This thesis presents and tests a new theory of human cultural origins. The point of departure is an economic finding: unlike non-human primates when they engage in hunting, human hunters normatively do not eat their own kills. This apparent self-denial, it is argued, is best seen as an expression of a cultural universal, the sexual division of labour, in which women obtain meat which their sexual partners have secured. It is suggested that the female sex may have played a part in the establishment of this arrangement, and – in particular – that menstrual bleeding may have been central to its symbolic underpinnings.

In much Native American mythology marriage is conceptualized as a monthly honeymoon interrupted at each dark moon by menstruation. Woman’s monthly alternation between marital sex and menstrual seclusion is coded as an alternation between her rival partners, Sun and Moon. Against this background, a Plains Indian myth attempts to come to terms with a novel problem. With the introduction of patrilocal residence, a woman must stay with her husband and his relatives even when she is menstruating. It is as if her two rival partners, instead of living apart, had come to occupy the same space together, limiting her movement and precluding her escape. Such permanency in marriage, overriding menstrual periodicity is experienced as a dangerous violation of ritual norms. Exploring the consequent difficulties and contradictions, the myth finds a way of validating the new arrangement. This story along with many others analysed by Lévi- Strauss analysis in the light of his own ‘exchange of women’ theory of human cultural origins. Re-analysed in the light of menstrual sex-strike theory however, it makes good sense, shedding light on the origins of women’s oppression.

Over much of Aboriginal Australia men exercise ritual power through ceremonies (stated in myths once to have been the prerogative of women) in which they symbolically “menstruate” and “give birth.” The resultant power is conceptualized as a rainbowlike snake, which is said to be the source of life and which “swallows” humans and then “regurgitates” them, now “reborn.” This chapter discusses examples of such rituals and beliefs. It suggests that Australian Aboriginal culture in certain regions exhibits a phenomenon known in Western medical science as “menstrual synchrony,” and that such synchrony has been conceptualized traditionally as “like a rainbow” and “like a snake.”