Produced by Amy E. Zelmer





ON THE RELATIONS OF MAN TO THE LOWER ANIMALS

By Thomas H. Huxley




     Multis videri poterit, majorem esso differentiam Simiae et
     Hominis, quam diei et noctis; verum tamen hi, comparatione
     instituta inter summos Europae Heroes et Hottentottos ad
     Caput bonae spei degentes, difficillime sibi persuadebunt,
     has eosdem habere natales; vel si virginem nobilem aulicam,
     maxime comtam et humanissimam, conferre vellent cum homine
     sylvestri et sibi relicto, vix augurari possent, hunc et
     illam ejusdem esse speciei.--'Linnaei Amoenitates Acad.
     "Anthropomorpha."'


THE question of questions for mankind--the problem which underlies
all others, and is more deeply interesting than any other--is the
ascertainment of the place which Man occupies in nature and of his
relations to the universe of things. Whence our race has come; what are
the limits of our power over nature, and of nature's power over us; to
what goal we are tending; are the problems which present themselves anew
and with undiminished interest to every man born into the world. Most of
us, shrinking from the difficulties and dangers which beset the seeker
after original answers to these riddles, are contented to ignore them
altogether, or to smother the investigating spirit under the featherbed
of respected and respectable tradition. But, in every age, one or two
restless spirits, blessed with that constructive genius, which can
only build on a secure foundation, or cursed with the spirit of mere
scepticism, are unable to follow in the well-worn and comfortable track
of their forefathers and contemporaries, and unmindful of thorns and
stumbling-blocks, strike out into paths of their own. The sceptics end
in the infidelity which asserts the problem to be insoluble, or in
the atheism which denies the existence of any orderly progress and
governance of things: the men of genius propound solutions which grow
into systems of Theology or of Philosophy, or veiled in musical language
which suggests more than it asserts, take the shape of the Poetry of an
epoch.

Each such answer to the great question, invariably asserted by the
followers of its propounder, if not by himself, to be complete and
final, remains in high authority and esteem, it may be for one century,
or it may be for twenty: but, as invariably, Time proves each reply
to have been a mere approximation to the truth--tolerable chiefly on
account of the ignorance of those by whom it was accepted, and wholly
intolerable when tested by the larger knowledge of their successors.

In a well-worn metaphor, a parallel is drawn between the life of man
and the metamorphosis of the caterpillar into the butterfly; but the
comparison may be more just as well as more novel, if for its former
term we take the mental progress of the race. History shows that the
human mind, fed by constant accessions of knowledge, periodically grows
too large for its theoretical coverings, and bursts them asunder
to appear in new habiliments, as the feeding and growing grub, at
intervals, casts its too narrow skin and assumes another, itself but
temporary. Truly the imago state of Man seems to be terribly distant,
but every moult is a step gained, and of such there have been many.

Since the revival of learning, whereby the Western races of Europe were
enabled to enter upon that progress towards true knowledge, which was
commenced by the philosophers of Greece, but was almost arrested in
subsequent long ages of intellectual stagnation, or, at most, gyration,
the human larva has been feeding vigorously, and moulting in proportion.
A skin of some dimension was cast in the 16th century, and another
towards the end of the 18th, while, within the last fifty years, the
extraordinary growth of every department of physical science has spread
among us mental food of so nutritious and stimulating a character that
a new ecdysis seems imminent. But this is a process not unusually
accompanied by many throes and some sickness and debility, or, it may
be, by graver disturbances; so that every good citizen must feel bound
to facilitate the process, and even if he have nothing but a scalpel to
work withal, to ease the cracking integument to the best of his ability.

In this duty lies my excuse for the publication of these essays. For it
will be admitted that some knowledge of man's position in the animate
world is an indispensable preliminary to the proper understanding of his
relations to the universe--and this again resolves itself, in the long
run, into an inquiry into the nature and the closeness of the ties which
connect him with those singular creatures whose history [1] has been
sketched in the preceding pages.

The importance of such an inquiry is indeed intuitively manifest Brought
face to face with these blurred copies of himself, the least thoughtful
of men is conscious of a certain shock, due perhaps, not so much to
disgust at the aspect of what looks like an insulting caricature, as
to the awakening of a sudden and profound mistrust of time-honoured
theories and strongly-rooted prejudices regarding his own position in
nature, and his relations to the under-world of life; while that which
remains a dim suspicion for the unthinking, becomes a vast argument,
fraught with the deepest consequences, for all who are acquainted with
the recent progress of the anatomical and physiological sciences.

I now propose briefly to unfold that argument, and to set forth, in
a form intelligible to those who possess no special acquaintance
with anatomical science, the chief facts upon which all conclusions
respecting the nature and the extent of the bonds which connect man with
the brute world must be based: I shall then indicate the one immediate
conclusion which, in my judgment, is justified by those facts, and I
shall finally discuss the bearing of that conclusion upon the hypotheses
which have been entertained respecting the Origin of Man.

The facts to which I would first direct the reader's attention, though
ignored by many of the professed instructors of the public mind, are
easy of demonstration and are universally agreed to by men of science;
while their significance is so great, that whoso has duly pondered over
them will, I think, find little to startle him in the other revelations
of Biology. I refer to those facts which have been made known by the
study of Development.

It is a truth of very wide, if not of universal, application, that every
living creature commences its existence under a form different from, and
simpler than, that which it eventually attains.

[Illustration: FIG. 12.--A. Egg of the Dog, with the vitelline membrane
burst, so as to give exit to the yelk, the germinal vesicle (a), and
its included spot (b). B. C. D. E F. Successive changes of the yelk
indicated in the text. After Bischoff.]

The oak is a more complex thing than the little rudimentary plant
contained in the acorn; the caterpillar is more complex than the egg;
the butterfly than the caterpillar; and each of these beings, in passing
from its rudimentary to its perfect condition, runs through a series
of changes, the sum of which is called its Development. In the higher
animals these changes are extremely complicated; but, within the last
half century, the labours of such men as Von Baer, Rathke, Reichert,
Bischof, and Remak, have almost completely unravelled them, so that
the successive stages of development which are exhibited by a Dog, for
example, are now as well known to the embryologist as are the steps of
the metamorphosis of the silkworm moth to the school-boy. It will be
useful to consider with attention the nature and the order of the
stages of canine development, as an example of the process in the higher
animals generally.

