To see what race means when considered apart, let us first of all take your individual self, and ask how you would proceed to separate your inherited nature from the nature which you have acquired in the course of living your life. It is not easy. Suppose, however, that you had a twin brother born, if indeed that were possible, as like you as one pea is like another. An accident in childhood, however, has caused him to lose a leg. So he becomes a clerk, living a sedentary life in an office. You, on the other hand, with your two lusty legs to help you, become a postman, always on the run. Well, the two of you are now very different men in looks and habits. He is pale and you are brown. You play football and he sits at home reading. Nevertheless, any friend who knows you both intimately will discover fifty little things that bespeak in you the same underlying nature and bent. You are both, for instance, slightly colour-blind, and both inclined to fly into violent passions on occasion. That is your common inheritance peeping out—if, at least, your friend has really managed to make allowance for your common bringing-up, which might mainly account for the passionateness, though hardly for the colour-blindness.
But now comes the great difficulty. Let us further suppose that you two twins marry wives who are also twins born as like as two peas; and each pair of you has a family. Which of the two batches of children will tend on the whole to have the stronger legs? Your legs are strong by use; your brother's are weak by disuse. But do use and disuse make any difference to the race? That is the theoretical question which, above all others, complicates and hampers our present-day attempts to understand heredity.
In technical language, this is the problem of use-inheritance, otherwise known as the inheritance of acquired characters. It is apt to seem obvious to the plain man that the effects of use and disuse are transmitted to offspring. So, too, thought Lamarck, who half a century before Darwin propounded a theory of the origin of species that was equally evolutionary in its way. Why does the giraffe have so long a neck? Lamarck thought it was because the giraffe had acquired a habit of stretching his neck out. Every time there was a bad season, the giraffes must all stretch up as high as ever they could towards the leafy tops of the trees; and the one that stretched up farthest survived, and handed on the capacity for a like feat to his fortunate descendants. Now Darwin himself was ready to allow that use and disuse might have some influence on the offspring's inheritance; but he thought that this influence was small as compared with the influence of what, for want of a better term, he called spontaneous variation. Certain of his followers, however, who call themselves Neo-Darwinians, are ready to go one better. Led by the German biologist, Weismann, they would thrust the Lamarckians, with their hypothesis of use-inheritance, clean out of the field. Spontaneous variation, they assert, is all that is needed to prepare the way for the selection of the tall giraffe. It happened to be born that way. In other words, its parents had it in them to breed it so. This is not a theory that tells one anything positive. It is merely a caution to look away from use and disuse to another explanation of variation that is not yet forthcoming.
After all, the plain man must remember that the effects of use and disuse, which he seems to see everywhere about him, are mixed up with plenty of apparent instances to the contrary. He will smile, perhaps, when I tell him that Weismann cut off the tails of endless mice, and, breeding them together, found that tails invariably decorated the race as before. I remember hearing Mr. Bernard Shaw comment on this experiment. He was defending the Lamarckianism of Samuel Butler, who declared that our heredity was a kind of race-memory, a lapsed intelligence. "Why," said Mr. Shaw, "did the mice continue to grow tails? Because they never wanted to have them cut off." But men-folk are wont to shave off their beards because they want to have them off; and, amongst people more conservative in their habits than ourselves, such a custom may persist through numberless generations. Yet who ever observed the slightest signs of beardlessness being produced in this way? On the other hand, there are beardless as well as bearded races in the world; and, by crossing them, you could, doubtless, soon produce ups and downs in the razor-trade. Only, as Weismann's school would say, the required variation is in this case spontaneous, that is, comes entirely of its own accord.
Leaving the question of use-inheritance open, I pass on to say a word about variation as considered in itself and apart from this doubtful influence. Weismann holds, that organisms resulting from the union of two cells are more variable than those produced out of a single one. On this view, variation depends largely on the laws of the interaction of the dissimilar characters brought together in cell-union. But what are these laws? The best that can be said is that we are getting to know a little more about them every day. Amongst other lines of inquiry, the so-called Mendelian experiments promise to clear up much that is at present dark.
The development of the individual that results from such cell-union is no mere mixture or addition, but a process of selective organization. To put it very absurdly, one does not find a pair of two-legged parents having a child with legs as big as the two sets of legs together, or with four legs, two of them of one shape and two of another. In other words, of the possibilities contributed by the father and mother, some are taken and some are left in the case of any one child. Further, different children will represent different selections from amongst the germinal elements. Mendelism, by the way, is especially concerned to find out the law according to which the different types of organization are distributed between the offspring. Each child, meanwhile, is a unique individual, a living whole with an organization of its very own. This means that its constituent elements form a system. They stand to each other in relations of mutual support. In short, life is possible because there is balance.
