We are never outside what the anthropologist Gayle Rubin has taught us to call a 'sex

gender system': it is the task of cultural critics - anthropologists, literary scholars, classicists, archaeologists - to specify the components and dynamics of such systems as they take cultural form, whether in societies or in artefacts like poems. Sex, sexuality, gender, reproduction, production and ideas about all of these are structurally linked in any society; consider, for example, Lévi-Strauss’s meditation on exogamy - the exchange or 'traffic in women' between social groups, fundamental to human communities thus far - as the foundational requirement for any human traffic, for society itself. Over the last thirty years scholars and activists have greatly refined our understanding about sex, sexuality and gender: a sex-gender system is not simply about men and women, nor even about 'masculinity' vs. 'femininity', or 'homosexuality' vs. 'heterosexuality'. Each of these categories has a history and a cultural specificity; it is a truism worth repeating that sexuality, gender and ideas thereof are culturally variable. Yet just as the linguist Émile Benveniste observed that nowhere do we find a human society without language, so we might also say that nowhere do we find a human society without a sex-gender system (however debated, brittle or fragile) - some way of organising sexual dimorphism, reproduction and child-rearing.