We carried out a study of farming and herding groups in the Tibetan borderlands in rural China—an area with huge cultural diversity—to uncover which factors actually determine who works the hardest in a household, and why. Our results, published in Current Biology, shed light on the gender division of work across many different kinds of society.

The majority of adults across the world are married. Marriage is a contract, so one might expect roughly equal costs and benefits from the union for both parties. But unequal bargaining power in a household—such as one person threatening divorce—can lead to unequal contributions to the partnership.

Leaving home

We decided to test the hypothesis that leaving your natal area after heterosexual marriage to live with your spouse's family may contribute to a higher level of workload. In such marriages, the new person typically isn't related to, and doesn't share a history with, anyone in their new household. Without blood relatives around them, they might therefore be at a disadvantage when it comes to bargaining power.

The most common form of marriage around the world is where women are the "dispersers," leaving their native home, while men stay with their families in their natal area. This is known as patrilocality.