3. By possessing the muscle termed 'peronaeus longus'. And if we desire
to ascertain whether the terminal division of a limb, in other Primates,
is to be called a foot or a hand, it is by the presence or absence of
these characters that we must be guided, and not by the mere proportions
and greater or lesser mobility of the great toe, which may vary
indefinitely without any fundamental alteration in the structure of the
foot.
Keeping these considerations in mind, let us now turn to the limbs
of the Gorilla. The terminal division of the fore limb presents no
difficulty--bone for bone and muscle for muscle, are found to be
arranged essentially as in man, or with such minor differences as are
found as varieties in man. The Gorilla's hand is clumsier, heavier, and
has a thumb somewhat shorter in proportion than that of man; but no one
has ever doubted its being a true hand.
(FIGURE 19.--Foot of Man, Gorilla, and Orang-Utan of the same absolute
length, to show the differences in proportion of each. Letters as in
Figure 18. Reduced from original drawings by Mr. Waterhouse Hawkins.
At first sight, the termination of the hind limb of the Gorilla looks
very hand-like, and as it is still more so in many of the lower apes,
it is not wonderful that the appellation "Quadrumana," or four-handed
creatures, adopted from the older anatomists* by Blumenbach, and
unfortunately rendered current by Cuvier, should have gained such wide
acceptance as a name for the Simian group. ([Footnote] *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 Quadru-manus 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 "himanous" 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.") But the most
cursory anatomical investigation at once proves that the resemblance of
the so-called "hind hand" to a true hand, is only skin deep, and that,
in all essential respects, the hind limb of the Gorilla is as truly
terminated by a foot as that of man. The tarsal bones, in all important
circumstances of number, disposition, and form, resemble those of
man (Figure 19). The metatarsals and digits, on the other hand, are
proportionally longer and more slender, while the great toe is not only
proportionally shorter and weaker, but its metatarsal bone is united by
a more moveable joint with the tarsus. At the same time, the foot is set
more obliquely upon the leg than in man.
As to the muscles, there is a short flexor, a short extensor, and a
'peronaeus longus', while the tendons of the long flexors of the great
toe and of the other toes are united together and with an accessory
fleshy bundle.
The hind limb of the Gorilla, therefore, ends in a true foot, with a
very moveable great toe. It is a prehensile foot, indeed, but is in no
sense a hand: it is a foot which differs from that of man not in
any fundamental character, but in mere proportions, in the degree of
mobility, and in the secondary arrangement of its parts.
It must not be supposed, however, because I speak of these differences
as not fundamental, that I wish to underrate their value. They are
important enough in their way, the structure of the foot being in strict
correlation with that of the rest of the organism in each case. Nor can
it be doubted that the greater division of physiological labour in Man,
so that the function of support is thrown wholly on the leg and foot, is
an advance in organization of very great moment to him; but, after all,
regarded anatomically, the resemblances between the foot of Man and
the foot of the Gorilla are far more striking and important than the
differences.
I have dwelt upon this point at length, because it is one regarding
which much delusion prevails; but I might have passed it over without
detriment to my argument, which only requires me to show that, be the
differences between the hand and foot of Man and those of the Gorilla
what they may--the differences between those of the Gorilla, and those
of the lower Apes are much greater.
It is not necessary to descend lower in the scale than the Orang for
conclusive evidence on this head.
The thumb of the Orang differs more from that of the Gorilla than
the thumb of the Gorilla differs from that of Man, not only by its
shortness, but by the absence of any special long flexor muscle. The
carpus of the Orang, like that of most lower apes, contains nine bones,
while in the Gorilla, as in Man and the Chimpanzee, there are only
eight.
The Orang's foot (Figure 19) is still more aberrant; its very long
toes and short tarsus, short great toe, short and raised heel, great
obliquity of articulation in the leg, and absence of a long flexor
tendon to the great toe, separating it far more widely from the foot of
the Gorilla than the latter is separated from that of Man.
But, in some of the lower apes, the hand and foot diverge still more
from those of the Gorilla, than they do in the Orang. The thumb ceases
to be opposable in the American monkeys; is reduced to a mere rudiment
covered by the skin in the Spider Monkey; and is directed forwards and
armed with a curved claw like the other digits, in the Marmosets--so
that, in all these cases, there can be no doubt but that the hand is
more different from that of the Gorilla than the Gorilla's hand is from
Man's.
And as to the foot, the great toe of the Marmoset is still more
insignificant in proportion than that of the Orang--while in the Lemurs
it is very large, and as completely thumb-like and opposable as in
the Gorilla--but in these animals the second toe is often irregularly
modified, and in some species the two principal bones of the tarsus,
the 'astragalus' and the 'os calcis', are so immensely elongated as to
render the foot, so far, totally unlike that of any other mammal.
So with regard to the muscles. The short flexor of the toes of the
Gorilla differs from that of Man by the circumstance that one slip of
the muscle is attached, not to the heel bone, but to the tendons of the
long flexors. The lower Apes depart from the Gorilla by an exaggeration
of the same character, two, three, or more, slips becoming fixed to the
long flexor tendons--or by a multiplication of the slips.--Again, the
Gorilla differs slightly from Man in the mode of interlacing of the long
flexor tendons: and the lower apes differ from the Gorilla in exhibiting
yet other, sometimes very complex, arrangements of the same parts, and
occasionally in the absence of the accessory fleshy bundle.
