Popular Science Monthly/Volume 1/May 1872/The Natural History of Man I
I.—The Unity of the Human Species.
GENTLEMEN: Each of my fellow laborers in science comes here to lecture to you; they each select the subject which habitually occupies them. Some tell you of the heavens, the earth, the waters; from others you get the history of vegetables and animals. As I am Professor of the Natural History of Man at the Museum, I ask myself why I should not speak to you of man.
There is evidently as much interest for us in our own species as in the history of animals, even of those most useful to us. Indeed, at this time, the mind is drawn toward this study by an irresistible movement. Formerly, Anthropology, the natural history of man, was not represented in philosophical bodies, nor by the periodical press. Now, in Paris alone there are two Philosophical Societies occupied exclusively with this science, and two large publications equally devoted to it. At the Museum the teaching of anthropology is older. It is there aided by a collection which is still the best in the world.
I do not hesitate to say that it is one of the glories of France to have given by these methods an example to the entire world—an example followed today in America as well as in Europe. And I wish to make you take a part in this movement, by giving you some serious notion of the ensemble of the human family.
This, gentlemen, is much more difficult for me than for my associates. In all these lectures we are to speak of only a single being, man. Consequently, there will be an intimate union between them, so much so that any person who should miss a lecture would find difficulty in thoroughly understanding those that follow. To remove this difficulty, I mean to shape my teaching so that each lecture will form as definite a whole as possible. Then, at the commencement of each lecture, I shall endeavor to give, in a few words, a résumé of the preceding. In this way I hope to carry you to the end without ceasing to be understood.
Each lecture, then, will be a sort of chapter of what we might call Popular Anthropology.
By and by I hope that these lectures will be collected into a volume, and I shall be very proud if one day they merit the adjective I have employed—if, in reality, they become popular among you.
Let us enter, then, upon our first chapter. Since man is the subject of our discourse, we must first ask what he is. But, before answering, I ought to enter into some explanation.
This question has been often asked, but generally by theologians or by philosophers. Theologians have answered in the name of dogma and religion; philosophers in the name of metaphysics and abstraction. Let it be well understood between us that I shall take neither of these grounds, but shall avoid, with great care, both that of theology and that of philosophy. Before I became professor at the Museum, I was occupied with the study of animals—I was a naturalist. It is as a naturalist that I have taken my chair at the Institute. At the Museum I remain what I was, and nothing else. I shall continue the same at Vincennes, leaving to theologians theology, to philosophers philosophy, limiting myself in the name of science, and, above all, in the name of natural science.
Let us now return to the question I was about to put: What is man?
It is evidently useless to insist that man is neither a mineral nor a vegetable—that he is neither a stone nor a plant. But is he an animal? No indeed, especially when we take into account all which exists in him. And I am sure that in this respect you all agree with me.
Certainly none of you would wish to be compared with cattle that ruminate, with hogs that wallow in the mire. Nor would you wish to be classed with the dog, notwithstanding all the qualities which make him the friend and companion of man; nor with the horse, though it should be with Gladiator,
Man is not an animal. He is widely distinguished from animals by numerous and important characters of different sorts. I shall here only refer to his intellectual superiority, to which belongs articulate speech, so that each people has its special language; writing, which permits the reproduction of this language; the fine arts, by the aid of which he conveys, and, in some sort, materializes the conceptions of his imagination. But he is distinguished from all animals by two fundamental characters which pertain only to him. Man is the only one among organized and living beings who has the abstract sentiment of good and evil; in him alone, consequently, exists moral sense.
He is also alone in the belief that there will be something after this life, and in the recognition of a Supreme Being, who can influence his life for good or for evil. It is upon this double idea that the great fact of religion rests.
By and by these two questions of morals and religion will turn up again. We shall, I repeat, examine them, not as theologians, but simply as naturalists. I will only say for the present that man, everywhere, however savage he may be, shows some signs of morality and of religion that we never find among animals.
Hence man is a being apart, separated from animals by two great characters, which, I repeat, distinguish him yet more than his incontestable intellectual superiority.
