"Species are fixed and permanent forms of being, exhibiting indeed certain modes of variation, of which they may be more or less susceptible, but maintaining throughout those modifications a sameness of structural essentials, transmitted from generation to generation, and never lost by the influence of causes which otherwise produce obvious effects. _Varieties_ are either accidental or the result of the care and culture of man."[198]--MARTIN.
Dr. Bachman gives another, substantially the same, from Aga.s.siz; and also one of his own, to which he appends, as an additional test of species, the production of "_fertile offspring by a.s.sociation_." In this definition the doctor _a.s.sumes_ one of the main points in dispute.
"_Varieties_," says Dr. Bachman, "are those that are produced within the limits of particular species, and have not existed from its origin. They sometimes originate in wild species, especially those that have a wide geographical range, and are thus exposed to change of climate and temperature," &c. * * *
"_Permanent varieties_ are such as, having once taken place, are propagated in perpetuity, and do not change their characteristics unless they breed with other varieties."
We may remark that the existence of such _permanent varieties_ as here described is also in dispute.
The same author continues:--
"On comparing these definitions, as given by various naturalists, each in his own language, it will be perceived that there is no essential difference in the various views expressed in regard to the characters by which a species is designated. They all regard it as "the lowest term to which we descend, with the exception of _varieties_, such as are seen in domestic animals." They are, to examine the external and internal organization of the animal or plant--they are, to compare it with kindred species, and if by this examination they are found to possess _permanent characters differing from those of other species, it proves itself to be a distinct species_. When this fact is satisfactorily ascertained, and the specimen is not found a domestic species, in which varieties always occur, presumptive evidence is afforded of its having had a primordial existence. We infer this from the fact that no species is the production of blind chance, and that within the _knowledge of history_ no true species, but _varieties_ only, whose origin can be _distinctly traced to existing and well-known species_, have made their appearance in the world. This, then, is the only means within the knowledge of man by which any species of plant or animal _can be shown_ to be primordial. The peculiar form and characters designated the species, and its origin was a necessary inference derived from the characters stamped on it by the hand of the Creator."
To all the positions thus far taken by Dr. Bachman, we most cheerfully subscribe; they are strictly scientific, and by such criteria alone do we desire to test the unity of the human family; but we must enter a decided demurrer to the a.s.sertion which follows, viz: that, "according to the universally received definition of species, all the individuals of the human race are proved to be of one species." When it shall be shown that all the races of men, dogs, horses, cattle, wolves, foxes, &c., are "varieties only, _whose origin can be distinctly traced to existing and well-known species_," we may then yield the point; but we must be permitted to say that Dr. Bachman is the only naturalist, as far as we know, who has a.s.sumed to know these original types.
Now, if the reader will turn back and review carefully all the definitions of species cited, he will perceive that they are not based upon _anatomical characters_, but simply on the _permanency_ of certain organic forms, and that this permanence of form is determined by its _history_ alone.
Professor Owen, of London, has thrown the weight of his great name into the scale, and tells us that "man is the sole species of his genus, the sole representative of his order." But proving that man is not a monkey, as the professor has done in the lecture alluded to, does not prove that men are all of _one_ species, according to any definition yet received: he has made the a.s.sertion, but has a.s.signed no scientific reasons to sustain it. No one would be more rejoiced than ourselves, to see the great talent and learning of Professor Owen brought fully to bear on this point; but, like most naturalists, he has overlooked one of the most important points in this discussion--_the monumental history of man_.
Will Professor Owen or Dr. Bachman tell us wherein the lion and tiger--the dog, wolf, fox, and jackal--the fossil horse, and living species--the Siberian mammoth and the Indian elephant, differ more from each other than the white man and the negro? Are not all these regarded by naturalists as distinct species, and yet who pretends to be able to distinguish the skeleton of one from the other by specific characters?
The examples just cited, of living species, have been decided upon simply from their permanency of type, as derived from their history; and we say that, by the same process of reasoning, the races of men depicted on the monuments of Egypt, five thousand years ago, and which have maintained their types through all time and all climates since, are _distinct species_.
