THE PILTDOWN MANDIBLE 
433 
raised on the inner aspect of the mandible. In the more 
highly evolved races of modern man these ridges reach 
a very emphatic development. In anthropoids, on the 
other hand, they are but slightly marked — only the part 
lying under the molar teeth being easily recognised (fig. 
i6i). We therefore conclude that a high development of 
the mylo-hyoid muscle is a human character, and we have 
also reason for supposing that this high development is 
more closely connected with speech than with swallowing. 
AUSTRALIAN 
MoJsr- teeth 
ror DENTAL NERVE 
Q-f<\cio ni-^sz 
SUB-UHauAL FOSSA 
YOUNG GORILLA 
Fig. i6o. — Right half of the mandiljle of an Australian native, viewed from the 
inner or mouth aspect to show certain human characters. Below it there is 
repiesented the corresponding half of the mandible of an infant gorilla, 
about two years old. 
Now, as may be seen from fig. i6i, the mylo-hyoid 
ridge in the Piltdown mandible has the slight develop- 
ment seen in anthropoids. It is possible that the surface 
of this fossil bone has been rubbed and smoothed some- 
what as it lay in the gravel bed of the ancient Sussex 
stream, but there is no evidence of any marked erosion 
on the inner aspect of the mandible. We must therefore 
conclude that the individual of which this mandible 
formed a part had the mouth and tongue movements of 
an anthropoid ape. And yet we have seen that the brain 
which lay within the skull was human in size and form. 
28 
