Part 3

Some day the historians will tell us of these things. Some day, too, they will tell our children of the age and the land in which we now live. They will portray the conquest of the continent. They will show the slow beginnings of settlement, the growth of the fishing and trading towns on the seacoast, the hesitating early ventures into the Indian-haunted forest. Then they will show the backwoodsmen, with their long rifles and their light axes, making their way with labor and peril through the wooded wilderness to the Mississippi; and then the endless march of the white-topped wagon-trains across plain and mountain to the coast of the greatest of the five great oceans. They will show how the land which the pioneers won slowly and with incredible hardship was filled in two generations by the overflow from the countries of western and central Europe. The portentous growth of the cities will be shown, and the change from a nation of farmers to a nation of business men and artisans, and all the far-reaching consequences of the rise of the new industrialism. The formation of a new ethnic type in this melting-pot of the nations will be told. The hard materialism of our age will appear, and also the strange capacity for lofty idealism which must be reckoned with by all who would understand the American character. A people whose heroes are Washington and Lincoln, a peaceful people who fought to a finish one of the bloodiest of wars, waged solely for the sake of a great principle and a noble idea, surely possess an emergency-standard far above mere money-getting.

Those who tell the Americans of the future what the Americans of to-day and of yesterday have done, will perforce tell much that is unpleasant. This is but saying that they will describe the arch-typical civilization of this age. Nevertheless, when the tale is finally told, I believe that it will show that the forces working for good in our national life outweigh the forces working for evil, and that, with many blunders and shortcomings, with much halting and turning aside from the path, we shall yet in the end prove our faith by our works, and show in our lives our belief that righteousness exalteth a nation.

BIOLOGICAL ANALOGIES IN HISTORY

BIOLOGICAL ANALOGIES IN HISTORY[2]

An American who, in response to such an invitation as I have received, speaks in this university of ancient renown, can not but feel with peculiar vividness the interest and charm of his surroundings, fraught as they are with a thousand associations. Your great universities, and all the memories that make them great, are living realities in the minds of scores of thousands of men who have never seen them and who dwell across the seas in other lands. Moreover, these associations are no stronger in the men of English stock than in those who are not. My people have been for eight generations in America; but in one thing I am like the Americans of to-morrow, rather than like many of the Americans of to-day; for I have in my veins the blood of men who came from many different European races. The ethnic make-up of our people is slowly changing, so that constantly the race tends to become more and more akin to that of those Americans who like myself are of the old stock but not mainly of English stock. Yet I think that, as time goes by, mutual respect, understanding, and sympathy among the English-speaking peoples grow greater and not less. Any of my ancestors, Hollander or Huguenot, Scotchman or Irishman, who had come to Oxford in “the spacious days of great Elizabeth,” would have felt far more alien than I, their descendant, now feel. Common heirship in the things of the spirit makes a closer bond than common heirship in the things of the body.

[2] Delivered at Oxford, June 7, 1910. This was the Romanes Lecture for 1910, and has been published by the Oxford University Press, with whose permission it is included in this volume.

More than ever before in the world’s history we of to-day seek to penetrate the causes of the mysteries that surround not only mankind but all life, both in the present and the past. We search, we peer, we see things dimly; here and there we get a ray of clear vision, as we look before and after. We study the tremendous procession of the ages, from the immemorial past when in “cramp elf and saurian forms” the creative forces “swathed their too-much power,” down to the yesterday, a few score thousand years distant only, when the history of man became the overwhelming fact in the history of life on this planet; and studying we see strange analogies in the phenomena of life and death, of birth, growth, and change, between those physical groups of animal life which we designate as species, forms, races, and the highly complex and composite entities which rise before our minds when we speak of nations and civilizations.

It is this study which has given science its present-day prominence. In the world of intellect, doubtless, the most marked features in the history of the past century have been the extraordinary advances in scientific knowledge and investigation, and in the position held by the men of science with reference to those engaged in other pursuits. I am not now speaking of applied science; of the science, for instance, which, having revolutionized transportation on the earth and the water, is now on the brink of carrying it into the air; of the science that finds its expression in such extraordinary achievements as the telephone and the telegraph; of the sciences which have so accelerated the velocity of movement in social and industrial conditions--for the changes in the mechanical appliances of ordinary life during the last three generations have been greater than in all the preceding generations since history dawned. I speak of the science which has no more direct bearing upon the affairs of our every-day life than literature or music, painting or sculpture, poetry or history. A hundred years ago the ordinary man of cultivation had to know something of these last subjects; but the probabilities were rather against his having any but the most superficial scientific knowledge. At present all this has changed, thanks to the interest taken in scientific discoveries, the large circulation of scientific books, and the rapidity with which ideas originating among students of the most advanced and abstruse sciences become, at least partially, domiciled in the popular mind.