The Dog, like all animals, save the very lowest (and further inquiries
may not improbably remove the apparent exception), commences its
existence as an egg: as a body which is, in every sense, as much an egg
as that of a hen, but is devoid of that accumulation of nutritive matter
which confers upon the bird's egg its exceptional size and domestic
utility; and wants the shell, which would not only be useless to an
animal incubated within the body of its parent, but would cut it off
from access to the source of that nutriment which the young creature
requires, but which the minute egg of the mammal does not contain within
itself.

The Dog's egg is, in fact, a little spheroidal bag (Fig. 12), formed
of a delicate transparent membrane called the 'vitelline membrane', and
about 1/130 to 1/120th of an inch in diameter. It contains a mass of
viscid nutritive matter--the 'yelk'--within which is inclosed a second
much more delicate spheroidal bag, called the 'germinal vesicle' (a). In
this, lastly, lies a more solid rounded body, termed the 'germinal spot'
(b).

The egg, or 'Ovum,' is originally formed within a gland, from which,
in due season, it becomes detached, and passes into the living chamber
fitted for its protection and maintenance during the protracted process
of gestation. Here, when subjected to the required conditions, this
minute and apparently insignificant particle of living matter becomes
animated by a new and mysterious activity. The germinal vesicle and
spot cease to be discernible (their precise fate being one of the yet
unsolved problems of embryology), but the yelk becomes circumferentially
indented, as if an invisible knife had been drawn round it, and thus
appears divided into two hemispheres (Fig. 12, C).

By the repetition of this process in various planes, these hemispheres
become subdivided, so that four segments are produced (D); and these,
in like manner, divide and subdivide again, until the whole yelk is
converted into a mass of granules, each of which consists of a minute
spheroid of yelk-substance, inclosing a central particle, the so-called
'nucleus' (F). Nature, by this process, has attained much the same
result as that at which a human artificer arrives by his operations in a
brickfield. She takes the rough plastic material of the yelk and breaks
it up into well-shaped tolerably even-sized masses, handy for building
up into any part of the living edifice.

[Illustration: FIG. 13.--Earliest rudiment of the Dog. B. Rudiment
further advanced, showing the foundations of the head, tail, and
vertebral column. C. The very young puppy, with attached ends of the
yelk-sac and allantois, and invested in the amnion.]

Next, the mass of organic bricks, or 'cells' as they are technically
called, thus formed, acquires an orderly arrangement, becoming converted
into a hollow spheroid with double walls. Then, upon one side of this
spheroid, appears a thickening, and, by and bye, in the centre of the
area of thickening, a straight shallow groove (Fig. 13, A) marks the
central line of the edifice which is to be raised, or, in other words,
indicates the position of the middle line of the body of the future
dog. The substance bounding the groove on each side next rises up into
a fold, the rudiment of the side wall of that long cavity, which will
eventually lodge the spinal marrow and the brain; and in the floor of
this chamber appears a solid cellular cord, the so-called 'notochord.'
One end of the inclosed cavity dilates to form the head (Fig. 13, B),
the other remains narrow, and eventually becomes the tail; the side
walls of the body are fashioned out of the downward continuation of the
walls of the groove; and from them, by and bye, grow out little buds
which, by degrees, assume the shape of limbs. Watching the fashioning
process stage by stage, one is forcibly reminded of the modeller in
clay. Every part, every organ, is at first, as it were, pinched up
rudely, and sketched out in the rough; then shaped more accurately; and
only, at last, receives the touches which stamp its final character.

Thus, at length, the young puppy assumes such a form as is shown in
Fig. 13, C. In this condition it has a disproportionately large head, as
dissimilar to that of a dog as the bud-like limbs are unlike his legs.

The remains of the yelk, which have not yet been applied to the
nutrition and growth of the young animal, are contained in a sac
attached to the rudimentary intestine, and termed the yelk sac,
or 'umbilical vesicle.' Two membranous bags, intended to subserve
respectively the protection and nutrition of the young creature, have
been developed from the skin and from the under and hinder surface
of the body; the former, the so-called 'amnion,' is a sac filled with
fluid, which invests the whole body of the embryo, and plays the part
of a sort of water-bed for it; the other, termed the 'allantois,' grows
out, loaded with blood-vessels, from the ventral region, and eventually
applying itself to the walls of the cavity, in which the developing
organism is contained, enables these vessels to become the channel
by which the stream of nutriment, required to supply the wants of the
offspring, is furnished to it by the parent.

The structure which is developed by the interlacement of the vessels of
the offspring with those of the parent, and by means of which the former
is enabled to receive nourishment and to get rid of effete matters, is
termed the 'Placenta.'

It would be tedious, and it is unnecessary for my present purpose, to
trace the process of development further; suffice it to say, that, by
a long and gradual series of changes, the rudiment here depicted and
described becomes a puppy, is born, and then, by still slower and less
perceptible steps, passes into the adult Dog.

There is not much apparent resemblance between a barndoor Fowl and the
Dog who protects the farm-yard. Nevertheless the student of development
finds, not only that the chick commences its existence as an egg,
primarily identical, in all essential respects, with that of the Dog,
but that the yelk of this egg undergoes division--that the primitive
groove arises, and that the contiguous parts of the germ are fashioned,
by precisely similar methods, into a young chick, which, at one stage
of its existence, is so like the nascent Dog, that ordinary inspection
would hardly distinguish the two.

The history of the development of any other vertebrate animal, Lizard,
Snake, Frog, or Fish, tells the same story. There is always, to
begin with, an egg having the same essential structure as that of the
Dog:--the yelk of that egg always undergoes division, or 'segmentation'
as it is often called: the ultimate products of that segmentation
constitute the building materials for the body of the young animal;
and this is built up round a primitive groove, in the floor of which
a notochord is developed. Furthermore, there is a period in which the
young of all these animals resemble one another, not merely in
outward form, but in all essentials of structure, so closely, that the
differences between them are inconsiderable, while, in their subsequent
course, they diverge more and more widely from one another. And it is a
general law, that, the more closely any animals resemble one another
in adult structure, the longer and the more intimately do their embryos
resemble one another: so that, for example, the embryos of a Snake and
of a Lizard remain like one another longer than do those of a Snake and
of a Bird; and the embryo of a Dog and of a Cat remain like one another
for a far longer period than do those of a Dog and a Bird; or of a Dog
and an Opossum; or even than those of a Dog and a Monkey.