Throughout all these modifications it must be recollected that the
foot loses no one of its essential characters. Every Monkey and Lemur
exhibits the characteristic arrangement of tarsal bones, possesses a
short flexor and short extensor muscle, and a 'peronaeus longus'. Varied
as the proportions and appearance of the organ may be, the terminal
division of the hind limb remains, in plan and principle of
construction, a foot, and never, in those respects, can be confounded
with a hand.
Hardly any part of the bodily frame, then, could be found better
calculated to illustrate the truth that the structural differences
between Man and the highest Ape are of less value than those between the
highest and the lower Apes, than the hand or the foot, and yet, perhaps,
there is one organ the study of which enforces the same conclusion in a
still more striking manner--and that is the Brain.
But before entering upon the precise question of the amount of
difference between the Ape's brain and that of Man, it is necessary that
we should clearly understand what constitutes a great, and what a small
difference in cerebral structure; and we shall be best enabled to
do this by a brief study of the chief modifications which the brain
exhibits in the series of vertebrate animals.
The brain of a fish is very small, compared with the spinal cord into
which it is continued, and with the nerves which come off from it: of
the segments of which it is composed--the olfactory lobes, the cerebral
hemisphere, and the succeeding divisions--no one predominates so much
over the rest as to obscure or cover them; and the so-called optic lobes
are, frequently, the largest masses of all. In Reptiles, the mass of
the brain, relatively to the spinal cord, increases and the cerebral
hemispheres begin to predominate over the other parts; while in Birds
this predominance is still more marked. The brain of the lowest Mammals,
such as the duck-billed Platypus and the Opossums and Kangaroos,
exhibits a still more definite advance in the same direction. The
cerebral hemispheres have now so much increased in size as, more or
less, to hide the representatives of the optic lobes, which remain
comparatively small, so that the brain of a Marsupial is extremely
different from that of a Bird, Reptile, or Fish. A step higher in the
scale, among the placental Mammals, the structure of the brain acquires
a vast modification--not that it appears much altered externally, in
a Rat or in a Rabbit, from what it is in a Marsupial--nor that the
proportions of its parts are much changed, but an apparently new
structure is found between the cerebral hemispheres, connecting them
together, as what is called the 'great commissure' or 'corpus callosum.'
The subject requires careful re-investigation, but if the currently
received statements are correct, the appearance of the 'corpus callosum'
in the placental mammals is the greatest and most sudden modification
exhibited by the brain in the whole series of vertebrated animals--it is
the greatest leap anywhere made by Nature in her brain work. For the
two halves of the brain being once thus knit together, the progress of
cerebral complexity is traceable through a complete series of steps from
the lowest Rodent, or Insectivore, to Man; and that complexity consists,
chiefly, in the disproportionate development of the cerebral hemispheres
and of the cerebellum, but especially of the former, in respect to the
other parts of the brain.
In the lower placental mammals, the cerebral hemispheres leave the
proper upper and posterior face of the cerebellum completely visible,
when the brain is viewed from above; but, in the higher forms, the
hinder part of each hemisphere, separated only by the tentorium (p.
281) from the anterior face of the cerebellum, inclines backwards and
downwards, and grows out, as the so-called "posterior lobe," so as at
length to overlap and hide the cerebellum. In all Mammals, each cerebral
hemisphere contains a cavity which is termed the 'ventricle,' and as
this ventricle is prolonged, on the one hand, forwards, and on the other
downwards, into the substance of the hemisphere, it is said to have two
horns or 'cornua', an 'anterior cornu,' and a 'descending cornu.'
When the posterior lobe is well developed, a third prolongation of the
ventricular cavity extends into it, and is called the "posterior cornu."
In the lower and smaller forms of placental Mammals the surface of the
cerebral hemispheres is either smooth or evenly rounded, or exhibits
a very few grooves, which are technically termed 'sulci,' separating
ridges or 'convolutions' of the substance of the brain; and the smaller
species of all orders tend to a similar smoothness of brain. But, in the
higher orders, and especially the larger members of these orders, the
grooves, or sulci, become extremely numerous, and the intermediate
convolutions proportionately more complicated in their meanderings,
until, in the Elephant, the Porpoise, the higher Apes, and Man, the
cerebral surface appears a perfect labyrinth of tortuous foldings.
Where a posterior lobe exists and presents its customary cavity--the
posterior cornu--it commonly happens that a particular sulcus appears
upon the inner and under surface of the lobe, parallel with and beneath
the floor of the cornu--which is, as it were, arched over the roof of
the sulcus. It is as if the groove had been formed by indenting the
floor of the posterior horn from without with a blunt instrument, so
that the floor should rise as a convex eminence. Now this eminence is
what has been termed the 'Hippocampus minor;' the 'Hippocampus major'
being a larger eminence in the floor of the descending cornu. What may
be the functional importance of either of these structures we know not.
As if to demonstrate, by a striking example, the impossibility of
erecting any cerebral barrier between man and the apes, Nature has
provided us, in the latter animals, with an almost complete series of
gradations from brains little higher than that of a Rodent, to brains
little lower than that of Man. And it is a remarkable circumstance that
though, so far as our present knowledge extends, there 'is' one true
structural break in the series of forms of Simian brains, this hiatus
does not lie between Man and the man-like apes, but between the lower
and the lowest Simians; or, in other words, between the old and new
world apes and monkeys, and the Lemurs. Every Lemur which has yet been
examined, in fact, has its cerebellum partially visible from above, and
its posterior lobe, with the contained posterior cornu and hippocampus
minor, more or less rudimentary. Every Marmoset, American monkey,
old-world monkey, Baboon, or Man-like ape, on the contrary, has its
cerebellum entirely hidden, posteriorly, by the cerebral lobes, and
possesses a large posterior cornu, with a well-developed hippocampus
minor.
