A	>>	B	>>	C	>>	D	>>	E
F	>>	G	>>	H	>>	I	>>	J
K	>>	L	>>	M	>>	N	>>	O
P	>>	R	>>	S	>>	T	>>	U
V	>>	W	>>			X	>>	Z

Thomas a Kempis - "The Imitation of Christ"

H. B. Irving - "A Book of Remarkable Criminals"

John Lawson - "A New Voyage to Carolina"

Judith Boss, Omaha, Nebraska. - "The Turn of the Screw, by Henry James"

The Descent of Man and Selection in Relation to Sex

C >> Charles Darwin >> The Descent of Man and Selection in Relation to Sex




CORRELATED VARIATION.

In man, as in the lower animals, many structures are so intimately related,
that when one part varies so does another, without our being able, in most
cases, to assign any reason. We cannot say whether the one part governs
the other, or whether both are governed by some earlier developed part.
Various monstrosities, as I. Geoffroy repeatedly insists, are thus
intimately connected. Homologous structures are particularly liable to
change together, as we see on the opposite sides of the body, and in the
upper and lower extremities. Meckel long ago remarked, that when the
muscles of the arm depart from their proper type, they almost always
imitate those of the leg; and so, conversely, with the muscles of the legs.
The organs of sight and hearing, the teeth and hair, the colour of the skin
and of the hair, colour and constitution, are more or less correlated.
(55. The authorities for these several statements are given in my
'Variation of Animals under Domestication,' vol. ii. pp. 320-335.)
Professor Schaaffhausen first drew attention to the relation apparently
existing between a muscular frame and the strongly-pronounced supra-orbital
ridges, which are so characteristic of the lower races of man.

Besides the variations which can be grouped with more or less probability
under the foregoing heads, there is a large class of variations which may
be provisionally called spontaneous, for to our ignorance they appear to
arise without any exciting cause. It can, however, be shewn that such
variations, whether consisting of slight individual differences, or of
strongly-marked and abrupt deviations of structure, depend much more on the
constitution of the organism than on the nature of the conditions to which
it has been subjected. (56. This whole subject has been discussed in
chap. xxiii. vol. ii. of my 'Variation of Animals and Plants under
Domestication.')

RATE OF INCREASE.

Civilised populations have been known under favourable conditions, as in
the United States, to double their numbers in twenty-five years; and,
according to a calculation, by Euler, this might occur in a little over
twelve years. (57. See the ever memorable 'Essay on the Principle of
Population,' by the Rev. T. Malthus, vol. i. 1826. pp. 6, 517.) At the
former rate, the present population of the United States (thirty millions),
would in 657 years cover the whole terraqueous globe so thickly, that four
men would have to stand on each square yard of surface. The primary or
fundamental check to the continued increase of man is the difficulty of
gaining subsistence, and of living in comfort. We may infer that this is
the case from what we see, for instance, in the United States, where
subsistence is easy, and there is plenty of room. If such means were
suddenly doubled in Great Britain, our number would be quickly doubled.
With civilised nations this primary check acts chiefly by restraining
marriages. The greater death-rate of infants in the poorest classes is
also very important; as well as the greater mortality, from various
diseases, of the inhabitants of crowded and miserable houses, at all ages.
The effects of severe epidemics and wars are soon counterbalanced, and more
than counterbalanced, in nations placed under favourable conditions.
Emigration also comes in aid as a temporary check, but, with the extremely
poor classes, not to any great extent.

There is reason to suspect, as Malthus has remarked, that the reproductive
power is actually less in barbarous, than in civilised races. We know
nothing positively on this head, for with savages no census has been taken;
but from the concurrent testimony of missionaries, and of others who have
long resided with such people, it appears that their families are usually
small, and large ones rare. This may be partly accounted for, as it is
believed, by the women suckling their infants during a long time; but it is
highly probable that savages, who often suffer much hardship, and who do
not obtain so much nutritious food as civilised men, would be actually less
prolific. I have shewn in a former work (58. 'Variation of Animals and
Plants under Domestication,' vol ii. pp. 111-113, 163.), that all our
domesticated quadrupeds and birds, and all our cultivated plants, are more
fertile than the corresponding species in a state of nature. It is no
valid objection to this conclusion that animals suddenly supplied with an
excess of food, or when grown very fat; and that most plants on sudden
removal from very poor to very rich soil, are rendered more or less
sterile. We might, therefore, expect that civilised men, who in one sense
are highly domesticated, would be more prolific than wild men. It is also
probable that the increased fertility of civilised nations would become, as
with our domestic animals, an inherited character: it is at least known
that with mankind a tendency to produce twins runs in families. (59. Mr.
Sedgwick, 'British and Foreign Medico-Chirurgical Review,' July 1863, p.
170.)