Thus the study of development affords a clear test of closeness of
structural affinity, and one turns with impatience to inquire what
results are yielded by the study of the development of Man. Is he
something apart? Does he originate in a totally different way from Dog,
Bird, Frog, and Fish, thus justifying those who assert him to have no
place in nature and no real affinity with the lower world of animal
life? Or does he originate in a similar germ, pass through the same
slow and gradually progressive modifications,--depend on the same
contrivances for protection and nutrition, and finally enter the world
by the help of the same mechanism? The reply is not doubtful for a
moment, and has not been doubtful any time these thirty years. Without
question, the mode of origin and the early stages of the development of
man are identical with those of the animals immediately below him in the
scale:--without a doubt, in these respects, he is far nearer the Apes,
than the Apes are to the Dog.

The Human ovum is about 1/125 of an inch in diameter, and might be
described in the same terms as that of the Dog, so that I need only
refer to the figure illustrative (14 A) of its structure. It leaves the
organ in which it is formed in a similar fashion and enters the organic
chamber prepared for its reception in the same way, the conditions of
its development being in all respects the same. It has not yet been
possible (and only by some rare chance can it ever be possible) to
study the human ovum in so early a developmental stage as that of yelk
division, but there is every reason to conclude that the changes
it undergoes are identical with those exhibited by the ova of
other vertebrated animals; for the formative materials of which the
rudimentary human body is composed, in the earliest conditions in which
it has been observed, are the same as those of other animals. Some of
these earliest stages are figured below, and, as will be seen, they are
strictly comparable to the very early states of the Dog; the marvellous
correspondence between the two which is kept up, even for some time, as
development advances, becoming apparent by the simple comparison of the
figures with those on page 249.

[Illustration: Fig. 14.--A. Human ovum (after Kolliker). a. germinal
vesicle. b. germinal spot. B. A very early condition of Man, with
yelk-sac, allantois, and amnion (original). C. A more advanced stage
(after Kolliker), compare Fig. 13, C.]

Indeed, it is very long before the body of the young human being can be
readily discriminated from that of the young puppy; but, at a tolerably
early period, the two become distinguishable by the different form of
their adjuncts, the yelk-sac and the allantois. The former, in the Dog,
becomes long and spindle-shaped, while in Man it remains spherical; the
latter, in the Dog, attains an extremely large size, and the vascular
processes which are developed from it and eventually give rise to the
formation of the placenta (taking root, as it were, in the parental
organism, so as to draw nourishment therefrom, as the root of a tree
extracts it from the soil) are arranged in an encircling zone, while
in Man, the allantois remains comparatively small, and its vascular
rootlets are eventually restricted to one disk-like spot. Hence, while
the placenta of the Dog is like a girdle, that of Man has the cake-like
form, indicated by the name of the organ.

But, exactly in those respects in which the developing Man differs
from the Dog, he resembles the ape, which, like man, has a spheroidal
yelk-sac and a discoidal--sometimes partially lobed--placenta. So that
it is only quite in the later stages of development that the young human
being presents marked differences from the young ape, while the latter
departs as much from the dog in its development, as the man does.

Startling as the last assertion may appear to be, it is demonstrably
true, and it alone appears to me sufficient to place beyond all doubt
the structural unity of man with the rest of the animal world, and more
particularly and closely with the apes.

Thus, identical in the physical processes by which he
originates--identical in the early stages of his formation--identical in
the mode of his nutrition before and after birth, with the animals which
lie immediately below him in the scale--Man, if his adult and perfect
structure be compared with theirs, exhibits, as might be expected, a
marvellous likeness of organization. He resembles them as they resemble
one another--he differs from them as they differ from one another.--And,
though these differences and resemblances cannot be weighed and
measured, their value may be readily estimated; the scale or standard
of judgment, touching that value, being afforded and expressed by the
system of classification of animals now current among zoologists.

A careful study of the resemblances and differences presented by
animals has, in fact, led naturalists to arrange them into groups, or
assemblages, all the members of each group presenting a certain amount
of definable resemblance, and the number of points of similarity being
smaller as the group is larger and 'vice versa'. Thus, all creatures
which agree only in presenting the few distinctive marks of animality
form the 'Kingdom' ANIMALIA. The numerous animals which agree only in
possessing the special characters of Vertebrates form one 'Sub-Kingdom'
of this Kingdom. Then the Sub-kingdom VERTEBRATA is subdivided into the
five 'Classes,' Fishes, Amphibians, Reptiles, Birds, and Mammals, and
these into smaller groups called 'Orders'; these into 'Families'
and 'Genera'; while the last are finally broken up into the smallest
assemblages, which are distinguished by the possession of constant,
not-sexual, characters. These ultimate groups are Species.

Every year tends to bring about a greater uniformity of opinion
throughout the zoological world as to the limits and characters of these
groups, great and small. At present, for example, no one has the
least doubt regarding the characters of the classes Mammalia, Aves, or
Reptilia; nor does the question arise whether any thoroughly well-known
animal should be placed in one class or the other. Again, there is
a very general agreement respecting the characters and limits of
the orders of Mammals, and as to the animals which are structurally
necessitated to take a place in one or another order.

No one doubts, for example, that the Sloth and the Ant-eater, the
Kangaroo and the Opossum, the Tiger and the Badger, the Tapir and
the Rhinoceros, are respectively members of the same orders. These
successive pairs of animals may, and some do, differ from one another
immensely, in such matters as the proportions and structure of their
limbs; the number of their dorsal and lumbar vertebrae; the adaptation
of their frames to climbing, leaping, or running; the number and form
of their teeth; and the characters of their skulls and of the contained
brain. But, with all these differences, they are so closely connected in
all the more important and fundamental characters of their organization,
and so distinctly separated by these same characters from other animals,
that zoologists find it necessary to group them together as members
of one order. And if any new animal were discovered, and were found to
present no greater difference from the Kangaroo and the Opossum, for
example, than these animals do from one another, the zoologist would not
only be logically compelled to rank it in the same order with these, but
he would not think of doing otherwise.