But here the differences end. So far as the body is concerned, man is an animal, nothing more, nothing less. Except some differences of form and disposition, he is the equal, only the equal, of the superior animals that surround him.
If we take, for terms of comparison, the species that approach us nearest in general form, anatomy shows us that our organs are exactly the same as theirs. We can trace in them, almost muscle by muscle and nerve by nerve, those which we find in man himself.
Physiology, in its turn, shows us, in the body of man, the organs, muscles, nerves, performing exactly the same functions as in the animal. This is a capital fact which daily profits us, both from a purely scientific and from a practical point of view. We cannot experiment upon man—we can upon animals. Human physiology has employed this means to discover the functions of our organs. Physicians go further still; they bring to the sick bed the fruit of experiments made upon animals. Anthropology also, as we have just seen, applies to these inferior creatures for very important instruction.
But Anthropology should descend much lower than the animals when it would enlighten us completely. Vegetables are not animals, any more than animals are man. But men, animals, and vegetables, are all organized and living beings. They are distinguished from minerals, which are neither the one nor the other, by certain general facts common to all.
All organized beings have a limited duration; all are born small and feeble; during part of their existence, all grow and strengthen, then decrease in energy and vitality, sometimes also in size; finally all die. Throughout life, all organized and living beings need nourishment. Before death, all reproduce their kind by a seed or an egg (we speak here of species, not of individuals), and this is true even of those which seem to come directly from a bud, from a layer, from a graft, etc.; for from bud to bud, from layer to layer, from graft to graft, we can rise to the seed and to the egg. Finally, then, all organized and living beings have had a father and a mother.
These grand phenomena, common to all living beings, and consequently to man, imply general laws which control them, and which must therefore govern man as well as the plant.
Science every day confirms this conclusion, which might have been reached by reason alone, but which may now be regarded as a fact of experience. And I believe I need not dwell here, to make you understand the magnificence of this result.
As for me, I find it admirable that man and the lowest insect, that the king of the earth and the lowliest of the mosses, are so linked together that the entire living world forms but one whole where all harmonizes in the closest mutual dependence.
From this community in certain phenomena, from this subjection to certain laws equally common, results a consequence of the highest importance. Whatever questions concerning man you may have to examine, if they touch upon any of these properties, of these phenomena common to all organized and living beings, you must interrogate not only animals, but vegetables also, if you would reach the truth.
When one of these questions is put and answered, to make the answer good, to make it true, you must bring man under all the general laws which rule other organized and living beings.
If the solution tends to make man an exception to general laws, you may affirm that it is bad and false.
But also, when you have resolved the question so as to include man in these great general laws, you may be certain that the solution is good, that it is true, and really scientific.
With these data, and these alone, we will now consider the second question of Anthropology, and here it is:
Are there several species of men, or is there but one, including several races?
To be understood, this question requires some explanation.
Look at the drawings I have hung at the bottom of the hall. These figures are part of those I employ in the course at the Jardin des Plantes.
I have brought but a small number, but they suffice to give an idea of the principal varieties which the human type presents. You have here individuals taken from nearly every part of the world; and this I regard as a very important point. You see that they differ considerably from each other in color, often also in hair, sometimes in proportions, sometimes in features.
Well, our question is, whether the differences presented by the human groups from which these designs were taken are differences of species, or if they indicate only differences among races that belong to one and the same species.
To answer this question, we must begin by getting a clear idea of what is meant by the words species and race. In fact, the whole discussion turns on these two words.
Unhappily, they have been often taken one for the other, or else they have been badly defined. The discussions which have hence arisen would very quickly cease, if we would study them a little more closely.
Let us see if we cannot get precise ideas without going into details impossible here.
Certainly none of you would ever confound an ass with a horse: not even when a horse is small, and there are horses no larger than a Newfoundland dog; nor when an ass attains the size of an ordinary horse, as, for example, our large asses of Poitou. You say immediately, they are different species: here is a big ass and a little horse. And you say the same on seeing, side by side, a dog and a wolf.
