Lesbian feminism has often been scorned as a marginal political dogma. Susan Cavin, a lesbian feminist sociologist, advances a new theory of women's oppression and women's liberation, based on cross-cultural data. She holds that original human societies were woman-centered, with females greatly outnumbering males; men occupied a marginal position. When armed men overthrew women's societies they integrated themselves into society, breaking women's power.

Examining the sex ratio of societies across the globe, Cavin challenges conventional wisdom about the "natural" numerical balance between the sexes. She finds a frequent occurrence of societies with a high-female sex ratio (54% or more female) among Africans, Pacific islanders and Native Americans (in both North and South America). Moreover, she finds that these cultures tend to subsist by hunting and gathering, with extended-family households centered around mothers' kin-groups, and a lack of sharp social stratification in the culture. She thus hypothesizes that original human society had a high-female sex ratio. Cavin also finds that lesbian relations have existed in pre-industrial societies at every level of economy and subsistence pattern, with woman-to woman marriage practiced in several African and Native American cultures. Her investigation provides a sociological basis for lesbian feminism.

Cavin disputes the liberal notion that sex separation invariably places women in a subordinate role. "The entrance of the mass of males into everyday residential contact with female society brings dominance hierarchies into society," she asserts. "These male dominance hierarchies economically, socially, and politically segregate the mass of women from positions of power in society." She also challenges standard feminist views of women's liberation, arguing that women will not win their freedom by integrating into male-dominated power structures.