IT is manifest
that man is now subject to
much variability.
No two individuals of the same
race are quite alike. We may
compare millions of faces, and
each will be distinct. There
is an equally great amount of
diversity in the proportions
and dimensions of the various
parts of the body; the length
of the legs being one of the
most variable points.* Although
in some quarters of the world
an elongated skull, and in other
quarters a short skull prevails,
yet there is great diversity
of shape even within the limits
of the same race, as with the
aborigines of America and South
Australia- the
latter a race "probably as pure and homogeneous in blood, customs, and language
as any in existence"- and even with the inhabitants of so confined an area as
the Sandwich Islands.*(2) An eminent dentist assures me that there is nearly
as much diversity in the teeth as in the features. The chief arteries so frequently
run in abnormal courses, that is has been found useful for surgical purposes
to calculate from 1040 corpses how often each course prevails.*(3) The muscles
are eminently variable: thus those of the foot were found by Prof. Turner*(4)
not to be strictly alike in any two out of fifty bodies; and in some the deviations
were considerable. He adds, that the power of performing the appropriate movements
must have been modified in accordance with the several deviations. Mr. J. Wood
has recorded*(5) the occurrence of 295 muscular variations in thirty-six subjects,
and in another set of the same number no less than 558 variations, those occurring
on both sides of the body being only reckoned as one. In the last set, not one
body out of the thirty-six
was "found totally wanting in departures from the standard descriptions of the
muscular system given in anatomical text books." A single body presented the
extraordinary number of twenty-five distinct abnormalities. The same muscle sometimes
varies in many ways: thus Prof. Macalister describes*(6) no less than twenty
distinct variations
in the palmaris accessorius.
* Investigations in the Military
and Anthropological Statistics
of American Soldiers, by B. A.
Gould, 1869, p. 256.
*(2) With respect
to the " Cranial
forms of the American aborigines," see
Dr. Aitken Meigs in Proc. Acad.
Nat. Sci. Philadelphia, May,
1868. On the Australians, see
Huxley, in Lyell's Antiquity
of Man, 1863, p. 87. On the Sandwich
Islanders, Prof. J. Wyman, Observations
on Crania, Boston, 1868, p. 18.
*(3) Anatomy of the Arteries,
by R. Quain. Preface, vol. i.,
1844.
*(4) Transactions of the Royal
Society of Edinburgh, vol. xxiv.,
pp. 175, 189.
*(5) Proceedings Royal Society,
1867, p. 544; also 1868, pp.
483, 524. There is a previous
paper, 1866, p. 229.
*(6) Proc. R. Irish Academy,
vol. x., 1868, p. 141.
The famous old
anatomist, Wolff,* insists
that the internal viscera
are more variable than the external
parts: Nulla particula est quae
non aliter et aliter in aliis
se habeat hominibus. He has even
written a treatise on the choice
of typical examples of the viscera
for representation. A discussion
on the beau-ideal of the liver,
lungs, kidneys, &c., as of the
human face divine, sounds strange
in our ears.
* Act. Acad. St. Petersburg,
1778, part ii., p. 217.
The variability or diversity
of the mental faculties in men
of the same race, not to mention
the greater differences between
the men of distinct races, is
so notorious that not a word
need here be said. So it is with
the lower animals. All who have
had charge of menageries admit
this fact, and we see it plainly
in our dogs and other domestic
animals. Brehm especially insists
that each individual monkey of
those which he kept tame in Africa
had its own peculiar disposition
and temper: he mentions one baboon
remarkable for its high intelligence;
and the keepers in the Zoological
Gardens pointed out to me a monkey,
belonging to the New World division,
equally remarkable for intelligence.
Rengger, also, insists on the
diversity in the various mental
characters of the monkeys of
the same species which he kept
in Paraguay; and this diversity,
as he adds, is partly innate,
and partly the result of the
manner in which they have been
treated or educated.*
* Brehm, Illustriertes Thierleben,
B. i., ss. 58, 87. Rengger, Saugethiere
von Paraguay, s. 57.
I have elsewhere*
so fully discussed the subject
of Inheritance, that
I need here add hardly anything.
A greater number of facts have
been collected with respect to
the transmission of the most
trifling, as well as of the most
important characters in man,
than in any of the lower animals;
though the facts are copious
enough with respect to the latter.
So in regard to mental qualities,
their transmission is manifest
in our dogs, horses, and other
domestic animals. Besides special
tastes and habits, general intelligence,
courage, bad and good temper, &c.,
are certainly transmitted. With
man we see similar facts in almost
every family; and we now know,
through the admirable labours
of Mr. Galton,*(2) that genius
which implies a wonderfully complex
combination of high faculties,
tends to be inherited; and, on
the other hand, it is too certain
that insanity and deteriorated
mental powers likewise run in
families.
* Variation of Animals and Plants
under Domestication, vol. ii.,
chap. xii.
*(2) Hereditary Genius: an Inquiry
into its Laws and Consequences,
1869.
With respect
to the causes of variability,
we are in all cases
very ignorant; but we can see
that in man as in the lower animals,
they stand in some relation to
the conditions to which each
species has been exposed, during
several generations. Domesticated
animals vary more than those
in a state of nature; and this
is apparently due to the diversified
and changing nature of the conditions
to which they have been subjected.
In this respect the different
races of man resemble domesticated
animals, and so do the individuals
of the same race, when inhabiting.
a very wide area, like that of
America. We see the influence
of diversified conditions in
the more civilised nations; for
the members belonging to different
grades of rank, and following
different occupations, present
a greater range of character
than do the members of barbarous
nations. But the uniformity of
savages has often been exaggerated,
and in some cases can hardly
be said to exist.* It is, nevertheless,
an error to speak of man, even
if we look only to the conditions
to which he has been exposed,
as "far more domesticated"*(2)
than any other animal. Some savage
races, such as the Australians,
are not exposed to more diversified
conditions than are many species
which have a wide range. In another
and much more important respect,
man differs widely from any strictly
domesticated animal; for his
breeding has never long been
controlled, either by methodical
or unconscious selection. No
race or body of men has been
so completely subjugated by other
men, as that certain individuals
should be preserved, and thus
unconsciously selected, from
somehow excelling in utility
to their masters. Nor have certain
male and female individuals been
intentionally picked out and
matched, except in the well-known
case of the Prussian grenadiers;
and in this case man obeyed,
as might have been expected,
the law of methodical selection;
for it is asserted that many
tall men were reared in the villages
inhabited by the grenadiers and
their tall wives. In Sparta,
also, a form of selection was
followed, for it was enacted
that all children should be examined
shortly after birth; the well-formed
and vigorous being preserved,
the others left to perish.*(3)
* Mr. Bates
remarks (The Naturalist on
the Amazons, 1863, vol. ii
p. 159), with respect to the
Indians of the same South American
tribe, "no two of them were at
all similar in the shape of the
head; one man had an oval visage
with fine features, and another
was quite Mongolian in breadth
and prominence of cheek, spread
of nostrils, and obliquity of
eyes."
*(2) Blumenbach, Treatises on
Anthropology., Eng. translat.,
1865, p. 205.
*(3) Mitford's History of Greece,
vol. i., p. 282. It appears from
a passage in Xenophon's Memorabilia,
B. ii. 4 (to which my attention
has been called by the Rev. J.
N. Hoare), that it was a well
recognised principle with the
Greeks, that men ought to select
their wives with a view to the
health and vigour of their children.
The Grecian poet, Theognis, who
lived 550 B. C., clearly saw
how important selection, if carefully
applied, would be for the improvement
of mankind. He saw, likewise,
that wealth often checks the
proper action of sexual selection.
