EVEN if it be granted that the
difference between man and his
nearest allies is as great in
corporeal structure as some naturalists
maintain, and although we must
grant that the difference between
them is immense in mental power,
yet the facts given in the earlier
chapters appear to declare, in
the plainest manner, that man
is descended from some lower
form, notwithstanding that connecting-links
have not hitherto been discovered.
Man is liable to numerous, slight,
and diversified variations, which
are induced by the same general
causes, are governed and transmitted
in accordance with the same general
laws, as in the lower animals.
Man has multiplied so rapidly,
that he has necessarily been
exposed to struggle for existence,
and consequently to natural selection.
He has given rise to many races,
some of which differ so much
from each other, that they have
often been ranked by naturalists
as distinct species. His body
is constructed on the same homological
plan as that of other mammals.
He passes through the same phases
of embryological development.
He retains many rudimentary and
useless structures, which no
doubt were once serviceable.
Characters occasionally make
their re-appearance in him, which
we have reason to believe were
possessed by his early progenitors.
If the origin of man had been
wholly different from that of
all other animals, these various
appearances would be mere empty
deceptions; but such an admission
is incredible. These appearances,
on the other hand, are intelligible,
at least to a large extent, if
man is the co-descendant with
other mammals of some unknown
and lower form.
Some naturalists, from being
deeply impressed with the mental
and spiritual powers of man,
have divided the whole organic
world into three kingdoms, the
Human, the Animal, and the Vegetable,
thus giving to man a separate
kingdom.* Spiritual powers cannot
be compared or classed by the
naturalist: but he may endeavour
to shew, as I have done, that
the mental faculties of man and
the lower animals do not differ
in kind, although immensely in
degree. A difference in degree,
however great, does not justify
us in placing man in a distinct
kingdom, as will perhaps be best
illustrated by comparing the
mental powers of two insects,
namely, a coccus or scale-insect
and an ant, which undoubtedly
belong to the same class. The
difference is here greater than,
though of a somewhat different
kind from, that between man and
the highest mammal. The female
coccus, whilst young, attaches
itself by its proboscis to a
plant; sucks the sap, but never
moves again; is fertilised and
lays eggs; and this is its whole
history. On the other hand, to
describe the habits and mental
powers of worker-ants, would
require, as Pierre Huber has
shewn, a large volume; I may,
however, briefly specify a few
points. Ants certainly communicate
information to each other, and
several unite for the same work,
or for games of play. They recognise
their fellow-ants after months
of absence, and feel sympathy
for each other. They build great
edifices, keep them clean, close
the doors in the evening, and
post sentries. They make roads
as well as tunnels under rivers,
and temporary bridges over them,
by clinging together. They collect
food for the community, and when
an object, too large for entrance,
is brought to the nest, they
enlarge the door, and afterwards
build it up again. They store
up seeds, of which they prevent
the germination, and which, if
damp, are brought up to the surface
to dry. They keep aphides and
other insects as milch-cows.
They go out to battle in regular
bands, and freely sacrifice their
lives for the common weal. They
emigrate according to a preconcerted
plan. They capture slaves. They
move the eggs of their aphides,
as well as their own eggs and
cocoons, into warm parts of the
nest, in order that they may
be quickly hatched; and endless
similar facts could be given.*(2)
On the whole, the difference
in mental power between an ant
and a coccus is immense; yet
no one has ever dreamed of placing
these insects in distinct classes,
much less in distinct kingdoms.
No doubt the difference is bridged
over by other insects; and this
is not the case with man and
the higher apes. But we have
every reason to believe that
the breaks in the series are
simply the results of many forms
having become extinct.
* Isidore Geoffroy St-Hilaire
gives a detailed account of the
position assigned to man by various
naturalists in their classifications:
Hist. Nat. Gen. tom. ii., 1859,
pp. 170-189.
*(2) Some of
the most interesting facts
ever published on the habits
of ants are given by Mr. Belt,
in his The Naturalist in Nicaragua,
1874. See also Mr. Moggridge's
admirable work, Harvesting Ants, &c.,
1873, also "L'Instinct chez les
insectes," by M. George Pouchet,
Revue des Deux Mondes, Feb.,
1870, p. 682.
Professor Owen, relying chiefly
on the structure of the brain,
has divided the mammalian series
into four sub-classes. One of
these he devotes to man; in another
he places both the marsupials
and the Monotremata; so that
he makes man as distinct from
all other mammals as are these
two latter groups conjoined.
This view has not been accepted,
as far as I am aware, by any
naturalist capable of forming
an independent judgment, and
therefore need not here be further
considered.
We can understand why a classification
founded on any single character
or organ- even an organ so wonderfully
complex and important as the
brain- or on the high development
of the mental faculties, is almost
sure to prove unsatisfactory.
This principle has indeed been
tried with hymenopterous insects;
but when thus classed by their
habits or instincts, the arrangement
proved thoroughly artificial.*
Classifications may, of course,
be based on any character whatever,
as on size, colour, or the element
inhabited; but naturalists have
long felt a profound conviction
that there is a natural system.
This system, it is now generally
admitted, must be, as far as
possible, genealogical in arrangement,-
that is, the co-descendants of
the same form must be kept together
in one group, apart from the
co-descendants of any other form;
but if the parent-forms are related,
so will be their descendants,
and the two groups together will
form a larger group. The amount
of difference between the several
groups- that is the amount of
modification which each has undergone-
is expressed by such terms as
genera, families, orders, and
classes. As we have no record
of the lines of descent, the
pedigree can be discovered only
by observing the degrees of resemblance
between the beings which are
to be classed. For this object
numerous points of resemblance
are of much more importance than
the amount of similarity or dissimilarity
in a few points. If two languages
were found to resemble each other
in a multitude of words and points
of construction, they would be
universally recognised as having
sprung from a common source,
notwithstanding that they differed
greatly in some few words or
points of construction. But with
organic beings the points of
resemblance must not consist
of adaptations to similar habits
of life: two animals may, for
instance, have had their whole
frames modified for living in
the water, and yet they will
not be brought any nearer to
each other in the natural system.
