Piltdown Man 
17 
It is, however, essentially human, and its bulk, probably nearly 
1,300 cubic centimetres, is equal to that of the smaller human 
brains at the present day. In modern Europeans the brain 
capacity averages 1,480 c.c, while in Australians it rarely exceeds 
1,1250 c.c. 
While the Piltdown skull is thus completely human, the half 
of the lower jaw, so far as preserved (Plate IV), is almost 
precisely that of an ape. The condyle for articulation with the 
skull is unfortunately missing, and the upper part of the front 
end of the jaw is also broken away ; but the rest of the bone is 
in good condition. The hinder or ascending portion is wide in 
proportion to its depth, and the notch in its upper border is rather 
shallow, as in some low types of man (figs. 6, 7). Its anterior 
border is so much widened for the insertion of an unusually 
powerful temporal (or biting) muscle, that it ends inwardly in 
a sharp edge, and the bone is strengthened by a distinct ridge on 
the inner face running obliquely upwards to the articular condyle 
(fig. 7b). This arrangement is specially characteristic of the apes 
and rare in man. The slight groove (mylohyoid groove, m.g.) 
which almost invariably starts from the edge of the perforation 
(dental foramen) on the inner face in man (fig. 7 c, d) is repre- 
sented in the fossil by a still slighter groove well below the 
foramen (fig. 7b), exactly as in all chimpanzees (fig. 7a) and 
orang-utans. The inner face of the anterior or horizontal portion 
of the bone is only gently convex, as in the apes, without any 
trace of the ridge (m.r.) which is almost always conspicuous where 
the floor of the mouth (mylohyoid muscle) arises in man. Finally, 
and still more remarkably, as the half of the jaw curves round in 
front to the middle line (symphysis), its lower border (fig. 8) does 
not remain simply rounded, as in all known men, but exhibits an 
increasingly wider flattening, which begins beneath the second 
molar, slopes upwards and outwards, and ends in front in a 
strongly retreating chin. This chin is therefore essentially similar 
to that of all the existing apes, with a nearly horizontal plate or 
flange of bone extending inwards and backwards from its lower 
border. The muscles which work the bones at the base of the 
tongue and arise in man on little bony prominences inside the 
chin, would here originate in a pit, as in all the apes and monkeys. 
In fact, all the peculiarities so far noted are those of a jaw which 
is commonly regarded as incapable of producing articulate speech ; 
but as the whole jaw in Piltdown man must have been much 
wider and more capacious than that of any ape, there seems to 