Notwithstanding that savages appear to be less prolific than civilised
people, they would no doubt rapidly increase if their numbers were not by
some means rigidly kept down. The Santali, or hill-tribes of India, have
recently afforded a good illustration of this fact; for, as shewn by Mr.
Hunter (60. 'The Annals of Rural Bengal,' by W.W. Hunter, 1868, p. 259.),
they have increased at an extraordinary rate since vaccination has been
introduced, other pestilences mitigated, and war sternly repressed. This
increase, however, would not have been possible had not these rude people
spread into the adjoining districts, and worked for hire. Savages almost
always marry; yet there is some prudential restraint, for they do not
commonly marry at the earliest possible age. The young men are often
required to shew that they can support a wife; and they generally have
first to earn the price with which to purchase her from her parents. With
savages the difficulty of obtaining subsistence occasionally limits their
number in a much more direct manner than with civilised people, for all
tribes periodically suffer from severe famines. At such times savages are
forced to devour much bad food, and their health can hardly fail to be
injured. Many accounts have been published of their protruding stomachs
and emaciated limbs after and during famines. They are then, also,
compelled to wander much, and, as I was assured in Australia, their infants
perish in large numbers. As famines are periodical, depending chiefly on
extreme seasons, all tribes must fluctuate in number. They cannot steadily
and regularly increase, as there is no artificial increase in the supply of
food. Savages, when hard pressed, encroach on each other's territories,
and war is the result; but they are indeed almost always at war with their
neighbours. They are liable to many accidents on land and water in their
search for food; and in some countries they suffer much from the larger
beasts of prey. Even in India, districts have been depopulated by the
ravages of tigers.

Malthus has discussed these several checks, but he does not lay stress
enough on what is probably the most important of all, namely infanticide,
especially of female infants, and the habit of procuring abortion. These
practices now prevail in many quarters of the world; and infanticide seems
formerly to have prevailed, as Mr. M'Lennan (61. 'Primitive Marriage,'
1865.) has shewn, on a still more extensive scale. These practices appear
to have originated in savages recognising the difficulty, or rather the
impossibility of supporting all the infants that are born. Licentiousness
may also be added to the foregoing checks; but this does not follow from
failing means of subsistence; though there is reason to believe that in
some cases (as in Japan) it has been intentionally encouraged as a means of
keeping down the population.

If we look back to an extremely remote epoch, before man had arrived at the
dignity of manhood, he would have been guided more by instinct and less by
reason than are the lowest savages at the present time. Our early semi-
human progenitors would not have practised infanticide or polyandry; for
the instincts of the lower animals are never so perverted (62. A writer in
the 'Spectator' (March 12, 1871, p. 320) comments as follows on this
passage:--"Mr. Darwin finds himself compelled to reintroduce a new doctrine
of the fall of man. He shews that the instincts of the higher animals are
far nobler than the habits of savage races of men, and he finds himself,
therefore, compelled to re-introduce,--in a form of the substantial
orthodoxy of which he appears to be quite unconscious,--and to introduce as
a scientific hypothesis the doctrine that man's gain of KNOWLEDGE was the
cause of a temporary but long-enduring moral deterioration as indicated by
the many foul customs, especially as to marriage, of savage tribes. What
does the Jewish tradition of the moral degeneration of man through his
snatching at a knowledge forbidden him by his highest instinct assert
beyond this?") as to lead them regularly to destroy their own offspring, or
to be quite devoid of jealousy. There would have been no prudential
restraint from marriage, and the sexes would have freely united at an early
age. Hence the progenitors of man would have tended to increase rapidly;
but checks of some kind, either periodical or constant, must have kept down
their numbers, even more severely than with existing savages. What the
precise nature of these checks were, we cannot say, any more than with most
other animals. We know that horses and cattle, which are not extremely
prolific animals, when first turned loose in South America, increased at an
enormous rate. The elephant, the slowest breeder of all known animals,
would in a few thousand years stock the whole world. The increase of every
species of monkey must be checked by some means; but not, as Brehm remarks,
by the attacks of beasts of prey. No one will assume that the actual power
of reproduction in the wild horses and cattle of America, was at first in
any sensible degree increased; or that, as each district became fully
stocked, this same power was diminished. No doubt, in this case, and in
all others, many checks concur, and different checks under different
circumstances; periodical dearths, depending on unfavourable seasons, being
probably the most important of all. So it will have been with the early
progenitors of man.

