"The common American wolf, Richardson observes, sometimes shows remarkable diversity of color. On the banks of the Mackenzie River I saw five young wolves leaping and tumbling over each other with all the playfulness of the puppies of the domestic dog, and it is not improbable they were all of one litter. One of them was pied, another black, and the rest showed the colors of the common gray wolves."
The same diversity is seen in the prairie wolf, and naturalists have been much embarra.s.sed in cla.s.sifying the various wolves on account of colors, size, &c.
All this is independent of _domestication_, and shows the uncertainty of a.n.a.logues; and still it is remarkable that though considerable variety exists in the native dogs of America in color and size, they do not run into the thousand grotesque forms seen on the old continent, where a much greater mixture exists. The dogs of America, like the aboriginal races of men, are comparatively uniform. In the East, where various races have come together, the men, like the dogs, present endless varieties, Egypt, a.s.syria, India, &c.
Let us suppose that one variety of hog had been discovered in Africa, one in Asia, one in Europe, one in Australia, another in America, as well marked as those Dr. B. describes; that these varieties had been transferred to other climates as have been Jews, gypsies, negroes, &c., and had remained for ages without change of form or color, would they be considered as distinct species or not?--can any one doubt? The rule must work both ways, or the argument falls to the ground.
In fact the Dr. himself makes admissions which fully refute his whole theory.
"Whilst," says he, "we are willing to allow some weight to the argument advanced by President Smyth, who endeavors to account for the varieties in man from the combined influences of three causes, "climate, the state of society, and manner of living," we are free to admit that it is impossible to account for the varieties in the human family from the causes which he has a.s.signed."[202]
The Dr. further admits, in the same work, that the races have been _permanent_ since the time of the old Egyptian empire, and _supposes_ that at some extremely remote time, of which we have no record, that "they were more susceptible of producing varieties than at a later period." These suppositions answer a very good purpose in theology, but do not meet the requirements of science.
HYBRIDITY.
Having shown the insufficiency of all the other arguments in establishing the landmarks of _species_, let us now turn to those based on _hybridity_, which seems to be the last stronghold of the unity party. On this point hang all the difficulties of M. Gobineau, and had he been posted up to date here, his doubts would all have vanished. The last twelve months have added some very important facts to those previously published, and we shall, with as little detail as possible, present the subject in its newest light.
It is contended that when two animals of distinct species, or, in other words, of distinct origin, are bred together, they produce a hybrid which is _infertile_, or which at least becomes sterile in a few generations if preserved free from admixture with the parent stocks. It is a.s.sumed that unlimited prolificness is a certain test of community of origin.
We, on the contrary, contend that there is no abrupt line of demarcation; that no complete laws of hybridity have yet been established; that there is a _regular gradation_ in the prolificness of the species, and that, according to the best lights we now possess, there is a continued series from perfect sterility to perfect prolificacy. The degrees may be expressed in the following language:--
1. That in which hybrids never reproduce; in other words, where the mixed progeny begins and ends with the first cross.
2. That in which the hybrids are incapable of producing _inter se_, but multiply by union with the parent stock.
3. That in which animals of unquestionably distinct species produce a progeny which are prolific _inter se_, but have a tendency to run out.
4. That which takes place between closely proximate species; among mankind, for example, and among those domestic animals most essential to human wants and happiness; here the prolificacy is unlimited.
It seems to be a law that in those genera where several or many species exist, there is a certain gradation which is shown in degrees of hybridity; some having greater affinity than others. Experiments are still wanting to make our knowledge perfect, but we know enough to establish our points.
There are many points we have not s.p.a.ce to dwell on, as the relative influence of the male and female on the offspring; the tendency of one species to predominate over another; the tendency of types to "crop out"
after lying dormant for many generations; the fact that in certain species some of the progeny take after one parent and some after the other, while in other cases the offspring presents a medium type, &c.
The genus _Equus_ (Horse) comprises six species, of which three belong to Asia, and three to Africa. The Asiatic species are the _Equus Caballus_ (Horse), _Equus Hemionus_ (Dzigguetai), and _Equus Asinus_ (a.s.s). Those of Africa are the _Equus Zebra_ (Zebra), _Equus Monta.n.u.s_ (Daw), and the _Equus Quaccha_ (Quagga). The horse and a.s.s alone have been submitted to domestication from time immemorial; the others have remained wild.