This general state of balance, however, is able to go along with a lot of special balancings that seem largely independent of each other. It is important to remember this when we come a little later on to consider the instincts. All sorts of lesser systems prevail within the larger system represented by the individual organism. It is just as if within the state with its central government there were a number of county councils, municipal corporations, and so on, each of them enjoying a certain measure of self-government on its own account. Thus we can see in a very general way how it is that so much variation is possible. The selective organization, which from amongst the germinal elements precipitates ever so many and different forms of fresh life, is so loose and elastic that a working arrangement between the parts can be reached in all sorts of directions. The lesser systems are so far self-governing that they can be trusted to get along in almost any combination; though of course some combinations are naturally stronger and more stable than the rest, and hence tend to outlast them, or, as the phrase goes, to be preserved by natural selection.
It is time to take account of the principle of natural selection. We have done with the subject of variation. Whether use and disuse have helped to shape the fresh forms of life, or whether these are purely spontaneous combinations that have come into being on what we are pleased to call their own account, at any rate let us take them as given. What happens now? At this point begins the work of natural selection. Darwin's great achievement was to formulate this law; though it is only fair to add that it was discovered by A.R. Wallace at the same moment. Both of them get the first hint of it from Malthus. This English clergyman, writing about half a century earlier, had shown that the growth of population is apt very considerably to outstrip the development of food-supply; whereupon natural checks such as famine or war must, he argued, ruthlessly intervene so as to redress the balance. Applying these considerations to the plant and animal kingdoms at large, Darwin and Wallace perceived that, of the multitudinous forms of life thrust out upon the world to get a livelihood as best they could, a vast quantity must be weeded out. Moreover, since they vary exceedingly in their type of organization, it seemed reasonable to suppose that, of the competitors, those who were innately fitted to make the best of the ever-changing circumstances would outlive the rest. An appeal to the facts fully bore out this hypothesis. It must not, indeed, be thought that all the weeding out which goes on favours the fittest. Accidents will always happen. On the whole, however, the type that is most at home under the surrounding conditions, it may be because it is more complex, or it may be because it is of simpler organization, survives the rest.
Now to survive is to survive to breed. If you live to eighty, and have no children, you do not survive in the biological sense; whereas your neighbour who died at forty may survive in a numerous progeny. Natural selection is always in the last resort between individuals; because individuals are alone competent to breed. At the same time, the reason for the individual's survival may lie very largely outside him. Amongst the bees, for instance, a non-working type of insect survives to breed because the sterile workers do their duty by the hive. So, too, that other social animal, man, carries on the race by means of some whom others die childless in order to preserve. Nevertheless, breeding being a strictly individual and personal affair, there is always a risk lest a society, through spending its best too freely, end by recruiting its numbers from those in whom the engrained capacity to render social service is weakly developed. To rear a goodly family must always be the first duty of unselfish people; for otherwise the spirit of unselfishness can hardly be kept alive the world.
Enough about heredity as a condition of evolution. We return, with a better chance of distinguishing them, to the consideration of the special effects that it brings about. It was said just now that heredity is the stiffening in human nature, a stiffening bound up with a more or less considerable offset of plasticity. Now clearly it is in some sense true that the child's whole nature, its modicum of plasticity included, is handed on from its parents. Our business in this chapter, however, is on the whole to put out of our thoughts this plastic side of the inherited life-force. The more or less rigid, definite, systematized characters—these form the hereditary factor, the race. Now none of these are ever quite fixed. A certain measure of plasticity has to be counted in as part of their very nature. Even in the bee, with its highly definite instincts, there is a certain flexibility bound up with each of these; so that, for instance, the inborn faculty of building up the comb regularly is modified if the hive happens to be of an awkward shape. Yet, as compared with what remains over, the characters that we are able to distinguish as racial must show fixity. Unfortunately, habits show fixity too. Yet habits belong to the plastic side of our nature; for, in forming a habit, we are plastic at the start, though hardly so once we have let ourselves go. Habits, then, must be discounted in our search for the hereditary bias in our lives. It is no use trying to disguise the difficulties attending an inquiry into race.