developed; but in the female gorilla, and in a less degree in the
female orang, these teeth project considerably beyond the others:
therefore the fact, of which I have been assured, that women sometimes
have considerably projecting canines, is no serious objection to the
belief that their occasional great development in man is a case of
reversion to an ape-like progenitor. He who rejects with scorn the
belief that the shape of his own canines and their occasional great
development in other men are due to our early forefathers having been
provided with these formidable weapons, will probably reveal, by
sneering, the line of his descent. For, though he no longer intends,
nor has the power, to use these teeth as weapons, he will unconsciously
retract his “snarling muscles” (thus named by Sir C. Bell), so as to
expose them ready for action, like a dog prepared to fight.
Many muscles are occasionally developed in man, which are proper to
the _Quadrumana_ or other mammals. Professor Vlacovich examined forty
male subjects, and found a muscle, called by him the ischio-pubic,
in nineteen of them; in three others there was a ligament which
represented this muscle; and in the remaining eighteen no trace of it.
In only two out of thirty female subjects was this muscle developed on
both sides, but in three others the rudimentary ligament was present.
This muscle, therefore, appears to be much more common in the male
than in the female sex; and on the belief in the descent of man from
some lower form the fact is intelligible; for it has been detected in
several of the lower animals, and in all of these it serves exclusively
to aid the male in the act of reproduction.
* * * * *
[Page 43.]
That this unknown factor is reversion to a former state of existence
may be admitted as in the highest degree probable. It is quite
incredible that a man should through mere accident abnormally resemble
certain apes in no less than seven of his muscles, if there had been
no genetic connection between them. On the other hand, if man is
descended from some ape-like creature, no valid reason can be assigned
why certain muscles should not suddenly reappear after an interval
of many thousand generations, in the same manner as with horses,
asses, and mules, dark-colored stripes suddenly reappear on the legs
and shoulders, after an interval of hundreds, or more probably of
thousands, of generations.
REVERSION IN THE HUMAN FAMILY.
[Animals and
Plants, vol.
ii, page 1.]
When the child resembles either grandparent more closely than its
immediate parents, our attention is not much arrested, though in truth
the fact is highly remarkable; but when the child resembles some remote
ancestor or some distant member in a collateral line--and in the last
case we must attribute this to the descent of all the members from a
common progenitor--we feel a just degree of astonishment. When one
parent alone displays some newly-acquired and generally inheritable
character, and the offspring do not inherit it, the cause may lie
in the other parent having the power of prepotent transmission. But
when both parents are similarly characterized, and the child does
not, whatever the cause may be, inherit the character in question,
but resembles its grandparents, we have one of the simplest cases of
reversion. We continually see another and even more simple case of
atavism, though not generally included under this head, namely, when
the son more closely resembles his maternal than his paternal grandsire
in some male attribute, as in any peculiarity in the beard of man, the
horns of the bull, the hackles or comb of the cock, or, as in certain
diseases necessarily confined to the male sex; for, as the mother can
not possess or exhibit such male attributes, the child must inherit
them, through her blood, from his maternal grandsire.
The cases of reversion may be divided into two main classes, which,
however, in some instances, blend into one another; namely, first,
those occurring in a variety or race which has not been crossed, but
has lost by variation some character that it formerly possessed, and
which afterward reappears. The second class includes all cases in which
an individual with some distinguishable character, a race, or species,
has at some former period been crossed, and a character derived from
this cross, after having disappeared during one or several generations,
suddenly reappears.
* * * * *
[Page 21.]
From these facts we may perhaps infer that the degraded state of so
many half-castes is in part due to reversion to a primitive and savage
condition, induced by the act of crossing, even if mainly due to the
unfavorable moral conditions under which they are generally reared.
PREPOTENCE IN THE TRANSMISSION OF CHARACTER.
[Animals and
Plants, vol.
ii, page 40.]
