Is human ovulation concealed? Evidence from conception beliefs in a hunter-gatherer society.

Several researchers have suggested that ovulation may not be concealed in humans living under natural conditions with minimal hygiene. Because measuring coital frequency in such a population is problematic, I tested this proposition indirectly by asking Hadza hunter-gatherers of Tanzania when a woman can get pregnant. If people (1) know that pregnancy is caused by sex, and people (2) say that women conceive in the middle of the menstrual cycle, we might infer that people think women conceive in the middle of the cycle because most copulations occur then. If copulation peaks strongly around ovulation, it is not concealed. The Hadza know that pregnancy is caused by sex but most say conception occurs right after menstruation ends. Hadza conception beliefs therefore do not suggest that ovulation is more detectable in humans under more natural conditions.