He thus writes:
With kine and horses, Kurnus!
we proceed
By reasonable rules, and choose
a breed
For profit and increase at
any price:
Of a sound stock, without defect
or vice.
But, in the daily matches that
we make,
The price is everything: for
money's sake,
Men marry: women are in marriage
given
The churl or ruffian, that
in wealth has thriven,
May match his offspring with
the proudest race:
Thus everything is mix'd, noble
and base!
If then in outward manner,
form, and mind,
You find us a degraded, motley
kind,
Wonder no more, my friend!
the cause is plain,
And to lament the consequence
is vain.
(The Works of J. Hookham Frere,
vol. ii., 1872, p. 334.)
If we consider all the races
of man as forming a single species,
his range is enormous; but some
separate races, as the Americans
and Polynesians, have very wide
ranges. It is a well-known law
that widely-ranging species are
much more variable than species
with restricted ranges; and the
variability of man may with more
truth be compared with that of
widely-ranging species, than
with that of domesticated animals.
Not only does variability appear
to be induced in man and the
lower animals by the same general
causes, but in both the same
parts of the body are effected
in a closely analogous manner.
This has been proved in such
full detail by Godron and Quatrefages,
that I need here only refer to
their works.* Monstrosities,
which graduate into slight variations,
are likewise so similar in man
and the lower animals, that the
same classification and the same
terms can be used for both, as
has been shewn by Isidore Geoffroy
St-Hilaire.*(2) In my work on
the variation of domestic animals,
I have attempted to arrange in
a rude fashion the laws of variation
under the following heads:- The
direct and definite action of
changed conditions, as exhibited
by all or nearly all the individuals
of the same species, varying
in the same manner under the
same circumstances. The effects
of the long-continued use or
disuse of parts. The cohesion
of homologous parts. The variability
of multiple parts. Compensation
of growth; but of this law I
have found no good instance in
the case of man. The effects
of the mechanical pressure of
one part on another; as of the
pelvis on the cranium of the
infant in the womb. Arrests of
development, leading to the diminution
or suppression of parts. The
reappearance of long-lost characters
through reversion. And lastly,
correlated variation. All these
so-called laws apply equally
to man and the lower animals;
and most of them even to plants.
It would be superfluous here
to discuss all of them;*(3) but
several are so important, that
they must be treated at considerable
length.
* Godron, De l'Espece, 1859,
tom. ii., livre 3. Quatrefages,
Unite de l'Espece Humaine, 1861.
Also Lectures on Anthropology,
given in the Revue des Cours
Scientifiques, 1866-1868.
*(2) Hist. Gen. et Part. des
Anomalies de l'Organisation,
tom. i., 1832.
*(3) I have
fully discussed these laws
in my Variation of
Animals and Plants under Domestication,
vol. ii., chaps. xxii. and xxiii.
M. J. P. Durand has lately (1868)
published a valuable essay, De
l'Influence des Milieux, &c.
He lays much stress, in the case
of plants, on the nature of the
soil.
The Direct and Definite Action
of Changed Conditions.- This
is a most perplexing subject.
It cannot be denied that changed
conditions produce some, and
occasionally a considerable effect,
on organisms of all kinds; and
it seems at first probable that
if sufficient time were allowed
this would be the invariable
result. But I have failed to
obtain clear evidence in favour
of this conclusion; and valid
reasons may be urged on the other
side, at least as far as the
innumerable structures are concerned,
which are adapted for special
ends. There can, however, be
no doubt that changed conditions
induce an almost indefinite amount
of fluctuating variability, by
which the whole organisation
is rendered in some degree plastic.
In the United
States, above 1,000,000 soldiers,
who served
in the late war, were measured,
and the States in which they
were born and reared were recorded.*
From this astonishing number
of observations it is proved
that local influences of some
kind act directly on stature;
and we further learn that "the
State where the physical growth
has in great measure taken place,
and the State of birth, which
indicates the ancestry, seem
to exert a marked influence on
the stature." For instance, it
is established, "that residence
in the Western States, during
the years of growth, tends to
produce increase of stature." On
the other hand, it is certain
that with sailors, their life
delays growth, as shewn "by the
great difference between the
statures of soldiers and sailors
at the ages of seventeen and
eighteen years." Mr. B. A. Gould
endeavoured to ascertain the
nature of the influences which
thus act on stature; but he arrived
only at negative results, namely
that they did not relate to climate,
the elevation of the land, soil,
nor even "in any controlling
degree" to the abundance or the
need of the comforts of life.
This latter conclusion is directly
opposed to that arrived at by,
Villerme, from the statisties
of the height of the conscripts
in different parts of France.
When we compare the differences
in stature between the Polynesian
chiefs and the lower orders within
the same islands, or between
the inhabitants of the fertile
volcanic and low barren coral
islands of the same ocean,*(2)
or again between the Fuegians
on the eastern and western shores
of their country, where the means
of subsistence are very different,
it is scarcely possible to avoid
the conclusion that better food
and greater comfort do influence
stature. But the preceding statements
shew how difficult it is to arrive
at any precise result. Dr. Beddoe
has lately proved that, with
the inhabitants of Britain, residence
in towns and certain occupations
have a deteriorating influence
on height; and he infers that
the result is to a certain extent
inherited, as is likewise the
case in the United States. Dr.
Beddoe further believes that
wherever a "race attains its
maximum of physical development,
it rises highest in energy and
moral vigour."*(3)
* Investigations
in Military and Anthrop. Statistics, &c.,
1869, by B. A. Gould, pp. 93,
107, 126, 131, 134.
*(2) For the Polynesians, see
Prichard's Physical History of
Mankind, vol. v., 1847, pp. 145,
283. Also Godron, De l'Espece,
tom. ii., p. 289. There is also
a remarkable difference in appearance
between the closely-allied Hindoos
inhabiting the Upper Ganges and
Bengal; see Elphinstone's History
of India, vol. i., p. 324.
*(3) Memoirs, Anthropological
Society, vol. iii., 1867-69,
pp. 561, 565, 567. Whether external
conditions produce any other
direct effect on man is not known.
It might have been expected that
differences of climate would
have had a marked influence,
inasmuch as the lungs and kidneys
are brought into activity under
a low temperature, and the liver
and skin under a high one.* It
was formerly thought that the
colour of the skin and the character
of the hair were determined by
light or heat; and although it
can hardly be denied that some
effect is thus produced, almost
all observers now agree that
the effect has been very small,
even after exposure during many
ages. But this subject will be
more properly discussed when
we treat of the different races
of mankind. With our domestic
animals there are grounds for
believing that cold and damp
directly affect the growth of
the hair; but I have not met
with any evidence on this head
in the case of man.
* Dr. Brakenridge, "Theory of
Diathesis," Medical Times, June
19 and July 17, 1869.
Effects of the increased Use
and Disuse of Parts.- It is well
known that use strengthens the
muscles in the individual, and
complete disuse, or the destruction
of the proper nerve, weakens
them. When the eye is destroyed,
the optic nerve often becomes
atrophied. When an artery is
tied, the lateral channels increase
not only in diameter, but in
the thickness and strength of
their coats. When one kidney
ceases to act from disease, the
other increases in size, and
does double work. Bones increase
not only in thickness, but in
length, from carrying a greater
weight.* Different occupations,
habitually followed, lead to
changed proportions in various
parts of the body. Thus it was
ascertained by the United States
Commission*(2) that the legs
of the sailors employed in the
late war were longer by 0.217
of an inch than those of the
soldiers, though the sailors
were on an average shorter men;
whilst their arms were shorter
by 1.09 of an inch, and therefore,
out of proportion, shorter in
relation to their lesser height.