Dr. Morton defines species--"a primordial organic form," and determines these forms by their permanence through all human records; and Mr.
Aga.s.siz, who adopts this definition, adds: "Species are thus distinct forms of organic life, the origin of which is lost in the primitive establishment of the state of things now existing; and varieties are such modification of the species as may return to the typical form under temporary influences."
Dr. Bachman objects very strongly to this definition, and declares it a "cunning device, and, to all intents, an _ex post facto_ law," suddenly conjured up during a controversy, to avoid the difficulties of the case; but we have serious doubts whether these gentlemen are capable of such subterfuge in matters of science, and confess that we cannot see any substantial difference between their definition and those given by Dr.
Bachman. Morton and Aga.s.siz determine a form to be "_primordial_" by its permanency, as proved by history, and the other definitions a.s.sign no other test.
Professor Leidy, who has not only studied the "lower departments of zoology," like Mr. Aga.s.siz, but also the "higher forms of animal life,"
says that "too much importance has been attached to the term species,"
and gives the following definition: "A species of plant or animal may be defined to be an immutable organic form, whose characteristic distinctions may always be recognized by _a study of its history_."[199]
M. Jourdain, under the head "Espece," in his _Dictionnaire des Termes des Sciences Naturelles_, after citing a long list of definitions from leading authors, concludes with the following remarks, which, as the question now stands before the world, places the term species just where it should be:--
"It is evident that we can, among organized bodies, regard as a _species_ only such a collection of beings as resemble each other more than they resemble others, and which, by a consent more or less unanimous, it is agreed to designate by a common name; for a _species_ is but a simple _abstraction of the mind_, and not a group, exactly determined by nature herself, as ancient as she is, and of which she has irrevocably traced the limits. It is in the definition of species that we recognize how far the influence of ideas adopted without examination in youth is powerful in obscuring the most simple ideas of general physics."
Although not written with the expectation of publication, I will take the liberty of publishing the following private letter just received from Prof. Leidy. He has not appeared at all in this controversy before the public, and we may safely say that no one can be better qualified than he is to express an opinion on this question of species.
"With all the contention about the question of what const.i.tutes a _species_, there appears to be almost no difficulty, comparatively, in its practical recognition. Species of plants and animals are daily determined, and the characters which are given to distinguish them are viewed by the great body of naturalists as sufficient. All the definitions, however, which have been given for a species, are objectionable. Morton says: "A species is a primordial organic form." But how shall we distinguish the latter? How can it be proved that any existing forms primordially were distinct? In my attempted definition, I think, I fail, for I only direct how species are discovered.
"According to the practical determination of a species by naturalists, in a late number of the _Proceedings_ of our Academy (vol. vii. p. 201), I observe: "A species is a mere convenient word with which naturalists empirically designate groups of organized beings possessing characters of comparative constancy, as far as historic experience has guided them in giving due weight to such constancy."
"According to this definition, the races of men are evidently distinct species. But it may be said that the definition is given to suit the circ.u.mstances. So it is, and so it should be; or, if not, then all characterized species should conform to an arbitrary definition. The species of gypaetus, haliaetus, tanagra, and of many other genera of birds, are no more distinguishable than the species of men; and, I repeat, the anatomy of one species of haliaetus, or of any other genus, will answer for that of all the other species of the same genus. The same is the case with mammals. One species of felis, ursus, or equus will give the exact anatomy of all the other species in each genus, just as you may study the anatomy of the white man upon the black man. While Prof.
Richard Owen will compare the orang with man, and therefore deduce all races of the latter to be of one species, he divides the genus cervus into several other genera, and yet there is no difference in their internal anatomy; while he considers the horse and the a.s.s as two distinct genera, and says that a certain fossil horse-tooth, carefully compared with the corresponding tooth of the recent horse, showed no differences, excepting in being a little more curved, he considers it a distinct species, under the name of equus curvidens; and yet, with differences of greater value in the jaws of the negro and white man, he considers them the same.