When individuals, belonging to the same family, but distinct enough
to be recognized, or when two well-marked races, or two species, are
crossed, the usual result, as stated in the previous chapter, is, that
the offspring in the first generation are intermediate between their
parents, or resemble one parent in one part and the other parent in
another part. But this is by no means the invariable rule, for in
many cases it is found that certain individuals, races, and species,
are prepotent in transmitting their likeness. This subject has been
ably discussed by Prosper Lucas, but is rendered extremely complex by
the prepotency sometimes running equally in both sexes, and sometimes
more strongly in one sex than in the other; it is likewise complicated
by the presence of secondary sexual characters, which render the
comparison of crossed breeds with their parents difficult.
It would appear that in certain families some one ancestor, and after
him others in the same family, have had great power in transmitting
their likeness through the male line; for we can not otherwise
understand how the same features should so often be transmitted after
marriages with many females, as in the case of the Austrian emperors;
and so it was, according to Niebuhr, with the mental qualities of
certain Roman families. The famous bull Favorite is believed to have
had a prepotent influence on the short-horn race. It has also been
observed with English race-horses that certain mares have generally
transmitted their own character, while other mares of equally pure
blood have allowed the character of the sire to prevail. A famous black
greyhound, Bedlamite, as I hear from Mr. C. M. Brown, “invariably got
all his puppies black, no matter what was the color of the bitch”; but
then Bedlamite “had a preponderance of black in his blood, both on the
sire and dam side.”
NATURAL SELECTION IN THE DEVELOPMENT OF MAN.
[Descent of
Man, page 48.]
Man in the rudest state in which he now exists is the most dominant
animal that has ever appeared on this earth. He has spread more
widely than any other highly organized form; and all others have
yielded before him. He manifestly owes this immense superiority to
his intellectual faculties, to his social habits, which lead him
to aid and defend his fellows, and to his corporeal structure. The
supreme importance of these characters has been proved by the final
arbitrament of the battle for life. Through his powers of intellect,
articulate language has been evolved; and on this his wonderful
advancement has mainly depended. As Mr. Chauncey Wright remarks: “A
psychological analysis of the faculty of language shows that even the
smallest proficiency in it might require more brain-power than the
greatest proficiency in any other direction.” He has invented and is
able to use various weapons, tools, traps, etc., with which he defends
himself, kills or catches prey, and otherwise obtains food. He has made
rafts or canoes for fishing or crossing over to neighboring fertile
islands. He has discovered the art of making fire, by which hard and
stringy roots can be rendered digestible, and poisonous roots or herbs
innocuous. This discovery of fire, probably the greatest ever made by
man, excepting language, dates from before the dawn of history. These
several inventions, by which man in the rudest state has become so
pre-eminent, are the direct results of the development of his powers of
observation, memory, curiosity, imagination, and reason.
* * * * *
[Page 50.]
Archæologists are convinced that an enormous interval of time elapsed
before our ancestors thought of grinding chipped flints into smooth
tools. One can hardly doubt that a man-like animal who possessed a
hand and arm sufficiently perfect to throw a stone with precision, or
to form a flint into a rude tool, could, with sufficient practice, as
far as mechanical skill alone is concerned, make almost anything which
a civilized man can make. The structure of the hand in this respect
may be compared with that of the vocal organs, which in the apes are
used for uttering various signal-cries, or, as in one genus, musical
cadences; but in man the closely similar vocal organs have become
adapted through the inherited effects of use for the utterance of
articulate language.