Hence we can see how it is that
resemblances in several unimportant
structures, in useless and rudimentary
organs, or not now functionally
active, or in an embryological
condition, are by far the most
serviceable for classification;
for they can hardly be due to
adaptations within a late period;
and thus they reveal the old
lines of descent or of true affinity.
* Westwood, Modern Classification
of Insects, vol. ii., 1840, p.
87.
We can further see why a great
amount of modification in some
one character ought not to lead
us to separate widely any two
organisms. A part which already
differs much from the same part
in other allied forms has already,
according to the theory of evolution,
varied much; consequently it
would (as long as the organism
remained exposed to the same
exciting conditions) be liable
to further variations of the
same kind; and these, if beneficial,
would be preserved, and thus
be continually augmented. In
many cases the continued development
of a part, for instance, of the
beak of a bird, or of the teeth
of a mammal, would not aid the
species in gaining its food,
or for any other object; but
with man we can see no definite
limit to the continued development
of the brain and mental faculties,
as far as advantage is concerned.
Therefore in determining the
position of man in the natural
or genealogical system, the extreme
development of his brain ought
not to outweigh a multitude of
resemblances in other less important
or quite unimportant points.
The greater
number of naturalists who have
taken into consideration
the whole structure of man, including
his mental faculties, have followed
Blumenbach and Cuvier, and have
placed man in a separate Order,
under the title of the Bimana,
and therefore on an equality
with the orders of the Quadrumana,
Carnivora, &c. Recently many
of our best naturalists have
recurred to the view first propounded
by Linnaeus, so remarkable for
his sagacity, and have placed
man in the same Order with the
Quadrumana, under the title of
the primates. The justice of
this conclusion will be admitted:
for in the first place, we must
bear in mind the comparative
insignificance for classification
of the great development of the
brain in man, and that the strongly-marked
differences between the skulls
of man and the Quadrumana (lately
insisted upon by Bischoff, Aeby,
and others) apparently follow
from their differently developed
brains. In the second place,
we must remember that nearly
all the other and more important
differences between man and the
Quadrumana are manifestly adaptive
in their nature, and relate chiefly
to the erect position of man;
such as the structure of his
hand, foot, and pelvis, the curvature
of his spine, and the position
of his head. The family of seals
offers a good illustration of
the small importance of adaptive
characters for classification.
These animals differ from all
other Carnivora in the form of
their bodies and in the structure
of their limbs, far more than
does man from the higher apes;
yet in most systems, from that
of Cuvier to the most recent
one by Mr. Flower,* seals are
ranked as a mere family in the
Order of the Carnivora. If man
had not been his own classifier,
he would never have thought of
founding a separate order for
his own reception.
* Proceedings Zoological Society,
1863, p. 4.
It would be
beyond my limits, and quite
beyond my knowledge,
even to name the innumerable
points of structure in which
man agrees with the other primates.
Our great anatomist and philosopher,
Prof. Huxley, has fully discussed
this subject,* and concludes
that man in all parts of his
organization differs less from
the higher apes, than these do
from the lower members of the
same group. Consequently there "is
no justification for placing
man in a distinct order."
* Evidence as to Man's Place
in Nature, 1863, p. 70, et passim
In an early part of this work
I brought forward various facts,
shewing how closely man agrees
in constitution with the higher
mammals; and this agreement must
depend on our close similarity
in minute structure and chemical
composition. I gave, as instances,
our liability to the same diseases,
and to the attacks of allied
parasites; our tastes in common
for the same stimulants, and
the similar effects produced
by them, as well as by various
drugs, and other such facts.
As small unimportant points
of resemblance between man and
the Quadrumana are not commonly
noticed in systematic works,
and as, when numerous, they clearly
reveal our relationship, I will
specify a few such points. The
relative position of our features
is manifestly the same; and the
various emotions are displayed
by nearly similar, movements
of the muscles and skin, chiefly
above the eyebrows and round
the mouth. Some few expressions
are, indeed, almost the same,
as in the weeping of certain
kinds of monkeys and in the laughing
noise made by others, during
which the corners of the mouth
are drawn backwards, and the
lower eyelids wrinkled. The external
ears are curiously alike. In
man the nose is much more prominent
than in most monkeys; but we
may trace the commencement of
an aquiline curvature in the
nose of the Hoolock gibbon; and
this in the Semnopithecus nasica
is carried to a ridiculous extreme.
The faces of many monkeys are
ornamented with beards, whiskers,
or moustaches. The hair on the
head grows to a great length
in some species of Semnopithecus;*
and in the bonnet monkey (Macacus
radiatus) it radiates from a
point on the crown, with a parting
down the middle. It is commonly
said that the forehead gives
to man his noble and intellectual
appearance; but the thick hair
on the head of the bonnet monkey
terminates downwards abruptly,
and is succeeded by hair so short
and fine that at a little distance
the forehead, with the exception
of the eyebrows, appears quite
naked. It has been erroneously
asserted that eyebrows are not
present in any monkey. In the
species just named the degree
of nakedness of the forehead
differs in different individuals;
and Eschricht states*(2) that
in our children the limit between
the hairy scalp and the naked
forehead is sometimes not well
defined; so that here we seem
to have a trifling case of reversion
to a progenitor, in whom the
forehead had not as yet become
quite naked.
* Isidore Geoffroy St-Hilaire,
Hist. Nat. Gen., tom. ii., 1859,
p. 217.
*(2) "Uber die Richtung der
Haare, &c.," Muller's Archiv
fur Anat. und Phys., 1837, s.
51.
It is well known
that the hair on our arms tends
to converge
from above and below to a point
at the elbow. This curious arrangement,
so unlike that in most of the
lower mammals, is common to the
gorilla, chimpanzee, orang, some
species of Hylobates, and even
to some few American monkeys.