This shortness of the arms is
apparently due to their greater
use, and is an unexpected result:
but sailors chiefly use their
arms in pulling, and not in supporting
weights. With sailors, the girth
of the neck and the depth of
the instep are greater, whilst
the circumference of the chest,
waist, and hips is less, than
in soldiers.
* I have given
authorities for these several
statements in my
Variation of Animals and Plants
under Domestication, vol. ii.,
pp. 297-300. Dr. Jaeger, "Uber
das Langenwachsthum der Knochen," Jenaische
Zeitschrift, B. v., Heft. i.
*(2) Investigations, &c.,
by B. A. Gould, 1869, p. 288.
Whether the
several foregoing modifications
would become hereditary,
if the same habits of life were
followed during many generations,
is not known, but it is probable.
Rengger* attributes the thin
legs and thick arms of the Payaguas
Indians to successive generations
having passed nearly their whole
lives in canoes, with their lower
extremities motionless. Other
writers have come to a similar
conclusion in analogous cases.
According to Cranz,*(2) who lived
for a long time with the Esquimaux, "The
natives believe that ingenuity
and dexterity in seal-catching
(their highest art and virtue)
is hereditary; there is is really
something in it, for the son
of a celebrated seal-catcher
will distinguish himself, though
he lost his father in childhood." But
in this case it is mental aptitude,
quite as much as bodily structure,
which appears to be inherited.
It is asserted that the hands
of English labourers are at birth
larger than those of the gentry.*(3)
From the correlation which exists,
at least in some cases,*(4) between
the development of the extremities
and of the jaws, it is possible
that in those classes which do
not labour much with their hands
and feet, the jaws would be reduced
in size from this cause. That
they are generally smaller in
refined and civilized men than
in hard-working men or savages,
is certain. But with savages,
as Mr. Herbert Spencer*(5) has
remarked, the greater use of
the jaws in chewing coarse, uncooked
food, would act in a direct manner
on the masticatory muscles, and
on the bones to which they are
attached. In infants, long before
birth, the skin on the soles
of the feet is thicker than on
any other part of the body;*(6)
and it can hardly be doubted
that this is due to the inherited
effects of pressure during a
long series of generations.
* Saugethiere von Paraguay,
1830, s. 4.
*(2) History of Greenland, Eng.
translat., 1767, vol. i., p.
230
*(3) Intermarriage, by Alex.
Walker, 1838, p. 377.
*(4) The Variation of Animals
and Plants under Domestication,
vol. i., p. 173.
*(5) Principles of Biology,
vol. i., p. 455.
*(6) Paget, Lectures on Surgical
Pathology, vol. ii, 1853, p.
209.
It is familiar to every one
that watchmakers and engravers
are liable to be short-sighted,
whilst men living much out of
doors, and especially savages,
are generally long-sighted.*
Short-sight and long-sight certainly
tend to be inherited.*(2) The
inferiority of Europeans, in
comparison with savages, in eyesight
and in the other senses, is no
doubt the accumulated and transmitted
effect of lessened use during
many generations; for Rengger*(3)
states that he has repeatedly
observed Europeans, who had been
brought up and spent their whole
lives with the wild Indians,
who nevertheless did not equal
them in the sharpness of their
senses. The same naturalist observes
that the cavities in the skull
for the reception of the several
sense-organs are larger in the
American aborigines than in Europeans;
and this probably indicates a
corresponding difference in the
dimensions of the organs themselves.
Blumenbach has also remarked
on the large size of the nasal
cavities in the skulls of the
American aborigines, and connects
this fact with their remarkably
acute power of smell. The Mongolians
of the plains of northern Asia,
according to Pallas, have wonderfully
perfect senses; and Prichard
believes that the great breadth
of their skulls across the zygomas
follows from their highly-developed
sense organs.*(4)
* It is a singular
and unexpected fact that sailors
are inferior
to landsmen in their mean distance
of distinct vision. Dr. B. A.
Gould (Sanitary Memoirs of the
War of the Rebellion, 1869 p.
530), has proved this to be the
case; and he accounts for it
by the ordinary range of vision
in sailors being "restricted
to the length of the vessel and
the height of the masts."
*(2) The Variation of Animal
and Plants under Domestication,
vol. i., p. 8.
*(3) Saugethiere
von Paraguay, s. 8, 10. I have
had good opportunities
for observing the extraordinary
power of eyesight in the Fuegians.
See also Lawrence (Lectures on
Physiology, &c., 1822, p. 404)
on this same subject. M. Giraud-Teulon
has recently collected (Revue
des Cours Scientifiques, 1870,
p. 625) a large and valuable
body of evidence proving that
the cause of short-sight, "C'est
le travail assidu, de pres."
*(4) Prichard, Physical History
of Mankind, on the authority
of Blumenbach, vol. i., 1841,
p. 311; for the statement by
Pallas, vol. iv., 1844, p. 407.
The Quechua Indians inhabit
the lofty plateaux of Peru; and
Alcide d'Orbigny states* that,
from continually breathing a
highly rarefied atmosphere, they
have acquired chests and lungs
of extraordinary dimensions.
The cells, also, of the lungs
are larger and more numerous
than in Europeans. These observations
have been doubted, but Mr. D.
Forbes carefully measured many
Aymaras, an allied race, living
at the height of between 10,000
and 15,000 feet; and he informs
me*(2) that they differ conspicuously
from the men of all other races
seen by him in the circumference
and length of their bodies. In
his table of measurements, the
stature of each man is taken
at 1000, and the other measurements
are reduced to this standard.
It is here seen that the extended
arms of the Aymaras are shorter
than those of Europeans, and
much shorter than those of Negroes.
The legs are likewise shorter;
and they present this remarkable
peculiarity, that in every Aymara
measured, the femur is actually
shorter than the tibia. On an
average, the length of the femur
to that of the tibia is as 211
to 252; whilst in two Europeans,
measured at the same time, the
femora to the tibiae were as
244 to 230; and in three Negroes
as 258 to 241. The humerus is
likewise shorter relatively to
the forearm. This shortening
of that part of the limb which
is nearest to the body, appears
to be, as suggested to me by
Mr. Forbes, a case of compensation
in relation with the greatly
increased length of the trunk.
The Aymaras present some other
singular points of structure,
for instance, the very small
projection of the heel.
* Quoted by Prichard, Researches
into the Physical History of
Mankind, vol. v., p. 463.
*(2) Mr. Forbes' valuable paper
is now published in the Journal
of the Ethnological Society of
London, new series, vol. ii.,
1870, p. 193.
These men are so thoroughly
acclimatised to their cold and
lofty abode, that when formerly
carried down by Spaniards to
the low eastern plains, and when
now tempted down by high wages
to the gold-washings, they suffer
a frightful rate of mortality.
Nevertheless Mr. Forbes found
a few pure families which had
survived during two generations:
and he observed that they still
inherited their characteristic
peculiarities. But it was manifest,
even without measurement, that
these peculiarities had all decreased;
and on measurement, their bodies
were found not to be so much
elongated as those of the men
on the high plateau; whilst their
femora had become somewhat lengthened,
as had their tibiae, although
in a less degree. The actual
measurements may be seen by consulting
Mr. Forbes's memoir. From these
observations, there can, I think,
be no doubt that residence during
many generations at a great elevation
tends, both directly and indirectly,
to induce inherited modifications
in the proportions of the body.*
* Dr. Wilckens (Landwirthschaft.