Bearing this obvious course of zoological reasoning in mind, let us
endeavour for a moment to disconnect our thinking selves from the mask
of humanity; let us imagine ourselves scientific Saturnians, if you
will, fairly acquainted with such animals as now inhabit the Earth, and
employed in discussing the relations they bear to a new and singular
'erect and featherless biped,' which some enterprising traveller,
overcoming the difficulties of space and gravitation, has brought from
that distant planet for our inspection, well preserved, may be, in a
cask of rum. We should all, at once, agree upon placing him among the
mammalian vertebrates; and his lower jaw, his molars, and his brain,
would leave no room for doubting the systematic position of the new
genus among those mammals, whose young are nourished during gestation by
means of a placenta, or what are called the 'placental mammals.'

Further, the most superficial study would at once convince us that,
among the orders of placental mammals, neither the Whales, nor the
hoofed creatures, nor the Sloths and Ant-eaters, nor the carnivorous
Cats, Dogs, and Bears, still less the Rodent Rats and Rabbits, or the
Insectivorous Moles and Hedgehogs, or the Bats, could claim our 'Homo',
as one of themselves.

There would remain then, but one order for comparison, that of the Apes
(using that word in its broadest sense), and the question for discussion
would narrow itself to this--is Man so different from any of these Apes
that he must form an order by himself? Or does he differ less from them
than they differ from one another, and hence must take his place in the
same order with them?

Being happily free from all real, or imaginary, personal interest in the
results of the inquiry thus set afoot, we should proceed to weigh the
arguments on one side and on the other, with as much judicial calmness
as if the question related to a new Opossum. We should endeavour to
ascertain, without seeking either to magnify or diminish them, all the
characters by which our new Mammal differed from the Apes; and if
we found that these were of less structural value, than those which
distinguish certain members of the Ape order from others universally
admitted to be of the same order, we should undoubtedly place the newly
discovered tellurian genus with them.

I now proceed to detail the facts which seem to me to leave us no choice
but to adopt the last mentioned course.

It is quite certain that the Ape which most nearly approaches man,
in the totality of its organization, is either the Chimpanzee or the
Gorilla; and as it makes no practical difference, for the purposes of
my present argument, which is selected for comparison, on the one hand,
with Man, and on the other hand, with the rest of the Primates, [2]
I shall select the latter (so far as its organization is known)--as a
brute now so celebrated in prose and verse, that all must have heard of
him, and have formed some conception of his appearance. I shall take up
as many of the most important points of difference between man and
this remarkable creature, as the space at my disposal will allow me to
discuss, and the necessities of the argument demand; and I shall inquire
into the value and magnitude of these differences, when placed side by
side with those which separate the Gorilla from other animals of the
same order.

In the general proportions of the body and limbs there is a remarkable
difference between the Gorilla and Man, which at once strikes the eye.
The Gorilla's brain-case is smaller, its trunk larger, its lower limbs
shorter, its upper limbs longer in proportion than those of Man.

I find that the vertebral column of a full-grown Gorilla, in the Museum
of the Royal College of Surgeons, measures 27 inches along its anterior
curvature, from the upper edge of the atlas, or first vertebra of the
neck, to the lower extremity of the sacrum; that the arm, without the
hand, is 31-1/2 inches long; that the leg, without the foot, is 26-1/2
inches long; that the hand is 9-3/4 inches long; the foot 11-1/4 inches
long.

In other words, taking the length of the spinal column as 100, the arm
equals 115, the leg 96, the hand 36, and the foot 41.

In the skeleton of a male Bosjesman, in the same collection, the
proportions, by the same measurement, to the spinal column, taken as
100, are--the arm 78, the leg 110, the hand 26, and the foot 32. In a
woman of the same race the arm is 83, and the leg 120, the hand and foot
remaining the same. In a European skeleton I find the arm to be 80, the
leg 117, the hand 26, the foot 35.

Thus the leg is not so different as it looks at first sight, in its
proportion to the spine in the Gorilla and in the Man--being very
slightly shorter than the spine in the former, and between 1/10 and 1/5
longer than the spine in the latter. The foot is longer and the hand
much longer in the Gorilla; but the great difference is caused by the
arms, which are very much longer than the spine in the Gorilla, very
much shorter than the spine in the Man.

The question now arises how are the other Apes related to the Gorilla
in these respects--taking the length of the spine, measured in the same
way, at 100. In an adult Chimpanzee, the arm is only 96, the leg 90, the
hand 43, the foot 39--so that the hand and the leg depart more from the
human proportion and the arm less, while the foot is about the same as
in the Gorilla.

In the Orang, the arms are very much longer than in the Gorilla (122),
while the legs are shorter (88); the foot is longer than the hand (52
and 48), and both are much longer in proportion to the spine.

In the other man-like Apes again, the Gibbons, these proportions are
still further altered; the length of the arms being to that of the
spinal column as 19 to 11; while the legs are also a third longer than
the spinal column, so as to be longer than in Man, instead of shorter.
The hand is half as long as the spinal column, and the foot, shorter
than the hand, is about 5/11ths of the length of the spinal column.

Thus 'Hylobates' is as much longer in the arms than the Gorilla, as the
Gorilla is longer in the arms than Man; while, on the other hand, it
is as much longer in the legs than the Man, as the Man is longer in the
legs than the Gorilla, so that it contains within itself the extremest
deviations from the average length of both pairs of limbs (See the
illustration on page 196).

The Mandrill presents a middle condition, the arms and legs being nearly
equal in length, and both being shorter than the spinal column; while
hand and foot have nearly the same proportions to one another and to the
spine, as in Man.

In the Spider monkey ('Ateles') the leg is longer than the spine, and
the arm than the leg; and, finally, in that remarkable Lemurine form,
the Indri ('Lichanotus'), the leg is about as long as the spinal column,
while the arm is not more than 11/18 of its length; the hand having
rather less and the foot rather more, than one-third the length of the
spinal column.

These examples might be greatly multiplied, but they suffice to show
that, in whatever proportion of its limbs the Gorilla differs from
Man, the other Apes depart still more widely from the Gorilla and that,
consequently, such differences of proportion can have no ordinal value.

We may next consider the differences presented by the trunk, consisting
of the vertebral column, or backbone, and the ribs and pelvis, or
bony hip-basin, which are connected with it, in Man and in the Gorilla
respectively.