But in Hylobates agilis the hair
on the forearm is directed downwards
or towards the wrist in the ordinary
manner; and in H. lar it is nearly
erect, with only a very slight
forward inclination; so that
in this latter species it is
in a transitional state. It can
hardly be doubted that with most
mammals the thickness of the
hair on the back and its direction,
is adapted to throw off the rain;
even the transverse hairs on
the fore-legs of a dog may serve
for this end when he is coiled
up asleep. Mr. Wallace, who has
carefully studied the habits
of the orang, remarks that the
convergence of the hair towards
the elbow on the arms of the
orang may be explained as serving
to throw off the rain, for this
animal during rainy weather sits
with its arms bent, and with
the hands clasped round a branch
or over its head. According to
Livingstone, the gorilla also "sits
in pelting rain with his hands
over his head."* If the above
explanation is correct, as seems
probable, the direction of the
hair on our own arms offers a
curious record of our former
state; for no one supposes that
it is now of any use in throwing
off the rain; nor, in our present
erect condition, is it properly
directed for this purpose.
* Quoted by Reade, African Sketch
Book, vol i., 1873, p. 152.
It would, however, be rash to
trust too much to the principle
of adaptation in regard to the
direction of the hair in man
or his early progenitors; for
it is impossible to study the
figures given by Eschricht of
the arrangement of the hair on
the human foetus (this being
the same as in the adult) and
not agree with this excellent
observer that other and more
complex causes have intervened.
The points of convergence seem
to stand in some relation to
those points in the embryo which
are last closed in during development.
There appears, also, to exist
some relation between the arrangement
of the hair on the limbs, and
the course of the medullary arteries.*
* On the hair in Hylobates,
see Natural History of Mammals,
by C. L. Martin, 1841, p. 415.
Also, Isidore Geoffroy on the
American monkeys and other kinds,
Hist. Nat. Gen., vol. ii., 1859,
pp. 216, 243. Eschricht, ibid.,
ss. 46, 55, 61. Owen, Anatomy
of Vertebrates, vol. iii., p.
619. Wallace, Contributions to
the Theory of Natural Selection,
1870, p. 344.
It must not
be supposed that the resemblances
between man
and certain apes in the above
and in many other points- such
as in having a naked forehead,
long tresses on the head, &c.,-
are all necessarily the result
of unbroken inheritance from
a common progenitor, or of subsequent
reversion. Many of these resemblances
are more probably due to analogous
variation, which follows, as
I have elsewhere attempted to
shew,* from co-descended organisms
having a similar constitution,
and having been acted on by like
causes inducing similar modifications.
With respect to the similar direction
of the hair on the fore-arms
of man and certain monkeys, as
this character is common to almost
all the anthropomorphous apes,
it may probably be attributed
to inheritance; but this is not
certain, as some very distinct
American monkeys are thus characterised.
* Origin of Species. The Variation
of Animals and Plants under Domestication,
vol. ii., 1868, p. 348.
Although, as we have now seen,
man has no just right to form
a separate Order for his own
reception, he may perhaps claim
a distinct sub-order or family.
Prof. Huxley, in his last work,*
divides the primates into three
suborders; namely, the Anthropidae
with man alone, the Simiadae
including monkeys of all kinds,
and the Lemuridae with the diversified
genera of lemurs. As far as differences
in certain important points of
structure are concerned, man
may no doubt rightly claim the
rank of a sub-order; and this
rank is too low, if we look chiefly
to his mental faculties. Nevertheless,
from a genealogical point of
view it appears that this rank
is too high, and that man ought
to form merely a family, or possibly
even only a sub-family. If we
imagine three lines of descent
proceeding from a common stock,
it is quite conceivable that
two of them might after the lapse
of ages be so slightly changed
as still to remain as species
of the same genus, whilst the
third line might become so greatly
modified as to deserve to rank
as a distinct sub-family, or
even Order. But in this case
it is almost certain that the
third line would still retain
through inheritance numerous
small points of resemblance with
the other two. Here, then, would
occur the difficulty, at present
insoluble, how much weight we
ought to assign in our classifications
to strongly-marked differences
in some few points,- that is,
to the amount of modification
undergone; and how much to close
resemblance in numerous unimportant
points, as indicating the lines
of descent or genealogy. To attach
much weight to the few but strong
differences is the most obvious
and perhaps the safest course,
though it appears more correct
to pay great attention to the
many small resemblances, as giving
a truly natural classification.
* An Introduction to the Classification
of Animals, 1869, p. 99.
In forming a judgment on this
head with reference to man, we
must glance at the classification
of the Simiadae. This family
is divided by almost all naturalists
into the catarhine group, or
Old World monkeys, all of which
are characterised (as their name
expresses) by the peculiar structure
of their nostrils, and by having
four premolars in each jaw; and
into the platyrhine group or
New World monkeys (including
two very distinct sub-groups),
all of which are characterised
by differently constructed nostrils,
and by having six premolars in
each jaw. Some other small differences
might be mentioned. Now man unquestionably
belongs in his dentition, in
the structure of his nostrils,
and some other respects, to the
catarhine or Old World division;
nor does he resemble the platyrhines
more closely than the catarhines
in any characters, excepting
in a few of not much importance
and apparently of an adaptive
nature. It is therefore against
all probability that some New
World species should have formerly
varied and produced a man-like
creature, with all the distinctive
characters proper to the Old
World division; losing at the
same time all its own distinctive
characters. There can, consequently,
hardly be a doubt that man is
an off-shoot from the Old World
simian stem; and that under a
genealogical point of view he
must be classed with the catarhine
division.*
* This is nearly the same classification
as that provisionally adopted
by Mr. St. G. Mivart, Transactions,
Philosophical Society, 1867,
p. 300, who, after separating
the Lemuridae, divides the remainder
of the Primates into the Hominidae,
the Simiadae which answer to
the catarhines, the Cebidae,
and the Hapalidae,- these two
latter groups answering to the
platyrhines. Mr. Mivart still
abides by the same view; see
Nature, 1871, p. 481.