Turning now to the nearest allies of men, and therefore to the best
representatives of our early progenitors, we find that the hands of the
_Quadrumana_ are constructed on the same general pattern as our own,
but are far less perfectly adapted for diversified uses. Their hands
do not serve for locomotion so well as the feet of a dog; as may be
seen in such monkeys as the chimpanzee and orang, which walk on the
outer margins of the palms, or on the knuckles. Their hands, however,
are admirably adapted for climbing trees. Monkeys seize thin branches
or ropes, with the thumb on one side and the fingers and palm on the
other, in the same manner as we do. They can thus also lift rather
large objects, such as the neck of a bottle, to their mouths. Baboons
turn over stones and scratch up roots with their hands. They seize
nuts, insects, or other small objects with the thumb in opposition
to the fingers, and no doubt they thus extract eggs and the young
from the nests of birds. American monkeys beat the wild oranges on
the branches until the rind is cracked, and then tear it off with the
fingers of the two hands. In a wild state they break open hard fruits
with stones. Other monkeys open mussel-shells with the two thumbs. With
their fingers they pull out thorns and burs, and hunt for each other’s
parasites. They roll down stones, or throw them at their enemies;
nevertheless, they are clumsy in these various actions, and, as I have
myself seen, are quite unable to throw a stone with precision.
HOW MAN BECAME UPRIGHT.
[Descent of
Man, page 52.]
If it be an advantage to man to stand firmly on his feet and to have
his hands and arms free, of which, from his pre-eminent success in the
battle of life, there can be no doubt, then I can see no reason why it
should not have been advantageous to the progenitors of man to have
become more and more erect or bipedal. They would thus have been better
able to defend themselves with stones or clubs, to attack their prey,
or otherwise to obtain food. The best built individuals would in the
long run have succeeded best, and have survived in larger numbers. If
the gorilla and a few allied forms had become extinct, it might have
been argued, with great force and apparent truth, that an animal could
not have been gradually converted from a quadruped into a biped, as all
the individuals in an intermediate condition would have been miserably
ill-fitted for progression. But we know (and this is well worthy of
reflection) that the anthropomorphous apes are now actually in an
intermediate condition; and no one doubts that they are on the whole
well adapted for their conditions of life. Thus the gorilla runs with
a sidelong, shambling gait, but more commonly progresses by resting on
its bent hands. The long-armed apes occasionally use their arms like
crutches, swinging their bodies forward between them, and some kinds
of Hylobates, without having been taught, can walk or run upright with
tolerable quickness; yet they move awkwardly, and much less securely
than man. We see, in short, in existing monkeys a manner of progression
intermediate between that of a quadruped and a biped; but, as an
unprejudiced judge insists, the anthropomorphous apes approach in
structure more nearly to the bipedal than to the quadrupedal type.
As the progenitors of man became more and more erect, with their hands
and arms more and more modified for prehension and other purposes,
with their feet and legs at the same time transformed for firm support
and progression, endless other changes of structure would have become
necessary. The pelvis would have to be broadened, the spine peculiarly
curved, and the head fixed in an altered position, all which changes
have been attained by man.
* * * * *
[Page 53.]
The free use of the arms and hands, partly the cause and partly the
result of man’s erect position, appears to have led in an indirect
manner to other modifications of structure. The early male forefathers
of man were, as previously stated, probably furnished with great canine
teeth; but, as they gradually acquired the habit of using stones,
clubs, or other weapons, for fighting with their enemies or rivals,
they would use their jaws and teeth less and less. In this case, the
jaws, together with the teeth, would become reduced in size, as we may
feel almost sure from innumerable analogous cases.
THE BRAIN ENLARGES AS THE MENTAL FACULTIES DEVELOP.
[Descent of
Man, page 54.]
As the various mental faculties gradually developed themselves the
brain would almost certainly become larger. No one, I presume, doubts
that the large proportion which the size of man’s brain bears to his
body, compared to the same proportion in the gorilla or orang, is
closely connected with his higher mental powers. We meet with closely
analogous facts with insects, for in ants the cerebral ganglia are of
extraordinary dimensions, and in all the _Hymenoptera_ these ganglia
are many times larger than in the less intelligent orders, such as
beetles. On the other hand, no one supposes that the intellect of any
two animals or of any two men can be accurately gauged by the cubic
contents of their skulls. It is certain that there may be extraordinary
mental activity with an extremely small absolute mass of nervous
matter: thus the wonderfully diversified instincts, mental powers, and
affections of ants are notorious, yet their cerebral ganglia are not so
large as the quarter of a small pin’s head. Under this point of view,
the brain of an ant is one of the most marvelous atoms of matter in the
world, perhaps more so than the brain of a man.
