

 done it becomes abundantly clear that evolution has 

 not worked on the body of man, ape, or of any animal 

 form whatsoever in a simple and straightforward 

 manner. For example, in that primitive but aberrant 

 primate Tarsius, the embryo establishes itself in the 

 maternal womb in exactly the same manner as do 

 the developing ova of man and anthropoids, and yet 

 the monkeys of the New and of the Old World , which 

 have a simpler type of placentation, are yet infinitely 



