It is only in human social life that coöperation, or altruism, attains its full development. Human society is characterized by the protection it affords to its weaker members, and in human society the natural process of eliminating the inferior often seems reversed. As Huxley has pointed out, human society tries to fit as many as possible to survive, and we may add, not only to survive, but to live well. Altruism and its resulting coöperation have come especially to characterize human social evolution. To some extent this is due, no doubt, to the necessities of group survival; for only that nation, for example, can survive that can maintain the most loyal citizenship, the best institutions, and the largest spirit of self-sacrifice in its members. Human social groups, therefore, try to fit as many individuals as possible for the most efficient membership, and this necessitates caring for the temporarily weak, and also for the permanently incapacitated, in order that the sentiments of social solidarity may be strengthened to their utmost. It is evident, then, that all the factors at work in organic evolution are at work also in social evolution, though in some part modified and varying in degree. The struggle for existence in human society, for example, has been greatly modified from the condition in the early animal world, while coöperation, or altruism, is much more highly developed. Nevertheless, these factors of organic evolution are at work in social evolution and must be taken into full account by the student of social problems. Social evolution rests upon organic evolution. Some Effects upon Industry.--These factors in organic evolution express themselves more or less in the industrial phase of human society. Thus, the first factor, the multiplication of organisms through reproduction in some geometric ratio, was first studied by Malthus, an economist in the beginning of the nineteenth century, and exclusively with reference to its effect upon economic conditions. Malthus perceived the tendency for human beings to multiply in some geometric ratio where food supply was sufficiently abundant, and argued from this that if better wages, and so a larger food supply, were given the lower classes, they would multiply so much more rapidly that worse poverty would result than before. There is no doubt that in certain classes of human society there is a tendency for population to press against food supply, and it is in these classes that the struggle for existence takes on its most animal-like forms.