Wo here see what stranj^o rehitiojis and what a singtihir
confuHioti rise from a consiilcratjoii of the stattue. Nmubers
given in the same order, repro.
i'ntinij the size of the skull,
tho cephalic indices, the weigiit of the brain, will j^'ivu the
Kanie striking; rcsnlt. •
1 -( j(
r. 11 -^c.
C. 1 -82
. 1 -'.1 1 .-.
r, 3 7.-.
Application to Man. 6r
We must also observe that there is a great majority of
moans in this tabic. Now we sec that tlie discrepancies
between these means are less than the discrepancies between
the maximum and minimum of a single race, so much so
that races widely distinct from each other intervene between
Now let us mentally compare instead of these groups, the
individuals of which they are composed. Is it not clear
that if they were placed according to height, we should pass
from one to the other with scarcely the ditference of a
millimetre ; but is it not also clear that the confusion would
become much greater than it appears even in the table ?
I ask anyone who possesses even the smallest knowledge
of zoology and zoutechny whether it v.ould be in a collection
of species that he would expect to find the most evident
affinities destroyed by the application of this method?
Would it not be rather in a collection of races that siujilar
facts would be met with, as, fur example, in canine races,
where the mastiff anel its young, the greyhound of Saintonge
and the Italian greyhound, the large and the i^mall carriage
dt)g would be separated from each other by a number of other
riices if stature alone were taken into account.
The intercrossing and fusion of characters, so marked
between human groups, are inexplicable if we consider these
groups as species, unless we admit that the morphological
relations between these human tti^ecie^ arc of an entirely
jlifferent nature to the relations established between animal
species. But this hijpolJte.sls makes an exception of man ;
we have, therefore, the right to regard it as false.
If, on the contrary, we look upon these groups as nothing
more than races of a single species, all these facts of inter-
crossing and fusion agree with what may be observed in
plants and animals and replace man under the dominion of
Thus, without quitting morphological considerations,
which corres}x»nd to the idea of resemblance contained in
the definition of species, we are jii^tifiid in rdiieliuling in
62 The Hum an Species.
favour of monogonism. To confiiin this conclusion, however,
we must turn our attention to other facts which correspond
to the idea of Jlliation, and consider the teachings of
physiology concerning the phenomena o( yeneration.
CROSSING OF RACES AND SPECIES IN THE ANIMAL AND
VEGETABLE KINCDOMS. — MONGRELS AND IIYHRTDS.
1. Sexl'al unions in plants, as in animals, can take place
between individuals of the same species and the same race ;
further, between different races of the sam^ species, and,
finally, between different species. In the two latter cases
we have what is called a cross. This crossing itself is dif-
ferently named according to whether it takes place between
different races or different species. In the first case it pro-
duces a moiifjrel, in the second a hybrid. When the cross
unions arc fertile the product of the union of mongrels is
called a mongrel, the product of the union of hybrids a
If the difference of the relations existing between the race
and the species has been properly understood, we ought to
be inclined to admit that mongrels and hybrids would not
present the same phenomena ; experience and observation
' "iifirm this presentiment.
We have, therefore, in this crossing a means of judgino-
wliether the human groups are only races of a single species,
or rather distinct species. For this purpose it will bo
sufficient to study the phenomena which, in other organisecl
and living beings, accompany the production of mongrel.-?
and hybrids, and then to compare with both the phenomena
which characterise the crosses effected between human
groups. If, in the latter case, the phenomena arc those
which characteri.se hybridism, we must conclude that the
groups are specifically distinct, and admit the multiplicity
of human species. If, however, cro.sses between human
64 The IIiDuan Species.
groups, moipliologicall}' different, arc accompanied by plicno-
mena peculiar to tlic production of monrfrels, we shall only
be justified in considering tbcsc groups as races of one
species ; we must take our stand upon the doctrine of the
Specific Unity of all mankind.
The qtiestion before us becomes then entirely a physiological
one, and depends simply upon observation and experiment.
For its solution we must again turn our attention to plants
as well as to animals. It is in the phenomena of reproduc-
tion that the two kingdoms show the greatest resemblance.
