FROM APE TO MAN
THE recent discoveries of the actual bones of very early races of man
raise again a general interest in the inquiry as to what are the actual
differences of structure between men and apes, and what were probably
the steps by which, as the result of "survival of the fittest," some
early man-like apes became ape-like men. The question also arises as
to how long ago the transition actually took place, and whether it was
a very gradual or a rapid one. We are to-day in possession of some
important facts bearing upon this inquiry which were unknown to Huxley
when he wrote his ever-memorable essay on "Man's Place in Nature," and
triumphantly closed the controversy between himself and Sir Richard
Owen. That was nearly fifty years ago.
Owen had maintained that the structural difference between man and
the highest apes was so great that it could only be rightly expressed
by placing man in a separate sub-class of the class "Mammalia"--the
hairy vertebrate animals which have warm blood and suckle their
young. He pointed chiefly to the large size of the brain in man, the
existence on each side of its central cavity of a little internal
swelling called the "hippocampus minor," in the fanciful language of
anatomists, and of the overlapping (within the skull) of the cerebellum
by the hinder part of the large brain-hemispheres, or cerebrum. He
called the sub-class (in which he proposed to place man alone) the
"archencephala," or that of the highest developed brains (Greek,
"archi," chief, and "encephalon," a brain), and proposed three other
sub-classes, to contain the other orders of mammals (the Gyrencephala,
Lissencephala, and Lyencephala), grouped according to three grades
of complexity of the brain. Huxley denied the justification of this
special grouping, by which man was placed in a separate and highest
sub-class apart from the apes and monkeys. He pointed out that every
bone and every part recognized by the anatomist in the higher apes is
present in man (though other mammals present no such identity with him
or them), and that there are only three little muscles belonging to
the hand and the foot which are present in man and not present in the
higher apes. He showed that the term "four-handed," or "quadrumanous,"
as applied to the apes and monkeys, is misleading, inasmuch as, though
modified in the proportions of the digits and the mobility of the
great toe, the foot of the apes has the same bones and muscles as the
foot of man, and differs in structure from their hand as the foot of
man differs from his hand, whilst the true hand of the apes agrees in
structure with the hand of man.
Huxley (supported by many other anatomists) also showed conclusively
that the little lobe in the interior of the brain called the
"hippocampus minor" is present in the apes as in man, and that the
posterior part of the greater brain, or "cerebrum," does overlap the
"cerebellum" in apes and many monkeys to an even greater extent than
it does in man. Owen's statements on this matter appear to have been
due to his reliance on specimens of apes' brains removed from the
skull and badly preserved in spirit--in which condition the parts in
question had slipped out of their natural position. Owen's statements
were thus fully demonstrated to be contrary to the fact, and Huxley
declared, and conclusively showed, that so far from being entitled, on
anatomical grounds, to a separate sub-class, man differs less from the
higher apes--the four animals known as the gorilla, the chimpanzee,
the orang-utan, and the gibbon--than does any one of these differ from
the lower monkeys. Huxley came, therefore, to the conclusion that man
could not logically be dissociated from the apes and monkeys in the
way proposed by Owen, and that he should be placed with them in one
"order," to which the name "Primates" (pronounced as three syllables,
and having no reference to the clergy of the Anglican Church) is
applied. This name was given by the great naturalist Linnæus, one
hundred and fifty years ago, to the same group, in which, however, he
erroneously included also the bats.
It was distinctly pointed out by Huxley, and has been maintained by all
those who have since occupied themselves with the matter, that there
are certain very obvious differences between man and the highest ape,
or that which comes nearest to him in the largest number of important
features--the gorilla. The chimpanzee is practically, for the purpose
of such a comparison, very nearly identical with the gorilla. Both are
inhabitants of tropical Africa, whilst the next nearest, the orang
and the gibbons, are inhabitants of tropical Asia. The differences
separating man from these near kindred animals are differences of the
size and proportion of structures present in them all, and are not due
to the existence in man of actual parts or structures which are present
in him and not present in these apes. Man has developed from the ape,
not by the production of any new organ or part, but by the definite
modification of parts already present in the apes. Even that obscure
internal worm-like outgrowth of the intestine, called the "vermiform
appendix," which has become so unhappily familiar to the general public
of late years on account of its frequent ulceration and the consequent
danger to life, is present in full size in those higher apes which I
have cited by name, and is present in them and man alone amongst all
the varied members of the class of mammals until we come to the little
Australian beaver-like "wombat," which has a vermiform appendix or
narrowed tube-like extremity to the intestinal sac, called the cæcum,
like that of man and the higher apes.