On the other hand, all of you here would give the single name of dog to animals which differ from each other, as do the bulldog and water spaniel, the greyhound and the lapdog, the Newfoundland dog and the King Charles; and you are right.
However, judging by sight alone, even after detailed observation, you see, between the dogs I have just named, differences of size, of proportion, of color, much greater than those which separate the horse from the ass. An ass and a horse of the same size certainly resemble each other much more than the types of dog I have just named.
Further, if you place side by side a black and a white water spaniel, you will not designate them by different names. You will call them both water spaniels, although one is black and the other white.
In the case of vegetables you do exactly the same thing. A red rose and a white rose are equally roses; a pear is always a pear, whether you buy two for a sous in the street, or pay three francs at Chevet.
Well, without doubt, your decision is exactly like that of the naturalists. You have answered, just as they do, the question of species and race—a question that at first appears very complicated, because of the confusion before referred to. Here, then, is one more example to prove that, under many circumstances, popular observation and good sense go straight to the mark, as well as the labors of science.
Indeed, let us translate into general scientific language what I have just said of your views, and I am very sure not to be mistaken with regard to them.
The meaning of this judgment is, that an animal or a vegetable may vary within certain limits. The dog remains a dog, whatever its general form, its size, its hair; the pear remains a pear, whatever its size, its savor, the color of its skin.
From these facts, which I simply allude to, it results that these variations may be transmitted by way of generation. You all know that the union of two water spaniels will produce water spaniels; that the union of two bulldogs gives bulldogs.
It results, finally, in a more general way, that individuals of the same species may cease to resemble each other in an absolute manner, may sometimes even take very different characters, without becoming isolated and forming different species. As we have just said, the dog remains a dog, whatever its modifications.
Well, these groups, formed by individuals which have departed from the primitive type, and have formed distinct secondary groups, are precisely the ones that naturalists call races.
You understand why we constantly speak of races of cattle, horses, etc. There is, in fact, but one species of domestic cattle, which has given birth to the race bretonne, as well as to the great cattle of Uri, with their savage aspect, and to the peaceful Durham. We have, again, but one species of domestic horse, and this species has given birth to the little Shetland pony, of which I spoke just now, and to those enormous brewers' horses that we see in the streets of London. Finally, the various races of sheep, goats, etc., have arisen from one and the same species.
We must give more precision to our ideas on this point, because the least vagueness here will make very serious inconvenience. I will cite some further examples taken from vegetables and animals, being careful to choose such as are entirely familiar.
You all know the seed of the coffee tree. Permit me to give its history. You will see that it is instructive.
The coffee tree came originally from Africa, where from time immemorial it has been cultivated on the declivities of Abyssinia that elope toward the Red Sea. About the fifteenth century, something like four hundred years ago, the coffee tree crossed this sea and penetrated into Arabia, where it has since been cultivated, and whence especially we get the famous coffee of Mocha.
The use of coffee spread very early and with great rapidity in the East. It penetrated Europe much more slowly, and it was first taken in France at Marseilles.
Coffee was first drunk in Paris in 1667. The seeds which furnished it were brought in small quantity by a French traveller named Thevenot. Two years afterward, in 1669, Soliman Aga, ambassador of the Sublime Porte in the time of Louis XIV., induced the courtesans of that great king to taste it, and they found it very agreeable. However, its use did not spread for a long time. It. was not until the eighteenth century that it began to be generally used.
You see that coffee has not been very long in circulation. In fact, it is scarcely a century and a half since it became an article of general consumption by the people of Europe.
Well, during many years Europe remained tributary to Arabia for this commodity. All the coffee consumed in Europe came from Arabia, and particularly from Mocha. Toward the commencement of the eighteenth century the Dutch attempted to import it into Batavia, one of their colonies in the Indian Archipelago. They succeeded very well. From Batavia some stalks were taken to Holland and put in a hothouse, where they succeeded equally well. One of these stalks was brought to France toward 1710, and was placed in the conservatory of the Jardin des Plantes, and there also it prospered and gave birth to a certain number of sprouts.