Wochenblatt, No. 10, 1869) has
lately published an interesting
essay shewing how domestic animals,
which live in mountainous regions,
have their frames modified.
Although man may not have been
much modified during the latter
stages of his existence through
the increased or decreased use
of parts, the facts now given
shew that his liability in this
respect has not been lost; and
we positively know that the same
law holds good with the lower
animals. Consequently we may
infer that when at a remote epoch
the progenitors of man were in
a transitional state, and were
changing from quadrupeds into
bipeds, natural selection would
probably have been greatly aided
by the inherited effects of the
increased or diminished use of
the different parts of the body.
Arrests of Development.-
There is a difference between
arrested
development and arrested growth,
for parts in the former state
continue to grow whilst still
retaining their early condition.
Various monstrosities come under
this head; and some, as a cleft
palate, are known to be occasionally
inherited. It will suffice for
our purpose to refer to the arrested
brain-development of microcephalous
idiots, as described in Vogt's
memoir.* Their skulls are smaller,
and the convolutions of the brain
are less complex than in normal
men. The frontal sinus, or the
projection over the eyebrows,
is largely developed, and the
jaws are prognathous to an "effrayant" degree;
so that these idiots somewhat
resemble the lower types of mankind.
Their intelligence, and most
of their mental faculties, are
extremely feeble. They cannot
acquire the power of speech,
and are wholly incapable of prolonged
attention, but are much given
to imitation. They are strong
and remarkably active, continually
gambolling and jumping about,
and making grimaces. They often
ascend stairs on all-fours; and
are curiously fond of climbing
up furniture or trees. We are
thus reminded of the delight
shewn by almost all boys in climbing
trees; and this again reminds
us how lambs and kids, originally
alpine animals, delight to frisk
on any hillock, however small.
Idiots also resemble the lower
animals in some other respects;
thus several cases are recorded
of their carefully smelling every
mouthful of food before eating
it. One idiot is described as
often using his mouth in aid
of his hands, whilst hunting
for lice. They are often filthy
in their habits, and have no
sense of decency; and several
cases have been published of
their bodies being remarkably
hairy.*(2)
* Memoires sur les Microcephales,
1867, pp. 50, 125, 169, 171,
184-198.
*(2) Prof. Laycock sums up the
character of brute-like idiots
by calling them theroid; Journal
of Mental Science,, July, 1863.
Dr. Scott (The Deaf and Dumb,
2nd ed., 1870, p. 10) has often
observed the imbeciles smelling
their food. See, on this same
subject, and on the hairiness
of idiots, Dr. Maudsley, Body
and Mind, 1870, pp. 46-51. Pinel
has also given a striking case
of hairiness in an idiot.
Reversion.- Many of the cases
to be here given, might have
been introduced under the last
heading. When a structure is
arrested in its development,
but still continues growing,
until it closely resembles a
corresponding structure in some
lower and adult member of the
same group, it may in one sense
be considered as a case of reversion.
The lower members in a group
give us some idea how the common
progenitor was probably constructed;
and it is hardly credible that
a complex part, arrested at an
early phase of embryonic development,
should go on growing so as ultimately
to perform its proper function,
unless it had acquired such power
during some earlier state of
existence, when the present exceptional
or arrested structure was normal.
The simple brain of a microcephalous
idiot, in as far as it resembles
that of an ape' may in this sense
be said to offer a case of reversion.*
There are other cases which come
more strictly under our present
head of reversion. Certain structures,
regularly occurring in the lower
members of the group to which
man belongs, occasionally make
their appearance in him, though
not found in the normal human
embryo; or, if normally present
in the human embryo, they become
abnormally developed, although
in a manner which is normal in
the lower members of the group.
These remarks will be rendered
clearer by the following illustrations.
* In my Variation of Animals
under Domestication (vol. ii.,
p. 57), I attributed the not
very rare cases of supernumerary
mammae in women to reversion.
I was led to this as a probable
conclusion, by the additional
mammae being generally placed
symmetrically on the breast;
and more especially from one
case, in which a single efficient
mamma occurred in the inguinal
region of a woman, the daughter
of another woman with supernumerary
mammae. But I now find (see,
for instance, Prof. Preyer, Der
Kampf um das Dasein, 1869, s.
45) that mammae erraticae, occur
in other situations, as on the
back, in the armpit, and on the
thigh; the mammae in this latter
instance having given so much
milk that the child was thus
nourished. The probability that
the additional mammae are due
to reversion is thus much weakened;
nevertheless, it still seems
to me probable, because two pairs
are often found symmetrically
on the breast; and of this I
myself have received information
in several cases. It is well
known that some lemurs normally
have two pairs of mammae on the
breast. Five cases have been
recorded of the presence of more
than a pair of mammee (of course
rudimentary) in the male sex
of mankind; see Journal of Anat.
and Physiology, 1872, p. 56,
for a case given by Dr. Handyside
in which two brothers exhibited
this peculiarity; see also a
paper by Dr. Bartels, in Reichert's
and du Bois-Reymond's Archiv.,
1872, p. 304. In one of the cases
alluded to by Dr. Bartels, a
man bore five mammae, one being
medial and placed above the navel;
Meckel von Hemsbach thinks that
this latter case is illustrated
by a medial mamma occurring in
certain Cheiroptera. On the whole,
we may well doubt if additional
mammae would ever have been developed
in both sexes of mankind, had
not his early progenitors been
provided with more than a single
pair.
In the above
work (vol. ii., p. 12), I also
attributed, though
with much hesitation, the frequent
cases of polydactylism in men
and various animals to reversion.
I was partly led to this through
Prof. Owen's statement, that
some of the Ichthyopterygia possesses
more than five digits, and therefore,
as I supposed, had retained a
primordial condition; but Prof.
Gegenbaur (Jenaische Zeitschrift,
B. v., Heft 3, s. 341), disputes
Owen's conclusion. On the other
hand, according to the opinion
lately advanced by Dr. Gunther,
on the paddle of Ceratodus, which
is provided with articulated
bony rays on both sides of a
central chain of bones, there
seems no great difficulty in
admitting that six or more digits
on one side, or on both sides,
might reappear through reversion.
I am informed by Dr. Zouteveen
that there is a case on record
of a man having twenty-four fingers
and twenty-four toes! I was chiefly
led to the conclusion that the
presence of supernumerary digits
might be due to reversion from
the fact that such digits, not
only are strongly inherited,
but, as I then believed, had
the power of regrowth after amputation,
like the normal digits of the
lower Vertebrata. But I have
explained in the second edition
of my Variation under Domestication
why I now place little reliance
on the recorded cases of such
regrowth. Nevertheless it deserves
notice, inasmuch as arrested
development and reversion are
intimately related processes;
that various structures in an
embryonic or arrested condition,
such as a cleft palate, bifid
uterus, &c., are frequently accompanied
by polydactylism. This has been
strongly insisted on by Meckel
and Isidore Geoffroy St-Hilaire.
But at present it is the safest
course to give up altogether
the idea that there is any relation
between the development of supernumerary
digits and reversion to some
lowly organized progenitor of
man.
In various mammals
the uterus graduates from a
double organ
with two distinct orifices and
two passages, as in the marsupials,
into a single organ, which is
in no way double except from
having a slight internal fold,
as in the higher apes and man.