(FIGURE 20.--Drawings of the internal casts of a Man's and of a
Chimpanzee's skull, of the same absolute length, and placed in
corresponding positions. 'A'. Cerebrum; 'B'. Cerebellum. The former
drawing is taken from a cast in the Museum of the Royal College of
Surgeons, the latter from the photograph of the cast of a Chimpanzee's
skull, which illustrates the paper by Mr. Marshall 'On the Brain of the
Chimpanzee' in the 'Natural History Review' for July, 1861. The sharper
definition of the lower edge of the cast of the cerebral chamber in the
Chimpanzee arises from the circumstance that the tentorium remained in
that skull and not in the Man's. The cast more accurately represents the
brain in Chimpanzee than in the Man; and the great backward projection
of the posterior lobes of the cerebrum of the former, beyond the
cerebellum, is conspicuous.)
In many of these creatures, such as the Saimiri ('Chrysothrix'), the
cerebral lobes overlap and extend much further behind the cerebellum,
in proportion, than they do in man (Figure 16)--and it is quite
certain that, in all, the cerebellum is completely covered behind, by
well-developed posterior lobes. The fact can be verified by every one
who possesses the skull of any old or new world monkey. For, inasmuch
as the brain in all mammals completely fills the cranial cavity, it
is obvious that a cast of the interior of the skull will reproduce the
general form of the brain, at any rate with such minute and, for the
present purpose, utterly unimportant differences as may result from the
absence of the enveloping membranes of the brain in the dry skull. But
if such a cast be made in plaster, and compared with a similar cast of
the interior of a human skull, it will be obvious that the cast of the
cerebral chamber, representing the cerebrum of the ape, as completely
covers over and overlaps the cast of the cerebellar chamber,
representing the cerebellum, as it does in the man (Figure 20). A
careless observer, forgetting that a soft structure like the brain loses
its proper shape the moment it is taken out of the skull, may indeed
mistake the uncovered condition of the cerebellum of an extracted and
distorted brain for the natural relations of the parts; but his error
must become patent even to himself if he try to replace the brain
within the cranial chamber. To suppose that the cerebellum of an ape is
naturally uncovered behind is a miscomprehension comparable only to that
of one who should imagine that a man's lungs always occupy but a small
portion of the thoracic cavity--because they do so when the chest is
opened, and their elasticity is no longer neutralized by the pressure of
the air.
And the error is the less excusable, as it must become apparent to
every one who examines a section of the skull of any ape above a Lemur,
without taking the trouble to make a cast of it. For there is a
very marked groove in every such skull, as in the human skull--which
indicates the line of attachment of what is termed the 'tentorium'--a
sort of parchment-like shelf, or partition, which, in the recent state,
is interposed between the cerebrum and cerebellum, and prevents the
former from pressing upon the latter. (See Figure 16.)
This groove, therefore, indicates the line of separation between that
part of the cranial cavity which contains the cerebrum, and that which
contains the cerebellum; and as the brain exactly fills the cavity of
the skull, it is obvious that the relations of these two parts of the
cranial cavity at once informs us of the relations of their contents.
Now in man, in all the old-world, and in all the new-world Simiae,
with one exception, when the face is directed forwards, this line of
attachment of the tentorium, or impression for the lateral sinus, as it
is technically called, is nearly horizontal, and the cerebral chamber
invariably overlaps or projects behind the cerebellar chamber. In the
Howler Monkey or 'Mycetes' (see Figure 16), the line passes obliquely
upwards and backwards, and the cerebral overlap is almost nil; while in
the Lemurs, as in the lower mammals, the line is much more inclined in
the same direction, and the cerebellar chamber projects considerably
beyond the cerebral.
When the gravest errors respecting points so easily settled as
this question respecting the posterior lobes can be authoritatively
propounded, it is no wonder that matters of observation, of no very
complex character, but still requiring a certain amount of care, should
have fared worse. Any one who cannot see the posterior lobe in an ape's
brain is not likely to give a very valuable opinion respecting the
posterior cornu or the hippocampus minor. If a man cannot see a church,
it is preposterous to take his opinion about its altar-piece or painted
window--so that I do not feel bound to enter upon any discussion of
these points, but content myself with assuring the reader that the
posterior cornu and the hippocampus minor, have now been seen--usually,
at least as well developed as in man, and often better--not only in the
Chimpanzee, the Orang, and the Gibbon, but in all the genera of the old
world baboons and monkeys, and in most of the new world forms, including
the Marmosets.* ([Footnote] *See the note at the end of this essay for a
succinct history of the controversy to which allusion is here made.)
(FIGURE 21.--Drawings of the cerebral hemispheres of a Man and of a
Chimpanzee of the same length, in order to show the relative proportions
of the parts: the former taken from a specimen, which Mr. Flower,
Conservator of the Museum of the Royal College of Surgeons, was good
enough to dissect for me; the latter, from the photograph of a similarly
dissected Chimpanzee's brain, given in Mr. Marshall's paper above
referred to. 'a', posterior lobe; 'b', lateral ventricle; 'c', posterior
cornu; 'x', the hippocampus minor.)