The changes of bodily form and proportions noticeable when we compare
man with the gorilla or the chimpanzee are precisely those which fit in
with the supposition of a gradual change of form and habits favoured by
natural selection in the struggle for existence of ape-like creatures
living originally in tropical forests, but gradually spreading beyond
the special conditions of tropical life into other conditions and
seeking to hold their own and to nourish themselves and their young.
They have had to contend with one another for food and safety and to
defend themselves either by violence or by craft against predatory
animals and competitors of all kinds.
There are certain notions still current dating from Roman times as
to differences between man and apes, which are simply erroneous and
fanciful in origin. Thus, at one time the possession of a tail was
supposed to separate animals, including monkeys and apes, from man.
The rare abnormal cases in which the end of the vertebral column of
man is free and projects as a tail, were, a couple of hundred years
ago, cited with wonder and head-shakings as a proof that there was,
after all, a real similarity in man's structure to that of animals,
and pictures of the "Homo caudatus," or tailed man, were to be found
in ancient books dealing with marvels and mysteries. As a matter of
fact, three or four small insignificant vertebræ, almost immovable, are
always present in man attached to the great bone called the sacrum,
formed by the union of five vertebræ. These small vertebræ, to which
the name "coccyx" is applied, are sunk beneath the skin and fat, at the
end of the backbone, and though they correspond to bones of the tail of
other animals, they are, in normal mankind, thus concealed from view.
Precisely the same atrophy and concealment of the bones of the tail is
found in the gorilla, chimpanzee, orang, and gibbons. They are all of
them, seen in the flesh, as tail-less as man is, and seen in skeleton
have precisely the same number of minute tail bones forming a "coccyx."
This is true not only of the higher apes mentioned, but of the Barbary
ape--which lives at Gibraltar--whilst others, such as the mandrill,
have very short tails. In fact, the tail is a very variable appendage
in monkeys, and, as the Manx breed shows, also in cats. It is mainly
"decorative" in the old-world monkeys, and is probably maintained by
sexual selection. It is only in the new-world monkeys that it has
acquired obvious mechanical value. In them it is prehensile, and is
used with great effect in swinging among the trees from branch to
branch, whilst the hands and feet are left free to grasp any new
support.
Another feature which is commonly, but erroneously, supposed to
constitute a great difference between man and apes is the hairiness
of the latter. This is only a difference of degree, for the whole
surface of the body of man, excepting the eyelids, lips, palms of the
hands, and soles of the feet, is covered by hair, as it is, with the
same exceptions, in the apes. It is true that the hair is very fine
and small on most parts of the body of man and longer on the head.
But there are races of men (the Ainos of Japan and the pygmies of the
Upper Nile) in which the hair on the body is coarser and more uniformly
distributed than in others, and there are individuals of exceptional
"hairiness" in all races of man. Moreover, before birth a coat of
relatively coarse and abundant hair, called the "lanugo," is shed by
the human fœtus. One variety of chimpanzee is practically bald--that
is to say, has no obvious hair on the cranial region of the head. The
celebrated "Sally," who lived so long in the Zoological Gardens in
London, was one of this variety. When she died, I placed her brain, a
remarkable one, in the museum at Oxford. Thus we see that neither tail
nor hairiness separates apes from men.
So, too, the notion that animals, and therefore apes, do not and
cannot laugh is erroneous. Many animals, including chimpanzees, laugh.