The rodents exhibit a perfect
series of gradations between
these two extreme states. In
all mammals the uterus is developed
from two simple primitive tubes,
the inferior portions of which
form the cornua; and it is in
the words of Dr. Farre, "by the
coalescence of the two cornua
at their lower extremities that
the body of the uterus is formed
in man; while in those animals
in which no middle portion or
body exists, the cornua remain
ununited. As the development
of the uterus proceeds, the two
cornua become gradually shorter,
until at length they are lost,
or, as it were, absorbed into
the body of the uterus." The
angles of the uterus are still
produced into cornua, even in
animals as high up in the scale
as the lower apes and lemurs.
Now in women,
anomalous cases are not very
infrequent, in which
the mature uterus is furnished
with cornua, or is partially
divided into two organs; and
such cases, according to Owen,
repeat "the grade of concentrative
development," attained by certain
rodents. Here perhaps we have
an instance of a simple arrest
of embryonic development, with
subsequent growth and perfect
functional development; for either
side of the partially double
uterus is capable of performing
the proper office of gestation.
In other and rarer cases, two
distinct uterine cavities are
formed, each having its proper
orifice and passage.* No such
stage is passed through during
the ordinary development of the
embryo; and it is difficult to
believe, though perhaps not impossible,
that the two simple, minute,
primitive tubes should know how
(if such an expression may be
used) to grow into two distinct
uteri, each with a well-constructed
orifice,and passage, and each
furnished with numerous muscles,
nerves, glands and vessels, if
they had not formerly passed
through a similar course of development,
as in the case of existing marsupials.
No one will pretend that so perfect
a structure as the abnormal double
uterus in woman could be the
result of mere chance. But the
principle of reversion, by which
a long-lost structure is called
back into existence, might serve
as the guide for its full development,
even after the lapse of an enormous
interval of time.
* See Dr. A. Farre's well-known
article in the Cyclopaedia of
Anatomy and Physiology, vol.
v., 1859, p. 642. Owen, Anatomy
of Vertebrates, vol. iii., 1868,
p. 687. Professor Turner, in
Edinburgh Medical Journal, February,
1865.
Professor Canestrini, after
discussing the foregoing and
various analogous cases, arrives
at the same conclusion as that
just given. He adduces another
instance, in the case of the
malar bone,* which, in some of
the Quadrumana and other mammals,
normally consists of two portions.
This is its condition in the
human foetus when two months
old; and through arrested development,
it sometimes remains thus in
man when adult, more especially
in the lower prognathous races.
Hence Canestrini concludes that
some ancient progenitor of man
must have had this bone normally
divided into two portions, which
afterwards became fused together.
In man the frontal bone consists
of a single piece, but in the
embryo, and in children, and
in almost all the lower mammals,
it consists of two pieces separated
by a distinct suture. This suture
occasionally persists more or
less distinctly in man after
maturity; and more frequently
in ancient than in recent crania,
especially, as Canestrini has
observed, in those exhumed from
the Drift, and belonging to the
brachycephalic type. Here again
he comes to the same conclusion
as in the analogous case of the
malar bones. In this, and other
instances presently to be given,
the cause of ancient races approaching
the lower animals in certain
characters more frequently than
do the modern races, appears
to be, that the latter stand
at a somewhat greater distance
in the long line of descent from
their early semi-human progenitors.
* Annuario della
Soc. dei Naturalisti, Modena,
1867, p. 83. Prof. Canestrini
gives extracts on this subject
from various authorities. Laurillard
remarks, that as he has found
a complete similarity in the
form, proportions, and connection
of the two malar bones in several
human subjects and in certain
apes, he cannot consider this
disposition of the parts as simply
accidental. Another paper on
this same anomaly has been published
by Dr. Saviotti in the Gazzetta
delle Cliniche, Turin, 1871,
where he says that traces of
the division may be detected
in about two per cent of adult
skulls; he also remarks that
it more frequently occurs in
prognathous skulls, not of the
Aryan race, than in others. See
also G. Delorenzi on the same
subject; "Tre nuovi casi d'anomalia
dell' osso malare," Torino, 1872.
Also, E. Morselli, "Sopra una
rara anomalia dell' osso malare," Modena,
1872. Still more recently Gruber
has written a pamphlet on the
division of this bone. I give
these references because a reviewer,
without any grounds or scruples,
has thrown doubts on my statements.
Various other anomalies in man,
more or less analogous to the
foregoing, have been advanced
by different authors, as cases
of reversion; but these seem
not a little doubtful, for we
have to descend extremely low
in the mammalian series, before
we find such structures normally
present.*
* A whole series
of cases is given by Isidore
Geoffroy St-Hilaire,
Hist. des Anomalies, tom, iii,
p. 437. A reviewer (Journal of
Anatomy and Physiology, 1871,
p. 366) blames me much for not
having discussed the numerous
cases, which have been recorded,
of various parts arrested in
their development. He says that,
according to my theory, "every
transient condition of an organ,
during its development, is not
only a means to an end, but once
was an end in itself." This does
not seem to me necessarily to
hold good. Why should not variations
occur during an early period
of development, having no relation
to reversion; yet such variations
might be preserved and accumulated,
if in any way serviceable, for
instance, in shortening and simplifying
the course of development? And
again, why should not injurious
abnormalities, such as atrophied
or hypertrophied parts, which
have no relation to a former
state of existence, occur at
an early period, as well as during
maturity?
In man, the
canine teeth are perfectly
efficient instruments
for mastication. But their true
canine character, as Owen* remarks, "is
indicated by the conical form
of the crown, which terminates
in an obtuse point, is convex
outward and flat or sub-concave
within, at the base of which
surface there is a feeble prominence.
The conical form is best expressed
in the Melanian races, especially
the Australian. The canine is
more deeply implanted, and by
a stronger fang than the incisors." Nevertheless,
this tooth no longer serves man
as a special weapon for tearing
his enemies or prey; it may,
therefore, as far as its proper
function is concerned, be considered
as rudimentary. In every large
collection of human skulls some
may be found, as Haeckel*(2)
observes, with the canine teeth
projecting considerably beyond
the others in the same manner
as in the anthropomorphous apes,
but in a less degree. In these
cases, open spaces between the
teeth in the one jaw are left
for the reception of the canines
of the opposite jaw. An inter-space
of this kind in a Kaffir skull,
figured by Wagner, is surprisingly
wide.*(3) Considering how few
are the ancient skulls which
have been examined, compared
to recent skulls, it is an interesting
fact that in at least three cases
the canines project largely;
and in the Naulette jaw they
are spoken of as enourmous.*(4)
* Anatomy of Vertebrates, vol.
iii., 1868, p. 323.
*(2) Generelle Morphologie,
1866, B. ii., s. clv.
*(3) Carl Vogt's Lectures on
Man, Eng. translat., 1864, p.
151.
*(4) C. Carter Blake, on a jaw
from La Naulette, Anthropological
Review, 1867, p. 295. Schaaffhausen,
ibid., 1868, p. 426.
Of the anthropomorphous
apes the males alone have their
canines
fully 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.
* The Anatomy of Expression,
1844, pp. 110, 131.
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.
* Quoted by Prof. Canestrini
in the Annuario, della Soc. dei
Naturalisti, 1867, p. 90.
Mr. J. Wood,
in his valuable series of papers,*
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 Quadrumans,
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.*(2)
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,*(3) and it
occurs in about one out of sixty
human subjects. In the lower
extremities Mr. Bradley*(4) 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.*(5)
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 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."*(6)
* These papers deserve 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.
*(2) See also Prof. Macalister
in Proceedings, Royal Irish Academy,
vol. x., 1868, p. 124.
*(3) Mr. Champneys in Journal
of Anatomy and Physiology, Nov.,
1871, p. 178.