In fact, all the abundant and trustworthy evidence (consisting of the
results of careful investigations directed to the determination of these
very questions, by skilled anatomists) which we now possess, leads
to the conviction that, so far from the posterior lobe, the posterior
cornu, and the hippocampus minor, being structures peculiar to and
characteristic of man, as they have been over and over again asserted
to be, even after the publication of the clearest demonstration of the
reverse, it is precisely these structures which are the most marked
cerebral characters common to man with the apes. They are among the most
distinctly Simian peculiarities which the human organism exhibits.
As to the convolutions, the brains of the apes exhibit every stage of
progress, from the almost smooth brain of the Marmoset, to the Orang
and the Chimpanzee, which fall but little below Man. And it is most
remarkable that, as soon as all the principal sulci appear, the pattern
according to which they are arranged is identical with that of the
corresponding sulci of man. The surface of the brain of a monkey
exhibits a sort of skeleton map of man's, and in the man-like apes
the details become more and more filled in, until it is only in minor
characters, such as the greater excavation of the anterior lobes, the
constant presence of fissures usually absent in man, and the different
disposition and proportions of some convolutions, that the Chimpanzee's
or the Orang's brain can be structurally distinguished from Man's.
So far as cerebral structure goes, therefore, it is clear that Man
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.
([Footnote] * 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.)
Thus, whatever system of organs be studied, the comparison of their
modifications in the ape series leads to one and the same result--that
the structural differences which separate Man from the Gorilla and the
Chimpanzee are not so great as those which separate the Gorilla from the
lower apes.
But in enunciating this important truth I must guard myself against a
form of misunderstanding, which is very prevalent. I find, in fact, that
those who endeavour to teach what nature so clearly shows us in this
matter, are liable to have their opinions misrepresented and their
phraseology garbled, until they seem to say that the structural
differences between man and even the highest apes are small and
insignificant. Let me take this opportunity then of distinctly
asserting, on the contrary, that they are great and significant; that
every bone of a Gorilla bears marks by which it might be distinguished
from the corresponding bone of a Man; and that, in the present creation,
at any rate, no intermediate link bridges over the gap between 'Homo'
and 'Troglodytes'.
It would be no less wrong than absurd to deny the existence of this
chasm; but it is at least equally wrong and absurd to exaggerate its
magnitude, and, resting on the admitted fact of its existence, to refuse
to inquire whether it is wide or narrow. Remember, if you will, that
there is no existing link between Man and the Gorilla, but do not forget
that there is a no less sharp line of demarcation, a no less complete
absence of any transitional form, between the Gorilla and the Orang, or
the Orang and the Gibbon. I say, not less sharp, though it is somewhat
narrower. The structural differences between Man and the Man-like apes
certainly justify our regarding him as constituting a family apart from
them; though, inasmuch as he differs less from them than they do from
other families of the same order, there can be no justification for
placing him in a distinct order.
And thus the sagacious foresight of the great lawgiver of systematic
zoology, Linnaeus, becomes justified, and a century of anatomical
research brings us back to his conclusion, that man is a member of the
same order (for which the Linnaean term PRIMATES ought to be retained)
as the Apes and Lemurs. This order is now divisible into seven families,
of about equal systematic value: the first, the ANTHROPINI, contains
Man alone; the second, the CATARHINI, embraces the old-world apes; the
third, the PLATYRHINI, all new-world apes, except the Marmosets; the
fourth, the ARCTOPITHECINI, contains the Marmosets; the fifth, the
LEMURINI, the Lemurs--from which 'Cheiromys' should probably be excluded
to form a sixth distinct family, the CHEIROMYINI; while the seventh,
the GALEOPITHECINI, contains only the flying Lemur 'Galeopithecus',--a
strange form which almost touches on the Bats, as the 'Cheiromys' puts
on a rodent clothing, and the Lemurs simulate Insectivora.
Perhaps no order of mammals presents us with so extraordinary a series
of gradations as this--leading us insensibly from the crown and summit
of the animal creation down to creatures, from which there is but a
step, as it seems, to the lowest, smallest, and least intelligent of
the placental Mammalia. It is as if nature herself had foreseen
the arrogance of man, and with Roman severity had provided that his
intellect, by its very triumphs, should call into prominence the slaves,
admonishing the conqueror that he is but dust.
These are the chief facts, this the immediate conclusion from them
to which I adverted in the commencement of this Essay. The facts, I
believe, cannot be disputed; and if so, the conclusion appears to me to
be inevitable.
But if Man be separated by no greater structural barrier from the brutes
than they are from one another--then it seems to follow that if any
process of physical causation can be discovered by which the genera
and families of ordinary animals have been produced, that process of
causation is amply sufficient to account for the origin of Man. In other
words, if it could be shown that the Marmosets, for example, have
arisen by gradual modification of the ordinary Platyrhini, or that
both Marmosets and Platyrhini are modified ramifications of a primitive
stock--then, there would be no rational ground for doubting that man
might have originated, in the one case, by the gradual modification of
a man-like ape; or, in the other case, as a ramification of the same
primitive stock as those apes.
