66 THE ROYAL SOCIETY OF CANADA 



the mature skulls bearing little resemblance to those of the young 

 undifferentiated forms. 



Nehring has shown that the masseter or masticatory muscles 

 do really affect the form of the skull by his investigations upon dogs 

 and apes; and he is of the opinion that the occurrence of a constriction 

 between the orbital and cerebral regions of the skull has direct relation 

 to the strength of the facial musculature and especially of the mas- 

 seter muscles. 



It is a well-known fact that decrease in the size and action of 

 the jaw invariably follows upon primitive man's advance in culture; 

 and the well-known experiments upon certain students at Cambridge 

 have shown that increased mental activity results in increased brain 

 volume. Thus a rise in the culture-status of a primitive people 

 should be followed by three effects — an increase in brain volume, a 

 decrease in facial musculature and a consequent freer expansion of 

 the brain case. Are not these just the features which differentiate 

 the High-terrace men and the Cromagniards from Neanderthal 

 man? Low races, like that of the Mousterian epoch, always have 

 heavy, strong jaws. The muscles which work these jaws arise from 

 the side walls of the skull. In heavy-jawed races these muscles 

 rise higher on the head than in light-jawed races, their limit being 

 marked by the curved line of the temporal crest. Sergi has shown 

 that excessive development of the masseter muscles in the lower 

 races of mankind results in the production of a median ridge like that 

 seen in some of the mature anthropoids. He tells us it is found in 

 Australia, in New Zealand and in many parts of Oceania. The 

 h'gher these muscles rise the more they tend to compress the skull 

 and modify its shape. Hence the difference in the skulls of the young 

 and the mature apes, and hence the difference in the skulls of Homo 

 neanderthalensis and of the Cromagniards. 



The presence of the same features in Neanderthal man as seen 

 in the anthropoids, that is, their excessive musculature, as disclosed 

 by their heavy jaws and prominent tori, makes it quite clear that the 

 men of the Mousterian epoch had followed along the same lines of 

 development, in this respect, as the anthropoids and hence their 

 degenerate and more ape-like appearance. We thus find what we 

 might have expected to find, namely, that as some species or genera 

 of anthropoids, such as Pithecanthropus and others, followed in 

 certain respects the lines of human development, and hence their 

 more human-like appearance, so some species or genera of men, 

 such as Homo neanderthalensis and probably also Homo heidel- 

 bergensis, followed in other respects the line of anthropoid develop- 