*(4) Ibid., May, 1872, p. 421.
*(5) 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, &c.
*(6) 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 shows 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.*
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.
* 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
shows 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."
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.* 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.
* The authorities for these
several statements are given
in my Variation of Animals and
Plants under Domestication, vol.
ii., pp. 320-335.
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.*
* 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.*
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.
* See the ever memorable Essay
on the Principle of Population,
by the Rev. T. Malthus, vol.
i. 1826. pp. 6, 517.
There is great 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
hardships, and who do not obtain
so much nutritious food as civilised
men, would be actually less prolific.
I have shewn in a former work,*
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.*(2)
* Variation of Animals and Plants
under Domestication, vol ii.,
pp. 111-113, 163.
*(2) 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,* 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.
* The Animals of Rural Bengal,
by W. W. Hunter, 1868, p. 259.
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* 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.
* Primitive Marriage, 1865.
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* 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.
* 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?"
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 migration,* 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.*(2)
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,*(3)
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.
* See some good
remarks to this effect by W.
Stanley Jevons, "A
Deduction from Darwin's Theory," Nature
1869, p. 231.
*(2) Latham, Man and his Migrations,
1851, p. 135.
*(3) 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.
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: "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, &c.,
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*(2) maintains,
that "natural selection could
only have endowed the savage
with a brain a little superior
to that of an ape."
* "Limits of Natural Selection," North
American Review, Oct., 1870,
p. 295.
*(2) 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."
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,* 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.
* 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.
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 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.
* Owen, Anatomy of Vertebrates,
vol. iii., p. 71.
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* 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.*(2)
* Quarterly Review, April, 1869,
p. 392.
*(2) 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, Illustriertes
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 hooklike.
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;* 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*(2) 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.*(3)
* Brehm, Illustriertes Thierleben,
B. i., s. 80.
*(2) "The Hand," &c.,
Bridgewater Treatise, 1833,
p. 38.
*(3) 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* insists,
the anthropomorphous apes approach
in structure more nearly to the
bipedal than to the quadrupedal
type.
* Prof. Broca, "La Constitution
des vertebres caudales"; La Revue
d'Anthropologie, 1872, p. 26,
(separate copy).
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. Prof. Schaaffhausen*
maintains that "the powerful
mastoid processes of the human
skull are the result of his erect
position"; and these processes
are absent in the orang, chimpanzee, &c.,
and are smaller in the gorilla
than in man. Various other structures,
which appear connected with man's
erect position, might here have
been added. It is very difficult
to decide how far these correlated
modifications are the result
of natural selection, and how
far of the inherited effects
of the increased use of certain
parts, or of the action of one
part on another. No doubt these
means of change often co-operate:
thus when certain muscles, and
the crests of bone to which they
are attached, become enlarged
by habitual use, this shews that
certain actions are habitually
performed and must be serviceable.
Hence the individuals which performed
them best, would tend to survive
in greater numbers.
* "On the Primitive Form of
the Skull," translated in Anthropological
Review, Oct., 1868, p. 428. Owen
(Anatomy of Vertebrates, vol.
ii., 1866, p. 551) on the mastoid
processes in the higher apes.
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. In a future
chapter we shall meet with a
closely parallel case, in the
reduction or complete disappearance
of the canine teeth in male ruminants,
apparently in relation with the
development of their horns; and
in horses, in relation to their
habit of fighting with their
incisor teeth and hoofs.
In the adult
male anthropomorphous apes,
as Rutimeyer,* and others,
have insisted, it is the effect
on the skull of the great development
of the jaw-muscles that causes
it to differ so greatly in many
respects from that of man, and
has given to these animals "a
truly frightful physiognomy." Therefore,
as the jaws and teeth in man's
progenitors gradually become
reduced in size, the adult skull
would have come to resemble more
and more that of existing man.
As we shall hereafter see, a
great reduction of the canine
teeth in the males would almost
certainly affect the teeth of
the females through inheritance.
* Die Grenzen der Thierwelt,
eine Betrachtung zu Darwin's
Lehre, 1868, s. 51.
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 marvellous atoms of
matter in the world, perhaps
more so than the brain of a man.
* Dujardin, Annales des Sciences
Nat., 3rd series, Zoolog., tom.
xiv., 1850, p. 203. See also
Mr. Lowne, Anatomy and Phys.
of the Musca vomitoria, 1870,
p. 14. My son, Mr. F. Darwin,
dissected for me the cerebral
ganglia of the Formica rufa.
The belief that
there exists in man some close
relation between
the size of the brain and the
development of the intellectual
faculties is supported by the
comparison of the skulls of savage
and civilised races, of ancient
and modern people, and by the
analogy of the whole vertebrate
series. Dr. J. Barnard Davis
has proved,* by many careful
measurements, that the mean internal
capacity of the skull in Europeans
is 92.3 cubic inches; in Americans
87.5; in Asiatics 87.1; and in
Australians only 81.9 cubic inches.
Professor Broca*(2) found that
the nineteenth century skulls
from graves in Paris were larger
than those from vaults of the
twelfth century, in the proportion
of 1484 to 1426; and that the
increased size, as ascertained
by measurements, was exclusively
in the frontal part of the skull-
the seat of the intellectual
faculties. Prichard is persuaded
that the present inhabitants
of Britain have "much more capacious
braincases" than the ancient
inhabitants. Nevertheless, it
must be admitted that some skulls
of very high antiquity, such
as the famous one of Neanderthal,
are well developed and capacious.*(3)
With respect to the lower animals,
M. E. Lartet,*(4) by comparing
the crania of tertiary and recent
mammals belonging to the same
groups, has come to the remarkable
conclusion that the brain is
generally larger and the convolutions
are more complex in the more
recent forms. On the other hand,
I have shewn*(5) that the brains
of domestic rabbits are considerably
reduced in bulk, in comparison
with those of the wild rabbit
or hare; and this may be attributed
to their having been closely
confined during many generations,
so that they have exerted their
intellect, instincts, senses
and voluntary movements but little.
* Philosophical Transactions,
1869, p. 513.
*(2) "Les Selections," M.
P. Broca, Revue d'Anthropologie,,
1873; see also, as quoted in
C. Vogt's Lectures on Man, Engl.
translat., 1864, pp. 88, 90.
Prichard, Physical History of
Mankind, vol. i., 1838, p. 305.
*(3) In the interesting article
just referred to, Prof. Broca
has well remarked, that in civilised
nations, the average capacity
of the skull must be lowered
by the preservation of a considerable
number of individuals, weak in
mind and body, who would have
been promptly eliminated in the
savage state. On the other hand,
with savages, the average includes
only the more capable individuals,
who have been able to survive
under extremely hard conditions
of life. Broca thus explains
the otherwise inexplicable fact,
that the mean capacity of the
skull of the ancient troglodytes
of Lozere is greater than that
of modern Frenchmen.
*(4) Comptes-rendus
des Sciences, &c.,
June 1, 1868.
*(5) The Variation of Animals
and Plants under Domestication,
vol. i., pp. 124-129.
The gradually
increasing weight of the brain
and skull in man
must have influenced the development
of the supporting spinal column,
more especially whilst 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 shew how easily the skull
is thus effected. 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 backwards, 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 shewn
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, whilst 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.*(2) 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";*(3)
and tall men may be compared
with the larger and longer-bodied
rabbits, all of which have elongated
skulls or are dolichocephalic.
* Schaaffhausen gives from Blumenbach
and Busch, the cases of the spasms
and cicatrix in Anthropological
Review, Oct., 1868, p. 420. Dr.
