Women’s reproductive health is often appropriately the focus of medical attention and intervention in developed countries today. We argue, however, that clinical treatment can benefit from a greater understanding of the conditions under which female reproductive biology evolved. Reproductive factors such as timing of menarche and first reproduction, ovulatory cycles, levels of reproductive hormones, and fertility are shaped by local conditions, lived experiences of each woman, and evolutionary forces that have operated for many millennia on ancestral women. Aspects of our reproductive biology that we take for granted and think of as “natural” are actually products of our recent and current lifestyles—this includes monthly menstrual periods for much of women’s reproductive years for a total of as many as 450 cycles in their lifetimes. More typical of the human experience relevant to evolution is less frequent menstrual periods interrupted by pregnancy and several years of lactation for a total of fewer than 100.