The anthropomorphous
apes, namely the gorilla, chimpanzee,
orang,
and Hylobates, are by most naturalists
separated from the other Old
World monkeys, as a distinct
sub-group. I am aware that Gratiolet,
relying on the structure of the
brain, does not admit the existence
of this sub-group, and no doubt
it is a broken one. Thus the
orang, as Mr. St. G. Mivart remarks, "is
one of the most peculiar and
aberrant forms to be found in
the Order."* The remaining non-anthropomorphous
Old World monkeys, are again
divided by some naturalists into
two or three smaller subgroups;
the genus Semnopithecus, with
its peculiar sacculated stomach,
being the type of one sub-group.
But it appears from M. Gaudry's
wonderful discoveries in Attica,
that during the Miocene period
a form existed there, which connected
Semnopithecus and Macacus; and
this probably illustrates the
manner in which the other and
higher groups were once blended
together.
* Transactions, Zoolog. Soc.,
vol. vi., 1867, p. 214.
If the anthropomorphous
apes be admitted to form a
natural
sub-group, then as man agrees
with them, not only in all those
characters which he possesses
in common with the whole catarhine
group, but in other peculiar
characters, such as the absence
of a tail and of callosities,
and in general appearance, we
may infer that some ancient member
of the anthropomorphous sub-group
gave birth to man. It is not
probable that, through the law
of analogous variation, a member
of one of the other lower sub-groups
should have given rise to a man-like
creature, resembling the higher
anthropomorphous apes in so many
respects. No doubt man, in comparison
with most of his allies, has
undergone an extraordinary amount
of modification, chiefly in consequence
of the great development of his
brain and his erect position;
nevertheless, we should bear
in mind that he "is but one of
several exceptional forms of
primates."*
* Mr. St. G. Mivart, Transactions
of the Philosophical Society,
1867, p. 410.
Every naturalist, who believes
in the principle of evolution,
will grant that the two main
divisions of the Simiadae, namely
the catarhine and platyrhine
monkeys, with their sub-groups,
have all proceeded from some
one extremely ancient progenitor.
The early descendants of this
progenitor, before they had diverged
to any considerable extent from
each other, would still have
formed a single natural group;
but some of the species or incipient
genera would have already begun
to indicate by their diverging
characters the future distinctive
marks of the catarhine and platyrhine
divisions. Hence the members
of this supposed ancient group
would not have been so uniform
in their dentition, or in the
structure of their nostrils,
as are the existing catarhine
monkeys in one way and the platyrhines
in another way, but would have
resembled in this respect the
allied Lemuridae, which differ
greatly from each other in the
form of their muzzles,* and to
an extraordinary degree in their
dentition.
* Messrs. Murie and Mivart on
the Lemuroidea, Transactions,
Zoological Society, vol. vii,
1869, p. 5.
The catarhine and platyrhine
monkeys agree in a multitude
of characters, as is shewn by
their unquestionably belonging
to one and the same Order. The
many characters which they possess
in common can hardly have been
independently acquired by so
many distinct species; so that
these characters must have been
inherited. But a naturalist would
undoubtedly have ranked as an
ape or a monkey, an ancient form
which possessed many characters
common to the catarhine and platyrhine
monkeys, other characters in
an intermediate condition, and
some few, perhaps, distinct from
those now found in either group.
And as man from a genealogical
point of view belongs to the
catarhine or Old World stock,
we must conclude, however much
the conclusion may revolt our
pride, that our early progenitors
would have been properly thus
designated.* But we must not
fall into the error of supposing
that the early progenitors of
the whole simian stock, including
man, was identical with, or even
closely resembled, any existing
ape or monkey.
* Haeckel has
come to this same conclusion.
See "Uber die Entstehung
des Menschengeschlechts," in
Virchow's Sammlung. gemein. wissen.
Vortrage, 1868, s. 61. Also his
Naturliche Schopfungsgeschicte,
1868, in which he gives in detail
his views on the genealogy of
man.
On the Birthplace and Antiquity
of Man.- We are naturally led
to enquire, where was the birthplace
of man at that stage of descent
when our progenitors diverged
from the catarhine stock? The
fact that they belonged to the
stock clearly shews that they
inhabited the Old World; but
not Australia nor any oceanic
island, as we may infer from
the laws of geographical distribution.
In each great region of the world
the living mammals are closely
related to the extinct species
of the same region. It is therefore
probable that Africa was formerly
inhabited by extinct apes closely
allied to the gorilla and chimpanzee;
and as these two species are
now man's nearest allies, it
is somewhat more probable that
our early progenitors lived on
the African continent than elsewhere.
But it is useless to speculate
on this subject; for two or three
anthropomorphous apes, one the
Dryopithecus* of Lartet, nearly
as large as a man, and closely
allied to Hylobates, existed
in Europe during the Miocene
age; and since so remote a period
the earth has certainly undergone
many great revolutions, and there
has been ample time for migration
on the largest scale.
* Dr. C Forsyth
Major, "Sur
les Singes fossiles trouves en
Italie," Soc. Ital. des Sc. Nat.,
tom., xv., 1872.
At the period and place, whenever
and wherever it was, when man
first lost his hairy covering,
he probably inhabited a hot country;
a circumstance favourable for
the frugi-ferous diet on which,
judging from analogy, he subsisted.
We are far from knowing how long
ago it was when man first diverged
from the catarhine stock; but
it may have occurred at an epoch
as remote as the Eocene period;
for that the higher apes had
diverged from the lower apes
as early as the Upper Miocene
period is shewn by the existence
of the Dryopithecus. We are also
quite ignorant at how rapid a
rate organisms, whether high
or low in the scale, may be modified
under favourable circumstances;
we know, however, that some have
retained the same form during
an enormous lapse of time. From
what we see going on under domestication,
we learn that some of the co-descendants
of the same species may be not
at all, some a little, and some
greatly changed, all within the
same period. Thus it may have
been with man, who has undergone
a great amount of modification
in certain characters in comparison
with the higher apes.
