200 SECTIONAL ADDRESSES. 



than the temporals, the skull would be freer to expand along both diameters 

 instead of almost exclusively in length. More chewing and less tearing 

 and pulling would less definitely pull the jaws lengthwise. More power 

 for chewing would be gained by growth in length of the ascending ramus 

 of the jaw, and this added growth is a feature of most broad-headed tjrpes. 

 Increase of power of the masseters above a certain amount can be secured 

 probably only by increased width of the malar bones, and thus by increased 

 width of the face. If the face and jaws tend towards width rather than 

 length the same tendency is likely to show itself in the head. After men 

 had attained the upright posture a strong forward projection of the face 

 would have to be balanced by a backward projection of the head ; on 

 the other hand, a reduction of such a forward projection would allow the 

 reduction of the backward projection. On the whole, then, with the 

 changes indicated, it is possible to think that men among whom chewing 

 was far more important than tearing and pulling with the jaws, might find 

 their normal head-growth leading rather to an increase than to a 

 decrease of relative cranial breadth. Broad-headed people spread very 

 early into Europe, and their skulls are known from Ofnet and Mugem. 

 Some of the Ofnet skulls show a frontal region which suggests dolicho- 

 cephaly, while the parietal region demonstrates brachycephaly ; this is 

 a natural feature in skulls of early date if we remember the restrictions 

 operating in early times on frontal growth in breadth. 



There has been no attempt to argue that emphasis on chewing rather 

 than on tearing and pulling by the jaws has led to a change from 

 dolichocephaly to brachycephaly. The suggestion has rather been that 

 modern types of men may well have started medium-headed with indices 

 not very different from those of ancient man (the frontal torus of 

 Neanderthal types not being counted with the skull for purposes of 

 measurement). On this has been built up the idea that growth would 

 express itself in form changes which would on the whole tend towards 

 growth in length in some cases and more towards growth in breadth in 

 others. 



The skulls of early modern men, in which the growth in length is fully 

 seen, rarely have a cranial index of more than 72, and this gives, for them, 

 an index not above 73-4 on the living head. Specimens with indices below 

 these respective limits form a much better-marked group than those 

 below the ' 75 ' limit of dolichocephaly often quoted and used. 



Skulls with indices 72 or so to 77.5 (say 73.5-79 on the living head) 

 are a more heterogeneous group, including perhaps survivors of early 

 types with increase of fore-brain space but only relatively slight increase 

 of relative length. They probably also include cases in which there has 

 been an evolution from long-headedness of the extremer type, thanks to 

 the reduction of restraining influences of the temporal muscles during 

 the period of growth. 



No sharp divisions in a continuous series, such as that of skull forms, 

 can be really satisfactory, but 72 aud 77.5 on the skull or 73.5 and 79 

 on the living head would be more useful than the limits generally 

 chosen. 



Another factor seems to have operated in the evolution of the broader- 

 headed types. The nasal chambers, as Thomson has pointed out, are 



