"Nature's" proscriptions or plans as controlling animal life, the
anthropomorphism is substantially harmless. But man keeps out of the way
of most of such proscriptions, has plans of his own, and has acquired
considerable skill in varying his projects without running foul of such
biological prohibitions.

It is time to abandon the notion that biology prescribes in detail how
we shall run society. True, this foundation has never received a surplus
of intelligent consideration. Sometimes human societies have built so
foolishly upon it that the result has been collapse. Somebody is always
digging around it in quest of evidence of some vanished idyllic state of
things which, having had and discarded, we should return to. This little
excursion into biology is made in the full consciousness that social
mandates are not to be found there. Human projects are the primary
material of social science. It is indispensable to check these against
biological fact, in order to ascertain which are feasible and which are
not. The biological basis may _help_ in explaining old social structures
or in planning new ones; but much wild social theory has been born of a
failure to appreciate the limitations of such material.

All the so-called higher animals, mammals and others, are divided into
two sexes, male and female. Besides the differentiation of germ-cells
there are rather obvious differences in the bodies of the two sexes. In
common with many other mammals, the human male has a larger and stronger
body, on an average, than has the human female. This is true also of the
anthropoid apes, the species which most resemble man physically and are
commonly supposed to be his nearest blood relatives in the animal
kingdom. It has been true of man himself as far back as we have any
records.