444 THE ANTIQUITY OF MAN 
the joint of his jaw is concerned he shows the typical 
features of his race. There is a raised articular plateau, 
on which the condyle moves, somewhat similar to the 
form found in the chimpanzee. The posterior part of 
the plateau is slightly depressed ; there is just a suspicion 
of a glenoid cavity. The bony floor of the ear-passage 
is shaped as in the ape ; in the Piltdown skull it is 
fashioned exactly as in modern man. 
What are the advantages of the articular plateau in the 
mechanism of the ape's mandible .'' Both the advantages 
and disadvantages are shown in fig. 164. As the condyle 
is dragged forwards on the articular plateau, the mouth 
opens and the muscles of mastication are stretched. The 
gape thus produced differs from that seen when the human 
mouth is opened. The front teeth — the canines and 
incisors — are moved further apart than the hinder teeth or 
the molar teeth — which are especially used in grinding. 
With long projecting canine teeth a wide gape in front 
is a necessity. Our first impulse is to regard an articular 
plateau as an adaptation for the long and prominent canine 
teeth, but the impulse is checked when we see a very 
similar form of articular plateau in Neanderthal man, in 
whom the canine teeth are ground flush with their neigh- 
bours in the dental series. An articular plateau, then, 
does not necessarily indicate the presence of simian canine 
teeth. The particular question we have to answer, how- 
ever, is this : Is a true articular eminence compatible 
with projecting simian canine teeth ? We know that the 
movements of the Piltdown mandible were determined 
by the contour of the joint surfaces on the temporal bone ; 
these are exactly similar to those of modern man. The 
mandibular movements must have been the same in 
Piltdown man as in us. Are such movements compatible 
with the presence of projecting canine teeth ? The 
solution of that problem must wait until the canine tooth 
found at Piltdown has been fixed in the mandible — a 
task which awaits us in another chapter. 
Up to this point I have passed under review the various 
characters of the mandible found at Piltdown to see if 