This is not a ca.se of mere analofjij, but almost of identity,
and it is not the superior which lowers itself but the inferior
which is raised. We might say that, cnnubled by the im-
portance of the function, the plant, as far as its reproductive
system is concerned, becomes, for the time, animal.
II. In these kingdoms the unions between races of the
same sjyecies, that is to say, the ;:>}-0(?«c/ic)>i of mongrels,
may be accomplished without any interventiuu on the part
of man, or it may take place under his direction. It is
consequently cither natural or artificial.
Mongrels among plants could only be recognised after the
discovery of the distinction of the sexes in 1744'. The honour
of this great discovery belongs to Linna-us. He at once
comprehended the importance of the subject, and even
exaggerated it, as we shall presently see. Linnanis admitted
that cross-unions, which iiad been observed for centuries
between animals, might be repeateil between i)lants. And he
thus explained the appearance of variegated tulips in the
midst of borders originally formed of uniformly coloured
llowers. Observation and experiment have confirmed the
views of the founder of the natural .sciences again and again.
.Moreover, it has been ob.served that the crossing may become
apparent in all part.s of the plant by a nnxture of cliaractcrs
Himiiar to that exhibited by the colouring of the tulips.
M. Naudin, among others, who, during one year, watched the
development of more than 1200 gourd-s saw the seeds of a
single fruit rrproduro all the rnrrs contained in the garden
Crossiiii;- of Races ami Species. 65
in which liis observations were made, Supcrfetation had
taken phice. It is a fact of great importance, as it demon-
strates the eijiiality of action enjoyed by the pollen of all
these races, which, morphologically, differ so widely from
each other. No better example could be given of the faculty
of crossing heivxen races.
The natural and spontaneous production of mongrels
among animals presents the same characters. Facilitated by
lucomotion it is accomplished every day in our houses, our
jHjultry-yards, and our farms. The difficulty does not consist
in the accomplishment of the cross but in its prevention, and
in the preservation of the purity of the race. The careful
observations made by Isidore Geoffrey at the Paris Museum,
have shown that with sheep, dogs, pigs, and fowls, mongrels
between the most different races were invaiiably fertile.
Here again the phenomena of supcrfetation was often
proved. Bitches produced, by males of several races
successively, young which showed three or four distinct
sources. Here the Ciise was the same as with the gourds of
We see that man has found no difficulty in breeding
mongrels, and tiiat, when he has wished to do so for any
purpose whatever, he has been able to regulate it by merely
choosing the animal or plant. This kind of \mion ha.s,
indeed, been long in daily practice for the amelioration,
modification, and diver.'^ification of the living beings upon
which human industry is exercised. It is useless to insist
iiptm facts which are known to all gardeners and breeders,
and I shall confine myself to one remark, the importance
of which will be understood later.
We have already seen that in the endeavour to iterfcct a
vegetable or animal race, the physiological e(|uilibrium has
sometimes been destroyed at the expense of the reproductive
power. In such ca.ses, crossing with another race which is
less modified, generally revives the extinguished fertility.
For example, the English pigs imported into the mid<lle of
France by M. de (Jinostous became sterile after several
66 The I/itifian Spccit's.
generation.?. Upon cros.sing tlicm with a leaner and less
perfect local race, their fertility returned.
All these facts, and their inevitable conse(iuencc.s, have
been admitted by every naturalist who has studied the
question. Even Darwin has recognised the truth of them in
his valuable work upon the Vanat'toii of Animals and
Plants. At that time he confined himself to the conclusion
that the crosses between some races of plants are less fertile
than between others, a proposition whicii no one would think
of denying. He has gone further in the latest editions of
his work upon the Origin of Species. Without bringing
forward clear facts, the meaning of which would go further
than the wise conclusions he had previously admitted, he
invokes our relative ignorance of what takes place among
wild varieties, and concludes that we must admit that the
cros.ses between varieties must always be perfectly fertile.