In Man, in consequence partly of the disposition of the articular
surfaces of the vertebrae, and largely of the elastic tension of some of
the fibrous bands, or ligaments, which connect these vertebrae together,
the spinal column, as a whole, has an elegant S-like curvature, being
convex forwards in the neck, concave in the back, convex in the loins,
or lumbar region, and concave again in the sacral region; an arrangement
which gives much elasticity to the whole backbone, and diminishes the
jar communicated to the spine, and through it to the head, by locomotion
in the erect position.

Furthermore, under ordinary circumstances, Man has seven vertebrae in
his neck, which are called 'cervical'; twelve succeed these, bearing
ribs and forming the upper part of the back, whence they are termed
'dorsal'; five lie in the loins, bearing no distinct, or free, ribs, and
are called 'lumbar'; five, united together into a great bone, excavated
in front, solidly wedged in between the hip bones, to form the back of
the pelvis, and known by the name of the 'sacrum', succeed these; and
finally, three or four little more or less movable bones, so small as to
be insignificant, constitute the 'coccyx' or rudimentary tail.

In the Gorilla, the vertebral column is similarly divided into cervical,
dorsal, lumbar, sacral, and coccygeal vertebrae, and the total number
of cervical and dorsal vertebrae, taken together, is the same as in
Man; but the development of a pair of ribs to the first lumbar vertebra,
which is an exceptional occurrence in Man, is the rule in the Gorilla;
and hence, as lumbar are distinguished from dorsal vertebrae only by the
presence or absence of free ribs, the seventeen "dorso-lumbar" vertebrae
of the Gorilla are divided into thirteen dorsal and four lumbar, while
in Man they are twelve dorsal and five lumbar.

[Illustration: FIG. 15.--Front and side views of the bony pelvis of Man,
the Gorilla and Gibbon: reduced from drawings made from nature, of the
same absolute length, by Mr. Waterhouse Hawkins.]

Not only, however, does Man occasionally possess thirteen pair of
ribs, but the Gorilla sometimes has fourteen pairs, while an Orang-Utan
skeleton in the Museum of the Royal College of Surgeons has twelve
dorsal and five lumbar vertebrae, as in Man. Cuvier notes the same
number in a 'Hylobates'. On the other hand, among the lower Apes, many
possess twelve dorsal and six or seven lumbar vertebrae; the
Douroucouli has fourteen dorsal and eight lumbar, and a Lemur ('Stenops
tardigradus') has fifteen dorsal and nine lumbar vertebrae.

The vertebral column of the Gorilla, as a whole, differs from that
of Man in the less marked character of its curves, especially in the
slighter convexity of the lumbar region. Nevertheless, the curves are
present, and are quite obvious in young skeletons of the Gorilla and
Chimpanzee which have been prepared without removal of the ligaments. In
young Orangs similarly preserved, on the other hand, the spinal column
is either straight, or even concave forwards, throughout the lumbar
region.

Whether we take these characters then, or such minor ones as those which
are derivable from the proportional length of the spines of the cervical
vertebrae, and the like, there is no doubt whatsoever as to the marked
difference between Man and the Gorilla; but there is as little, that
equally marked differences, of the very same order, obtain between the
Gorilla and the lower Apes.

The Pelvis, or bony girdle of the hips, of Man is a strikingly human
part of his organization; the expanded haunch bones affording support
for his viscera during his habitually erect posture, and giving space
for the attachment of the great muscles which enable him to assume and
to preserve that attitude. In these respects the pelvis of the Gorilla
differs very considerably from his (Fig. 15). But go no lower than the
Gibbon, and see how vastly more he differs from the Gorilla than the
latter does from Man, even in this structure. Look at the flat, narrow
haunch bones--the long and narrow passage--the coarse, outwardly curved,
ischiatic prominences on which the Gibbon habitually rests, and which
are coated by the so-called "callosities," dense patches of skin, wholly
absent in the Gorilla, in the Chimpanzee, and in the Orang, as in Man!

In the lower Monkeys and in the Lemurs the difference becomes more
striking still, the pelvis acquiring an altogether quadrupedal
character.

But now let us turn to a nobler and more characteristic organ--that
by which the human frame seems to be, and indeed is, so strongly
distinguished from all others,--I mean the skull. The differences
between a Gorilla's skull and a Man's are truly immense (Fig. 16).
In the former, the face, formed largely by the massive jaw-bones,
predominates over the brain case, or cranium proper: in the latter, the
proportions of the two are reversed. In the Man, the occipital foramen,
through which passes the great nervous cord connecting the brain with
the nerves of the body, is placed just behind the centre of the base of
the skull, which thus becomes evenly balanced in the erect posture; in
the Gorilla, it lies in the posterior third of that base. In the Man,
the surface of the skull is comparatively smooth, and the supraciliary
ridges or brow prominences usually project but little--while, in the
Gorilla, vast crests are developed upon the skull, and the brow ridges
overhang, the cavernous orbits, like great penthouses.

Sections of the skulls, however, show that some of the apparent defects
of the Gorilla's cranium arise, in fact, not so much from deficiency of
brain case as from excessive development of the parts of the face.
The cranial cavity is not ill-shaped, and the forehead is not truly
flattened or very retreating, its really well-formed curve being simply
disguised by the mass of bone which is built up against it (Fig. 16).

But the roofs of the orbits rise more obliquely into the cranial cavity,
thus diminishing the space for the lower part of the anterior lobes of
the brain, and the absolute capacity of the cranium is far less than
that of Man. So far as I am aware, no human cranium belonging to an
adult man has yet been observed with a less cubical capacity than
62 cubic inches, the smallest cranium observed in any race of men by
Morton, measuring 63 cubic inches; while, on the other hand, the most
capacious Gorilla skull yet measured has a content of not more than
34-1/2 cubic inches. Let us assume, for simplicity's sake, that the
lowest Man's skull has twice the capacity of that of the highest
Gorilla. [4]

No doubt, this is a very striking difference, but it loses much of its
apparent systematic value, when viewed by the light of certain other
equally indubitable facts respecting cranial capacities.

The first of these is, that the difference in the volume of the cranial
cavity of different races of mankind is far greater, absolutely, than
that between the lowest Man and the highest Ape, while, relatively,
it is about the same. For the largest human skull measured by Morton
contained 114 cubic inches, that is to say, had very nearly double the
capacity of the smallest; while its absolute preponderance, of 52 cubic
inches--is far greater than that by which the lowest adult male human
cranium surpasses the largest of the Gorillas (62 - 34-1/2 = 27-1/2).
Secondly, the adult crania of Gorillas which have as yet been measured
differ among themselves by nearly one-third, the maximum capacity being
34.5 cubic inches, the minimum 24 cubic inches; and, thirdly, after
making all due allowance for difference of size, the cranial capacities
of some of the lower Apes fall nearly as much, relatively, below those
of the higher Apes as the latter fall below Man.

