Popular Science Monthly/Volume 77/July 1910/The Future of the Human Race
|THE FUTURE OF THE HUMAN RACE|
UNIVERSITY OF COLORADO
EVOLUTION is not an orderly march along a well-defined highway, to the slow time of the music of the spheres. In its details, it is an irregular process, sometimes so slow that millions of years seem to make no difference; sometimes so rapid that a single generation marks a notable advance. Many of its most remarkable products come into existence only to perish shortly afterwards, because they are exclusively adapted to conditions which are not permanent. Rapid progress seems usually to go with a high percentage of failures, as though progress itself were only an attempt to dodge the stroke of doom. Out of all this man, the species Homo sapiens, zoologically speaking one of the higher apes, has in these latter days evolved. A creature in many ways inferior to his brother mammalia, but favored by the gods. Denuded of hair, he is obliged to spend much of his time and energy providing artificial clothing; slow of foot, he is compelled to devise means of travel not depending upon his muscular activities; so deficient in the sense of smell, that he does not know, as do the dog and the ant, that it is the most important of all the senses; lacking a tail, and with no grasping power in his feet, he rarely ventures to climb the trees; a poor creature indeed, well-fitted to be the laughing stock of the rest of animal creation.
All this would not be so bad if, like his sylvan ancestors, he could go on his way with a placid sense of his own sufficiency. Alas! even this poor privilege is denied to him; in the Garden of Eden, at the very beginning of his career, he acquired the sense of sin, and was henceforth to be a wanderer in a spiritual as well as a physical sense. Hence it comes that we, in this year 1910, think it proper to enquire anxiously about the future of our species, an inquiry which would certainly never occur to any other species of mammal.
At the very outset we are bound to observe that without exception the species of mammalia are short-lived. The records of the Tertiary rocks show a continually changing panorama of mammalian life, in which genera and species come and go, while plants, mollusca and other lowly organisms remain almost unaltered. We further notice that the comparatively brief existence of these animals may be terminated in either of two ways—by extinction, or by change into something else. When the creatures are very highly developed in special ways, they seem nearly always destined to die out, being supplanted by the descendants of simpler and more plastic forms. Supposing the career of man to resemble that of other specialized mammalia, he might be expected to have before him perhaps another hundred thousand years, and then in all probability the end of the world, so far as he was concerned with it as an animal. Even on this hypothesis, he would have as much occasion to prepare for his terrestrial future as a young child has for its adult life, but there are very good reasons for supposing that the fate of man need not necessarily be the same as that of the animals to which he is most nearly allied. Prior to the existence of man, living beings might have been divided roughly into two groups, those related to very simple or unchanging environments, such as the amoeba or the oyster, and those specially adapted to complex conditions, such as the yucca moth and the giraffe. The former have proved successful through their very simplicity, have been saved by their lack of progress; the latter are nature's masterpieces, often destined, as such things are, to go out of fashion. Any single man may be taken as a rather extreme example of the latter type; he is extraordinarily dependent upon a special set of conditions, but the race as a whole is relatively independent, and without sacrificing anything of its organic complexity, is able to meet and overcome the dangers which have destroyed so many of the higher mammals. If with this man can secure a genuine but moderate progress in his fundamental organism, not sufficient to break the continuity of tradition or destroy his essential specific unity, he may be assured a career such as no mammal ever had before.
The causes of the extinction of other animals have been principally related to climate, food and natural enemies, including here the germs of disease. With regard to climate, man at first, through racial differentiation, became adapted to everything from tropical heat to arctic cold; but here he was on the way to split up into a number of distinct species. Now through devices of housing and clothing he can almost create climatic environments for himself, and so single races, or mixtures of races, are to be found nearly everywhere. At the same time, like the bird, he knows how to migrate when necessary, so that he will never be destroyed by changes confined to a single continent or even hemisphere.
In the case of food, he is relatively unspecialized, and no doubt his omnivorousness has greatly aided his spread over the globe. So long as he had to depend upon the supplies furnished gratis by nature this was a necessary condition of his cosmopolitanism; but now that he can so largely control his food supply, and can carry any given product to the opposite end of the earth, it is a question whether there will not be a distinct gain in a return to primitive simplicity in diet.