This is one of those appeals to the unknown, one of those
arguments where even our ignorance is invoked as a proof,
w hich we too often meet with in Darwin, who is often carried
;iw;iy by his convictions, I shall have to return to this point,
l)ut I here make the statement as an established fact, on the
authority even of Darwin, that all knoivn facts attest the
jx'i'fcct fertilHy of mongrels.
Finally, the formation of crosses between races, or tiie
production of mongrels, is spontaneous, and may bo pro-
moted by man without the least difticulty ; the results are
as certain as those with the union of individuals of tlie same
rare ; in certain ca.ses, indeed, fertility is increased or revived
under the influence of this crossing.
Crosses hctwi-en species, or liyhrids, will exhibit facts of an
entirely contrary nature
J II. The formation nf hybrids, as of mongrels, may be
either natural or artificial.
The former is so rare that eminent naturalists have
(lotibtcd its reality. There are, however, according to M.
Dccaisne, a K«'ore of well proved oxaniplcs among plants.
What is this nuiiilur conipareil with the thousands of
Mongrels and Hybrids. 67
mongrels proJuccJ every clay uiuler our eyes. And yet
the niiiterial comlitions of fertility arc identically the same
with races a.s with species, anil our botanical gardens, which
group luunbers of species side by side, fiicilitate crossing still
Among wild animals living in liberty hybrids are still more
rare. It is unknown, for example, among mammalia, accord-
ing to Isidore Geolfroy, whose experience has here a double
value. The order of birds alone presents some facts of this
kind, nearly all of which are in the order of Gallina-.
Acconling to Valenciennes, they arc unknown among fishes.
In domestication and captivity spontaneous crossing between
ilirterent species is a little less rare.
The intelligent intervention of man has multiplied unions
of this kind in a remarkable manner, especially among
plants, but without being able to extend their limits.
Litinajus thought crossing was possible between species of
different families. But in 17G1 Koebreuter showed that
he was mistaken. From these investigations, which were
carried on for twenty-seven years, and from those of M.
Naudin, his worthy rival, it appears that artificial crossing
between species of different families never succeeds, and
very rarely between species of different genera ; that it is
dways very difficult, and demands the most minute pre-
cautions to insure success ; that it often fails between species
of the same genus closely allied in appeai-ance, and finally,
that there are whole families among which hybrids are impos-
sible. Amongst the latter figures the family of the cucur-
bitaccae, so thoroughly studied by M. Naudin, where the
most jxMfcct mongrels were produced spontaneously. We
coidd not imagine, evidently, a more complete contrast.
This contra.st is carried into the minutest details. For
example, any flower which has in the least possible degree
undergimc the action of pollen of its own species becomes
ab.<Nolutcly insensible to the action of pollen of a different
>p(cii's. How different to the equality of action disjdayed
by the several pollens of most distant races !
68 The Unman Species.
All experimenters agree further in declaring that even in
the unions between species which have been most successful,
the fertility is constantly diminished, and often in immense
proportions. The head of the Papaver somnifera generally
contains 2000 seeds or more. In a hybrid of this species
Goertner only found si.x which had been matured ; all the rest
were more or less abortive. Here again, what a contrast
between the crossing productive of such fertility in M. De
Ginestous' English pigs.
Hybridism in animals presents exactly the same phenomena
as in plants. Man has been able, by diverting and deceiving
animal instincts, to multiply crosses between species. But
he has not been able to extend the very narrow limits at
wliich these phenomena cea.se. Not one fertile \mion has
taken place between dilferent families ; they arc very rare
between genera, and even between species they are far from
numerous, a fact the more remarkable as animal hybridation
is an ancient institution. The mule was known to the
Hebrews before the time of David, and to the Greeks in the
age of Homer. T'd'ircs and musmons, products of crossings
between the he-goat and the sheep and the ram with the
she-goat, received their distinctive names from the Romans.
The uncertainty of the result is another point of resem-
blance between animal and vegetiible hybrid.s. The same
experiments executed with the same care anil by equally
(liver experimenters have sometimes succeeded and some-
times failed without any apparent cause. Buffon and Dau-
JHiisun often tried to reproduce titires and nnismons. Tliey
sueceeded twice, while Lsidore GeoftVoy has invariably faileil.
