Darwinian selection has operated in favor of large body size to enhance fertility in women and provide for successful competition for mates in men. But large size in men also is desireable in the context of intra- and inter-population conflicts, which have been common throughout human history (132). Within technologically advanced societies large men and large women have higher fertility than smaller men and women, and taller men tend to be more successful economically and in leadership positions. On the other hand, in traditional or small-scale societies (that have characterized much of our evolutionary history), the energy cost of reproduction and producing large infants, children, and adults is often more than can be sustained by existing resources. In these cases, the selective pressures favoring large body size may be countered by selection for smaller body size and balances are achieved