NATURAL SELECTION.

We have now seen that man is variable in body and mind; and that the
variations are induced, either directly or indirectly, by the same general
causes, and obey the same general laws, as with the lower animals. Man has
spread widely over the face of the earth, and must have been exposed,
during his incessant migrations (63. See some good remarks to this effect
by W. Stanley Jevons, "A Deduction from Darwin's Theory," 'Nature,' 1869,
p. 231.), to the most diversified conditions. The inhabitants of Tierra
del Fuego, the Cape of Good Hope, and Tasmania in the one hemisphere, and
of the arctic regions in the other, must have passed through many climates,
and changed their habits many times, before they reached their present
homes. (64. Latham, 'Man and his Migrations,' 1851, p. 135.) The early
progenitors of man must also have tended, like all other animals, to have
increased beyond their means of subsistence; they must, therefore,
occasionally have been exposed to a struggle for existence, and
consequently to the rigid law of natural selection. Beneficial variations
of all kinds will thus, either occasionally or habitually, have been
preserved and injurious ones eliminated. I do not refer to strongly-marked
deviations of structure, which occur only at long intervals of time, but to
mere individual differences. We know, for instance, that the muscles of
our hands and feet, which determine our powers of movement, are liable,
like those of the lower animals, (65. Messrs. Murie and Mivart in their
'Anatomy of the Lemuroidea' ('Transact. Zoolog. Soc.' vol. vii. 1869, pp.
96-98) say, "some muscles are so irregular in their distribution that they
cannot be well classed in any of the above groups." These muscles differ
even on the opposite sides of the same individual.) to incessant
variability. If then the progenitors of man inhabiting any district,
especially one undergoing some change in its conditions, were divided into
two equal bodies, the one half which included all the individuals best
adapted by their powers of movement for gaining subsistence, or for
defending themselves, would on an average survive in greater numbers, and
procreate more offspring than the other and less well endowed half.

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 organised 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
(66. Limits of Natural Selection, 'North American Review,' Oct. 1870, p.
295.): "a psychological analysis of the faculty of language shews, 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 neighbouring 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. I cannot, therefore, understand how it is that
Mr. Wallace (67. 'Quarterly Review,' April 1869, p. 392. This subject is
more fully discussed in Mr. Wallace's 'Contributions to the Theory of
Natural Selection,' 1870, in which all the essays referred to in this work
are re-published. The 'Essay on Man,' has been ably criticised by Prof.
Claparede, one of the most distinguished zoologists in Europe, in an
article published in the 'Bibliotheque Universelle,' June 1870. The remark
quoted in my text will surprise every one who has read Mr. Wallace's
celebrated paper on 'The Origin of Human Races Deduced from the Theory of
Natural Selection,' originally published in the 'Anthropological Review,'
May 1864, p. clviii. I cannot here resist quoting a most just remark by
Sir J. Lubbock ('Prehistoric Times,' 1865, p. 479) in reference to this
paper, namely, that Mr. Wallace, "with characteristic unselfishness,
ascribes it (i.e. the idea of natural selection) unreservedly to Mr.
Darwin, although, as is well known, he struck out the idea independently,
and published it, though not with the same elaboration, at the same time.")
maintains, that "natural selection could only have endowed the savage with
a brain a little superior to that of an ape."

Although the intellectual powers and social habits of man are of paramount
importance to him, we must not underrate the importance of his bodily
structure, to which subject the remainder of this chapter will be devoted;
the development of the intellectual and social or moral faculties being
discussed in a later chapter.

Even to hammer with precision is no easy matter, as every one who has tried
to learn carpentry will admit. To throw a stone with as true an aim as a
Fuegian in defending himself, or in killing birds, requires the most
consummate perfection in the correlated action of the muscles of the hand,
arm, and shoulder, and, further, a fine sense of touch. In throwing a
stone or spear, and in many other actions, a man must stand firmly on his
feet; and this again demands the perfect co-adaptation of numerous muscles.
To chip a flint into the rudest tool, or to form a barbed spear or hook
from a bone, demands the use of a perfect hand; for, as a most capable
judge, Mr. Schoolcraft (68. Quoted by Mr. Lawson Tait in his 'Law of
Natural Selection,' 'Dublin Quarterly Journal of Medical Science,' Feb.
1869. Dr. Keller is likewise quoted to the same effect.), remarks, the
shaping fragments of stone into knives, lances, or arrow-heads, shews
"extraordinary ability and long practice." This is to a great extent
proved by the fact that primeval men practised a division of labour; each
man did not manufacture his own flint tools or rude pottery, but certain
individuals appear to have devoted themselves to such work, no doubt
receiving in exchange the produce of the chase. Archaeologists 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 civilised 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. (69. Owen, 'Anatomy of Vertebrates,' vol. iii. p.
71.) 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 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.

