in the rearing of offspring. The family group, even in the lower
animals, seems to be the chief source of altruism. At any rate,
sympathetic or altruistic instincts grow up in all animals, probably
chiefly through the necessities of reproduction.

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.