In 1720 or 1725 (I have not been able to find the precise date), an officer of the French Navy, Captain Desclieux, thought that, since Holland had cultivated coffee at Batavia, he might also acclimate it in our colonies of the Gulf of Mexico. When embarking for Martinique, he took from the Jardin des Plantes three stalks of coffee, and carried them with him. The voyage was long and difficult, by reason of contrary winds. The supply of water proving insufficient, it was necessary to put the crew on rations. Captain Desclieux, like the others, had but a small quantity of water to drink each day. He divided it with his coffee plants. Notwithstanding all his care, two died on the passage; only one arrived safe and sound at Martinique. Put at once into the earth, it prospered so much and so well that from it have descended all the coffee trees now spread over the Antilles and tropical America. Twenty years after, our Western colonies exported millions of pounds of coffee.
You see the coffee tree, starting from Africa, has reached the extremity of Asia on the east and America on the west. Hence, it has nearly travelled round the world. Now, in this long voyage, coffee has become modified.
Passing by the tree, of which we know little, let us consider the seed. We need not be grocers to know the different qualities of coffees and their different production. Nobody would confound Mocha with Bourbon, Rio Janeiro with Martinique. Each of these seeds carries in its form, in its proportions, in its aroma, the certificate, so to say, of its birth.
Whence came these changes? We cannot know with certainty and explain the why and the how, and follow rigorously the filiation of cause and effect; but, considering the phenomena as a whole, it becomes evident that it is to differences of temperature, of climate, of culture, that all these modifications are due.
This example, taken from vegetables, shows that if we transport to considerable distances different specimens of the same vegetable, placing them in different conditions of cultivation, we obtain different races. Tea transported some years ago into tropical America would present us with like facts.
Take, now, an example from animals. You all know the turkey but, perhaps, some of you do not know that it came from America. Its introduction into Europe is quite recent.
In America the turkey is wild; and there, in its natural conditions of existence, it presents many characters which distinguish it from our domesticated individuals. The wild turkey is a very beautiful bird, of a deep brown color, very iridescent, presenting reflections of blue, copper, and gold, which make it truly ornamental. It was because of its fine plumage that it was first introduced into France. In the beginning no one thought of the turkey as food; and the first turkey served at table in France was in 1570, at the wedding of Charles IX., two hundred and ninety seven years ago.
As soon as one has tasted the turkey, one finds that he is too good to be merely looked at. He passes from the park to the poultry yard, from the poultry yard to the farm, and from one farm to another, east, west, north, and south. At present, in almost all France, turkeys are raised and are a considerable object of commerce.
But, in going from farm to farm, in travelling all over our country, this bird has encountered different conditions of existence, differences of nourishment and temperature, and never the primitive conditions that it had naturally in America. As a consequence of all this, the turkey has also varied, and, today, not a turkey in France resembles the wild stock. Generally, it has become much smaller; when it has preserved its deep plumage it has become darker and duller; but some have become fawn colored, others are more or less white, and others again are spotted with white, gray, or fawn color.
In a word, almost all the localities to which the turkey has become addicted have given birth to new varieties which have been transformed into races.
Now, in spite of these changes, and although they do not resemble their first parents in America, and do not resemble each other, are our French turkeys less the children of the wild turkey of America? Or if you like that better, are they less brothers and sisters? Have they ceased to be part of the same species? Evidently not. What I have just said of the turkey might also be said of the rabbit. The wild rabbit lives all around us—in our downs, in our woods—and he does not resemble, or resembles but little, our domestic rabbit. These, you know, are both great and small, with short hair, and with silky hair; that they are black and white, yellow and gray, spotted and of uniform color. In a word, this species comprehends a great number of different races, all constituting one and the same species with the wild stock which still lives around us.
From these facts, that could be multiplied, we have to draw an important consequence, to which I call your attention:
A pair of rabbits, left in a plain where they would encounter no enemies, in a few years would fill it with their descendants, and, in a little while, all France would be easily peopled. We have just seen that a single stalk of coffee gave birth to all the coffee trees now found in America.