Of natural enemies, the grosser and more tangible kind, like the lion and tiger, have in most places been destroyed; but the small insidious germs or bacteria remain with us. Through a process of natural selection, we have acquired a comparative tolerance of or immunity from several of them, but they have at all times heavily taxed our resources, and have actually been the means of exterminating many races. It is perhaps not unlikely that man would have died out before this, had he been confined to any limited region; but since his distribution has always been wider than the prevalence of any one disease, he has managed to survive in spite of all of them.
A very interesting discussion of the insidious parasites of disease has been given by Dr. Ronald Ross in an address on "Malaria in Greece," delivered before the Oxford Medical Society.
Until recent times, the success of mankind in weathering the dangers of disease has been mainly due to the precautions he has been able to take, along with the limited distribution of diseases, and the process of evolution against them. In the future with the aid of science there can be little doubt that the bacteria of many will be exterminated, and it will no longer be necessary to think of them as possible dangers to human life. Thus, in England, by the universal practise of muzzling the dogs for a sufficiently long period, hydrophobia has been eliminated; in the tropics by the quite feasible if somewhat difficult plan of destroying the mosquitoes, yellow fever and malaria may be utterly stamped out in some regions. Other diseases are much less easily controlled, but it does not appear more difficult to destroy them than it once did to get rid of the wolves in England.
Along with the development of the medical and agricultural sciences, we may hope for great advances in social organization, reducing to a minimum the tremendous waste of life and property which goes on to-day. It is not too much to expect that every individual will be assured all the air, food, clothes and shelter necessary for a normal existence, and will find ample opportunities for exercising such talents as he may possess. Liberty will be curtailed in so far as it permits antisocial activities, but it will be tremendously extended, in the form of practical opportunities to develop ordinary or special abilities. All this may be a long way ahead, and there may exist great differences as to the program for the near future; but I suppose that few will deny that some such outcome as that indicated should logically follow from indefinite advance in the direction we are even now taking.
If we picture human society thus relatively perfected, and free from many of the ills which now so fearfully decimate it, what have we left to desire? Very much, I venture to think. Is there one of us who could honestly say that, if he had been born into such a society, he would be without any serious defects of mind or body? In other words, given as good an environment as could well be devised, should we then be perfect? It is exceedingly obvious that we should not.
Those who are enthusiastic, and very justly, concerning the possibilities of social reform, are somewhat too apt to assume that all deficiencies noted in people to-day are due to adverse external conditions. The student of heredity—even the farmer, when he is dealing with his crops—knows better than that. Figs do not grow on thistles, for all the fertilizers in the country. There is no doubt whatever that every year there are born thousands of persons who are not merely unfitted to succeed in the world as it now is, but would never be successful in any complete sense in any world which could be devised or imagined. Some of those who recognize this fact see in it the doom of all social amelioration. If to-day the tremendous destruction of the unfit which takes place leaves us so many incapables, what would happen if most of those who perish were to survive? Would not society be buried beneath a load of incompetency, which would make even such organization as we have impossible? To this gloomy suggestion it may be replied, in the first place, that much of the present-day elimination is of those who would be eminently fitted to become useful members of society, could they be saved. Those who die of bacterial diseases may be unfitted to cope with those diseases, but this does not imply all other forms of unfitness. This has been recognized from time immemorial, in the phrase, "those whom the gods love die young."
In the second place, it should be pointed out that while much of the elimination now occurring is desirable, it is no doubt preposterously haphazard, and those who so keenly recognize the need for elimination, should be the first to advocate a rational method of bringing it about. This rational method consists, not in the destruction, but in the prevention of the unfit.
At this point it will be useful to leave mankind for a while, and consider some of the recent results of the study of heredity; results obtained mainly from investigations on plants and lower animals. Without going into detail, it may be said that through the researches of Mendel, Bateson, de Vries, Davenport and many others, we have come to a very clear recognition of unit-characters in inheritance. That is to say, particular characters, such as hairiness, eye-color or susceptibility to some disease, are inherited separately, passing from one generation to another much as atoms pass without change from one to another chemical compound. These unit characters may be lost, and sometimes the loss is real and final, sometimes it is illusory, due merely to non-potency. In very simple cases, it is found that the inheritance of these units follows easily recognized laws, the distribution being in accordance with the laws of chance. In others, this is not evident, and in man especially, the results are often perplexing. Thus the mulatto is virtually a blend between the white and black races, and at first sight it is not at all apparent that the racial characters are inherited as separate units. Nevertheless, we have indications of this in the remarkable differences sometimes observed within a single family of mulattoes, and it may well be inferred that further investigation will yield results in accordance with recognizable laws, and in so far predicable in advance.