Another feature of the change, of the growth in the position of science in the eyes of every one, and of the greatly increased respect naturally resulting for scientific methods, has been a certain tendency for scientific students to encroach on other fields. This is particularly true of the field of historical study. Not only have scientific men insisted upon the necessity of considering the history of man, especially in its early stages, in connection with what biology shows to be the history of life, but furthermore there has arisen a demand that history shall itself be treated as a science. Both positions are in their essence right; but as regards each position, the more arrogant among the invaders of the new realm of knowledge take an attitude to which it is not necessary to assent. As regards the latter of the two positions, that which would treat history henceforth merely as one branch of scientific study, we must of course cordially agree that accuracy in recording facts and appreciation of their relative worth and interrelationship are just as necessary in historical study as in any other kind of study. The fact that a book, though interesting, is untrue, of course removes it at once from the category of history, however much it may still deserve to retain a place in the always desirable group of volumes which deal with entertaining fiction. But the converse also holds, at least to the extent of permitting us to insist upon what would seem to be the elementary fact that a book which is written to be read should be readable. This rather obvious truth seems to have been forgotten by some of the more zealous scientific historians, who apparently hold that the worth of a historical book is directly in proportion to the impossibility of reading it, save as a painful duty. Now I am willing that history shall be treated as a branch of science, but only on condition that it also remains a branch of literature; and, furthermore, I believe that as the field of science encroaches on the field of literature there should be a corresponding encroachment of literature upon science; and I hold that one of the great needs, which can only be met by very able men whose culture is broad enough to include literature as well as science, is the need of books for scientific laymen. We need a literature of science which shall be readable. So far from doing away with the school of great historians, the school of Polybius and Tacitus, Gibbon and Macaulay, we need merely that the future writers of history, without losing the qualities which have made these men great, shall also utilize the new facts and new methods which science has put at their disposal. Dryness is not in itself a measure of value. No “scientific” treatise about St. Louis will displace Joinville, for the very reason that Joinville’s place is in both history and literature; no minute study of the Napoleonic wars will teach us more than Marbot--and Marbot is as interesting as Walter Scott. Moreover, certain at least of the branches of science should likewise be treated by masters in the art of presentment, so that the layman interested in science, no less than the layman interested in history, shall have on his shelves classics which can be read. Whether this wish be or be not capable of realization, it assuredly remains true that the great historian of the future must essentially represent the ideal striven after by the great historians of the past. The industrious collector of facts occupies an honorable, but not an exalted, position, and the scientific historian who produces books which are not literature must rest content with the honor, substantial, but not of the highest type, that belongs to him who gathers material which some time some great master shall arise to use.

Yet, while freely conceding all that can be said of the masters of literature, we must insist upon the historian of mankind working in the scientific spirit, and using the treasure-houses of science. He who would fully treat of man must know at least something of biology, of the science that treats of living, breathing things; and especially of that science of evolution which is inseparably connected with the great name of Darwin. Of course, there is no exact parallelism between the birth, growth, and death of species in the animal world, and the birth, growth, and death of societies in the world of man. Yet there is a certain parallelism. There are strange analogies; it may be that there are homologies.

How far the resemblances between the two sets of phenomena are more than accidental, how far biology can be used as an aid in the interpretation of human history, we can not at present say. The historian should never forget, what the highest type of scientific man is always teaching us to remember, that willingness to admit ignorance is a prime factor in developing wisdom out of knowledge. Wisdom is advanced by research which enables us to add to knowledge; and, moreover, the way for wisdom is made ready when men who record facts of vast but unknown import, if asked to explain their full significance, are willing frankly to answer that they do not know. The research which enables us to add to the sum of complete knowledge stands first; but second only stands the research which, while enabling us clearly to pose the problem, also requires us to say that with our present knowledge we can offer no complete solution.

