Descent of Man [ 1871]

Part One: Descent or Origin of Man
Chapter I - The Evidence of the Descent of Man from some Lower Form

HE WHO wishes to decide whether man is the modified descendant of
some pre-existing form, would probably first enquire whether man
varies, however slightly, in bodily structure and in mental faculties;
and if so, whether the variations are transmitted to his offspring
in accordance with the laws which prevail with the lower animals.
Again, are the variations the result, as far as our ignorance
permits us to judge, of the same general causes, and are they governed
by the same general laws, as in the case of other organisms; for
instance, by correlation, the inherited effects of use and disuse,
&c.? Is man subject to similar malconformations, the result of
arrested development, of reduplication of parts, &c., and does he
display in any of his anomalies reversion to some former and ancient
type of structure? It might also naturally be enquired whether man,
like so many other animals, has given rise to varieties and sub-races,
differing but slightly from each other, or to races differing so
much that they must be classed as doubtful species? How are such races
distributed over the world; and how, when crossed, do they react on
each other in the first and succeeding generations? And so with many
other points.
The enquirer would next come to the important point, whether man
tends to increase at so rapid a rate, as to lead to occasional
severe struggles for existence; and consequently to beneficial
variations, whether in body or mind, being preserved, and injurious
ones eliminated. Do the races or species of men, whichever term may be
applied, encroach on and replace one another, so that some finally
become extinct? We shall see that all these questions, as indeed is
obvious in respect to most of them, must be answered in the
affirmative, in the same manner as with the lower animals. But the
several considerations just referred to may be conveniently deferred
for a time: and we will first see how far the bodily structure of
man shows traces, more or less plain, of his descent from some lower
form. In succeeding chapters the mental powers of man, in comparison
with those of the lower animals, will be considered.
The Bodily Structure of Man. It is notorious that man is constructed
on the same general type or model as other mammals. All the bones in
his skeleton can be compared with corresponding bones in a monkey,
bat, or seal. So it is with his muscles, nerves, blood-vessels and
internal viscera. The brain, the most important of all the organs,
follows the same law, as shewn by Huxley and other anatomists.
Bischoff,* who is a hostile witness, admits that every chief fissure
and fold in the brain of man has its analogy in that of the orang; but
he adds that at no period of development do their brains perfectly
agree; nor could perfect agreement be expected, for otherwise their
mental powers would have been the same. Vulpian*(2) remarks: "Les
differences reelles qui existent entre l'encephale de l'homme et celui
des singes superieurs, sont bien minimes. It ne faut pas se faire
d'illusions a cet egard. L'homme est bien plus pres des singes
anthropomorphes par les caracteres anatomiques de son cerveau que
ceux-ci ne le sont non seulement des autres mammiferes, mais meme de
certains quadrumanes, des guenons et des macaques." But it would be
superfluous here to give further details on the correspondence between
man and the higher mammals in the structure of the brain and all other
parts of the body.

* Grosshirnwindungen des Menschen, 1868, s. 96. The conclusions of
this author, as well as those of Gratiolet and Aeby, concerning the
brain, will be discussed by Prof. Huxley in the appendix.
*(2) Lec. sur la Phys., 1866, p. 890, as quoted by M. Dally, L'Ordre
des Primates et le Transformisme, 1868, p. 29.

It may, however, be worth while to specify a few points, not
directly or obviously connected with structure, by which this
correspondence or relationship is well shewn.
Man is liable to receive from the lower animals, and to
communicate to them, certain diseases, as hydrophobia, variola, the
glanders, syphilis, cholera, herpes, &c.;* and this fact proves the
close similarity*(2) of their tissues and blood, both in minute
structure and composition, far more plainly than does their comparison
under the best microscope, or by the aid of the best chemical
analysis. Monkeys are liable to many of the same non-contagious
diseases as we are; thus Rengger,*(3) who carefully observed for a
long time the Cebus azarae in its native land, found it liable to
catarrh, with the usual symptoms, and which, when often recurrent, led
to consumption. These monkeys suffered also from apoplexy,
inflammation of the bowels, and cataract in the eye.The younger ones
when shedding their milk-teeth often died from fever. Medicines
produced the same effect on them as on us. Many kinds of monkeys
have a strong taste for tea, coffee, and spirituous liquors: they will
also, as I have myself seen, smoke tobacco with pleasure.*(4) Brehm
asserts that the natives of north-eastern Africa catch the wild
baboons by exposing vessels with strong beer, by which they are made
drunk. He has seen some of these animals, which he kept in
confinement, in this state; and he gives a laughable account of
their behaviour and strange grimaces. On the following morning they
were very cross and dismal; they held their aching heads with both
hands, and wore a most pitiable expression: when beer or wine was
offered them, they turned away with disgust, but relished the juice of
lemons.*(5) An American monkey, an Ateles, after getting drunk on
brandy, would never touch it again, and thus was wiser than many
men. These trifling facts prove how similar the nerves of taste must
be in monkeys and man, and how similarly their whole nervous system is
affected.