The absolute distinction which at first seems to exist between characters which are inherited as separate units and those which blend may not be real. When the units are obviously separate, but are fairly numerous, they will produce every sort of mosaic, in the most confusing, and at first sight wholly disorderly manner. Let them be somewhat more numerous still and it becomes practically impossible, by mere inspection, to disentangle the result. It is just as black and white balls, if of large size, will appear as separate things when mixed, but if sufficiently small will give an apparent blend, of uniform gray. Because of this possibility, we are not as yet entitled to explain all blending away as illusory; but we may bear in mind that this may be the case. It can at least be said, that scarcely a month passes without some case of inheritance, formerly seeming inscrutable, being brought into the field of well-ascertained law.
With the incoming of the idea of unit characters, passes our former conception of continuous variability. Supposing every character to be at all times variable—that is in motion, as it were, away from its present center of stability—there is no doubt that continuous selection would be required to keep characters up to any particular standard. The extraordinary permanency of some organic characters should suffice to make us doubt this necessity. For millions of years, certain features in the lower animals have been handed down generation after generation, practically without change. When we remember the tremendous complexity of the protoplasm molecule and the much greater complexity of the least imaginable bearer of heredity, and the fact that it has not been possible to break up and then reform the combination, as in inorganic chemistry, the permanency of these units in time is simply amazing. Least particles of protoplasmic jelly, they have stood while the rocks have been ground to dust, and made over many times. They are entitled to be ranked among the most permanent things in nature.
What then of the facts of variability, as they appear to us? What is the use of denying continuous variability, in the face of the fact that no two human beings are alike? The paradox may be resolved, when we remember the extraordinary number of words in the English language, no two the same—yet made up of the undeniably unchanging letters of the alphabet. When we recall that, on the unit character theory, the units in man must be exceedingly numerous, and must be recombined in almost every conceivable way in bisexual inheritance, it is easy to see that the chances against any two individuals coming out exactly the same are so great that such a result is practically impossible. The only case which can come under this head are those of identical twins, where the resemblance is indeed amazing, throwing light on the extraordinary potency of inheritance. Such twins are believed to result from the division of a single fertilized ovum, and hence to be, in a biological sense, two halves of a single individual.
Much light has been thrown on the permanence of unit-characters by studies among plants and protozoan animals of what are called pure lines. A pure line is one in which all the individuals have the same ancestry, uncontaminated by crossing. The most remarkable results have been obtained by Professor Jennings in his studies of Paramecium.
All this indicates that if desirable qualities, represented by units in inheritance, are once obtained, and are not disturbed by crossing, they may continue from generation to generation indefinitely, without variation other than that produced in the individual by the immediate influence of the environment.
But, here, as Professor Jennings remarks, we have to ask how the different pure lines arise? That is to say, whence the different qualities which assuredly did not all coexist in the original form of life? We have seen that the unit in inheritance is, to say the least, a very complex object from a chemical point of view. No doubt it is easily destroyed, but its usual character seems to be that of resisting molecular change short of disintegration. Thus it is carried on from individual to individual, virtually unaltered, or in the alternative cases, destroyed. Occasionally, however, it must be subjected to some subtle influence which merely disturbs its internal structure, or perhaps deprives it of something it possessed. When this occurs, we have an original variation, the starting of something really new. Such original variations must be relatively rare, and we do not know what causes usually bring them about. Tower with beetles and MacDougal with plants seem to have produced them, in the one case by changes of temperature and moisture, in the other by chemical means. The fact that in some regions certain genera produce many species, as the asters in America, the brambles in Europe, seems to suggest that the disturbing influence may be different for different organisms, and may be locally distributed. Or it may be that, a line of disturbance once set up in some unknown manner, influences prevalent anywhere are sufficient to continue the line of change.
It may be that coming generations will see the causes of original variation fully elucidated, and the phenomenon itself brought largely under control. While mankind would thus be furnished with a weapon of extraordinary value, one trembles to think of the damage it might do. It might be made the means of producing new and wonderful variations in plants and animals, even in man himself; but inasmuch as there is every reason to suppose that its results could not often be accurately foretold, there is no telling what evil might result, even supposing that the power was never used with intentionally malicious purpose.