Let me illustrate what I mean by an instance or two taken from one of the most fascinating branches of world-history, the history of the higher forms of life, of mammalian life, on this globe.

Geologists and astronomers are not agreed as to the length of time necessary for the changes that have taken place. At any rate, many hundreds of thousands of years, some millions of years, have passed by since in the eocene, at the beginning of the tertiary period, we find the traces of an abundant, varied, and highly developed mammalian life on the land masses out of which have grown the continents as we see them to-day. The ages swept by, until, with the advent of man substantially in the physical shape in which we now know him, we also find a mammalian fauna not essentially different in kind, though widely differing in distribution, from that of the present day. Throughout this immense period form succeeds form, type succeeds type, in obedience to laws of evolution, of progress and retrogression, of development and death, which we as yet understand only in the most imperfect manner. As knowledge increases our wisdom is often turned into foolishness, and many of the phenomena of evolution which seemed clearly explicable to the learned master of science who founded these lectures, to us nowadays seem far less satisfactorily explained. The scientific men of most note now differ widely in their estimates of the relative parts played in evolution by natural selection, by mutation, by the inheritance of acquired characteristics; and we study their writings with a growing impression that there are forces at work which our blinded eyes wholly fail to apprehend; and where this is the case the part of wisdom is to say that we believe we have such and such partial explanations, but that we are not warranted in saying that we have the whole explanation. In tracing the history of the development of faunal life during this period, the age of mammals, there are some facts which are clearly established, some great and sweeping changes for which we can with certainty ascribe reasons. There are other facts as to which we grope in the dark, and vast changes, vast catastrophes, of which we can give no adequate explanation.

Before illustrating these types, let us settle one or two matters of terminology. In the changes, the development and extinction, of species we must remember that such expressions as “a new species,” or as “a species becoming extinct,” are each commonly and indiscriminately used to express totally different and opposite meanings. Of course the “new” species is not new in the sense that its ancestors appeared later on the globe’s surface than those of any old species tottering to extinction. Phylogenetically, each animal now living must necessarily trace its ancestral descent back through countless generations, through eons of time, to the early stages of the appearance of life on the globe. All that we mean by a “new” species is that from some cause, or set of causes, one of these ancestral stems slowly or suddenly develops into a form unlike any that has preceded it; so that, while in one form of life the ancestral type is continuously repeated and the old species continues to exist, in another form of life there is a deviation from the ancestral type and a new species appears.

Similarly, “extinction of species” is a term which has two entirely different meanings. The type may become extinct by dying out and leaving no descendants. Or it may die out because as the generations go by there is change, slow or swift, until a new form is produced. Thus in one case the line of life comes to an end. In the other case it changes into something different. The huge titanothere, and the small three-toed horse, both existed at what may roughly be called the same period of the world’s history, back in the middle of the mammalian age. Both are extinct in the sense that each has completely disappeared and that nothing like either is to be found in the world to-day. But whereas all the individual titanotheres finally died out, leaving no descendants, a number of the three-toed horses did leave descendants, and these descendants, constantly changing as the ages went by, finally developed into the highly specialized one-toed horses, asses, and zebras of to-day.

The analogy between the facts thus indicated and certain facts in the development of human societies is striking. A further analogy is supplied by a very curious tendency often visible in cases of intense and extreme specialization. When an animal form becomes highly specialized, the type at first, because of its specialization, triumphs over its allied rivals and its enemies, and attains a great development; until in many cases the specialization becomes so extreme that from some cause unknown to us, or at which we merely guess, it disappears. The new species which mark a new era commonly come from the less specialized types, the less distinctive, dominant, and striking types, of the preceding era.