It is well known that the horse and a.s.s produce together an unprolific mule, and as these two species are the furthest removed from each other in their physical structure, Dr. Morton long since suggested that intermediate species bred together would show a higher degree of prolificness, and this prediction has been vindicated by experiments recently made in the Garden of Plants at Paris, where the a.s.s and dzigguetai have been bred together for the last ten years. "What is very remarkable, these hybrids differ considerably from each other; some resemble much more closely the dzigguetai, others the a.s.s." In regard to the product of the male dzigguetai and the jenny, Mr. Geoffroy St.
Hilaire says:[203]--
"Another fact, not less worthy of interest, is the fecundity, if not of all the mules, at least the firstborn among them; with regard to this, the fact is certain; he has produced several times with Jennies, and once with the female dzigguetai, the only one he has covered."[204]
At a meeting of the "Societe Zoologique d"Acclimation,"
M. Richard (du Cantal) "parle des essais de crois.e.m.e.nts de l"hemione avec l"anesse, et dit qu"ils ont donne un mulet beaucoup _plus ardent_ que l"ane. Il a.s.serte que les produits de l"hemione avec l"ane, sont feconds, et que le metis, nomme Polka, a deja produit."
To what extent the prolificness of these two species will go is yet to be determined, and there is an unexplored field still open among the other species of this genus; it is highly probable that a gradation may be established from sterility, up to perfect prolificacy.
Not only do the female a.s.s and the male onager breed together, but a male offspring of this cross, with a mare, produces an animal more docile than either parent, and combining the best physical qualities, such as strength, speed, &c.; whence the ancients preferred the onager to the a.s.s, for the production of mules.[205] Mr. Gliddon, who lived upwards of twenty years in Egypt and other eastern countries, informs me this opinion is still prevalent in Egypt, and is acted upon more particularly in Arabia, Persia, &c., where the _gour_, or wild a.s.s, still roams the desert. The zebra has also been several times crossed with the horse.
The genus _canis_ contains a great many species, as domestic dogs, wolves, foxes, jackals, &c., and much discussion exists as to which are really species and which mere varieties. In this genus experiments in crossing have been carried a step further than in the _Equidae_, but there is much yet to be done. All the species produce prolific offspring, but how far the prolificness might extend in each instance is not known; there is reason to believe that every grade would be found except that of absolute sterility which is seen in the offspring of the horse and a.s.s.
The following facts are given by M. Flourens, and are the result of his own observations at the _Jardin des Plantes_.
"The hybrids of the dog and wolf are sterile after the _third_ generation; those of the jackal and dog, are so after the _fourth_.
"Moreover, if one of these hybrids is bred with one of the primitive species, they soon return, completely and totally, to this species.
"My experiments on the crossing of species have given me opportunities of making a great many observations of this kind.
"The union of the dog and jackal produces a hybrid--a mixed animal, an animal partaking almost equally of the two, but in which, however, the type of the _jackal_ predominates over that of the _dog_.
"I have remarked, in fact, in my experiments, that all types are not equally dominant and persistent. The type of the dog is more persistent than that of the wolf--that of the jackal more than that of the dog; that of the horse is less than that of the a.s.s, &c. The hybrid of the dog and the wolf partakes more of the dog than the wolf; the hybrid of the jackal and dog, takes more after the jackal than dog; the hybrid of the horse and the a.s.s partakes less of the horse than the a.s.s; it has the ears, back, rump, voice of the a.s.s; the horse neighs, the a.s.s brays, and the mule brays like the a.s.s, &c.
"The hybrid of the dog and jackal, then, partakes more of the jackal than dog--it has straight ears, hanging tail, does not bark, and is wild--it is more jackal than dog.
"So much for the FIRST cross product of the dog with the jackal. I continue to unite, from generation to generation, the successive products with one of the two primitive stocks--with that of the dog, for example. The hybrid of the _second generation_ does not yet bark, but has already the ears pendent at the ends, and is less savage. The hybrid of the third generation barks, has the ears pendent, the tail turned up, and is no longer wild. The hybrid of the _fourth generation_ is entirely a dog.