The wild turkeys and their domestic offspring, the wild rabbits and their captive descendants, may then be considered by the naturalist as equally arising from a primitive pair.
Gentlemen, this is the stamp of a species. Whenever you see a greater or less number of individuals, or groups of animals, or vegetables, if, for one reason or another, you can look upon them as descendants of a single primitive pair, you may say you have before you a species': if from group to group there are differences, you say these are the races of that species.
Observe carefully, gentlemen, that, in thus expressing myself, I have not stated for certain the existence of this primitive pair of the stock of rabbits or of the stock of turkeys. I affirm no such thing, because neither experiment nor observation—the two guides we should always follow in science—can aid us on this point. I only say to you, every thing is as if they had been derived from a single pair.
You see, after all, the question of species and of race is not very difficult to comprehend, nor even very difficult to settle when we know the wild type, when we have the historic data which enable us to connect with this type the more or less different groups which domestication has detached. But when we do not know the wild type, when the historic data are lost, the question, on the contrary, becomes extremely difficult at the first step, because differences that we encounter from individual to individual, and, above all, from group to group, might be considered as specific differences.
Happily, Physiology comes now to our relief. We encounter here one of those great and beautiful general laws upon which the established order depends, and which we admire more the more we study. This is the law of cross breeding—a law which governs animals as well as vegetables, and is, of course, applicable to man himself.
You know what is meant by the word crossing. We mean by it all marriage occurring between animals that belong either to two different species or to two different races. Well, the results of these marriages obey the following laws, which are:
When this union takes place between two animals belonging to different species—that is, when we attempt hybridization—in the immense majority of cases the marriage is sterile. Thus, for example, it has been tried thousands of times and in all the world, to unite rabbits and hares. It is said that they have succeeded twice. But these two quoted facts are much more doubtful than the results of experiments recently made by a man of true talent, skilled in the art of experimenting, and who believes in the possibility of these unions, who has completely failed. Although he furnished the best conditions for success, he was not more fortunate in his results than Buffon, and the two Geoffroy Saint-Hilaires before him.
So the rabbit and the hare are of such a nature that, although presenting in appearance a great conformity, they cannot reproduce together.
Such is the general result of crossing two different species.
In many cases, the union of two individuals of different species is fertile, but the offspring cannot reproduce. For example, I refer you to the union of the ass and horse. This union produces the mule. All the mules in the world are offspring of the jackass and the mare. Now, these animals are numerous, for in Spain and in tropical America they are much preferred for work to horses, because of their resistance to fatigue. The hinny, less in demand, because less robust than the mule, is the result of an inverse cross; it is the offspring of the horse and the ass. The hinny, like the mule, cannot reproduce its kind. When we wish for either, we must have recourse to the two species.
Finally, in extremely rare exceptions, the fertility persists in the offspring, but it is much diminished. It diminishes still more in the grandchildren, and it is extinguished in the third or fourth generation at the most. This is the case when we unite the canary bird with the goldfinch.
I might here accumulate a mass of analogous facts and details. But over them all would appear a great general fact including them, which is the expression of a law; and here is this fact: notwithstanding observations reaching back for thousands of years, and made on hundreds of species, we do not yet know a single example of intermediate species obtained by the crossing of animals belonging to different species.
This general fact explains how order is maintained in the present living creation. If it had been otherwise, the animal world and the vegetable world would be filled with intermediate groups, passing into each other by insensible shades, and, in the midst of this confusion, it would be impossible for even naturalists to discriminate.
The general conclusion from all this is, that infertility is the law when animals of different species unite (Hybridization). When, on the contrary, individuals which are only of different races, but of the same species, are brought together, that is to say, when we produce a mongrel, is the result the same? No, it is exactly contrary.
These crossings are always fertile, and sometimes more so than the union of animals of the same race. But especially the children and grandchildren are also as fertile as the parents and grandparents; so much so that they propagate their kind indefinitely. The difficulty here is not to procure mixed races: the difficulty is, when we have pure races that we desire to preserve, to keep strange blood from modifying them.