At the present moment, but one such process of physical causation
has any evidence in its favour; or, in other words, there is but one
hypothesis regarding the origin of species of animals in general
which has any scientific existence--that propounded by Mr. Darwin. For
Lamarck, sagacious as many of his views were, mingled them with so much
that was crude and even absurd, as to neutralize the benefit which his
originality might have effected, had he been a more sober and cautious
thinker; and though I have heard of the announcement of a formula
touching "the ordained continuous becoming of organic forms," it is
obvious that it is the first duty of a hypothesis to be intelligible,
and that a qua-qua-versal proposition of this kind, which may be read
backwards, or forwards, or sideways, with exactly the same amount of
signification, does not really exist, though it may seem to do so.
At the present moment, therefore, the question of the relation of man to
the lower animals resolves itself, in the end, into the larger question
of the tenability, or untenability of Mr. Darwin's views. But here
we enter upon difficult ground, and it behoves us to define our exact
position with the greatest care.
It cannot be doubted, I think, that Mr. Darwin has satisfactorily proved
that what he terms selection, or selective modification, must occur, and
does occur, in nature; and he has also proved to superfluity that such
selection is competent to produce forms as distinct, structurally, as
some genera even are. If the animated world presented us with none but
structural differences, I should have no hesitation in saying that Mr.
Darwin had demonstrated the existence of a true physical cause, amply
competent to account for the origin of living species, and of man among
the rest.
But, in addition to their structural distinctions, the species of
animals and plants, or at least a great number of them, exhibit
physiological characters--what are known as distinct species,
structurally, being for the most part either altogether incompetent to
breed one with another; or if they breed, the resulting mule, or hybrid,
is unable to perpetuate its race with another hybrid of the same kind.
A true physical cause is, however, admitted to be such only on one
condition--that it shall account for all the phenomena which come
within the range of its operation. If it is inconsistent with any
one phenomenon, it must be rejected; if it fails to explain any one
phenomenon, it is so far weak, so far to be suspected; though it may
have a perfect right to claim provisional acceptance.
Now, Mr. Darwin's hypothesis is not, so far as I am aware, inconsistent
with any known biological fact; on the contrary, if admitted, the facts
of Development, of Comparative Anatomy, of Geographical Distribution,
and of Palaeontology, become connected together, and exhibit a meaning
such as they never possessed before; and I, for one, am fully convinced,
that if not precisely true, that hypothesis is as near an approximation
to the truth as, for example, the Copernican hypothesis was to the true
theory of the planetary motions.
But, for all this, our acceptance of the Darwinian hypothesis must be
provisional so long as one link in the chain of evidence is wanting; and
so long as all the animals and plants certainly produced by selective
breeding from a common stock are fertile, and their progeny are fertile
with one another, that link will be wanting. For, so long, selective
breeding will not be proved to be competent to do all that is required
of it to produce natural species.
I have put this conclusion as strongly as possible before the reader,
because the last position in which I wish to find myself is that of
an advocate for Mr. Darwin's, or any other views--if by an advocate is
meant one whose business it is to smooth over real difficulties, and to
persuade where he cannot convince.
In justice to Mr. Darwin, however, it must be admitted that the
conditions of fertility and sterility are very ill understood, and that
every day's advance in knowledge leads us to regard the hiatus in his
evidence as of less and less importance, when set against the multitude
of facts which harmonize with, or receive an explanation from, his
doctrines.
I adopt Mr. Darwin's hypothesis, therefore, subject to the production of
proof that physiological species may be produced by selective breeding;
just as a physical philosopher may accept the undulatory theory of
light, subject to the proof of the existence of the hypothetical ether;
or as the chemist adopts the atomic theory, subject to the proof of the
existence of atoms; and for exactly the same reasons, namely, that it
has an immense amount of prima facie probability: that it is the only
means at present within reach of reducing the chaos of observed facts
to order; and lastly, that it is the most powerful instrument of
investigation which has been presented to naturalists since the
invention of the natural system of classification, and the commencement
of the systematic study of embryology.
But even leaving Mr. Darwin's views aside, the whole analogy of natural
operations furnishes so complete and crushing an argument against
the intervention of any but what are termed secondary causes, in the
production of all the phenomena of the universe; that, in view of the
intimate relations between Man and the rest of the living world, and
between the forces exerted by the latter and all other forces, I can see
no excuse for doubting that all are co-ordinated terms of Nature's great
progression, from the formless to the formed--from the inorganic to the
organic--from blind force to conscious intellect and will.
Science has fulfilled her function when she has ascertained and
enunciated truth; and were these pages addressed to men of science only,
I should now close this essay, knowing that my colleagues have learned
to respect nothing but evidence, and to believe that their highest duty
lies in submitting to it, however it may jar against their inclinations.
But desiring, as I do, to reach the wider circle of the intelligent
public, it would be unworthy cowardice were I to ignore the repugnance
with which the majority of my readers are likely to meet the conclusions
to which the most careful and conscientious study I have been able to
give to this matter, has led me.
On all sides I shall hear the cry--"We are men and women, not a mere
better sort of apes, a little longer in the leg, more compact in the
foot, and bigger in brain than your brutal Chimpanzees and Gorillas.
The power of knowledge--the conscience of good and evil--the pitiful
tenderness of human affections, raise us out of all real fellowship with
the brutes, however closely they may seem to approximate us."
