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 can not be compared or
classed by the naturalist: but he may endeavor to show, 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, while young, attaches itself
by its proboscis to a plant; sucks the sap, but never moves again; is
fertilized 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 shown, 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 recognize 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 afterward 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. 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.
MAN A SUB-ORDER.
[Page 149.]
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, etc. Recently many of our best
naturalists have recurred to the view first propounded by Linnæus, 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.
* * * * *
[Page 152.]
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, while the third line might become
so greatly modified as to deserve to rank as a distinct sub-family,
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 of 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.
In forming a judgment on this head with reference to man, we must
glance at the classification of the _Simiadæ_. This family is divided
by almost all naturalists into the Catarrhine group, or Old World
monkeys, all of which are characterized (as their name expresses)
by the peculiar structure of their nostrils, and by having four
premolars in each jaw; and into the Platyrrhine group or New World
monkeys (including two very distinct sub-groups), all of which are
characterized 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 Catarrhine
or Old World division; nor does he resemble the Platyrrhines more
closely than the Catarrhines 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 offshoot from the Old World Simian
stem, and that, under a genealogical point of view, he must be classed
with the Catarrhine division.
* * * * *
[Page 155.]
And, as man from a genealogical point of view belongs to the Catarrhine
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 progenitor of the whole Simian stock, including man, was
identical with, or even closely resembled, any existing ape or monkey.
THE BIRTHPLACE OF MAN.
[Page 155.]
We are naturally led to inquire, where was the birthplace of man at
that stage of descent when our progenitors diverged from the Catarrhine
stock? The fact that they belonged to this stock clearly shows 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.
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 favorable for the frugiferous diet on which, judging
from analogy, he subsisted. We are far from knowing how long ago it
was when man first diverged from the Catarrhine stock; but it may have
occurred at an epoch as remote as the Eocene[A] period; for that the
higher apes have diverged from the lower apes as early as the Upper
Miocene period is shown 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 favorable 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.
[A] EOCENE.--The earliest of the three divisions of the
Tertiary epoch of geologists. Rocks of this age contain
a small proportion of shells identical with species now
living.
The great break in the organic chain between man and his nearest
allies, which can not 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 _Lemuridæ_--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 civilized 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 civilized 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.
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 shows 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.
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.
ORIGIN OF THE VERTEBRATA.
[Page 158.]
[The Vertebrata are defined as “the highest division of the animal
kingdom, so called from the presence in most cases of a backbone
composed of numerous joints or _vertebræ_, which constitutes the center
of the skeleton and at the same time supports and protects the central
parts of the nervous system.”]
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
organized, and appeared before the others, we may conclude that all
the members of the vertebrate kingdom are derived from some fish-like
animal. The belief that animals so distinct as a monkey, an elephant, a
hummingbird, a snake, a frog, and a fish, etc., 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.
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 toward reptiles; and Professor 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 evidently
a widely-diffused remnant of a larger group) and the Archeopteryx, that
strange Secondary bird, with a long, lizard-like tail. Again, according
to Professor 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 generalized 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 harbors of refuge, and are
related to the great waters of the ocean in the same way that islands
are to continents.
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 Häckel 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, etc., so that it was classed by the older
naturalists among the worms. Many years ago Professor Goodsir 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 Molluscoida of Huxley--a lower division of the great kingdom of
the Mollusca; but they have recently been placed by some naturalists
among the Vermes or worms. Their larvæ somewhat resemble tadpoles in
shape, and have the power of swimming freely about. M. Kovalevsky
has lately observed that the larvæ 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 Professor Kupffer.
* * * * *
[Page 160.]
Thus, if we may rely on embryology, ever the safest guide in
classification, it seems that we have at last gained a clew to
the source whence the Vertebrata were derived. We should then be
justified in believing that at an extremely remote period a group of
animals existed, resembling in many respects the larvæ 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.
FROM NO BONE TO BACKBONE.
[Page 164.]
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 larvæ of existing Ascidians.
These animals probably gave rise to a group of fishes, as lowly
organized 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 _Lemuridæ_; and the interval is not very wide from these
to the _Simiadæ_. The _Simiadæ_ 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.
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 willfully close our eyes, we may, with our present knowledge,
approximately recognize 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 marvelous structure and properties.
DOES MANKIND CONSIST OF SEVERAL SPECIES?