Races thrive by crossing that is, by the union of different races of the same species, they multiply abundantly around us; such are our street dogs, our roof cats, our coach horses, all our animals where the race is indistinct; because of crossbreeding in all directions, the differential characters becoming confounded.
So far from experiencing difficulty in obtaining offspring from races, the men who are occupied with cattle, with sheep, with horses, amateurs in dogs, in pigeons, know with what watchful care they must protect their favorite race.
Here, then, is a general fact, and from this fact it results that fertility is the law of union between animals belonging to different races (Mixed Breeding).
Here, gentlemen, you see the great distinction, the fundamental distinction, between species and race. And, it is all the more important to recognize and record this distinction, as it facilitates experiment. When you have two different vegetables, or two different animals, and wish to know whether they belong to two distinct species, or only to two races of the same species, marry them. If the union proves immediately fertile, if the fertility is propagated and persists, you may affirm that, notwithstanding the differences which separate them, these vegetables and these animals are only races of the same species. If, on the contrary, you see the fertility disappear completely or diminish notably at the first union, if you see it decreasing, and go on diminishing, to disappear at the end of a few generations, you may without hesitation affirm that these vegetables and these animals belong to distinct species.
Gentlemen, I have discoursed at length of vegetables and animals, of the coffee tree, of the turkey, of the rabbit, of the dog, of the cat, of cattle, etc., and you may think that I am forgetting man. On the contrary, I have not ceased to think of him.
What is our question concerning man? Distinctly this.
Look once more at these designs. They show you differences, marked enough, between the human groups, although less considerable than at first appears.
Now, we do not know the type or the primitive types of these human groups. Even when we encounter one or several men, presenting the characters of these types, we cannot identify them, for lack of historical documents upon the subject. Consequently, if we judge by the looks. if we take account only of the men themselves, we cannot decide whether the differences they present are differences of race or differences of species: whether man is to be considered as arising from a single primitive stock, or whether we ought to suppose several primitive stocks.
But we have already said, and we again repeat, that man is an organized and living being; and, as such, he obeys all the general laws which govern all organized and living beings: he consequently obeys the laws of crossing. These, then, we must interrogate, to find out whether there is one or several species of men.
Take, for example, the two most distinct types, those which, more than any others, seem separated by profound differences — the white man and the negro.
If these types really constitute distinct species, their union ought to bear the stamp we have found to characterize the unions between animals and vegetables of different species. In the great majority of cases they should be infertile; in all the remainder, slightly fertile; the fertility should soon disappear, and they should not be able to form intermediate groups between the negro and the white. If these two men are only races of one and the same species, their union, on the contrary, should be very fertile; the fertility should be kept up by their descendants, and intermediate races ought to be formed.
Well, gentlemen, the facts here are decisive, and admit of no hesitation. It is scarcely three centuries since the white man par excellence—the European—made, so to say, the conquest of the world; he has gone everywhere, and everywhere he has found local races, human groups that do not resemble him; everywhere he has crossed with them, and the unions have been very fertile, sometimes very sensibly more fertile than those of the indigenous people themselves.
And further, in consequence of a detestable institution, which happily has never sullied the soil of France, in consequence of slavery, the white has taken the negro everywhere, everywhere he has crossed with his slaves, and everywhere a mulatto population has been formed. Everywhere, also, the negro has crossed with the local groups, and everywhere there have sprung up intermediate races, which, by their characters, proclaim this double origin. The white, finally, has crossed with these mixed breeds, and hence has resulted in certain parts of the globe, and notably in America, an inextricable mass of mixed peoples, perfectly comparable with our street dogs and roof cats.
The rapidity with which these mixed races cross and multiply is truly remarkable. It is hardly three centuries, about twelve generations, since the European spread over all parts of the world. Well, we estimate that already one seventieth of the total population of the globe are mixtures, resulting from the cross of the whites with indigenous peoples.
In certain states of South America where the mixture began earlier where the European arrived in the first days of discovery, a quarter of the population is composed of cross breeds, and in some regions the proportion is more than half.