Thus, even in the important matter of cranial capacity, Men differ more
widely from one another than they do from the Apes; while the lowest
Apes differ as much, in proportion, from the highest, as the latter does
from Man. The last proposition is still better illustrated by the study
of the modifications which other parts of the cranium undergo in the
Simian series.

It is the large proportional size of the facial bones and the great
projection of the jaws which confers upon the Gorilla's skull its small
facial angle and brutal character.

[Illustration: FIG. 16.--Sections of the skulls of Man and various Apes,
drawn so as to give the cerebral cavity the same length in each case,
thereby displaying the varying proportions of the facial bones. The line
'b' indicates the plane of the tentorium, which separates the cerebrum
from the cerebellum; 'd', the axis of the occipital outlet of the skull.
The extent of cerebral cavity behind 'c', which is a perpendicular
erected on 'b' at the point where the tentorium is attached posteriorly,
indicates the degree to which the cerebrum overlaps the cerebellum--the
space occupied by which is roughly indicated by the dark shading. In
comparing these diagrams, it must be recollected, that figures on so
small a scale as these simply exemplify the statements in the text, the
proof of which is to be found in the objects themselves.]

But if we consider the proportional size of the facial bones to the
skull proper only, the little 'Chrysothrix' (Fig. 16) differs very
widely from the Gorilla, and, in the same way, as Man does; while the
Baboons ('Cynocephalus', Fig. 16) exaggerate the gross proportions of
the muzzle of the great Anthropoid, so that its visage looks mild and
human by comparison with theirs. The difference between the Gorilla and
the Baboon is even greater than it appears at first sight; for the great
facial mass of the former is largely due to a downward development of
the jaws; an essentially human character, superadded upon that almost
purely forward, essentially brutal, development of the same parts which
characterizes the Baboon, and yet more remarkably distinguishes the
Lemur.

Similarly, the occipital foramen of 'Mycetes' (Fig. 16), and still
more of the Lemurs, is situated completely in the posterior face of the
skull, or as much further back than that of the Gorilla, as that of the
Gorilla is further back than that of Man; while, as if to render patent
the futility of the attempt to base any broad classificatory distinction
on such a character, the same group of Platyrhine, or American monkeys,
to which the Mycetes belongs, contains the Chrysothrix, whose occipital
foramen is situated far more forward than in any other ape, and nearly
approaches the position it holds in Man.

Again, the Orang's skull is as devoid of excessively developed
supraciliary prominences as a Man's, though some varieties exhibit great
crests elsewhere (See pp. 231, 232); and in some of the Cebine apes and
in the 'Chrysothrix', the cranium is as smooth and rounded as that of
Man himself.

What is true of these leading characteristics of the skull, holds good,
as may be imagined, of all minor features; so that for every constant
difference between the Gorilla's skull and the Man's, a similar constant
difference of the same order (that is to say, consisting in excess or
defect of the same quality) may be found between the Gorilla's skull
and that of some other ape. So that, for the skull, no less than for the
skeleton in general, the proposition holds good, that the differences
between Man and the Gorilla are of smaller value than those between the
Gorilla and some other Apes.

In connection with the skull, I may speak of the teeth--organs which
have a peculiar classificatory value, and whose resemblances and
differences of number, form, and succession, taken as a whole, are
usually regarded as more trustworthy indicators of affinity than any
others.

[Illustration: FIG. 17.--Lateral views, of the same length, of the upper
jaws of various Primates. 'i', incisors; 'c', canines' 'pm', premolars;
'm', molars. A line is drawn through the first molar of Man, 'Gorilla',
'Cynocephalus', and 'Cebus', and the grinding surface of the second
molar is shown in each, its anterior and internal angle being just above
the 'm' of 'm2'.]

Man is provided with two sets of teeth--milk teeth and permanent teeth.
The former consist of four incisors, or cutting teeth; two canines, or
eyeteeth; and four molars, or grinders, in each jaw--making twenty in
all. The latter (Fig. 17) comprise four incisors, two canines, four
small grinders, called premolars or false molars, and six large
grinders, or true molars, in each jaw--making thirty-two in all. The
internal incisors are larger than the external pair, in the upper jaw,
smaller than the external pair, in the lower jaw. The crowns of the
upper molars exhibit four cusps, or blunt-pointed elevations, and a
ridge crosses the crown obliquely, from the inner, anterior cusp to the
outer, posterior cusp (Fig. 17 m2). The anterior lower molars have five
cusps, three external and two internal. The premolars have two cusps,
one internal and one external, of which the outer is the higher.

In all these respects the dentition of the Gorilla may be described in
the same terms as that of Man; but in other matters it exhibits many and
important differences (Fig. 17).

Thus the teeth of man constitute a regular and even series--without any
break and without any marked projection of one tooth above the level of
the rest; a peculiarity which, as Cuvier long ago showed, is shared by
no other mammal save one--as different a creature from man as can well
be imagined--namely, the long extinct 'Anoplotherium'. The teeth of
the Gorilla, on the contrary, exhibit a break, or interval, termed the
'diastema', in both jaws: in front of the eye-tooth, or between it and
the outer incisor, in the upper jaw; behind the eyetooth, or between
it and the front false molar, in the lower jaw. Into this break in the
series, in each jaw, fits the canine of the opposite jaw; the size of
the eye-tooth in the Gorilla being so great that it projects, like a
tusk, far beyond the general level of the other teeth. The roots of the
false molar teeth of the Gorilla, again, are more complex than in Man,
and the proportional size of the molars is different. The Gorilla has
the crown of the hindmost grinder of the lower jaw more complex, and
the order of eruption of the permanent teeth is different; the permanent
canines making their appearance before the second and third molars in
Man, and after them in the Gorilla.

Thus, while the teeth of the Gorilla closely resemble those of Man in
number, kind, and in the general pattern of their crowns, they exhibit
marked differences from those of Man in secondary respects, such as
relative size, number of fangs, and order of appearance.

