Abstract

It is now more than twenty years since Knight (1987) first presented his paradigm-shifting theory of how and why the ‘human revolution’ occurred — and had to occur — in modern humans who, as climates dried under ice age conditions and African rainforests shrank, found themselves surrounded by vast prairies and savannahs, with rich herds of game animals roaming across them. The temptation for male hunters, far from any home base, to eat the best portions of meat at the kill site — as do other social carnivores — called for strong measures from human females, who were paying the heavy metabolic and physical costs of bearing large-brained but helpless children. Even in the modern west, with well stocked supermarkets, a pregnant or lactating woman can lose ten percent of the dry weight of her brain, because developing babies demand dietary lipids for brain growth (Horrobin, 1998). Hence the idea of the menstrual sex strike, designed to force males to deliver their kills entirely into the hands of women for cooking and distribution—a practice common in foraging communities to this day.