* * * * *
[Page 55.]
The gradually increasing weight of the brain and skull in man must
have influenced the development of the supporting spinal column, more
especially while he was becoming erect. As this change of position was
being brought about, the internal pressure of the brain will also have
influenced the form of the skull; for many facts show how easily the
skull is thus affected. Ethnologists believe that it is modified by the
kind of cradle in which infants sleep. Habitual spasms of the muscles
and a cicatrix from a severe burn have permanently modified the facial
bones. In young persons whose heads have become fixed either sideways
or backward, owing to disease, one of the two eyes has changed its
position, and the shape of the skull has been altered apparently by
the pressure of the brain in a new direction. I have shown that with
long-eared rabbits even so trifling a cause as the lopping forward of
one ear drags forward almost every bone of the skull on that side; so
that the bones on the opposite side no longer strictly correspond.
Lastly, if any animal were to increase or diminish much in general
size, without any change in its mental powers, or if the mental powers
were to be much increased or diminished, without any great change in
the size of the body, the shape of the skull would almost certainly be
altered. I infer this from my observations on domestic rabbits, some
kinds of which have become very much larger than the wild animal, while
others have retained nearly the same size, but in both cases the brain
has been much reduced relatively to the size of the body. Now, I was
at first much surprised on finding that in all these rabbits the skull
had become elongated or dolichocephalic; for instance, of two skulls
of nearly equal breadth, the one from a wild rabbit and the other from
a large domestic kind, the former was 3·15 and the latter 4·3 inches
in length. One of the most marked distinctions in different races of
men is that the skull in some is elongated, and in others rounded; and
here the explanation suggested by the case of the rabbits may hold
good; for Welcker finds that short “men incline more to brachycephaly,
and tall men to dolichocephaly”; and tall men may be compared with the
larger and longer-bodied rabbits, all of which have elongated skulls,
or are dolichocephalic.
From these several facts we can understand, to a certain extent, the
means by which the great size and more or less rounded form of the
skull have been acquired by man; and these are characters eminently
distinctive of him in comparison with the lower animals.
NAKEDNESS OF THE SKIN.
[Descent of
Man, page 56.]
Another most conspicuous difference between man and the lower animals
is the nakedness of the skin. Whales and porpoises (_Cetacea_),
dugongs (_Sirenia_), and the hippopotamus are naked; and this may
be advantageous to them for gliding through the water; nor would
it be injurious to them from the loss of warmth, as the species,
which inhabit the colder regions, are protected by a thick layer of
blubber, serving the same purpose as the fur of seals and otters.
Elephants and rhinoceroses are almost hairless; and, as certain extinct
species, which formerly lived under an Arctic climate, were covered
with long wool or hair, it would almost appear as if the existing
species of both genera had lost their hairy covering from exposure
to heat. This appears the more probable, as the elephants in India,
which live on elevated and cool districts, are more hairy than those
on the lowlands. May we then infer that man became divested of hair
from having aboriginally inhabited some tropical land? That the hair
is chiefly retained in the male sex on the chest and face, and in
both sexes at the junction of all four limbs with the trunk, favors
this inference--on the assumption that the hair was lost before man
became erect; for the parts which now retain most hair would then have
been most protected from the heat of the sun. The crown of the head,
however, offers a curious exception, for at all times it must have been
one of the most exposed parts, yet it is thickly clothed with hair. The
fact, however, that the other members of the order of _Primates_, to
which man belongs, although inhabiting various hot regions, are well
clothed with hair, generally thickest on the upper surface, is opposed
to the supposition that man became naked through the action of the sun.
* * * * *
[Descent of
Man, page 18.]