You see, our experience is today as complete as possible. Unless we deny all modern science, unless we would make man a solitary exception in the midst of organic and living beings, we must admit that all men form only one and the same species, composed of a certain number of different races; we must, therefore, admit that all men may be considered as descended from a single primitive pair.
You see, gentlemen, we have reached this conclusion, outside of all species of dogmatic or theological consideration, outside of all species of philosophical or metaphysical consideration. Observation and experiment alone, applied to the animal and vegetable kingdom, science, in a word, leads us logically to this conclusion: there exists but one species of men.
This result, I do not fear to say, is of great and serious importance, for it gives to the thought of universal brotherhood the only foundation that many people now recognize, that of science and reason.
I hope, gentlemen, that my demonstration has convinced you. However, I am not unaware of the fact, and you doubtless also know, that all anthropologists are not agreed. There are among my fellow laborers a certain number of men, even of great men, who believe in the plurality of the human species. Perhaps you may have come in contact with them. Well, listen, then, with attention to the reasons they bring in support of their view. You easily see that all these reasons may be summed up in this: There is too much difference between the negro and the white man to permit them to belong to the same species.
Then you reply: Between the white or black water spaniel and the greyhound, between the bulldog and the lapdog, there is much more difference than between the European and the inhabitant of Africa, and yet the greyhound and the water spaniel, the bulldog and the lap dog, are equally dogs.
They will perhaps add: How could the same primitive man, whatever his characters might be, give birth to the white man and the negro?
You will answer: How has the wild turkey, of which we know the origin, of which we know the grandparents, how has the wild rabbit, which we find still among us, how have they been able to give birth to all our domestic' races?
We cannot, I repeat, explain rigorously the how and the why; but this we know, the fact exists, and we find its general explanation in the conditions of existence, in the conditions of the environment.
Now, man, who has progressed upon the earth a much longer time than the turkey or the rabbit, who has been upon the globe for thousands of years, living under the most diverse, the most opposite conditions, multiplying further the causes of modification by his manners, his habits, his kind of life, by the more or less care he takes of himself—man, I say, is certainly found in conditions of variation much more marked than those which have been encountered by the animals we have cited. It is not, then, surprising that men, from one group to another, present differences of which we here see the specimens. If there is any thing in them to astonish us, it is that these differences are not more considerable.
In your turn you ask of the polygenesists—for this is the name given to the philosophers who believe in the multiplicity of the human species—how is it that when the white man comes to any country whatever, at the antipodes, in America, in Polynesia—how is it, I say, that everywhere he crosses with human groups that differ most completely from him; that these unions are always fertile, and that everywhere he has left traces of his passage in producing a mixed population?
If you press your interlocutor a little, he will quite often deny the reality of species; he will thus put himself in contradiction with all naturalists without exception, botanists or zoologists—with all the eminent minds who, following Buffon, Tournefort, Jussieu, Cuvier, Geoffroy Saint-Hilaire, have studied vegetables and animals, outside of all discussion, and without thought of man.
In thus dealing with the question, the polygenesist falls into disagreement with the best established science.
Sometimes, also, you will hear him declare that man is an exception, that he has his particular laws, that the arguments taken from plants and animals are not applicable to him. Answer him, then, in the name of physiology, in the name of all the natural sciences, that he is certainly mistaken.
It is quite as impossible that an organized and living body should escape the laws of organization and life as that material substances should escape the laws that govern inorganic matter. Therefore, man, an organized and living being, obeys, as such, all general laws, and those of crossing like the rest. The conclusion we have drawn is then legitimate, and the nature of the arguments employed to combat it is a further proof in its favor.
Gentlemen, the subject of this lecture, which has occupied about an hour, at the Museum took up an entire course. The exposition has necessarily been brief. But I hope you have seen reasons strong enough to make you accept my view.
If doubts remain, try to come to my lectures. Some of you will be able, perhaps. I sometimes see working-men on the seats of my lecture-room, and I can testify to the attention of some among them. I own I was happy to see the attention they gave to these exalted questions. It would give me great pleasure to see at the Jardin des Plantes some of my audience at Vincennes.