A distinguished professor, writing of the influence of climate upon man, for the sake of illustration supposes the case of a human being whose life should be prolonged through many ages, and who should pass that life in journeying slowly from the arctic regions southward through the varying climates of the earth to the eternal winter of the antarctic zone. Always preserving his personal identity, this traveler would undergo remarkable changes in form, feature and complexion, in habits and modes of life, and in mental and moral attributes. Though he might have been perfectly white at first, his skin would pass through every degree of darkness until he reached the equator, when it would be black. Proceeding onward, he would gradually become fairer, and on reaching the end of his journey he would again be pale. His intellectual powers would vary also, and with them the shape of his skull. His forehead, low and retreating, would by degrees assume a nobler form as he advanced to more genial climes, the facial angle reaching its maximum in the temperate zone, only to gradually diminish as he journeyed toward the torrid, and to again exhibit under the equator its original base development. As he continued his journey toward the south pole he would undergo a second time this series of progressing and retrograding changes, until at length, as he laid his weary bones to rest in some icy cave in the drear antarctics,
Multum ille et terris jactatus et alto,
he would be in every respect, save in age and a ripe experience, the same as at the outset of his wanderings.
Extravagant as this illustration may appear, the professor goes on to say, philosophically, on the doctrine of the unity of the human race, it is not so; for what else than such an imaginary prolonged individual life is the life of the race? And what greater changes have occurred to our imaginary traveler than have actually befallen the human family?
The facts are patent. Under the equator is found the negro, in the temperate zones the Indo-European, and toward the pole the Lapp and Esquimaux. They are as different as the climates in which they dwell; nevertheless, history, philology, the common traditions of the race, revelation, point to their brotherhood.
How is it that climate can bring about such modifications in man? Is it possible that the sun, shining upon his face and his children's faces for ages, can make their skin dark, and their hair crisp and curly, and their foreheads low? Or that sunshine and shadow, spring-time and autumn, summer's showers beating upon him and winter's snows falling about his path, can make him fair and free? Or that the dreary night and cheerless day of many changeless arctic years can make him short and fat and stolid as a seal? Surely not. These avail much; but other influences, indirect and obscure in their workings, but not the less essentially climatic, are required. Food, raiment, shelter, occupation, amusement, influences that tell upon the very citadel and stronghold of life—and all in their very nature climatic, since they are controlled and modified by climate—are the means by which such changes are effected. The savage living in the open air, not trammeled with much clothing, anointing his skin with oil, eating uncooked food, delighting in the chase and in battle, and living thus because his surroundings indicate it, becomes swart and athletic, fierce, cunning and cruel—takes ethnologically the lowest place. Of literature, science, art, he knows nothing: for him will is justice, fear law, some miserable fetich God. Still, in his nature lie dormant all the capabilities of the noblest manhood, awaiting only favorable surroundings to call them into glorious being. It might shock the salt of the earth to reflect that some centuries of life among them and their fair descendants would make him like them.
The arctic savage clad in furs and eating blubber does not differ essentially from his brother of the tropics. So much of his food is necessarily converted into heat that he cannot afford to lead so active a life; but he also, like him of the tropics, partakes with his surroundings in color. The one, living amid snowclad scenery, where the sparse vegetation is gray and grayish-green, and the birds and animals almost as white as the snow over which they wander, is pale, etiolated. The other, under a vertical sun, surrounded by a lush and lusty growth, whose flowers for variety and intensity of color are beyond description, and in which birds of brightest plumage and black and tawny beasts make their home, has the most marked supply of pigment—is dark-hued, black, in short a negro. Between these two extremes is the typical man, fair of face, with expanded brow and wavy hair, well fed, well clad, well housed, wresting from Nature her hidden things and making her mightiest forces the workers of his will; heaping together knowledge, cherishing art, reverencing justice, worshiping God. How startling the contrast between brothers!
Such changes do not take place in a few generations. For their completion hundreds, perhaps thousands, of years must elapse. The descendants of the blacks who were carried from Africa to America as slaves two centuries and a half ago, save where their color has been modified by a mixed parentage, are still black. Already the influence of new climatic surroundings and of association has wrought great changes upon them: they are no longer savages. But their complexion is as dark as that of their kidnapped forefathers. Their original physical condition remains almost unaltered, and with it many mental characteristics: their love of display and of bright colors, their fondness for tune and the power of music to move them, their weird and fantastic belief in ghosts and spirits, in signs, omens and charms, and many other traits, still bear witness to their savage origin. But even these are fading away, and these men are slowly but not the less surely becoming civilized and white.
The point of departure for every structural change in a living organism lies in the apparatus by which nutrition is maintained; and this in the higher classes is the blood. Most complex and wonderful of fluids, it contains in unexplained and inscrutable combination salts of iron, lime, soda and potassa, with water, oil, albumen, paraglobulin and fibrinogen, which united form fibrine—in fact, at times, some part of everything we eat and all that goes to form our bodies, which it everywhere permeates, vitalizes and sustains. Borne in countless numbers in its ever-ebbing and returning streams are little disks, flattened, bi-concave, not larger in man than one-three-thousandth of an inch in diameter, called red corpuscles, whose part it is to carry from the lungs to the tissues pure oxygen, without which the fire called life cannot be sustained, and back from the tissues to the lungs carbonic acid, one of the products of that fire; and larger, yet marvelously small, bodies called leucocytes or white corpuscles, whose precise origin and use to this day, in spite of all the labor that has been spent upon their study, remain unknown. But that which makes the blood wonderful above all other fluids is its vitality. Our common expression, "life's blood," is no idle phrase. The blood is indeed the very throne of life. If its springs are pure and bountiful, if its currents flow strong and free, muscle, bone and brain grow in symmetry and power, and there is cunning to devise and the strong right arm to execute. But if it be thin and poor, and its circulation feeble and uncertain, the will flags, the mind is weak and vacillating, the muscles grow puny, and the man becomes an unresisting prey to disease and circumstance. If it escape through a wound, strength ebbs with it, until at length life itself flows out with the unchecked crimson stream. Thus, then, by acting upon the blood, climate has wrought and is working such changes upon man. But why are constantly-acting causes so slow in producing their effects? How is it that countless generations must pass away before purely climatic causes, potent as they are, begin to manifest themselves in physical changes in the races of men exposed to them?
Fournier, physiologist, as I have said, by the education of the schools, but by the broader education of his travels sociologist and ethnologist, devoted himself again to science, and framed this hypothesis: Climatic influences, acting upon man, bring about physical changes exceedingly slowly, because they are resisted by an inveterate habit of assimilation. This habit pertains either to the blood or the tissues, possibly to both, probably to the blood alone.