The Descent of Man

in structure more nearly to the bipedal than to
the quadrupedal type.
As the progenitors of man became more and
more erect, with their hands and arms more
and more modified for prehension and other
purposes, with their feet and legs at the same
time transformed for firm support and progression,
endless other changes of structure would
have become necessary. The pelvis would have
to be broadened, the spine peculiarly curved,
and the head fixed in an altered position, all
which changes have been attained by man.
Prof. Schaaffhausen (76. 'On the Primitive Form
of the Skull,' translated in 'Anthropological
Review,' Oct. 1868, p. 428. Owen ('Anatomy of
Vertebrates,' vol. ii. 1866, p. 551) on the mastoid
processes in the higher apes.) maintains that
"the powerful mastoid processes of the human
skull are the result of his erect position;" and
these processes are absent in the orang, chimpanzee,
etc., and are smaller in the gorilla than