But, if the teeth of the Gorilla be compared with those of an Ape, no
further removed from it than a 'Cynocephalus', or Baboon, it will be
found that differences and resemblances of the same order are easily
observable; but that many of the points in which the Gorilla resembles
Man are those in which it differs from the Baboon; while various
respects in which it differs from Man are exaggerated in the
'Cynocephalus'. The number and the nature of the teeth remain the same
in the Baboon as in the Gorilla and in Man. But the pattern of the
Baboon's upper molars is quite different from that described above (Fig.
17), the canines are proportionally longer and more knife-like; the
anterior premolar in the lower jaw is specially modified; the posterior
molar of the lower jaw is still larger and more complex than in the
Gorilla.

Passing from the old-world Apes to those of the new world, we meet with
a change of much greater importance than any of these. In such a genus
as 'Cebus', for example (Fig. 17), it will be found that while in
some secondary points, such as the projection of the canines and the
diastema, the resemblance to the great ape is preserved; in other and
most important respects, the dentition is extremely different. Instead
of 20 teeth in the milk set, there are 24: instead of 32 teeth in the
permanent set, there are 36, the false molars being increased from eight
to twelve. And in form, the crowns of the molars are very unlike those
of the Gorilla, and differ far more widely from the human pattern.

The Marmosets, on the other hand, exhibit the same number of teeth as
Man and the Gorilla; but, notwithstanding this, their dentition is very
different, for they have four more false molars, like the other American
monkeys--but as they have four fewer true molars, the total remains the
same. And passing from the American apes to the Lemurs, the dentition
becomes still more completely and essentially different from that of
the Gorilla. The incisors begin to vary both in number and in form. The
molars acquire, more and more, a many-pointed, insectivorous character,
and in one Genus, the Aye-Aye ('Cheiromys'), the canines disappear, and
the teeth completely simulate those of a Rodent (Fig. 17).

Hence it is obvious that, greatly as the dentition of the highest Ape
differs from that of Man, it differs far more widely from that of the
lower and lowest Apes.

Whatever part of the animal fabric--whatever series of muscles, whatever
viscera might be selected for comparison--the result would be the
same--the lower Apes and the Gorilla would differ more than the Gorilla
and the Man. I cannot attempt in this place to follow out all these
comparisons in detail, and indeed it is unnecessary I should do so. But
certain real, or supposed, structural distinctions between man and the
apes remain, upon which so much stress has been laid, that they require
careful consideration, in order that the true value may be assigned to
those which are real, and the emptiness of those which are fictitious
may be exposed. I refer to the characters of the hand, the foot, and the
brain.

Man has been defined as the only animal possessed of two hands
terminating his fore limbs, and of two feet ending his hind limbs, while
it has been said that all the apes possess four hands; and he has been
affirmed to differ fundamentally from all the apes in the characters of
his brain, which alone, it has been strangely asserted and re-asserted,
exhibits the structures known to anatomists as the posterior lobe, the
posterior cornu of the lateral ventricle, and the hippocampus minor.

That the former proposition should have gained general acceptance is not
surprising--indeed, at first sight, appearances are much in its favour:
but, as for the second, one can only admire the surpassing courage
of its enunciator, seeing that it is an innovation which is not only
opposed to generally and justly accepted doctrines, but which is
directly negatived by the testimony of all original inquirers, who have
specially investigated the matter: and that it neither has been, nor can
be, supported by a single anatomical preparation. It would, in fact,
be unworthy of serious refutation, except for the general and natural
belief that deliberate and reiterated assertions must have some
foundation.

Before we can discuss the first point with advantage we must consider
with some attention, and compare together, the structure of the human
hand and that of the human foot, so that we may have distinct and clear
ideas of what constitutes a hand and what a foot.

The external form of the human hand is familiar enough to every one. It
consists of a stout wrist followed by a broad palm, formed of flesh, and
tendons, and skin, binding together four bones, and dividing into four
long and flexible digits, or fingers, each of which bears on the back of
its last joint a broad and flattened nail. The longest cleft between any
two digits is rather less than half as long as the hand. From the outer
side of the base of the palm a stout digit goes off, having only two
joints instead of three; so short, that it only reaches to a little
beyond the middle of the first joint of the finger next it; and further
remarkable by its great mobility, in consequence of which it can be
directed outwards, almost at a right angle to the rest. This digit is
called the 'pollex,' or thumb; and, like the others, it bears a
flat nail upon the back of its terminal joint. In consequence of the
proportions and mobility of the thumb, it is what is termed "opposable";
in other words, its extremity can, with the greatest ease, be brought
into contact with the extremities of any of the fingers; a property upon
which the possibility of our carrying into effect the conceptions of the
mind so largely depends.

The external form of the foot differs widely from that of the hand; and
yet, when closely compared, the two present some singular resemblances.
Thus the ankle corresponds in a manner with the wrist; the sole with the
palm; the toes with the fingers; the great toe with the thumb. But the
toes, or digits of the foot, are far shorter in proportion than the
digits of the hand, and are less moveable, the want of mobility being
most striking in the great toe--which, again, is very much larger
in proportion to the other toes than the thumb to the fingers. In
considering this point, however, it must not be forgotten that the
civilized great toe, confined and cramped from childhood upwards, is
seen to a great disadvantage, and that in uncivilized and barefooted
people it retains a great amount of mobility, and even some sort of
opposability. The Chinese boatmen are said to be able to pull an oar;
the artisans of Bengal to weave, and the Carajas to steal fishhooks, by
its help; though, after all, it must be recollected that the structure
of its joints and the arrangement of its bones, necessarily render its
prehensile action far less perfect than that of the thumb.

But to gain a precise conception of the resemblances and differences of
the hand and foot, and of the distinctive characters of each, we must
look below the skin, and compare the bony framework and its motor
apparatus in each (Fig. 18).

[Illustration: FIG. 18--The skeleton of the Hand and Foot of Man reduced
from Dr. Carter's drawings in Gray's 'Anatomy.' The hand is drawn to
a larger scale than the foot. The line 'a a' in the hand indicates the
boundary between the carpus and the metacarpus; 'b b' that between the
latter and the proximal phalanges; 'c c' marks the ends of the distal
phalanges. The line "a' a'" in the foot indicates the boundary between
the tarsus and metatarsus; "b' b'" marks that between the metatarsus
and the proximal phalanges; and "c' c'" bounds the ends of the distal
phalanges; 'ca', the calcaneum; 'as', the astragalus; 'sc', the scaphoid
bone in the tarsus.]