The different races differ much in hairiness; and in the individuals
of the same race the hairs are highly variable, not only in abundance,
but likewise in position: thus in some Europeans the shoulders are
quite naked, while in others they bear thick tufts of hair. There
can be little doubt that the hairs thus scattered over the body are
the rudiments of the uniform hairy coat of the lower animals. This
view is rendered all the more probable, as it is known that the fine,
short, and pale-colored hairs on the limbs and other parts of the body
occasionally become developed into “thick-set, long, and rather coarse
dark hairs,” when abnormally nourished near old-standing inflamed
surfaces.
I am informed by Sir James Paget that often several members of a family
have a few hairs in their eyebrows much longer than the others; so
that even this slight peculiarity seems to be inherited. These hairs,
too, seem to have their representatives; for in the chimpanzee, and in
certain species of Macacus, there are scattered hairs of considerable
length rising from the naked skin above the eyes, and corresponding to
our eyebrows; similar long hairs project from the hairy covering of the
superciliary ridges in some baboons.
IS MAN THE MOST HELPLESS OF THE ANIMALS?
[Descent of
Man, page 63.]
It has often been objected to such views as the foregoing, that man is
one of the most helpless and defenseless creatures in the world; and
that during his early and less well-developed condition he would have
been still more helpless. The Duke of Argyll, for instance, insists
that “the human frame has diverged from the structure of brutes, in
the direction of greater physical helplessness and weakness. That is
to say, it is a divergence which of all others it is most impossible
to ascribe to mere natural selection.” He adduces the naked and
unprotected state of the body, the absence of great teeth or claws for
defense, the small strength and speed of man, and his slight power of
discovering food or of avoiding danger by smell. To these deficiencies
there might be added one still more serious, namely, that he can not
climb quickly, and so escape from enemies. The loss of hair would not
have been a great injury to the inhabitants of a warm country. For we
know that the unclothed Fuegians can exist under a wretched climate.
When we compare the defenseless state of man with that of apes, we must
remember that the great canine teeth with which the latter are provided
are possessed in their full development by the males alone, and are
chiefly used by them for fighting with their rivals; yet the females,
which are not thus provided, manage to survive.
In regard to bodily size or strength, we do not know whether man is
descended from some small species, like the chimpanzee, or from one as
powerful as the gorilla; and, therefore, we can not say whether man has
become larger and stronger, or smaller and weaker, than his ancestors.
We should, however, bear in mind that an animal possessing great size,
strength, and ferocity, and which, like the gorilla, could defend
itself from all enemies, would not perhaps have become social; and
this would most effectually have checked the acquirement of the higher
mental qualities--such as sympathy and the love of his fellows. Hence
it might have been an immense advantage to man to have sprung from some
comparatively weak creature.
The small strength and speed of man, his want of natural weapons, etc.,
are more than counterbalanced, firstly, by his intellectual powers,
through which he has formed for himself weapons, tools, etc., though
still remaining in a barbarous state, and, secondly, by his social
qualities, which lead him to give and receive aid from his fellow-men.
No country in the world abounds in a greater degree with dangerous
beasts than Southern Africa; no country presents more fearful physical
hardships than the Arctic regions; yet one of the puniest of races,
that of the Bushmen, maintains itself in Southern Africa, as do the
dwarfed Esquimaux in the Arctic regions. The ancestors of man were,
no doubt, inferior in intellect, and probably in social disposition,
to the lowest existing savages; but it is quite conceivable that
they might have existed, or even flourished, if they had advanced in
intellect, while gradually losing their brute-like powers, such as that
of climbing trees, etc. But these ancestors would not have been exposed
to any special danger, even if far more helpless and defenseless than
any existing savages, had they inhabited some warm continent or large
island, such as Australia, New Guinea, or Borneo, which is now the
home of the orang. And natural selection arising from the competition
of tribe with tribe, in some such large area as one of these, together
with the inherited effects of habit, would, under favorable conditions,
have sufficed to raise man to his present high position in the organic
scale.
VIII.
MENTAL POWERS OF MAN AND THE LOWER ANIMALS COMPARED.
[Descent of
Man, page 65.]