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.