"In the restricted genera of vertebrata of modern naturalists, the specific characters are founded on the external appendages, for the most part--differences in the scales, horns, antlers, feathers, hairs, or bills. Just as you separate the black and white man by the difference in the color of the skin and the character of the hair, so do we separate the species of bears, or cats, &c.
"PHILADELPHIA, _April 18, 1855_."
We might thus go on and multiply, to the extent of an octavo volume, evidence to show how vague and unsettled is the term species among naturalists, and that, when we abandon historical records, we have no reliable guide left. Moreover, were we able to establish perfectly reliable landmarks between species, we still have no means of determining whether they were originally created in one pair, or many pairs. The latter is certainly the most rational supposition: there is every reason to believe that the earth and the sea brought forth "_abundantly_" of each species.
It must be clear to the reader, from the evidence above adduced, that Dr. Bachman claims far too much when he a.s.serts that--
"Naturalists can be found, in Europe and America, who, without any _vain boast_, can distinguish every species of bird and quadruped on their separate continents; and the characters which distinguish and separate the several species are as distinct and infallible as are those which form the genera."[200]
And, again, when he says:--
"From the opportunities we have enjoyed in the examination of the varieties and species of domesticated quadrupeds and birds, we have never found any difficulty in deciding on the species to which these varieties belong."
Those of us who are still groping in darkness certainly have a right to ask who are the authorities alluded to, and what are those "characters which distinguish and separate species" as distinctly and infallibly as "genera?" They are certainly not in print.
The doctor must pardon us for reminding him that there is printed evidence that his own mind is not always free from doubts. In the introduction of Audubon and Bachman"s _Quadrupeds of America_, p. vii., it is said:--
"Although _genera_ may be easily ascertained by the forms and dental arrangements peculiar to each, many _species_ so nearly approach each other in size, while they are so variable in color, that it is exceedingly difficult to separate them with positive certainty."
Again, in speaking of the genus _vulpes_ (foxes), the same work says:--
"The characters of this genus differ so slightly from those of the genus _canis_, that we are induced to pause before removing it from the sub-genus in which it had so long remained. As a general rule, we are obliged to _admit that a large fox is a wolf, and a small wolf may be termed a fox_. So inconveniently large, however, is the list of species in the old genus _canis_, that it is, we think, advisable to separate into distinct groups such species as possess any characters different from true wolves."
Speaking of the origin of the domestic dog, Dr. Bachman, in his work on _Unity of Races_, p. 63, says:--
"Notwithstanding all these difficulties--and we confess we are not free from some doubts in regard to their ident.i.ty (dog and wolf)--if we were called upon to decide on any wild species as the progenitor of our dogs, we would sooner fix upon the large wolf than on any other dog, hyena, or jackal," &c.
The doctor is unable, here at least (and we can point out many other cases), to "designate species;" and the recent investigations of Flourens, at the _Jardin des Plantes_, prove him wrong as regards the origin of the dog. The dog is not derived from the "large wolf," but, with it, produces hybrids, sterile after the third generation. The dog forms a genus apart.
We repeat, then, that in a large number of _genera_, the species cannot be separated by any anatomical characters, and that it is from their history alone naturalists have arrived at those minute divisions now generally received. We may, without the fear of contradiction, go a step further, and a.s.sert that several of the races of men are as widely separated in physical organization, physiological and psychological characters, as are the canidae, equidae, felines, elephants, bears and others. When the white races of Europe, the Mongols of Asia, the aborigines of America, the black races of Africa and Oceanica are placed beside each other, they are marked by stronger differences than are the species of the genera above named. It has been objected that these gaps are filled by intermediate links which make the chain complete from one extremity to the other. The admission of the fact does not invalidate our position, for we have shown elsewhere (see _Types of Mankind_) _gradation_ is the law of nature. The extreme types, we have proven, have been distinct for more than 5000 years, and no existing causes during that time have transformed one type into another. The well-marked negro type, for example, stands face to face with the white type on the monuments of Egypt; and they differ more from each other than the dog and wolf, a.s.s and _Equis Hemionus_, lion and tiger, &c. The hair and skin, the size and shape of head, the pelvis, the extremities, and other points, separate certain African and Oceanican negroes more widely than the above species. This will not be questioned, whatever difference of opinion may exist with regard to the permanency of these forms. In the language of Prof. Leidy, "the question to be determined is, whether the differences in the races of men are as permanent and of as much value as those which characterize species in the lower genera of animals." These races of men too are governed by the same laws of geographical distribution, as the species of the lower genera; they are found, as far back as history can trace them, as widely separated as possible, and surrounded by local Florae and Faunae.
