half the group. If this aggregation is to even hold
its own numerically, its women must have, on an average, two children
each, _plus about one more_ for unavoidable waste--death in infancy or
childhood, sterility, obvious unfitness for reproduction, etc., i.e.,
_three_ in all. If one woman has less than her three children, then
another must have more than three, or the group number will decrease.
_Group survival is the fundamental postulate in a problem of this kind._

The above figure is for civilized society. In primitive groups, the
terrific wastage makes a much higher birth-rate necessary, several times
as high in many cases. If we suppose such a group, where child
mortality, lack of sanitation, etc., necessitates an average of eight
children per woman (instead of three), the biological origin of the
division of labour between the sexes is much more clearly seen than it
is in civilized societies.

If men are better hunters or fighters than women, the latter could
nevertheless hunt and fight--it is a question of superior or inferior
adaptation to particular activities. But it is more than that. _Only_
the women are biologically specialized to the chief reproductive burden
(intra-parental environment and lactation). If half the women should
withdraw from child-bearing, the remainder would be obliged to average
_sixteen_ apiece. But even this is not all. Unfortunately, the half of
the women who would be found best adapted to hunting and fighting would
be the more vigorous half. The new generation would thus be born from
the leftovers, and would be poor quality. Such a division of labour
within a group would be fatally foolish and entirely uncalled for--since
there are plenty of men adapted to hunting and fighting, but entirely
unspecialized to child-bearing and nursing.

Group survival being the fundamental thing, the group is obliged to
develop a division of labour which directs the activities of the
individuals composing it to providing for its necessities, regardless
of any interference with their own desires. That is, if group survival
requires that woman use her specialization to child-bearing instead of
any adaptation she may possess in other directions, one of two things
inevitably result: (1) Either the group finds or evolves some social
control machinery which meets the necessity, or (2) it must give way to
some other group which can do so. In either case, the result is a
division of labour, which we see m