The Descent of Man

plainly retained, in certain bones of their skulls.
If the races of man had descended, as is supposed
by some naturalists, from two or more species,
which differed from each other as much,
or nearly as much, as does the orang from the
gorilla, it can hardly be doubted that marked
differences in the structure of certain bones
would still be discoverable in man as he now
exists.
Although the existing races of man differ in
many respects, as in colour, hair, shape of skull,
proportions of the body, etc., yet if their whole
structure be taken into consideration they are
found to resemble each other closely in a multitude
of points. Many of these are of so unimportant
or of so singular a nature, that it is extremely
improbable that they should have been
independently acquired by aboriginally distinct
species or races. The same remark holds good
with equal or greater force with respect to the
numerous points of mental similarity between