The formation of crosses between tiic hare and the rabbit,
which has fre<(uently been attempted in various parts of the
^^hjbe, apj)ear.s only to have been successful four or five times
at the most. The pretended cross between the camel and
the <ironiedMry, admitted by IhifTon and (jwoted by Nott, is
certainly a fal)le, alter the <letJiils which M. J)e Khanikofll"
kindly gave mc, and which I have published elsewhere. Wc
may, therefore, <lraw this conclusion fiom known facts, that
JMongrcls and Hybrids. 69
there are only two species of mammals, the ass and the
horse, the crossing of which is almost universally and invari-
Finally, crossing between specks, or hyhrldalton, is ex-
tremely exceptional among plants and animals when left to
themselves ; man can only produce them with great difficulty
in the two kingdoms, and then only between a very limited
number of species ; when he has succeeded, the fertility is
almost constantly diminished, and often to a very consider-
CROSSING BETWEEN VEGETABLE AND ANIMAL RACES AND
SPECIES; MONGRELS AND HYBRIDS; REALITY OF SPECIES.
I. From the very first, in the union of two individuals
belonging to different stocks, the race and the species dis-
play very distinct and characteristic plienomena. We shall
now see this opposition as strongly marked in the product of
these unions in Tnongrels and hybrids.
Several questions are raised by the mixed nature of these
btiiigs. I shall confine myself to those which refer to filia-
tion, and which have therefore a special interest for us. They
may be stated generally as follows : — are mongrel races, that
is, those derived from hvo distinct races, and hybrid races, that
i? those which are derived from the crossing of hvo species,
formed naturally, or can they be obtained artificially ? In
other -words, do mongrels and hybrids retain, during an
indefinite number of generations, the faculty of reproducing
and transmitting to their descendants the mixed character
they inherited from the first parents which effected the
II. In regard to mongrels there is not a shadow of doubt.
Facts which frc<[U('ntly occur, often Avithout our interven-
tion, and sometimes in spite of our precautions, prove again
and again that the mongrels of tlic first generation are as
I'trtile as tlie parents, and transmit cfpial fertility to their
(»ffspring. Our gardeners and breeders always take advan-
tage of this property of mongrels in order to vary, modify
or anK'liorate from their point of view the })lants and
animals in which they are interested ; the careful experi-
ments of Buffon, of Geoffroy St. Hilaire, father and son, and
Crossing beiivccn Races. 71
the testimony of Darwin, on this point very significant,
prove beyond a doubt that unions between different races
remain fertile, whatever morphological differences there may
be between them. I shall confine myself to quoting one
example from Darwin. The niata will unite indifferently
in both senses with the ordinary ox, and the offspring is
If several races of a single species are in habitual contact
and left to themselves, they will intermix in every degree.
This results in bastard offspring, devoid of definite charac-
ters, but which, when methodically studied, would lead
through insensible shades to the different primitive types.
In this manner our street dogs and cats have come into
existence, which remain perfectly fertile in spite of innu-
merable crossings of every kind.
With human intervention it is possible, when care is
taken, to regulate the crossing between two races, and to
obtain a mongrel race. After a few oscillations between
the paternal and maternal types it becomes consolidated
and settled. But whatever constancy it may have acquired
as a Avhole, it almost always happens that some individuals
reproduce, to a varying extent, the characters of one of the
types originally crossed.
This phenomenon is designated by the name of Atavism.
It sometimes occurs in the midst of a race considered to
be perfectly pure, and is the result of a single crossing
several generations back. Darwin qtiotes the case of a
breeder, Avho having crossed Ids fowls with the Malay race,
wished afterwards to free them from the stransfe blood.
After spending forty years in the attempt, he is still un-
successful, the Malay blood always reappearing in some of
In animals as in plants, univcrsid, free and indefinite
fertility, whether between themselves or between all the
races of the same species, is one of the characters of
mongrels. Atavism attests the physiological bon<l v.hich
unites all niontrrels.
