Demographic constraints on population growth of early humans

The human population grew at very low average rates for most of its existence. Mortality was reasonably severe and expectation of life at birth was low. The level of fertility necessary to achieve even inifinitesimal population growth under such mortality implies birth intervals sufficiently short to conflict with the ability to care for and carry children in a mobile foraging economy. Techniques for the control of mortality, especially of children before puberty and of women in childbirth, and of child care exchange, probably developed by females, may have been essential in permitting population growth under conditions of mobile foraging.