differs less from the Chimpanzee or the Orang, than these do even from
the Monkeys, and that the difference between the brains of the
Chimpanzee and of Man is almost insignificant, when compared with that
between the Chimpanzee brain and that of a Lemur.

It must not be overlooked, however, that there is a very striking
difference in absolute mass and weight between the lowest human brain
and that of the highest ape--a difference which is all the more
remarkable when we recollect that a full grown Gorilla is probably
pretty nearly twice as heavy as a Bosjes man, or as many an European
woman. It may be doubted whether a healthy human adult brain ever
weighed less than thirty-one or two ounces, or that the heaviest Gorilla
brain has exceeded twenty ounces.

This is a very noteworthy circumstance, and doubtless will one day help
to furnish an explanation of the great gulf which intervenes between the
lowest man and the highest ape in intellectual power;* but it has little
systematic value, for the simple reason that, as may be concluded from
what has been already said respecting cranial capacity, the difference
in weight of brain between the highest and the lowest men is far
greater, both relatively and absolutely, than that between the lowest
man and the highest ape. The latter, as has been seen, is represented
by, say twelve ounces of cerebral substance absolutely, or by 32:20
relatively; but as the largest recorded human brain weighed between 65
and 66 ounces, the former difference is represented by more than 33
ounces absolutely, or by 65:32 relatively. Regarded systematically, the
cerebral differences of man and apes are not of more than generic value;
his Family distinction resting chiefly on his dentition, his pelvis, and
his lower limbs.