72 The Human Species.
III. Ill liybriils we shall meet witli some very different
Let u.s first, with M. Godron, establish the fact that in
the vegetable hybrid the physiological equilibrium is de-
stroyed in favour of the organs conducive to the life of the
individual, and at the expense of those conducive to the
life of the species. The stalk and leaves are always deve-
loped in an exaggerated manner relatively to the flowers.
'J'he most common animal hybrid, the mule, is an entirely
similar case, being invariably stronger, more robust, more
hardy than its parents, but sterile.
This sterility is not absolute, however, among all hybrids
of the first generation. It generally affects the male organs
in an entirely special manner. Koelreuter, to whom we
should always refer when treating of plants, states that the
anthers scarcely ever enclose veritable pollen, but merely
irregular granulations. It was not quite so unusual to find
ovules in good condition in the ovary. Guided by these
ol)servations, Koelreuter artificially fertilised hybrid flowers
with pollen from the male species, and thus obtained a
vegetable qiuidroon. By continuing this process he soon
brought back again to the original male type the descen-
dants of the first hybrid, Avhich regained all their generative
faculties, but at the same time lost all trace of the female
type. These experiments have been repeated and varied,
but always with the same result.
In a small number of hybrids of the • first generation
the elements which characterise the two sexes remained
faj)able of reproduction. Nevertheless the fertility is always
iiMinonsely reduced. From liis hybrids of the datura, M.
Naudiii only obtained five or six fertile seeds from each
jtlant. All the otJiLis had completely failed, or were without
an embryo. The capsules them.selves were only half the
If two (jf these first hybrids are united they produce
hybrids of the second generation. In most cases, however,
tlif latter are citlicr sterile, or present the phciioiiK'non of a
Hybridation — Disordei'cd Variation. 73
sjwntaneous return to one or the other of the parent types,
or to both. M. Naudin crossed the large-leaved primrose
with the iwimula offi.cinal'is, and obtained an intermediate
hybrid between tlie two species, havingr seven fertile seeds.
When these were sown they produced three primroses of
the male species, three of the female, and a single hybrid
plant which was perfectly barren.
In some still rarer cases fertility continues during several
generations. Then, however, a curious phenomenon is ex-
hibited, called by M. Naudin, Avho discovered it, Disordered
variation. With the Linaria communis and the Linaria
'purpurea he produced a hybrid, the descendants of which
he was able to follow through seven generations, in each
of which several individuals reverted to the characters
either of the original male or female. The others neither
resembled the primitive types nor the hybrid resulting
from their crossing, nor the plants of which they were the
immediate offspring, nor was there any resemblance between
the plants themselves.
Thus the crossing does not produce a race, even in cases
where it allows a certain amount of fertility ; it only produces
varieties incapable of transmitting their individual characters.
In order to establish a series of generations presenting a
certivin amount of uniformity, the hybrid must lose some of
its mixed characters, and resume the normal livery of the
species, as M. Naudin .says ; in other words, it must return
to one of the parent types.
IV. The same facts which we have iust noticed amoiio-
plants, occur also among animals. We must observe in tiie
first place, that the only two species, the crossing of which
displays anything approaching to regular fertility, the horse
and the ass, merely produce a hybrid almost entirely devoid
of fertility. It is more than 2000 yeare since Herodotus
regarded tlie fertility of mules as a prodigy, and Jilmost 1800
years since Pliny expressed the same opinion.
And yet in .some works we read that the fertility of the
mule is displayed in the present day ; that it often propa-
74 ^/'^ Iluniaji Species.
gates in liot countries, especially in Algeria. The true value
of these singular assertions \s\\\ be recognised if we recall the
effect which was produced in 1S28 upon the whole Mussul-
man population of Algeria by the announcement that a mule
had conceived near Biskra. The astonishment was general ;
the Arabs gave themselves up to long fasts to conciliate the
wrath of heaven, thinking the end of the world had come.
Fortunately the mule miscarried ; but long afterwards the
Arabs still spoke Avith terror of this event.