The great break in the organic
chain between man and his nearest
allies, which cannot be bridged
over by any extinct or living
species, has often been advanced
as a grave objection to the belief
that man is descended from some
lower form; but this objection
will not appear of much weight
to those who, from general reasons,
believe in the general principle
of evolution. Breaks often occur
in all parts of the series, some
being wide, sharp and defined,
others less so in various degrees;
as between the orang and its
nearest allies- between the Tarsius
and the other Lemuridae- between
the elephant, and in a more striking
manner between the Ornithorhynchus
or Echidna, and all other mammals.
But these breaks depend merely
on the number of related forms
which have become extinct. At
some future period, not very
distant as measured by centuries,
the civilised races of man will
almost certainly exterminate,
and replace, the savage races
throughout the world. At the
same time the anthropomorphous
apes, as Professor Schaaffhausen
has remarked,* will no doubt
be exterminated. The break between
man and his nearest allies will
then be wider, for it will intervene
between man in a more civilised
state, as we may hope, even than
the Caucasian, and some ape as
low as a baboon, instead of as
now between the negro or Australian
and the gorilla.
* Anthropological Review, April,
1867, p. 236
With respect to the absence
of fossil remains, serving to
connect man with his ape-like
progenitors, no one will lay
much stress on this fact who
reads Sir C. Lyell's discussion,*
where he shews that in all the
vertebrate classes the discovery
of fossil remains has been a
very slow and fortuitous process.
Nor should it be forgotten that
those regions which are the most
likely to afford remains connecting
man with some extinct ape-like
creature, have not as yet been
searched by geologists.
* Elements of Geology, 1865,
pp. 583-585. Antiquity of Man,
1863, p. 145.
Lower Stages
in the Genealogy of Man.- We
have seen that man
appears to have diverged from
the catarhine or Old World division
of the Simiadae, after these
had diverged from the New World
division. We will now endeavour
to follow the remote traces of
his genealogy, trusting principally
to the mutual affinities between
the various classes and orders,
with some slight reference to
the periods, as far as ascertained,
of their successive appearance
on the earth. The Lemuridae stand
below and near to the Simiadae,
and constitute a very distinct
family of the primates, or, according
to Haeckel and others, a distinct
Order. This group is diversified
and broken to an extraordinary
degree, and includes many aberrant
forms. It has, therefore, probably
suffered much extinction. Most
of the remnants survive on islands,
such as Madagascar and the Malayan
archipelago, where they have
not been exposed to so severe
a competition as they would have
been on well-stocked continents.
This group likewise presents
many gradations, leading, as
Huxley remarks,* "insensibly
from the crown and summit of
the animal creation down to creatures
from which there is but a step,
as it seems, to the lowest, smallest,
and least intelligent of the
placental mammalia." From these
various considerations it is
probable that the Simiadae were
originally developed from the
progenitors of the existing Lemuridae;
and these in their turn from
forms standing very low in the
mammalian series.
* Man's Place in Nature, p.
105.
The marsupials stand in many
important characters below the
placental mammals. They appeared
at an earlier geological period,
and their range was formerly
much more extensive than at present.
Hence the Placentata are generally
supposed to have been derived
from the Implacentata or marsupials;
not, however, from forms closely
resembling the existing marsupials,
but from their early progenitors.
The Monotremata are plainly allied
to the marsupials, forming a
third and still lower division
in the great mammalian series.
They are represented at the present
day solely by the Ornithorhynchus
and Echidna; and these two forms
may be safely considered as relics
of a much larger group, representatives
of which have been preserved
in Australia through some favourable
concurrence of circumstances.
The Monotremata are eminently
interesting, as leading in several
important points of structure
towards the class of reptiles.
In attempting
to trace the genealogy of the
Mammalia, and therefore
of man, lower down in the series,
we become involved in greater
and greater obscurity; but as
a most capable judge, Mr. Parker,
has remarked, we have good reason
to believe, that no true bird
or reptile intervenes in the
direct line of descent. He who
wishes to see what ingenuity
and knowledge can effect, may
consult Prof. Haeckel's works.*
I will content myself with a
few general remarks. Every evolutionist
will admit that the five great
vertebrate classes, namely, mammals,
birds, reptiles, amphibians,
and fishes, are descended from
some one prototype; for they
have much in common, especially
during their embryonic state.
As the class of fishes is the
most lowly organised, and appeared
before the others, we may conclude
that all the members of the vertebrate
kingdom are derived from some
fishlike animal. The belief that
animals so distinct as a monkey,
an elephant, a humming-bird,
a snake, a frog, and a fish, &c.,
could all have sprung from the
same parents, will appear monstrous
to those who have not attended
to the recent progress of natural
history. For this belief implies
the former existence of links
binding closely together all
these forms, now so utterly unlike.
* Elaborate tables are given
in his Generelle Morphologie
(B. ii., s. cliii. and s. 425);
and with more especial reference
to man in his Naturliche Schopfungsgeschichte,
1868. Prof. Huxley, in reviewing
this latter work (The Academy,
1869, p. 42), says that he considers
the phylum or lines of descent
of the Vertebrata to be admirably
discussed by Haeckel, although
he differs on some points. He
expresses, also, his high estimate
of the general tenor and spirit
of the whole work.
Nevertheless, it is certain
that groups of animals have existed,
or do now exist, which serve
to connect several of the great
vertebrate classes more or less
closely. We have seen that the
Ornithorhynchus graduates towards
reptiles; and Prof. Huxley has
discovered, and is confirmed
by Mr. Cope and others, that
the dinosaurians are in many
important characters intermediate
between certain reptiles and
certain birds- the birds referred
to being the ostrich-tribe (itself
a widely-diffused remnant of
a larger group) and the Archeopteryx,
that strange secondary bird,
with a long lizard-like tail.