It seems to me far from true that because "objects are grasped clumsily" by
monkeys, "a much less specialised organ of prehension" would have served
them (70. 'Quarterly Review,' April 1869, p. 392.) equally well with their
present hands. On the contrary, I see no reason to doubt that more
perfectly constructed hands would have been an advantage to them, provided
that they were not thus rendered less fitted for climbing trees. We may
suspect that a hand as perfect as that of man would have been
disadvantageous for climbing; for the most arboreal monkeys in the world,
namely, Ateles in America, Colobus in Africa, and Hylobates in Asia, are
either thumbless, or their toes partially cohere, so that their limbs are
converted into mere grasping hooks. (71. In Hylobates syndactylus, as the
name expresses, two of the toes regularly cohere; and this, as Mr. Blyth
informs me, is occasionally the case with the toes of H. agilis, lar, and
leuciscus. Colobus is strictly arboreal and extraordinarily active (Brehm,
'Thierleben,' B. i. s. 50), but whether a better climber than the species
of the allied genera, I do not know. It deserves notice that the feet of
the sloths, the most arboreal animals in the world, are wonderfully hook-
like.

As soon as some ancient member in the great series of the Primates came to
be less arboreal, owing to a change in its manner of procuring subsistence,
or to some change in the surrounding conditions, its habitual manner of
progression would have been modified: and thus it would have been rendered
more strictly quadrupedal or bipedal. Baboons frequent hilly and rocky
districts, and only from necessity climb high trees (72. Brehm,
'Thierleben,' B. i. s. 80.); and they have acquired almost the gait of a
dog. Man alone has become a biped; and we can, I think, partly see how he
has come to assume his erect attitude, which forms one of his most
conspicuous characters. Man could not have attained his present dominant
position in the world without the use of his hands, which are so admirably
adapted to act in obedience to his will. Sir C. Bell (73. 'The Hand,'
etc., 'Bridgewater Treatise,' 1833, p. 38.) insists that "the hand supplies
all instruments, and by its correspondence with the intellect gives him
universal dominion." But the hands and arms could hardly have become
perfect enough to have manufactured weapons, or to have hurled stones and
spears with a true aim, as long as they were habitually used for locomotion
and for supporting the whole weight of the body, or, as before remarked, so
long as they were especially fitted for climbing trees. Such rough
treatment would also have blunted the sense of touch, on which their
delicate use largely depends. From these causes alone it would have been
an advantage to man to become a biped; but for many actions it is
indispensable that the arms and whole upper part of the body should be
free; and he must for this end stand firmly on his feet. To gain this
great advantage, the feet have been rendered flat; and the great toe has
been peculiarly modified, though this has entailed the almost complete loss
of its power of prehension. It accords with the principle of the division
of physiological labour, prevailing throughout the animal kingdom, that as
the hands became perfected for prehension, the feet should have become
perfected for support and locomotion. With some savages, however, the foot
has not altogether lost its prehensile power, as shewn by their manner of
climbing trees, and of using them in other ways. (74. Haeckel has an
excellent discussion on the steps by which man became a biped: 'Naturliche
Schopfungsgeschicte,' 1868, s. 507. Dr. Buchner ('Conferences sur la
Theorie Darwinienne,' 1869, p. 135) has given good cases of the use of the
foot as a prehensile organ by man; and has also written on the manner of
progression of the higher apes, to which I allude in the following
paragraph: see also Owen ('Anatomy of Vertebrates,' vol. iii. p. 71) on
this latter subject.

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 (75. Prof. Broca, La Constitution des
Vertebres caudales; 'La Revue d'Anthropologie,' 1872, p. 26, (separate
copy).) insists, the anthropomorphous apes approach in structure more
nearly to the bipedal than to the quadrupedal type.

Copyright (c) 2007. fullstories.net. All rights reserved.