Jarrold (Anthropologia, 1808,
pp. 115, 116) adduces from Camper
and from his own observations,
cases of the modification of
the skull from the head being
fixed in an unnatural position.
He believes that in certain trades,
such as that of a shoemaker,
where the head is habitually
held forward, the forehead becomes
more rounded and prominent.
*(2) Variation of Animals and
Plants under Domestication, vol.
i., p. 117, on the elongation
of the skull; p. 119, on the
effect of the lopping of one
ear.
*(3) Quoted by Schaaffhausen,
in Anthropological Review, Oct.,
1868, p. 419.
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.
Another most conspicuous difference
between man and the lower animals
is the nakedness of his 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, favours 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,*(2)
is opposed to the supposition
that man became naked through
the action of the sun. Mr. Belt
believes*(3) that within the
tropies it is an advantage to
man to be destitute of hair,
as he is thus enabled to free
himself of the multitude of ticks
(acari) and other parasites,
with which he is often infested,
and which sometimes cause ulceration.
But whether this evil is of sufficient
magnitude to have led to the
denudation of his body through
natural selection, may be doubted,
since none of the many quadrupeds
inhabiting the tropics have,
as far as I know, acquired any
specialised means of relief.
The view which seems to me the
most probable is that man, or
rather primarily woman, became
divested of hair for ornamental
purposes, as we shall see under
Sexual Selection; and, according
to this belief, it is not surprising
that man should differ so greatly
in hairiness from all other primates,
for characters, gained through
sexual selection, often differ
to an extraordinary degree in
closely related forms.
* Owen, Anatomy of Vertebrates,
vol. iii., p. 619.
*(2) Isidore Geoffroy St-Hilaire
remarks (Histoire Nat. Generale,
tom. ii., 1859, pp. 215-217)
on the head of man being covered
with long hair; also on the upper
surfaces of monkeys and of other
mammals being more thickly clothed
than the lower surfaces. This
has likewise been observed by
various authors. Prof. P. Gervais
(Histoire Nat. des Mammiferes,
tom. i., 1854, p. 28), however,
states that in the gorilla the
hair is thinner on the back,
where it is partly rubbed off,
than on the lower surface.
*(3) The Naturalist
in Nicaragua, 1874, p. 209.
As some confirmation
of Mr. Belt's view, I may quote
the following passage from Sir
W. Denison (Varieties of Vice-Regal
Life, vol. i., 1870, p. 440): "It
is said to be a practice with
the Australians, when the vermin
get troublesome, to singe themselves."
According to a popular impression,
the absence of a tail is eminently
distinctive of man; but as those
apes which come nearest to him
are destitute of this organ,
its disappearance does not relate
exclusively to man. The tail
often differs remarkably in length
within the same genus: thus in
some species of Macacus it is
longer than the whole body, and
is formed of twenty-four vertebrae;
in others it consists of a scarcely
visible stump, containing only
three or four vertebrae. In some
kinds of baboons there are twenty-five,
whilst in the mandrill there
are ten very small stunted caudal
vertebrae, or, according to Cuvier,*
sometimes only five. The tail,
whether it be long or short,
almost always tapers towards
the end; and this, I presume,
results from the atrophy of the
terminal muscles, together with
their arteries and nerves, through
disuse, leading to the atrophy
of the terminal bones. But no
explanation can at present be
given of the great diversity
which often occurs in its length.
Here, however, we are more specially
concerned with the complete external
disappearance of the tail. Professor
Broca has recently shewn*(2)
that the tail in all quadrupeds
consists of two portions, generally
separated abruptly from each
other; the basal portion consists
of vertebrae, more or less perfectly
channelled and furnished with
apophyses like ordinary vertebrae;
whereas those of the terminal
portion are not channelled, are
almost smooth, and scarcely resemble
true vertebrae. A tail, though
not externally visible, is really
present in man and the anthropomorphous
apes, and is constructed on exactly
the same pattern in both. In
the terminal portion the vertabrae,
constituting the os coccyx, are
quite rudimentary, being much
reduced in size and number. In
the basal portion, the vertebrae
are likewise few, are united
firmly together, and are arrested
in development; but they have
been rendered much broader and
flatter than the corresponding
vertebrae in the tails of other
animals: they constitute what
Broca calls the accessory sacral
vertebrae. These are of functional
importance by supporting certain
internal parts and in other ways;
and their modification is directly
connected with the erect or semi-erect
attitude of man and the anthropomorphous
apes. This conclusion is the
more trustworthy, as Broca formerly
held a different view, which
he has now abandoned. The modification,
therefore, of the basal caudal
vertebrae in man and the higher
apes may have been effected,
directly or indirectly, through
natural selection.
* Mr. St. George
Mivart, Proc. Zoolog. Soc.,
1865, pp. 562,
583. Dr. J. E. Gray, Cat. Brit.
Mus: " Skeletons." Owen, Anatomy
of Vertebrates, vol. ii., p.
517. Isidore Geoffroy, Hist.
Nat. Gen., tom. ii., p. 244.
*(2) Revue d'Anthropologie,
1872; "La Constitution des vertebres
caudales."
But what are
we to say about the rudimentary
and variable
vertebrae of the terminal portion
of the tail, forming the os coccyx?
A notion which has often been,
and will no doubt again be ridiculed,
namely, that friction has had
something to do with the disappearance
of the external portion of the
tail, is not so ridiculous as
it at first appears. Dr. Anderson*
states that the extremely short
tail of Macacus brunneus is formed
of eleven vertebrae, including
the imbedded basal ones. The
extremity is tendinous and contains
no vertebrae; this is succeeded
by five rudimentary ones, so
minute that together they are
only one line and a half in length,
and these are permanently bent
to one side in the shape of a
hook. The free part of the tail,
only a little above an inch in
length, includes only four more
small vertebrae. This short tail
is carried erect; but about a
quarter of its total length is
doubled on to itself to the left;
and this terminal part, which
includes the hook-like portion,
serves "to fill up the interspace
between the upper divergent portion
of the callosities"; so that
the animal sits on it, and thus
renders it rough and callous.
Dr. Anderson thus sums up his
observations: "These facts seem
to me to have only one explanation;
this tail, from its short size,
is in the monkey's way when it
sits down, and frequently becomes
placed under the animal while
it is in this attitude; and from
the circumstance that it does
not extend beyond the extremity
of the ischial tuberosities,
it seems as if the tail originally
had been bent round by the will
of the animal, into the interspace
between the callosities, to escape
being pressed between them and
the ground, and that in time
the curvature became permanent,
fitting in of itself when the
organ happens. to be sat upon." Under
these circumstances it is not
surprising that the surface of
the tail should have been roughened
and rendered callous, and Dr.
Murie,*(2) who carefully observed
this species in the Zoological
Gardens, as well as three other
closely allied forms with slightly
longer tails, says that when
the animal sits down, the tail "is
necessarily thrust to one side
of the buttocks; and whether
long or short its root is consequently
liable to be rubbed or chafed." As
we now have evidence that mutilations
occasionally produce an inherited
effect,*(3) it is not very improbable
that in short-tailed monkeys,
the projecting part of the tail,
being functionally useless, should
after many generations have become
rudimentary and distorted, from
being continually rubbed and
chafed. We see the projecting
part in this condition in the
Macacus brunneus, and absolutely
aborted in the M. ecaudatus and
in several of the higher apes.
Finally, then, as far as we can
judge, the tail has disappeared
in man and the anthropomorphous
apes, owing to the terminal portion
having been injured by friction
during a long lapse of time;
the basal and embedded portion
having been reduced and modified,
so as to become suitable to the
erect or semi-erect position.