"Four generations, then, have sufficed to re-establish one of the two primitive types--the type of the dog; and four generations suffice, also, to bring back the other type."[206]
From the foregoing facts, M. Flourens deduces, without a.s.signing a reason, the following _non sequitur_:--
"Thus, then, either hybrids, born of the union of two distinct species, unite and soon become sterile, or they unite with one of the parent stocks, and soon return to this type--they in no case give what may be called a new species, that is to say, an intermediate durable species."[207]
The dog also produces hybrids with the fox and hyena, but to what extent has not yet been determined. The hybrid fox is certainly prolific for several generations.
There are also bovine, camelline, caprine, ovine, feline, deer with the ram, and endless other hybrids, running through the animal kingdom, but they are but repet.i.tions of the above facts, and experiments are still far from being complete in establishing the _degrees_ which attach to each two species. We have abundant proofs, however, of the three first degrees of hybridity. 1st. Where the hybrid is infertile. 2d. Where it produces with the parent stock. 3d. Where it is prolific for one, two, three, or four generations, and then becomes sterile. Up to this point there is no diversity of opinion. Let us now inquire what evidence there is of the existence of the 4th degree, in which hybrids may form a new and permanent race.
To show how slow has been our progress in this question, and what difficulties beset our path, we need only state that the facts respecting the dog, wolf, and jackal, quoted above from Flourens, have only been published within the last twelve months. The ident.i.ty of the dog and wolf has heretofore been undetermined, and the _degrees_ of hybridity of the dog with the wolf and jackal were before unknown. These experiments do not extend beyond one species of wolf.
M. Flourens says:--
"_Les especes ne s"alterent point, ne changent point, ne pa.s.sent point de l"une a l"autre; les especes sont_ FIXeS."
"If species have a tendency to transformation, to pa.s.s one into another, why has not time, which, in everything, effects all that can happen, ended by disclosing, by betraying, by implying this tendency.
"But time, they may tell me, is wanting. It is not wanting. It is 2000 years since Aristotle wrote, and we recognize in our day all the animals which he describes; and we recognize them by the characters which he a.s.signs.... Cuvier states that the history of the elephant is more exact in Aristotle than in Buffon. They bring us every day from Egypt, the remains of animals which lived there two or three thousand years ago--the ox, crocodiles, ibis, &c.
&c., which are the same as those of the present day. We have under our eyes _human mummies_--the skeleton of that day is identical with that of the Egyptian of our day."
(M. Flourens might have added that the mummies of the white and black races show them to have been as distinct then as now, and that the monumental drawings represent the different races more than a thousand years further back.)
"Thus, then, through three thousand years, no species has changed. An experiment which continues through three thousand years, is not an experiment to be made--it is an experiment _made_. Species do not change."[208]
_Permanence of type_, then, is the only test which he can adduce for the designation of species, and he here comes back plainly to the position we have taken. Let us now test the races of men by this rule. The white Asiatic races, the Jew, the Arab, the Egyptian, the negro, at least, are distinctly figured on the monuments of Egypt and a.s.syria, as distinct as they are now, and _time_ and change of climate have not transformed any one type into another. In whatever unexplored regions of the earth the earliest voyagers have gone, they have found races equally well marked.
These races are all prolific _inter se_, and there is every reason to believe that we here find the fourth and last degree of hybridity.
Whether the prolificacy is _unlimited_ between all the races or species of men is still an unsettled point, and experiments have not yet been fully and fairly made to determine the question. The dog and wolf become sterile at the _third_. The dog and jackal at the fourth generation, and who can tell whether the law of hybridity might not show itself in man, after a longer succession of generations. There are no observations yet of this kind in the human family. It is a common belief in our Southern States, that mulattoes are less prolific, and attain a less longevity than the parent stocks. I am convinced of the truth of this remark, when applied to the mulatto from the strictly white and black races, and I am equally convinced, from long personal observation, that the _dark_-skinned European races, as Spaniards, Portuguese, Italians, Basques, &c., mingle much more perfectly with the negroes than do fair races, thus carrying out the law of gradation in hybridity. If the mulattoes of New Orleans and Mobile be compared with those of the Atlantic States, the fact will become apparent.
The argument in favor of unlimited prolificacy between species may be strongly corroborated by an appeal to the history of our domestic animals, whose history is involved in the same impenetrable mystery as that of man. M. Geoffroy St. Hilaire very justly remarks that we know nothing of the origin of our domestic animals; because we find wild hogs, goats, sheep, &c., in certain parts of Europe, several thousand years subsequent to the early migrations of man, this does not prove that the domestic come from these wild ones. The reverse may be the case.[209]