To this I can only reply that the exclamation would be most just and
would have my own entire sympathy, if it were only relevant. But, it is
not I who seek to base Man's dignity upon his great toe, or insinuate
that we are lost if an Ape has a hippocampus minor. On the contrary, I
have done my best to sweep away this vanity. I have endeavoured to show
that no absolute structural line of demarcation, wider than that between
the animals which immediately succeed us in the scale, can be drawn
between the animal world and ourselves; and I may add the expression of
my belief that the attempt to draw a psychical distinction is equally
futile, and that even the highest faculties of feeling and of intellect
begin to germinate in lower forms of life.* At the same time, no one is
more strongly convinced than I am of the vastness of the gulf between
civilized man and the brutes; or is more certain that whether FROM them
or not, he is assuredly not OF them. No one is less disposed to think
lightly of the present dignity, or despairingly of the future hopes, of
the only consciously intelligent denizen of this world.
([Footnote] * 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,
etc., 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!)
We are indeed told by those who assume authority in these matters, that
the two sets of opinions are incompatible, and that the belief in
the unity of origin of man and brutes involves the brutalization and
degradation of the former. But is this really so? Could not a sensible
child confute by obvious arguments, the shallow rhetoricians who would
force this conclusion upon us? Is it, indeed, true, that the Poet, or
the Philosopher, or the Artist whose genius is the glory of his age, is
degraded from his high estate by the undoubted historical probability,
not to say certainty, that he is the direct descendant of some naked
and bestial savage, whose intelligence was just sufficient to make him a
little more cunning than the Fox, and by so much more dangerous than
the Tiger? Or is he bound to howl and grovel on all fours because of the
wholly unquestionable fact, that he was once an egg, which no ordinary
power of discrimination could distinguish from that of a Dog? Or is the
philanthropist or the saint to give up his endeavours to lead a noble
life, because the simplest study of man's nature reveals, at its
foundations, all the selfish passions and fierce appetites of the merest
quadruped? Is mother-love vile because a hen shows it, or fidelity base
because dogs possess it?
The common sense of the mass of mankind will answer these questions
without a moment's hesitation. Healthy humanity, finding itself hard
pressed to escape from real sin and degradation, will leave the brooding
over speculative pollution to the cynics and the 'righteous overmuch'
who, disagreeing in everything else, unite in blind insensibility to
the nobleness of the visible world, and in inability to appreciate the
grandeur of the place Man occupies therein.
Nay more, thoughtful men, once escaped from the blinding influences
of traditional prejudice, will find in the lowly stock whence Man has
sprung, the best evidence of the splendour of his capacities; and will
discern in his long progress through the Past, a reasonable ground of
faith in his attainment of a nobler Future.
They will remember that in comparing civilised man with the animal
world, one is as the Alpine traveller, who sees the mountains soaring
into the sky and can hardly discern where the deep shadowed crags and
roseate peaks end, and where the clouds of heaven begin. Surely the
awe-struck voyager may be excused if, at first, he refuses to believe
the geologist, who tells him that these glorious masses are, after all,
the hardened mud of primeval seas, or the cooled slag of subterranean
furnaces--of one substance with the dullest clay, but raised by inward
forces to that place of proud and seemingly inaccessible glory.
But the geologist is right; and due reflection on his teachings, instead
of diminishing our reverence and our wonder, adds all the force
of intellectual sublimity to the mere aesthetic intuition of the
uninstructed beholder.
And after passion and prejudice have died away, the same result will
attend the teachings of the naturalist respecting that great Alps
and Andes of the living world--Man. Our reverence for the nobility of
manhood will not be lessened by the knowledge that Man is, in substance
and in structure, one with the brutes; for, he alone possesses the
marvellous endowment of intelligible and rational speech, whereby,
in the secular period of his existence, he has slowly accumulated and
organized the experience which is almost wholly lost with the cessation
of every individual life in other animals; so that now he stands raised
upon it as on a mountain top, far above the level of his humble fellows,
and transfigured from his grosser nature by reflecting, here and there,
a ray from the infinite source of truth.
A SUCCINCT HISTORY OF THE CONTROVERSY RESPECTING THE CEREBRAL STRUCTURE OF MAN AND THE APES.
Up to the year 1857 all anatomists of authority, who had occupied
themselves with the cerebral structure of the Apes--Cuvier, Tiedemann,
Sandifort, Vrolik, Isidore G. St. Hilaire, Schroeder van der Kolk,
Gratiolet--were agreed that the brain of the Apes possesses a POSTERIOR
LOBE.
Tiedemann, in 1825, figured and acknowledged in the text of his 'Icones'
the existence of the POSTERIOR CORNU of the lateral ventricle in
the Apes, not only under the title of 'Scrobiculus parvus loco cornu
posterioris'--a fact which has been paraded--but as 'cornu posterius'
('Icones', p. 54), a circumstance which has been, as sedulously, kept in
the background.
Cuvier ('Lecons', T. iii. p. 103) says, "the anterior or lateral
ventricles possess a digital cavity (posterior cornu) only in Man and
the Apes...its presence depends on that of the posterior lobes."
Schroeder van der Kolk and Vrolik, and Gratiolet, had also figured and
described the posterior cornu in various Apes. As to the HIPPOCAMPUS
MINOR Tiedemann had erroneously asserted its absence in the Apes; but
Schroeder van der Kolk and Vrolik had pointed out the existence of what
they considered a rudimentary one in the Chimpanzee, and Gratiolet had
expressly affirmed its existence in these animals. Such was the state of
our information on these subjects in the year 1856.