The skeleton of the hand exhibits, in the region which we term the
wrist, and which is technically called the 'carpus'--two rows of closely
fitted polygonal bones, four in each row, which are tolerably equal in
size. The bones of the first row with the bones of the forearm, form the
wrist joint, and are arranged side by side, no one greatly exceeding or
overlapping the rest.

The four bones of the second row of the carpus bear the four long bones
which support the palm of the hand. The fifth bone of the same character
is articulated in a much more free and moveable manner than the others,
with its carpal bone, and forms the base of the thumb. These are called
'metacarpal' bones, and they carry the 'phalanges', or bones of the
digits, of which there are two in the thumb, and three in each of the
fingers.

The skeleton of the foot is very like that of the hand in some respects.
Thus there are three phalanges in each of the lesser toes, and only
two in the great toe, which answers to the thumb. There is a long bone,
termed 'metatarsal', answering to the metacarpal, for each digit; and
the 'tarsus', which corresponds with the carpus, presents four short
polygonal bones in a row, which correspond very closely with the four
carpal bones of the second row of the hand. In other respects the foot
differs very widely from the hand. Thus the great toe is the longest
digit but one; and its metatarsal is far less moveably articulated with
the tarsus, than the metacarpal of the thumb with the carpus. But a far
more important distinction lies in the fact that, instead of four
more tarsal bones there are only three; and, that these three are not
arranged side by side, or in one row. One of them, the 'os calcis' or
heel bone ('ca'), lies externally, and sends back the large projecting
heel; another, the 'astragalus' ('as'), rests on this by one face, and
by another, forms, with the bones of the leg, the ankle joint; while a
third face, directed forwards, is separated from the three inner tarsal
bones of the row next the metatarsus by a bone called the 'scaphoid'
('sc').

Thus there is a fundamental difference in the structure of the foot and
the hand, observable when the carpus and the tarsus are contrasted; and
there are differences of degree noticeable when the proportions and
the mobility of the metacarpals and metatarsals, with their respective
digits, are compared together.

The same two classes of differences become obvious when the muscles of
the hand are compared with those of the foot.

Three principal sets of muscles, called "flexors," bend the fingers and
thumb, as in clenching the fist, and three sets--the extensors--extend
them, as in straightening the fingers. These muscles are all "long
muscles"; that is to say, the fleshy part of each, lying in and being
fixed to the bones of the arm, is, at the other end, continued into
tendons, or rounded cords, which pass into the hand, and are ultimately
fixed to the bones which are to be moved. Thus, when the fingers are
bent, the fleshy parts of the flexors of the fingers, placed in the arm,
contract, in virtue of their peculiar endowment as muscles; and pulling
the tendinous cords, connected with their ends, cause them to pull down
the bones of the fingers towards the palm.

Not only are the principal flexors of the fingers and of the thumb long
muscles, but they remain quite distinct from one another through their
whole length.

In the foot, there are also three principal flexor muscles of the digits
or toes, and three principal extensors; but one extensor and one flexor
are short muscles; that is to say, their fleshy parts are not situated
in the leg (which corresponds with the arm), but in the back and in the
sole of the foot--regions which correspond with the back and the palm of
the hand.

Again, the tendons of the long flexor of the toes, and of the long
flexor of the great toe, when they reach the sole of the foot, do not
remain distinct from one another, as the flexors in the palm of the
hand do, but they become united and commingled in a very curious
manner--while their united tendons receive an accessory muscle connected
with the heel-bone.

But perhaps the most absolutely distinctive character about the muscles
of the foot is the existence of what is termed the 'peronaeus longus',
a long muscle fixed to the outer bone of the leg, and sending its tendon
to the outer ankle, behind and below which it passes, and then crosses
the foot obliquely to be attached to the base of the great toe. No
muscle in the hand exactly corresponds with this, which is eminently a
foot muscle.

To resume--the foot of man is distinguished from his hand by the
following absolute anatomical differences:--

1. By the arrangement of the tarsal bones.

2. By having a short flexor and a short extensor muscle of the digits.

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.

[Illustration: FIG 19.--Foot of Man, Gorilla, and Orang-Utan of the same
absolute length, to show the differences in proportion of each.
Letters as in Fig. 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 [5] by Blumenbach, and
unfortunately rendered current by Cuvier, should have gained such
wide acceptance as a name for the Simian group. 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 (Fig. 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 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."

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 (Fig. 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.

[Illustration: FIG. 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 (Fig. 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 (Fig. 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 Fig. 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 Fig. 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.

[Illustration: FIG. 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; [6] 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.

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. [7] 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 desparingly of the future
hopes, of the only consciously intelligent denizen of this world.

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-informed 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 "pecular 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 pecular 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, fig. 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, [8] F.R.S., Mr. Marshall, [9] F.R.S., Mr. Flower,
[10] Mr. Turner, [11] and myself, [12] 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.




FOOTNOTES:

[Footnote 1: 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.

[Footnote 2: 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.]

[Footnote 3: "More than once," says Peter Camper, "have I met with more
than six lumbar vertebrae in man.... Once I found thirteen ribs and four
lumbar vertebrae." Fallopius noted thirteen pair of ribs and only four
lumbar vertebrae; and Eustachius once found eleven dorsal vertebrae and
six lumbar vertebrae.--'Oeuvres de Pierre Camper', T. 1, p. 42. As
Tyson states, his 'Pygmie' had thirteen pair of ribs and five lumbar
vertebrae. The question of the curves of the spinal column in the Apes
requires further investigation.]

[Footnote 4: 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.]

[Footnote 5: 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."]

[Footnote 6: 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.]

[Footnote 7: 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!]

[Footnotes 8: On the Affinities of the Brain of the Orang. 'Nat. Hist.
Review', April, 1861.]

[Footnotes 9: On the Brain of a young Chimpanzee. 'Ibid.', July, 1861.]

[Footnotes 10: On the Posterior lobes of the Cerebrum of the Quadrumana.
'Philosophical Transactions', 1862.]

[Footnotes 11: 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.]

[Footnotes 12: On the Brain of Ateles. 'Proceedings of Zoological
Society', 1861.]