[25] It will be understood that, in the preceding Essay, I have selected
for notice from the vast mass of papers which have been written upon the
man-like Apes, only those which seem to me to be of special moment.
[26] We are not at present thoroughly acquainted with the brain of the
Gorilla, and therefore, in discussing cerebral characters, I shall take
that of the Chimpanzee as my highest term among the Apes.
[27] "More than once," says Peter Camper, "have I met with more than six
lumbar vertebræ in man.... Once I found thirteen ribs and four lumbar
vertebræ." Fallopius noted thirteen pair of ribs and only four lumbar
vertebræ; and Eustachius once found eleven dorsal vertebræ and six
lumbar vertebræ.--"OEuvres de Pierre Camper," T. 1, p. 42. As Tyson
states, his "Pygmie" had thirteen pair of ribs and five lumbar vertebræ.
The question of the curves of the spinal column in the Apes requires
further investigation.
[28] It has been affirmed that Hindoo crania sometimes contain as little
as 27 ounces of water, which would give a capacity of about 46 cubic
inches. The minimum capacity which I have assumed above, however, is
based upon the valuable tables published by Professor R. Wagner in his
"Vorstudien zu einer wissenschaftlichen Morphologie und Physiologie des
menschlichen Gehirns." As the result of the careful weighing of more
than 900 human brains, Professor Wagner states that one-half weighed
between 1200 and 1400 grammes, and that about two-ninths, consisting for
the most part of male brains, exceed 1400 grammes. The lightest brain of
an adult male, with sound mental faculties, recorded by Wagner, weighed
1020 grammes. As a gramme equals 15.4 grains, and a cubic inch of water
contains 252.4 grains, this is equivalent to 62 cubic inches of water;
so that as brain is heavier than water, we are perfectly safe against
erring on the side of diminution in taking this as the smallest capacity
of any adult male human brain. The only adult male brain, weighing as
little as 970 grammes, is that of an idiot; but the brain of an adult
woman, against the soundness of whose faculties nothing appears, weighed
as little as 907 grammes (55.3 cubic inches of water); and Reid gives an
adult female brain of still smaller capacity. The heaviest brain (1872
grammes, or about 115 cubic inches) was, however, that of a woman; next
to it comes the brain of Cuvier (1861 grammes), then Byron (1807
grammes), and then an insane person (1783 grammes). The lightest adult
brain recorded (720 grammes) was that of an idiotic female. The brains
of five children, four years old, weighed between 1275 and 992 grammes.
So that it may be safely said, that an average European child of four
years old has a brain twice as large as that of an adult Gorilla.
[29] In speaking of the foot of his "Pygmie," Tyson remarks, p.
13:--"But this part in the formation and in its function too, being
liker a Hand than a Foot: for the distinguishing this sort of animals
from others, I have thought whether it might not be reckoned and called
rather Quadrumanus than Quadrupes, _i.e._ a four-handed rather than a
four-footed animal."
As this passage was published in 1699, M. I. G. St. Hilaire is clearly
in error in ascribing the invention of the term "quadrumanous" to
Buffon, though "bimanous" may belong to him. Tyson uses "Quadrumanus" in
several places, as at p. 91.... "Our _Pygmie_ is no Man, nor yet the
_common Ape_, but a sort of _Animal_ between both; and though a _Biped_,
yet of the _Quadrumanus_-kind: though some _Men_ too have been observed
to use their _Feet_ like _Hands_, as I have seen several."
[30] See the note at the end of this essay for a succinct history of the
controversy to which allusion is here made.
[31] I say _help_ to furnish: for I by no means believe that it was any
original difference of cerebral quality, or quantity, which caused that
divergence between the human and the pithecoid stirpes, which has ended
in the present enormous gulf between them. It is no doubt perfectly
true, in a certain sense, that all difference of function is a result of
difference of structure; or, in other words, of difference in the
combination of the primary molecular forces of living substance; and,
starting from this undeniable axiom, objectors occasionally, and with
much seeming plausibility, argue that the vast intellectual chasm
between the Ape and Man implies a corresponding structural chasm in the
organs of the intellectual functions; so that, it is said, the
non-discovery of such vast differences proves, not that they are absent,
but that Science is incompetent to detect them. A very little
consideration, however, will, I think, show the fallacy of this
reasoning. Its validity hangs upon the assumption, that intellectual
power depends altogether on the brain--whereas the brain is only one
condition out of many on which intellectual manifestations depend; the
others being, chiefly, the organs of the senses and the motor
apparatuses, especially those which are concerned in prehension and in
the production of articulate speech.
A man born dumb, notwithstanding his great cerebral mass and his
inheritance of strong intellectual instincts, would be capable of few
higher intellectual manifestations than an Orang or a Chimpanzee, if he
were confined to the society of dumb associates. And yet there might not
be the slightest discernible difference between his brain and that of a
highly intelligent and cultivated person. The dumbness might be the
result of a defective structure of the mouth, or of the tongue, or a
mere defective innervation of these parts; or it might result from
congenital deafness, caused by some minute defect of the internal ear,
which only a careful anatomist could discover.
The argument, that because there is an immense difference between a
Man's intelligence and an Ape's, therefore, there must be an equally
immense difference between their brains, appears to me to be about as
well based as the reasoning by which one should endeavour to prove that,
because there is a "great gulf" between a watch that keeps accurate time
and another that will not go at all, there is therefore a great
structural hiatus between the two watches. A hair in the balance-wheel,
a little rust on a pinion, a bend in a tooth of the escapement, a
something so slight that only the practised eye of the watchmaker can
discover it, may be the source of all the difference.
And believing, as I do, with Cuvier, that the possession of articulate
speech is the grand distinctive character of man (whether it be
absolutely peculiar to him or not), I find it very easy to comprehend,
that some equally inconspicuous structural difference may have been the
primary cause of the immeasurable and practically infinite divergence of
the Human from the Simian Stirps.
[32] It is so rare a pleasure for me to find Professor Owen's opinions
in entire accordance with my own, that I cannot forbear from quoting a
paragraph which appeared in his Essay "On the Characters, &c., of the
Class Mammalia," in the "Journal of the Proceedings of the Linnean
Society of London" for 1857, but is unaccountably omitted in the "Reade
Lecture" delivered before the University of Cambridge two years later,
which is otherwise nearly a reprint of the paper in question. Prof. Owen
writes:
"Not being able to appreciate or conceive of the
distinction between the psychical phenomena of a
Chimpanzee and of a Boschisman or of an Aztec, with
arrested brain growth, as being of a nature so essential
as to preclude a comparison between them, or as being
other than a difference of degree, I cannot shut my eyes
to the significance of that all-pervading similitude of
structure--every tooth, every bone, strictly
homologous--which makes the determination of the
difference between _Homo_ and _Pithecus_ the anatomist's
difficulty."
Surely it is a little singular that the "anatomist," who finds it
"difficult" to "determine the difference" between _Homo_ and _Pithecus_,
should yet range them on anatomical grounds, in distinct sub-classes!
[33] On the Affinities of the Brain of the Orang. Nat. Hist. Review,
April, 1861.
[34] On the Brain of a young Chimpanzee. Ibid., July, 1861.
[35] On the Posterior lobes of the Cerebrum of the Quadrumana.
Philosophical Transactions, 1862.
[36] On the anatomical Relations of the Surfaces of the Tentorium to the
Cerebrum and Cerebellum in Man and the lower Mammals. Proceedings of the
Royal Society of Edinburgh, March, 1862.
[37] On the Brain of Ateles. Proceedings of Zoological Society, 1861.