In the year 1857, however, Professor Owen, either in ignorance of these
well-known facts or else unjustifiably suppressing them, submitted to
the Linnaean Society a paper "On the Characters, Principles of Division,
and Primary Groups of the Class Mammalia," which was printed in the
Society's Journal, and contains the following passage:--"In Man,
the brain presents an ascensive step in development, higher and
more strongly marked than that by which the preceding sub-class
was distinguished from the one below it. Not only do the cerebral
hemispheres overlap and the olfactory lobes and cerebellum, but they
extend in advance of the one and further back than the other. The
posterior development is so marked, that anatomists have assigned to
that part the character of a third lobe; 'it is peculiar to the
genus Homo, and equally peculiar is the posterior horn of the lateral
ventricle and the 'hippocampus minor,' which characterise the hind
lobe of each hemisphere'."--'Journal of the Proceedings of the Linnaean
Society, Vol. ii. p. 19.
As the essay in which this passage stands had no less ambitious an aim
than the remodelling of the classification of the Mammalia, its
author might be supposed to have written under a sense of peculiar
responsibility, and to have tested, with especial care, the statements
he ventured to promulgate. And even if this be expecting too much,
hastiness, or want of opportunity for due deliberation, cannot now be
pleaded in extenuation of any shortcomings; for the propositions cited
were repeated two years afterwards in the Reade Lecture, delivered
before so grave a body as the University of Cambridge, in 1859.
When the assertions, which I have italicised in the above extract,
first came under my notice, I was not a little astonished at so flat a
contradiction of the doctrines current among well-indormed anatomists;
but, not unnaturally imagining that the deliberate statements of a
responsible person must have some foundation in fact, I deemed it my
duty to investigate the subject anew before the time at which it
would be my business to lecture thereupon came round. The result of my
inquiries was to prove that Mr. Owen's three assertions, that "the third
lobe, the posterior horn of the lateral ventricle, and the hippocampus
minor," are "peculiar to the genus 'Homo'," are contrary to the plainest
facts. I communicated this conclusion to the students of my class;
and then, having no desire to embark in a controversy which could not
redound to the honour of British science, whatever its issue, I turned
to more congenial occupations.
The time speedily arrived, however, when a persistence in this reticence
would have involved me in an unworthy paltering with truth.
At the meeting of the British Association at Oxford, in 1860, Professor
Owen repeated these assertions in my presence, and, of course, I
immediately gave them a direct and unqualified contradiction, pledging
myself to justify that unusual procedure elsewhere. I redeemed that
pledge by publishing, in the January number of the 'Natural History
Review' for 1861, an article wherein the truth of the three following
propositions was fully demonstrated (l. c. p. 71):--
"1. That the third lobe is neither peculiar to, nor characteristic of,
man, seeing that it exists in all the higher quadrumana."
"2. That the posterior cornu of the lateral ventricle is neither
peculiar to, nor characteristic of, man, inasmuch as it also exists in
the higher quadrumana."
"3. That the 'hippocampus minor' is neither peculiar to, nor
characteristic of, man, as it is found in certain of the higher
quadrumana."
Furthermore, this paper contains the following paragraph (p. 76):
"And lastly, Schroeder van der Kolk and Vrolik (op. cit. p. 271), though
they particularly note that 'the lateral ventricle is distinguished from
that of Man by the very defective proportions of the posterior cornu,
wherein only a stripe is visible as an indication of the hippocampus
minor;' yet the Figure 4, in their second Plate, shows that this
posterior cornu is a perfectly distinct and unmistakeable structure,
quite as large as it often is in Man. It is the more remarkable that
Professor Owen should have overlooked the explicit statement and figure
of these authors, as it is quite obvious, on comparison of the figures,
that his woodcut of the brain of a Chimpanzee (l. c. p. 19) is a reduced
copy of the second figure of Messrs. Schroeder van der Kolk and Vrolik's
first Plate.
"As M. Gratiolet (l. c. p. 18), however is careful to remark,
'unfortunately the brain which they have taken as a model was greatly
altered (profondement affaisse), whence the general form of the brain
is given in these plates in a manner which is altogether incorrect.'
Indeed, it is perfectly obvious, from a comparison of a section of the
skull of the Chimpanzee with these figures, that such is the case; and
it is greatly to be regretted that so inadequate a figure should have
been taken as a typical representation of the Chimpanzee's brain."
From this time forth, the untenability of his position might have been
as apparent to Professor Owen as it was to every one else; but, so far
from retracting the grave errors into which he had fallen, Professor
Owen has persisted in and reiterated them; first, in a lecture delivered
before the Royal Institution on the 19th of March, 1861, which is
admitted to have been accurately reproduced in the 'Athenaeum' for the
23rd of the same month, in a letter addressed by Professor Owen to that
journal on the 30th of March. The 'Athenaeum report was accompanied by
a diagram purporting to represent a Gorilla's brain, but in reality so
extraordinary a misrepresentation, that Professor Owen substantially,
though not explicitly, withdraws it in the letter in question. In
amending this error, however, Professor Owen fell into another of
much graver import, as his communication concludes with the following
paragraph: "For the true proportion in which the cerebrum covers the
cerebellum in the highest Apes, reference should be made to the figure
of the undissected brain of the Chimpanzee in my 'Reade's Lecture on the
Classification, etc., of the Mammalia', p. 25, Figure 7, 8 vo. 1859."