VARIETIES.
This term is very conveniently introduced to explain all the difficulties which embarra.s.s this discussion. Dr. Bachman insists that all the races of men are mere _varieties_, and sustains the opinion by a repet.i.tion of those a.n.a.logies which have been so often drawn from the animal kingdom by Prichard and his school. It is well known that those animals which have been domesticated undergo, in a few generations, very remarkable changes in color, form, size, habits, &c. For example, all the hogs, black, white, brown, gray, spotted, &c., now found scattered over the earth, have, it is said, their parentage in one pair of wild hogs. "This being admitted," says Dr. B. "we invite the advocates of plurality in the human species to show wherein these varieties are less striking than their eight (alluding to Aga.s.siz) originally created nations." Again--
"And how has the discovery been made that all the permanent races are mere varieties, and not "originally created" species, or "primitive varieties?" Simply because the naturalists of Germany, finding that the original wild hog still exists in their forests, have, in a thousand instances, reclaimed them from the woods. By this means they have discovered that their descendants, _after a few generations_, lose their ferocity, a.s.sume all colors," &c.
The same reasoning is applied to horses, cattle, goats, sheep, &c., while many, if not most of the best naturalists of the day deny that we know anything of the origin of our domestic animals. Geoffroy St.
Hilaire, in his work, just out, denies it in toto. We are, however, for the sake of argument, willing to admit all the examples, and all he claims with regard to the origin of endless varieties in domesticated animals.[201]
Let us, on the other hand, "invite the advocates of _unity_ of the human species" to say when and where such varieties have sprung up in the human family. We not only have the written history of man for 2000 years, but his monumental history for 2000 more; and yet, while the naturalists of Germany are catching wild hogs, and recording in a thousand instances "after a few generations" these wonderful changes, no one has yet pointed out anything a.n.a.logous in the human family; the porcupine family in England, a few spotted Mexicans, &c., do not meet the case; history records the origin of no permanent variety. No race of men has in the same country turned black, brown, gray, white, and spotted. The negroes in America have not in ten generations turned to all colors, though fully _domesticated_, like pigs and turkeys. The Jews in all countries for 2000 years are still Jews. The gypsies are everywhere still gypsies. In India, the different castes, of different colors, have been living together several thousand years, and are still distinct, &c. &c.
Nor does domestication affect all animals and fowls equally; compare the camel, a.s.s, and deer, with the hog and dog; the Guinea fowl, pea fowl, and goose, with pigeons, turkeys, and common fowls. In fact, no one animal can be taken as an a.n.a.logue for another: each has its own physiological laws; each is influenced differently and in different degrees by the same external influences. How, then, can an animal be taken as an a.n.a.logue for man?
We have also abundant authority to show that all wild species do not present the same uniformity in external characters.
"All packs of American wolves usually consist of various shades of color, and varieties nearly black have been occasionally found in every part of the United States.... In a gang of wolves which existed in Colleton District, South Carolina, a few years ago (sixteen of which were killed by hunters in eighteen months), we were informed that about one-fifth were black, and the others of every shade of color, from black to dusky gray and yellowish white."--AUDUBON & BACHMAN, 2d Amer. ed., vol. ii. pp. 130-1.
Speaking of the white American wolf, the same authors say:--
"Their gait and movements are precisely the same as those of the common dog, and their mode of copulating and number of young brought forth at a litter, are about the same." (It might have been added that their number of bones, teeth, whole anatomical structure are the same.) "The diversity of their size and color is remarkable, no two being quite alike."... "The wolves of the prairies ... produce from six to eleven at a birth, of which there are very seldom two alike in color."--_Op. cit._, p. 159.