[Descent of
Man, page 176.]
The question whether mankind consists of one or several species has of
late years been much discussed by anthropologists, who are divided into
the two schools of monogenists and polygenists. Those who do not admit
the principle of evolution must look at species as separate creations,
or as in some manner as distinct entities; and they must decide what
forms of man they will consider as species by the analogy of the method
commonly pursued in ranking other organic beings as species. But it
is a hopeless endeavor to decide this point, until some definition of
the term “species” is generally accepted; and the definition must not
include an indeterminate element such as an act of creation. We might
as well attempt without any definition to decide whether a certain
number of houses should be called a village, town, or city. We have a
practical illustration of the difficulty in the never-ending doubts
whether many closely-allied mammals, birds, insects, and plants, which
represent each other respectively in North America and Europe, should
be ranked as species or geographical races; and the like holds true of
the productions of many islands situated at some little distance from
the nearest continent.
Those naturalists, on the other hand, who admit the principle of
evolution, and this is now admitted by the majority of rising men, will
feel no doubt that all the races of man are descended from a single
primitive stock; whether or not they may think fit to designate the
races as distinct species, for the sake of expressing their amount of
difference. With our domestic animals, the question whether the various
races have arisen from one or more species is somewhat different.
Although it may be admitted that all the races, as well as all the
natural species within the same genus, have sprung from the same
primitive stock, yet it is a fit subject for discussion whether all the
domestic races of the dog, for instance, have acquired their present
amount of difference since some one species was first domesticated by
man; or whether they owe some of their characters to inheritance from
distinct species which had already been differentiated in a state of
nature. With man no such question can arise, for he can not be said to
have been domesticated at any particular period.
During an early stage in the divergence of the races of man from a
common stock, the differences between the races and their number
must have been small; consequently, as far as their distinguishing
characters are concerned, they then had less claim to rank as distinct
species than the existing so-called races. Nevertheless, so arbitrary
is the term of species, that such early races would, perhaps, have been
ranked by some naturalists as distinct species, if their differences,
although extremely slight, had been more constant than they are at
present, and had not graduated into each other.
THE RACES GRADUATE INTO EACH OTHER.
[Page 174.]
But the most weighty of all the arguments against treating the races
of man as distinct species is, that they graduate into each other,
independently, in many cases, as far as we can judge, of their having
intercrossed. Man has been studied more carefully than any other
animal, and yet there is the greatest possible diversity among capable
judges whether he should be classed as a single species or race, or as
two (Virey), as three (Jacqninot), as four (Kant), five (Blumenbach),
six (Buffon), seven (Hunter), eight (Agassiz), eleven (Pickering),
fifteen (Bory St. Vincent), sixteen (Desmoulins), twenty-two (Morton),
sixty (Crawfurd), or as sixty-three, according to Burke. This diversity
of judgment does not prove that the races ought not to be ranked as
species, but it shows that they graduate into each other, and that it
is hardly possible to discover clear, distinctive characters between
them.
Every naturalist who has had the misfortune to undertake the
description of a group of highly-varying organisms, has encountered
cases (I speak after experience) precisely like that of man; and, if
of a cautious disposition, he will end by uniting all the forms which
graduate into each other under a single species; for he will say to
himself that he has no right to give names to objects which he can
not define. Cases of this kind occur in the order which includes man,
namely, in certain genera of monkeys; while in other genera, as in
_Cercopithecus_, most of the species can be determined with certainty.
In the American genus _Cebus_, the various forms are ranked by some
naturalists as species, by others as mere geographical races. Now, if
numerous specimens of _Cebus_ were collected from all parts of South
America, and those forms which at present appear to be specifically
distinct were found to graduate into each other by close steps, they
would usually be ranked as mere varieties or races; and this course has
been followed by most naturalists with respect to the races of man.
WAS THE FIRST MAN A SPEAKING ANIMAL?
[Page 180.]
From the fundamental differences between certain languages, some
philologists have inferred that when man first became widely diffused,
he was not a speaking animal; but it may be suspected that languages,
far less perfect than any now spoken, aided by gestures, might
have been used, and yet have left no traces on subsequent and more
highly-developed tongues. Without the use of some language, however
imperfect, it appears doubtful whether man’s intellect could have risen
to the standard implied by his dominant position at an early period.