It would not be credible, if it were not unfortunately true, that this
figure, to which the trusting public is referred, without a word of
qualification, "for the true proportion in which the cerebrum covers the
cerebellum in the highest Apes," is exactly that unacknowledged copy of
Schroeder van der Kolk and Vrolik's figure whose utter inaccuracy had
been pointed out years before by Gratiolet, and had been brought to
Professor Owen's knowledge by myself in the passage of my article in the
'Natural History Review' above quoted.
I drew public attention to this circumstance again in my reply to
Professor Owen, published in the 'Athenaeum' for April 13th, 1861; but
the exploded figure was reproduced once more by Professor Owen, without
the slightest allusion to its inaccuracy, in the 'Annals of Natural
History' for June 1861!
This proved too much for the patience of the original authors of the
figure, Messrs. Schroeder van der Kolk and Vrolik, who, in a note
addressed to the Academy of Amsterdam, of which they were members,
declared themselves to be, though decided opponents of all forms of the
doctrine of progressive development, above all things, lovers of truth:
and that, therefore, at whatever risk of seeming to lend support to
views which they disliked, they felt it their duty to take the first
opportunity of publicly repudiating Professor Owen's misuse of their
authority.
In this note they frankly admitted the justice of the criticisms of
M. Gratiolet, quoted above, and they illustrated, by new and careful
figures, the posterior lobe, the posterior cornu, and the hippocampus
minor of the Orang. Furthermore, having demonstrated the parts, at
one of the sittings of the Academy, they add, "la presence des parties
contestees y a ete universellement reconnue par les anatomistes presents
a la seance. Le seul doute qui soit reste se rapporte au pes Hippocampi
minor...A l'etat frais l'indice du petit pied d'Hippocampe etait plus
prononce que maintenant."
Professor Owen repeated his erroneous assertions at the meeting of the
British Association in 1861, and again, without any obvious necessity,
and without adducing a single new fact or new argument, or being able
in any way to meet the crushing evidence from original dissections of
numerous Apes' brains, which had in the meanwhile been brought forward
by Prof. Rolleston,* ([Footnote] *On the Affinities of the Brain of
the Orang. 'Nat. Hist. Review', April, 1861.) F.R.S., Mr. Marshall,*
([Footnote] *On the Brain of a young Chimpanzee. 'Ibid.', July, 1861.)
F.R.S., Mr. Flower,* ([Footnote] *On the Posterior lobes of the Cerebrum
of the Quadrumana. 'Philosophical Transactions', 1862.) Mr. Turner,*
([Footnote] *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.) and
myself,* ([Footnote] *On the Brain of Ateles. 'Proceedings of Zoological
Society', 1861.) revived the subject at the Cambridge meeting of the
same body in 1862. Not content with the tolerably vigorous repudiation
which these unprecedented proceedings met with in Section D, Professor
Owen sanctioned the publication of a version of his own statements,
accompanied by a strange misrepresentation of mine (as may be seen by
comparison of the 'Times' report of the discussion), in the 'Medical
Times' for October 11th, 1862. I subjoin the conclusion of my reply in
the same journal for October 25th.
"If this were a question of opinion, or a question of interpretation of
parts or of terms,--were it even a question of observation in which
the testimony of my own senses alone was pitted against that of another
person, I should adopt a very different tone in discussing this matter.
I should, in all humility, admit the likelihood of having myself erred
in judgment, failed in knowledge, or been blinded by prejudice.
"But no one pretends now, that the controversy is one of the terms or
of opinions. Novel and devoid of authority as some of Professor Owen's
proposed definitions may have been, they might be accepted without
changing the great features of the case. Hence though special
investigations into these matters have been undertaken during the last
two years by Dr. Allen Thomson, by Dr. Rolleston, by Mr. Marshall,
and by Mr. Flower, all, as you are aware, anatomists of repute in this
country, and by Professors Schroeder Van der Kolk, and Vrolik (whom
Professor Owen incautiously tried to press into his own service) on
the Continent, all these able and conscientious observers have with
one accord testified to the accuracy of my statements, and to the utter
baselessness of the assertions of Professor Owen. Even the venerable
Rudolph Wagner, whom no man will accuse of progressionist proclivities,
has raised his voice on the same side; while not a single anatomist,
great or small, has supported Professor Owen.
"Now, I do not mean to suggest that scientific differences should be
settled by universal suffrage, but I do conceive that solid proofs must
be met by something more than empty and unsupported assertions. Yet
during the two years through which this preposterous controversy has
dragged its weary length, Professor Owen has not ventured to bring
forward a single preparation in support of his often-repeated
assertions.
"The case stands thus, therefore:--Not only are the statements made by
me in consonance with the doctrines of the best older authorities,
and with those of all recent investigators, but I am quite ready to
demonstrate them on the first monkey that comes to hand; while Professor
Owen's assertions are not only in diametrical opposition to both old
and new authorities, but he has not produced, and, I will add, cannot
produce, a single preparation which justifies them."
I now leave this subject, for the present.--For the credit of my
calling I should be glad to be, hereafter, for ever silent upon it. But,
unfortunately, this is a matter upon which, after all that has occurred,
no mistake or confusion of terms is possible--and in affirming that the
posterior lobe, the posterior cornu, and the hippocampus minor exist in
certain Apes, I am stating either that which is true, or that which
I must know to be false. The question has thus become one of personal
veracity. For myself, I will accept no other issue than this, grave as
it is, to the present controversy.
End of On the Relations of Man to the Lower Animals.