Again, according to Prof. Owen,*
the ichthyosaurians- great sea-lizards
furnished with paddles- present
many affinities with fishes,
or rather, according to Huxley,
with amphibians; a class which,
including in its highest division
frogs and toads, is plainly allied
to the ganoid fishes. These latter
fishes swarmed during the earlier
geological periods, and were
constructed on what is called
a generalised type, that is,
they presented diversified affinities
with other groups of organisms.
The Lepidosiren is also so closely
allied to amphibians and fishes,
that naturalists long disputed
in which of these two classes
to rank it; it, and also some
few ganoid fishes, have been
preserved from utter extinction
by inhabiting rivers, which are
harbours of refuge, and are related
to the great waters of the ocean
in the same way that islands
are to continents.
* Palaeontology 1860, p. 199.
Lastly, one
single member of the immense
and diversified class
of fishes, namely, the lancelet
or amphioxus, is so different
from all other fishes, that Haeckel
maintains that it ought to form
a distinct class in the vertebrate
kingdom. This fish is remarkable
for its negative characters;
it can hardly be said to possess
a brain, vertebral column, or
heart, &c.; so that it was classed
by the older naturalists amongst
the worms. Many years ago Prof.
Good sir perceived that the lancelet
presented some affinities with
the ascidians, which are invertebrate,
hermaphrodite, marine creatures
permanently attached to a support.
They hardly appear like animals,
and consist of a simple, tough,
leathery sack, with two small
projecting orifices. They belong
to the Mulluscoida of Huxley-
a lower division of the great
kingdom of the Mollusca; but
they have recently been placed
by some naturalists amongst the
Vermes or worms. Their larvae
somewhat resemble tadpoles in
shape,* and have the power of
swimming freely about. Mr. Kovalevsky*(2)
has lately observed that the
larvae of ascidians are related
to the Vertebrata, in their manner
of development, in the relative
position of the nervous system,
and in possessing a structure
closely like the chorda dorsalis
of vertebrate animals; and in
this he has been since confirmed
by Prof. Kupffer. M. Kovalevsky
writes to me from Naples, that
he has now carried these observations
yet further, and should his results
be well established, the whole
will form a discovery of the
very greatest value. Thus, if
we may rely on embryology, ever
safest guide in classification,
it seems that we have at last
gained a clue to the source whence
the Vertebrata were derived.*(3)
We should then be justified in
believing that at an extremely
remote period a group of animals
existed, resembling in many respects
the larvae of our present ascidians,
which diverged into two great
branches- the one retrograding
in development and producing
the present class of ascidians,
the other rising to the crown
and summit of the animal kingdom
by giving birth to the Vertebrata.
* At the Falkland Islands I
had the satisfaction of seeing,
in April, 1833, and therefore
some years before any other naturalist,
the locomotive larvae of a compound
ascidian, closely allied to Synoicum,
but apparently generically distinct
from it. The tail was about five
times as long as the oblong head,
and terminated in a very fine
filament. It was, as sketched
by me under a simple microscope,
plainly divided by transverse
opaque partitions, which I presume
represent the great cells figured
by Kovalevsky. At an early stage
of development the tail was closely
coiled round the head of the
larva.
*(2) Memoires de l'Acad. des
Sciences de St. Petersbourg,
tom. x., No. 15, 1866.
*(3) But I am
bound to add that some competent
judges dispute
this conclusion; for instance,
M. Giard, in a series of papers
in the Archives de Zoologie Experimentale,
for 1872. Nevertheless, this
naturalist remarks, p. 281, "L'organisation
de la larve ascidienne en dehors
de toute hypothese et de toute
theorie, nous montre comment
la nature peut produire la disposition
fondamentale du type vertebre
(l'existence d'une corde dorsale)
chez un invertebre par la seule
condition vitale de l'adaptation,
et cette simple possibilite du
passage supprime l'abime entre
les deux sous-regnes, encore
bien qu'en ignore par ou le passage
sest fait en realite."
We have thus far endeavoured
rudely to trace the genealogy
of the Vertebrata by the aid
of their mutual affinities. We
will now look to man as he exists;
and we shall, I think, be able
partially to restore the structure
of our early progenitors, during
successive periods, but not in
due order of time. This, can
be effected by means of the rudiments
which man still retains, by the
characters which occasionally
make their appearance in him
through reversion, and by the
aid of the principles of morphology
and embryology. The various facts,
to which I shall here allude,
have been given in the previous
chapters.
The early progenitors of man
must have been once covered with
hair, both sexes having beards;
their ears were probably pointed,
and capable of movement; and
their bodies were provided with
a tail, having the proper muscles.
Their limbs and bodies were also
acted on by many muscles which
now only occasionally reappear,
but are normally present in the
Quadrumana. At this or some earlier
period, the great artery and
nerve of the humerus ran through
a supra-condyloid foramen. The
intestine gave forth a much larger
diverticulum or caecum than that
now existing. The foot was then
prehensile, judging from the
condition of the great toe in
the foetus; and our progenitors,
no doubt, were arboreal in their
habits, and frequented some warm,
forest-clad land. The males had
great canine teeth, which served
them as formidable weapons. At
a much earlier period the uterus
was double; the excreta were
voided through a cloaca; and
the eye was protected by a third
eyelid or nictitating membrane.
At a still earlier period the
progenitors of man must have
been aquatic in their habits;
for morphology plainly tells
us that our lungs consist of
a modified swimbladder, which
once served as a float. The clefts
on the neck in the embryo of
man show where the branchiae
once existed. In the lunar or
weekly recurrent periods of some
of our functions we apparently
still retain traces of our primordial
birthplace, a shore washed by
the tides. At about this same
early period the true kidneys
were replaced by the corpora
wolffiana. The heart existed
as a simple pulsating vessel;
and the chorda dorsalis took
the place of a vertebral column.