When dealing with the changes, cataclysmic or gradual, which divide one period of paleontological history from another, we can sometimes assign causes, and again we can not even guess at them. In the case of single species, or of faunas of very restricted localities, the explanation is often self-evident. A comparatively slight change in the amount of moisture in the climate, with the attendant change in vegetation, might readily mean the destruction of a group of huge herbivores with a bodily size such that they needed a vast quantity of food, and with teeth so weak or so peculiar that but one or two kinds of plants could furnish this food. Again, we now know that the most deadly foes of the higher forms of life are various lower forms of life, such as insects, or microscopic creatures conveyed into the blood by insects. There are districts in South America where many large animals, wild and domestic, can not live because of the presence either of certain ticks or of certain baleful flies. In Africa there is a terrible genus of poison fly, each species acting as the host of microscopic creatures which are deadly to certain of the higher vertebrates. One of these species, though harmless to man, is fatal to all domestic animals, and this although harmless to the closely related wild kinsfolk of these animals. Another is fatal to man himself, being the cause of the “sleeping-sickness” which in many large districts has killed out the entire population. Of course the development or the extension of the range of any such insects, and any one of many other causes which we see actually at work around us, would readily account for the destruction of some given species or even for the destruction of several species in a limited area of country.

When whole faunal groups die out over large areas, the question is different, and may or may not be susceptible of explanation with the knowledge we actually possess. In the old arctogæal continent, for instance, in what is now Europe, Asia, and North America, the glacial period made a complete, but of course explicable, change in the faunal life of the region. At one time the continent held a rich and varied fauna. Then a period of great cold supervened, and a different fauna succeeded the first. The explanation of the change is obvious.

But in many other cases we can not so much as hazard a guess at why a given change occurred. One of the most striking instances of these inexplicable changes is that afforded by the history of South America toward the close of the tertiary period. For ages South America had been an island by itself, cut off from North America at the very time that the latter was at least occasionally in land communication with Asia. During this time a very peculiar fauna grew up in South America, some of the types resembling nothing now existing, while others are recognizable as ancestral forms of the ant-eaters, sloths, and armadillos of to-day. It was a peculiar and diversified mammalian fauna, of, on the whole, rather small species, and without any representatives of the animals with which man has been most familiar during his career on this earth.

Toward the end of the tertiary period there was an upheaval of land between this old South American island and North America, near what is now the Isthmus of Panama, thereby making a bridge across which the teeming animal life of the northern continent had access to this queer southern continent. There followed an inrush of huge, or swift, or formidable creatures which had attained their development in the fierce competition of the arctogæal realm. Elephants, camels, horses, tapirs, swine, sabre-toothed tigers, big cats, wolves, bears, deer, crowded into South America, warring each against the other incomers and against the old long-existing forms. A riot of life followed. Not only was the character of the South American fauna totally changed by the invasion of these creatures from the north, which soon swarmed over the continent, but it was also changed through the development wrought in the old inhabitants by the severe competition to which they were exposed. Many of the smaller or less capable types died out. Others developed enormous bulk or complete armor protection, and thereby saved themselves from the new beasts. In consequence, South America soon became populated with various new species of mastodons, sabre-toothed tigers, camels, horses, deer, cats, wolves, hooved creatures of strange shapes, and some of them of giant size, all of these being descended from the immigrant types; and side by side with them there grew up large autochthonous ungulates, giant ground-sloths well-nigh as large as elephants, and armored creatures as bulky as an ox but structurally of the armadillo or ant-eater type; and some of these latter not only held their own, but actually in their turn wandered north over the isthmus and invaded North America. A fauna as varied as that of Africa to-day, as abundant in species and individuals, even more noteworthy, because of its huge size or odd type, and because of the terrific prowess of the more formidable flesh-eaters, was thus developed in South America, and flourished for a period which human history would call very long indeed, but which geologically was short.

Then, for no reason that we can assign, destruction fell on this fauna. All the great and terrible creatures died out, the same fate befalling the changed representatives of the old autochthonous fauna and the descendants of the migrants that had come down from the north. Ground-sloth and glyptodon, sabre-tooth, horse and mastodon, and all the associated animals of large size vanished, and South America, though still retaining its connection with North America, once again became a land with a mammalian life small and weak compared to that of North America and the Old World. Its fauna is now marked, for instance, by the presence of medium-sized deer and cats, fox-like wolves, and small camel-like creatures, as well as by the presence of small armadillos, sloths, and ant-eaters. In other words, it includes diminutive representatives of the giants of the preceding era, both of the giants among the older forms of mammalia, and of the giants among the new and intrusive kinds. The change was wide-spread and extraordinary, and with our present means of information it is wholly inexplicable. There was no ice age, and it is hard to imagine any cause which would account for the extinction of so many species of huge or moderate size, while smaller representatives, and here and there medium-sized representatives, of many of them were left.