* Proceedings Zoological Society,
1872, p. 210.
*(2) Proceedings Zoological
Society, 1872, p. 786.
*(3) I allude to Dr. Brown-Sequard's
observations on the transmitted
effect of an operation causing
epilepsy in guinea-pigs, and
likewise more recently on the
analogous effects of cutting
the sympathetic nerve in the
neck. I shall hereafter have
occasion to refer to Mr. Salvin's
interesting case of the apparently
inherited effects of motmots
biting off the barbs of their
own tail-feathers. See also on
the general subject Variation
of Animals and Plants under Domestication,
vol. ii., pp. 22-24.
I have now endeavoured to shew
that some of the most distinctive
characters of man have in all
probability been acquired, either
directly, or more commonly indirectly,
through natural selection. We
should bear in mind that modifications
in structure or constitution
which do not serve to adapt an
organism to its habits of life,
to the food which it consumes,
or passively to the surrounding
conditions, cannot have been
thus acquired. We must not, however,
be too confident in deciding
what modifications are of service
to each being: we should remember
how little we know about the
use of many parts, or what changes
in the blood or tissues may serve
to fit an organism for a new
climate or new kinds of food.
Nor must we forget the principle
of correlation, by which, as
Isidore Geoffroy has shewn in
the case of man, many strange
deviations of structure are tied
together. Independently of correlation,
a change in one part often leads,
through the increased or decreased
use of other parts, to other
changes of a quite unexpected
nature. It is also well to reflect
on such facts, as the wonderful
growth of galls on plants caused
by the poison of an insect, and
on the remarkable changes of
colour in the plumage of parrots
when fed on certain fishes, or
inoculated with the poison of
toads;* for we can thus see that
the fluids of the system, if
altered for some special purpose,
might induce other changes. We
should especially bear in mind
that modifications acquired and
continually used during past
ages for some useful purpose,
would probably become firmly
fixed, and might be long inherited.
* The Variation of Animals and
Plants under Domestication, vol.
ii., pp. 280, 282.
Thus a large yet undefined extension
may safely be given to the direct
and indirect results of natural
selection; but I now admit, after
reading the essay by Nageli on
plants, and the remarks by various
authors with respect to animals,
more especially those recently
made by Professor Broca, that
in the earlier editions of my
Origin of Species I perhaps attributed
too much to the action of natural
selection or the survival of
the fittest. I have altered the
fifth edition of the Origin so
as to confine my remarks to adaptive
changes of structure; but I am
convinced, from the light gained
during even the last few years,
that very many structures which
now appear to us useless, will
hereafter be proved to be useful,
and will therefore come within
the range of natural selection.
Nevertheless, I did not formerly
consider sufficiently the existence
of structures, which, as far
as we can at present judge, are
neither beneficial nor injurious;
and this I believe to be one
of the greatest oversights as
yet detected in my work. I may
be permitted to say, as some
excuse, that I had two distinct
objects in view; firstly, to
shew that species had not been
separately created, and secondly,
that natural selection had been
the chief agent of change, though
largely aided by the inherited
effects of habit, and slightly
by the direct action of the surrounding
conditions. I was not, however,
able to annul the influence of
my former belief, then almost
universal, that each species
had been purposely created; and
this led to my tacit assumption
that every detail of structure,
excepting rudiments, was of some
special, though unrecognised,
service. Any one with this assumption
in his mind would naturally extend
too far the action of natural
selection, either during past
or present times. Some of those
who admit the principle of evolution,
but reject natural selection,
seem to forget, when criticising
my book, that I had the above
two objects in view; hence if
I have erred in giving to natural
selection great power, which
I am very far from admitting,
or in having exaggerated its
power, which is in itself probable,
I have at least, as I hope, done
good service in aiding to overthrow
the dogma of separate creations.
It is, as I can now see, probable
that all organic beings, including
man, possess peculiarities of
structure, which neither are
now, nor were formerly of any
service to them, and which, therefore,
are of no physiological importance.
We know not what produces the
numberless slight differences
between the individuals of each
species, for reversion only carries
the problem a few steps backwards,
but each peculiarity must have
had its efficient cause. If these
causes, whatever they may be,
were to act more uniformly and
energetically during a lengthened
period (and against this no reason
can be assigned), the result
would probably be not a mere
slight individual difference,
but a well-marked and constant
modification, though one of no
physiological importance. Changed
structures, which are in no way
beneficial, cannot be kept uniform
through natural selection, though
the injurious will be thus eliminated.
Uniformity of character would,
however, naturally follow from
the assumed uniformity of the
exciting causes, and likewise
from the free intercrossing of
many individuals. During successive
periods, the same organism might
in this manner acquire successive
modifications, which would be
transmitted in a nearly uniform
state as long as the exciting
causes remained the same and
there was free intercrossing.
With respect to the exciting
causes we can only say, as when
speaking of so-called spontaneous
variations, that they relate
much more closely to the constitution
of the varying organism, than
to the nature of the conditions
to which it has been subjected.
Conclusion.- In this chapter
we have seen that as man at the
present day is liable, like every
other animal, to multiform individual
differences or slight variations,
so no doubt were the early progenitors
of man; the variations being
formerly induced by the same
general causes, and governed
by the same general and complex
laws as at present. As all animals
tend to multiply beyond their
means of subsistence, so it must
have been with the progenitors
of man; and this would inevitably
lead to a struggle for existence
and to natural selection. The
latter process would be greatly
aided by the inherited effects
of the increased use of parts,
and these two processes would
incessantly react on each other.
It appears, also, as we shall
hereafter see, that various unimportant
characters have been acquired
by man through sexual selection.
An unexplained residuum of change
must be left to the assumed uniform
action of those unknown agencies,
which occasionally induce strongly
marked and abrupt deviations
of structure in our domestic
productions.
Judging from the habits of savages
and of the greater number of
the Quadrumana, primeval men,
and even their ape-like progenitors,
probably lived in society. With
strictly social animals, natural
selection sometimes acts on the
individual, through the preservation
of variations which are beneficial
to the community. A community
which includes a large number
of well-endowed individuals increases
in number, and is victorious
over other less favoured ones;
even although each separate member
gains no advantage over the others
of the same community. Associated
insects have thus acquired many
remarkable structures, which
are of little or no service to
the individual, such as the pollen-collecting
apparatus, or the sting of the
worker-bee, or the great jaws
of soldier-ants. With the higher
social animals, I am not aware
that any structure has been modified
solely for the good of the community,
though some are of secondary
service to it. For instance,
the horns of ruminants and the
great canine teeth of baboons
appear to have been acquired
by the males as weapons for sexual
strife, but they are used in
defence of the herd or troop.
In regard to certain mental powers
the case, as we shall see in
the fifth chapter, is wholly
different; for these faculties
have been chiefly, or even exclusively,
gained for the benefit of the
community, and the individuals
thereof have at the same time
gained an advantage indirectly.
It has often
been objected to such views
as the foregoing,
that man is one of the most helpless
and defenceless 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 defence, 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
cannot 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 defenceless
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.
* Primeval Man, 1869, p. 66.
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 cannot
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, &c.,
are more than counterbalanced,
firstly, by his intellectual
powers, through which he has
formed for himself weapons, tools, &c.,
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,
whilst gradually losing their
brute-like powers such as that
of climbing trees, &c. But these
ancestors would not have been
exposed to any special danger,
even if far more helpless and
defenceless 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 favourable
conditions, have sufficed to
raise man to his present high
position in the organic scale. |