careful study by any one who desires to learn how frequently our muscles
vary, and in varying come to resemble those of the Quadrumana. The
following references relate to the few points touched on in my text:
'Proc. Royal Soc.' vol. xiv. 1865, pp. 379-384; vol. xv. 1866, pp. 241,
242; vol. xv. 1867, p. 544; vol. xvi. 1868, p. 524. I may here add that
Dr. Murie and Mr. St. George Mivart have shewn in their Memoir on the
Lemuroidea ('Transactions, Zoological Society,' vol. vii. 1869, p. 96), how
extraordinarily variable some of the muscles are in these animals, the
lowest members of the Primates. Gradations, also, in the muscles leading
to structures found in animals still lower in the scale, are numerous in
the Lemuroidea.), has minutely described a vast number of muscular
variations in man, which resemble normal structures in the lower animals.
The muscles which closely resemble those regularly present in our nearest
allies, the Quadrumana, are too numerous to be here even specified. In a
single male subject, having a strong bodily frame, and well-formed skull,
no less than seven muscular variations were observed, all of which plainly
represented muscles proper to various kinds of apes. This man, for
instance, had on both sides of his neck a true and powerful "levator
claviculae," such as is found in all kinds of apes, and which is said to
occur in about one out of sixty human subjects. (49. See also Prof.
Macalister in 'Proceedings, Royal Irish Academy,' vol. x. 1868, p. 124.)
Again, this man had "a special abductor of the metatarsal bone of the fifth
digit, such as Professor Huxley and Mr. Flower have shewn to exist
uniformly in the higher and lower apes." I will give only two additional
cases; the acromio-basilar muscle is found in all mammals below man, and
seems to be correlated with a quadrupedal gait, (50. Mr. Champneys in
'Journal of Anatomy and Physiology,' Nov. 1871, p. 178.) and it occurs in
about one out of sixty human subjects. In the lower extremities Mr.
Bradley (51. Ibid. May 1872, p. 421.) found an abductor ossis metatarsi
quinti in both feet of man; this muscle had not up to that time been
recorded in mankind, but is always present in the anthropomorphous apes.
The muscles of the hands and arms - parts which are so eminently
characteristic of man - are extremely liable to vary, so as to resemble the
corresponding muscles in the lower animals. (52. Prof. Macalister (ibid.
p. 121) has tabulated his observations, and finds that muscular
abnormalities are most frequent in the fore-arms, secondly, in the face,
thirdly, in the foot, etc.) Such resemblances are either perfect or
imperfect; yet in the latter case they are manifestly of a transitional
nature. Certain variations are more common in man, and others in woman,
without our being able to assign any reason. Mr. Wood, after describing
numerous variations, makes the following pregnant remark. "Notable
departures from the ordinary type of the muscular structures run in grooves
or directions, which must be taken to indicate some unknown factor, of much
importance to a comprehensive knowledge of general and scientific anatomy."
(53. The Rev. Dr. Haughton, after giving ('Proc. R. Irish Academy,' June
27, 1864, p. 715) a remarkable case of variation in the human flexor
pollicis longus, adds, "This remarkable example shews that man may
sometimes possess the arrangement of tendons of thumb and fingers
characteristic of the macaque; but whether such a case should be regarded
as a macaque passing upwards into a man, or a man passing downwards into a
macaque, or as a congenital freak of nature, I cannot undertake to say."
It is satisfactory to hear so capable an anatomist, and so embittered an
opponent of evolutionism, admitting even the possibility of either of his
first propositions. Prof. Macalister has also described ('Proceedings
Royal Irish Academy,' vol. x. 1864, p. 138) variations in the flexor
pollicis longus, remarkable from their relations to the same muscle in the
Quadrumana.)
That this unknown factor is reversion to a former state of existence may be
admitted as in the highest degree probable. (54. Since the first edition
of this book appeared, Mr. Wood has published another memoir in the
Philosophical Transactions, 1870, p. 83, on the varieties of the muscles of
the human neck, shoulder, and chest. He here shews how extremely variable
these muscles are, and how often and how closely the variations resemble
the normal muscles of the lower animals. He sums up by remarking, "It will
be enough for my purpose if I have succeeded in shewing the more important
forms which, when occurring as varieties in the human subject, tend to
exhibit in a sufficiently marked manner what may be considered as proofs
and examples of the Darwinian principle of reversion, or law of
inheritance, in this department of anatomical science.") 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-
coloured stripes suddenly reappear on the legs, and shoulders, after an
interval of hundreds, or more probably of thousands of generations.
These various cases of reversion are so closely related to those of
rudimentary organs given in the first chapter, that many of them might have
been indifferently introduced either there or here. Thus a human uterus
furnished with cornua may be said to represent, in a rudimentary condition,
the same organ in its normal state in certain mammals. Some parts which
are rudimentary in man, as the os coccyx in both sexes, and the mammae in
the male sex, are always present; whilst others, such as the supracondyloid
foramen, only occasionally appear, and therefore might have been introduced
under the head of reversion. These several reversionary structures, as
well as the strictly rudimentary ones, reveal the descent of man from some
lower form in an unmistakable manner.
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