We are not at present, however, in any danger of being overrun with original variations; and it must be remembered that most of the recent wonders of Burbank and others, which are new in a practical sense, owe their origin biologically to recombinations of characters which have existed from time immemorial in separate races. No doubt the great men which arise in human societies from time to time may be explained in the same manner, so far as they are regarded as biological phenomena.
This possibility of producing what is virtually new by recombination must now be considered. Through the work done by various breeders, beginning with Mendel, we know much about the manner of such combinations, and how to get rid of undesirable units. Where the cases have been simple almost ideal success has been attained: and in complicated cases it has been possible to produce definite results by concentrating attention on special characters. Thus Bateson in his presidential address before the zoological section of the British Association in 1904, said:
We come then to the conclusion that in the case of man, as with domesticated animals and cultivated plants, it is possible to get rid of many undesirable qualities, to combine others which are desirable, and to maintain indefinitely that which has been once secured. Where there is bisexual inheritance we can not have strictly pure lines, to be sure, but it is possible to have lines which are pure within practical limits. That is to say, we may have a race of people none of whom have a certain hereditary taint, all of whom have a certain hereditary quality. Beyond this, we would not go, were it possible; for no one would wish to sacrifice the interesting diversity of human types which makes life chiefly worth while. In our national aspirations, we have recognized the ideal of a moderate unity of type; thus all Englishmen will agree that a true, full-blooded countryman of theirs should possess certain attributes, and will admit that those who fail in this are not strictly of the elect. All Frenchmen, typically, should have a certain vivacity not found among the Englishmen, and so on throughout the series.
Thus the ideal of a relatively pure race of high quality is by no means a new one; but what is new is the practical knowledge of how this may be brought about, with the certain expectation of much more light on the subject in the near future. The realization of such an ideal involves selective mating; but this again is nothing new, all mating among civilized people is selective, with a wide range of reasons for the selection. To these will now be added a new one, or rather an old one in a somewhat new light.
Professor J. Arthur Thomson well says:
On the other hand, we have to consider the means of increasing and continuing good qualities. The economic burden of raising a family is at present such as to discourage many whose qualities should be continued to other generations, and there can be no doubt that it would pay society to furnish ample means for the industry of child raising to those who are especially fitted to engage in it. Mr. Francis Galton has tried to calculate the value of different classes of individuals:
- This is quoted, with much other pertinent matter, by Dr. L. O. Howard in Bulletin 78, Bureau of Entomology, U. S. Department of Agriculture (1909).
We now come face to face with that profoundly interesting subject, the political, economical and historical significance of this great disease. We know that malaria must have existed in Greece ever since the time of Hippocrates, about 400 B.C. What effect has it had on the life of the country? In prehistoric times Greece was certainly peopled by successive waves of Aryan invaders from the north—probably a fair-haired people—who made it what it became, who conquered Persia and Egypt, and who created the sciences, arts and philosophies which we are only developing further to-day. That race reached its climax of development during the time of Pericles. Those great and beautiful valleys were thickly peopled by a civilization which in some ways has not been excelled. Everywhere there were cities, temples, oracles, arts, philosophies and a population vigorous and well trained in arms. Lake Kopais, now almost deserted, was surrounded by towns whose massive works remain to this day. Suddenly, however, a blight fell over all. Was it due to internecine conflict or to foreign conquest? Scarcely; for history shows that war burns and ravages, but does not annihilate. Thebes was thrice destroyed, but thrice rebuilt. Or was it due to some cause, entering furtively and gradually sapping away the energies of the race by attacking the rural population, by slaying the new-born infant, by seizing the rising generation, and especially by killing out the fair-haired descendant of the original settlers, leaving behind chiefly the more immunized and darker children of their captives, won by the sword from Asia and Africa?. . . The whole life of Greece must suffer from this weight, which crushes its rural energies'. Where the children suffer so much how can the country create that fresh blood which keeps a nation young? But for a hamlet here and there, those famous valleys are deserted. I saw from a spur of Helicon the sun setting upon Parnassus, Apollo sinking, as he was wont to do, toward his own fane at Delphi, and pouring a flood of light over the great Kopaik Plain. But it seemed that he was the only inhabitant of it. There was nothing there. "Who," said a rich Greek to me, "would think of going to live in such a place as that?" I doubt much whether it is the Turk who has done all this. I think it is very largely the malaria.
- When two "opposing" units coexist after a cross, there not rarely occurs a blended result, due to what is called "imperfect dominance," but this does not prevent complete segregation in a later generation.