These early ancestors of man,
thus seen in the dim recesses
of time, must have been as simply,
or even still more simply organised
than the lancelet or amphioxus.
There is one other point deserving
a fuller notice. It has long
been known that in the vertebrate
kingdom one sex bears rudiments
of various accessory parts, appertaining
to the reproductive system, which
properly belong to the opposite
sex; and it has now been ascertained
that at a very early embryonic
period both sexes possess true
male and female glands. Hence
some remote progenitor of the
whole vertebrate kingdom appears
to have been hermaphrodite or
androgynous.* But here we encounter
a singular difficulty. In the
mammalian class the males possess
rudiments of a uterus with the
adjacent passage, in their vesiculae
prostaticae; they bear also rudiments
of mammae, and some male marsupials
have traces of a marsupial sack.*(2)
Other analogous facts could be
added. Are we, then, to suppose
that some extremely ancient mammal
continued androgynous, after
it had acquired the chief distinctions
of its class, and therefore after
it had diverged from the lower
classes of the vertebrate kingdom?
This seems very improbable, for
we have to look to fishes, the
lowest of all the classes, to
find any still existent androgynous
forms.*(3) That various accessory
parts, proper to each sex, are
found in a rudimentary condition
in the opposite sex, may be explained
by such organs having been gradually
acquired by the one sex, and
then transmitted in a more or
less imperfect state to the other.
When we treat of sexual selection,
we shall meet with innumerable
instances of this form of transmission,-
as in the case of the spurs,
plumes, and brilliant colours,
acquired for battle or ornament
by male birds, and inherited
by the females in an imperfect
or rudimentary condition.
* This is the
conclusion of Prof. Gegenbaur,
one of the highest
authorities in comparative anatomy:
see Grundzuge der vergleich.
Anat., 1870, s. 876. The result
has been arrived at chiefly from
the study of the Amphibia; but
it appears from the researches
of Waldeyer (as quoted in Journal
of Anat. and Phys., 1869, p.
161), that the sexual organs
of even "the higher vertebrata
are, in their early condition,
hermaphrodite." Similar views
have long been held by some authors,
though until recently without
a firm basis.
*(2) The male Thylacinus offers
the best instance. Owen, Anatomy
of Vertebrates, vol. iii., p.
771.
*(3) Hermaphroditism has been
observed in several species of
Serranus, as well as in some
other fishes, where it is either
normal and symmetrical, or abnormal
and unilateral. Dr. Zouteveen
has given me references on this
subject, more especially to a
paper by Prof. Halbertsma, in
the Transact. of the Dutch Acad.
of Sciences, vol. xvi. Dr. Gunther
doubts the fact, but it has now
been recorded by too many good
observers to be any longer disputed.
Dr. M. Lessona writes to me,
that he has verified the observations
made by Cavolini on Serranus.
Prof. Ercolani has recently shewn
(Acad. delle Scienze, Bologna,
Dec. 28, 1871) that eels are
androgynous.
The possession by male mammals
of functionally imperfect mammary
organs is, in some respects,
especially curious. The Monotremata
have the proper milk-secreting
glands with orifices, but no
nipples; and as these animals
stand at the very base of the
mammalian series, it is probable
that the progenitors of the class
also had milk-secreting glands,
but no nipples. This conclusion
is supported by what is known
of their manner of development;
for Professor Turner informs
me, on the authority of Kolliker
and Langer, that in the embryo
the mammary glands can be distinctly
traced before the nipples are
in the least visible; and the
development of successive parts
in the individual generally represents
and accords with the development
of successive beings in the same
line of descent. The marsupials
differ from the Monotremata by
possessing nipples; so that probably
these organs were first acquired
by the marsupials, after they
had diverged from, and risen
above, the Monotremata, and were
then transmitted to the placental
mammals.* No one will suppose
that the marsupials still remained
androgynous, after they had approximately
acquired their present structure.
How then are we to account for
male mammals possessing mammae?
It is possible that they were
first developed in the females
and then transferred to the males,
but from what follows this is
hardly probable.
* Prof. Gegenbaur has shewn
(Jenaische Zeitschrift, Bd. vii.,
p. 212) that two distinct types
of nipples prevail throughout
the several mammalian orders,
but that it is quite intelligible
how both could have been derived
from the nipples of the marsupials,
and the latter from those of
the Monotremata. See, also, a
memoir by Dr. Max Huss, on the
mammary glands, ibid., B. viii.,
p. 176.
It may be suggested, as another
view, that long after the progenitors
of the whole mammalian class
had ceased to be androgynous,
both sexes yielded milk, and
thus nourished their young; and
in the case of the marsupials,
that both sexes carried their
young in marsupial sacks. This
will not appear altogether improbable,
if we reflect that the males
of existing syngnathous fishes
receive the eggs of the females
in their abdominal pouches, hatch
them, and afterwards, as some
believe, nourish the young;*
- that certain other male fishes
hatch the eggs within their mouths
or branchial cavities;- that
certain male toads take the chaplets
of eggs from the females, and
wind them round their own thighs,
keeping them there until the
tadpoles are born;- that certain
male birds undertake the whole
duty of incubation, and that
male pigeons, as well as the
females, feed their nestlings
with a secretion from their crops.
But the above suggestion first
occurred to me from mammary glands
of male mammals being so much
more perfectly developed than
the rudiments of the other accessory
reproductive parts, which are
found in the one sex though proper
to the other. The mammary glands
and nipples, as they exist in
male mammals, can indeed hardly
be called rudimentary; they are
merely not fully developed, and
not functionally active. They
are sympathetically affected
under the influence of certain
diseases, like the same organs
in the female. They often secrete
a few drops of milk at birth
and at puberty: this latter fact
occurred in the curious case
before referred to, where a young
man possessed two pairs of mammee.
In man and some other male mammals
these organs have been known
occasionally to become so well
developed during maturity as
to yield a fair supply of milk.