These men-like apes also sing and dance and utter sounds (as do
lower monkeys) which have definite meaning, though those sounds are
very few in number and variety, and are separated by a long period
of elaboration (both of skill in vocalization and in the mental
development necessary to give significance to the sounds produced),
from what we call "human language"--even from the speech of the most
primitive of existing men.
It is often assumed as a matter of prejudice--with the intention of
marking off the animal world to which the apes belong, from ourselves,
the human race--that the apes show little intelligence, reasoning
power, and constructive aptitudes, which might serve as the beginning
of man's arts and crafts, were man derived by a slow process of
development from ape-like animals of a long past geologic period. The
fact is that there has been very little opportunity for studying the
capacities of apes in regard to such matters, since when kept in cages
they have not the opportunity of showing the skill and understanding
which in their natural conditions would be obvious. The monkeys show
(and this has been especially observed in the chimpanzee), in a degree
greater than is seen in other animals, the mental quality which we call
"curiosity." And this is combined with a persistence and determination
in observation and in experiment with the purpose of satisfying that
curiosity which is rarely, if ever, exhibited by other animals to
anything like the same extent.
The higher apes will use their fingers to turn the screws which fasten
down the lid of a box in order to see what is inside. Lately the
large orang in the Zoological Gardens of London succeeded, after long
efforts, in unwinding the wire fastenings of its cage and escaping
into the open. It climbed into a tree, and immediately constructed
for itself a platform of branches which it broke off from the tree.
It then sat upon this platform, as is its habit when in its native
forest. Many of the larger monkeys have great skill in throwing stones,
sending them with considerable force and good aim. They select stones
of size and weight appropriate to their purpose, and it would not be
surprising should apes have learnt to select stones for other purposes,
such as cracking nuts or the shells of molluscs, in order to extract
the soft nourishing food which they contain. They are known to make
use of stones for such purposes, and it would be but a short step in
advance for them to choose one suitable for use as a hammer, and
another suitable for use as a piercing or cutting tool. And from such a
stage there is a gradual and easy passage to the simplest breaking and
preparation of stones for use--in fact, to the earliest fabrication of
"implements."
It is obvious when we compare not only the structure but what we know
of the ways and habits of the lowest savages and the highest apes,
that it is not by mere strength, swiftness, or agility that man has
flourished and established himself, leaving the apes far behind him as
"inferior" creatures, though as a matter of fact he is not deficient
in these qualities. It is by his observation, knowledge, memory, and
purposive skill that he has succeeded, and it is easy to point out a
whole series of modifications of form separating man from apes, which
are clearly contributory to the development of the mental qualities
which give him his actual superiority. I think we are justified in
taking the large opposable thumb and fingers as the starting-point
in man's emergence from the ape stage of his ancestry. The exploring
hand, with its thumb and forefinger, is the great instrument by which
the intelligence, first of the monkey and then of man, has been
developed. The thumb of the gorilla is, in proportion to the size of
the fingers, very much smaller than that of man, but bigger than that
of the chimpanzee, and much bigger than that of the orang and of lower
monkeys. It is evident that the thumb has increased in size in the
man-like apes, and in man himself this increase has been carried much
further, and led to the perfecting of the hand as an instrument of
exploration and construction. Contributory to the perfecting of the
hand has been the gradual attainment of the upright carriage, and the
use of the feet alone for walking, and the reservation of the hand for
delicate exploring operations, and the bringing of objects near to the
eye, to the nose, the ear, and the mouth for investigation by the great
organs of special sense. The foot has become "plantigrade" in connexion
with the assumption of upright carriage. It has independently become
plantigrade in the gibbons and the baboons. That is to say, we and they
do not walk on the edge of the half-grasping foot as do the gorilla,
chimpanzee, and orang, but more steadily and firmly on its flat sole
(plantar surface), as do the bears and some other animals. At the same
time man has lost very greatly (but not entirely) the power of grasping
with his toes. The upright carriage enabled the early ancestors of man
to survey, and so to judge the conditions of safety or danger at a
distance from them, as well as to devote their hands to new and special
uses.