Now if we suppose that during
a former prolonged period male
mammals aided the females in
nursing their offspring,*(2)
and that afterwards from some
cause (as from the production
of a smaller number of young)
the males ceased to give this
aid, disuse of the organs during
maturity would lead to their
becoming inactive; and from two
well-known principles of inheritance,
this state of inactivity would
probably be transmitted to the
males at the corresponding age
of maturity. But at an earlier
age these organs would be left
unaffected, so that they would
be almost equally well developed
in the young of both sexes.
* Mr. Lockwood believes (as
quoted in Quart. Journal of Science,
April, 1868, p. 269), from what
he has observed of the development
of Hippocampus, that the walls
of the abdominal pouch of the
male in some way afford nourishment.
On male fishes hatching the ova
in their mouths, see a very interesting
paper by Prof. Wyman, in Proc.
Boston Soc. of Nat. Hist., Sept.
15, 1857; also Prof. Turner,
in Journal of Anatomy and Physiology,
Nov. 1, 1866, p. 78. Dr. Gunther
has likewise described similar
cases.
*(2) Mlle. C.
Royer has suggested a similar
view in her Origine
de l'homme, &c., 1870.
Conclusion.- Von Baer has defined
advancement or progress in the
organic scale better than any
one else, as resting on the amount
of differentiation and specialisation
of the several parts of a being,-
when arrived at maturity, as
I should be inclined to add.
Now as organisms have become
slowly adapted to diversified
lines of life by means of natural
selection, their parts will have
become more and more differentiated
and specialised for various functions
from the advantage gained by
the division of physiological
labour. The same part appears
often to have been modified first
for one purpose, and then long
afterwards for some other and
quite distinct purpose; and thus
all the parts are rendered more
and more complex. But each organism
still retains the general type
of structure of the progenitor
from which it was aboriginally
derived. In accordance with this
view it seems, if we turn to
geological evidence, that organisation
on the whole has advanced throughout
the world by slow and interrupted
steps. In the great kingdom of
the Vertebrata it has culminated
in man. It must not, however,
be supposed that groups of organic
beings are always supplanted,
and disappear as soon as they
have given birth to other and
more perfect groups. The latter,
though victorious over their
predecessors, may not have become
better adapted for all places
in the economy of nature. Some
old forms appear to have survived
from inhabiting protected sites,
where they have not been exposed
to very severe competition; and
these often aid us in constructing
our genealogies, by giving us
a fair idea of former and lost
populations. But we must not
fall into the error of looking
at the existing members of any
lowly-organised group as perfect
representatives of their ancient
predecessors.
The most ancient progenitors
in the kingdom of the Vertebrata,
at which we are able to obtain
an obscure glance, apparently
consisted of a group of marine
animals,* resembling the larvae
of existing ascidians. These
animals probably gave rise to
a group of fishes, as lowly organised
as the lancelet; and from these
the ganoids, and other fishes
like the Lepidosiren, must have
been developed. From such fish
a very small advance would carry
us on to the amphibians. We have
seen that birds and reptiles
were once intimately connected
together; and the Monotremata
now connect mammals with reptiles
in a slight degree. But no one
can at present say by what line
of descent the three higher and
related classes, namely, mammals,
birds, and reptiles, were derived
from the two lower vertebrate
classes, namely, amphibians and
fishes. In the class of mammals
the steps are not difficult to
conceive which led from the ancient
Monotremata to the ancient marsupials;
and from these to the early progenitors
of the placental mammals. We
may thus ascend to the Lemuridae;
and the interval is not very
wide from these to the Simiadae.
The Simiadae then branched off
into two great stems, the New
World and Old World monkeys;
and from the latter, at a remote
period, Man, the wonder and glory
of the Universe, proceeded.
* The inhabitants
of the seashore must be greatly
affected by the
tides; animals living either
about the mean high-water mark,
or about the mean low-water mark,
pass through a complete cycle
of tidal changes in a fortnight.
Consequently, their food supply
will undergo marked changes week
by week. The vital functions
of such animals, living under
these conditions for many generations,
can hardly fail to run their
course in regular weekly periods.
Now it is a mysterious fact that
in the higher and now terrestrial
Vertebrata, as well as in other
classes, many normal and abnormal
processes one or more whole weeks
as their periods; this would
be rendered intelligible if the
Vertebrata are descended from
an animal allied to the existing
tidal ascidians. Many instances
of such periodic processes might
be given, as the gestation of
mammals, the duration of fevers, &c.
The hatching of eggs affords
also a good example, for, according
to Mr. Bartlett (Land and Water,
Jan. 7, 1871), the eggs of the
pigeon are hatched in two weeks;
those of the fowl in three; those
of the duck in four; those of
the goose in five; and those
of the ostrich in seven weeks.
As far as we can judge, a recurrent
period, if approximately of the
right duration for any process
or function, would not, when
once gained, be liable to change;
consequently it might be thus
transmitted through almost any
number of generations. But if
the function changed, the period
would have to change, and would
be apt to change almost abruptly
by a whole week. This conclusion,
if sound, is highly remarkable;
for the period of gestation in
each mammal, and the hatching
of each bird's eggs, and many
other vital processes, thus betray
to us the primordial birthplace
of these animals.
Thus we have given to man a
pedigree of prodigious length,
but not, it may be said, of noble
quality. The world, it has often
been remarked, appears as if
it had long been preparing for
the advent of man: and this,
in one sense is strictly true,
for he owes his birth to a long
line of progenitors. If any single
link in this chain had never
existed, man would not have been
exactly what he now is. Unless
we wilfully close our eyes, we
may, with our present knowledge,
approximately recognise our parentage;
nor need we feel ashamed of it.
The most humble organism is something
much higher than the inorganic
dust under our feet; and no one
with an unbiased mind can study
any living creature, however
humble, without being struck
with enthusiasm at its marvellous
structure and properties. |