A cross-cultural analysis of ethnographic records has found that when women share a husband in polygynous marriages, physical fights between co-wives are common. The evidence, drawn from 19 cultures across five world regions, suggests that female competition can take direct, confrontational form when the stakes are high, challenging the view that rivalry among women is largely indirect. The study was published in Evolution and Human Behavior.
The research sits within longstanding debates about how women compete, including the idea that they avoid physical conflict to protect their offspring. The literature’s “staying alive” hypothesis, introduced by psychologist Anne Campbell in 1999, argued that natural selection favoured risk-averse strategies in women because injury could imperil infant survival. A 2013 review summarised the prevailing view that women primarily use indirect tactics—such as gossip or social exclusion—to compete for mates, a pattern echoed in a PsyPost report from 2023 about envy toward well-off same-sex peers.
Maryanne L. Fisher of Saint Mary’s University in Canada set out to test these ideas in a naturalistic context. She notes that much of the indirect-competition evidence comes from laboratory studies or surveys of young Western women facing low, hypothetical stakes with unknown rivals. In Fisher’s view, the staying alive hypothesis remains conditional: women weigh the costs of physical risk more heavily than men, but direct aggression should rise when the payoff justifies it. She examined co-wife arrangements as a test case, since co-wives repeatedly compete over resources that affect reproductive success and children’s survival.
To explore how co-wives compete, Fisher analysed ethnographic records from the eHRAF World Cultures database, a comprehensive collection of cultural texts. She looked at 19 distinct cultures spanning Africa, the Middle East, North America, South America and Oceania, ranging from hunter-gatherer groups to intensive agricultural communities. The records were coded using a four-part system focused on causes of co-wife competition, the modes of competition used, how conflicts were resolved, and what strategies prevented disputes in the first place.
Fisher searched for ethnographic accounts linking polygamy and wives with terms such as aggression, violent or fight, retaining only records that described competition or conflict between co-wives. Three cultures were excluded because their records described peaceful relations or no conflict. Each remaining culture was coded for whether a given behaviour appeared, with a second independent coder checking definitions until agreement was reached.
The analysis found that competition for the husband’s sexual and emotional attention was the primary cause of conflict, documented in 14 of the 19 cultures (73.7 per cent). Jealousy over sleeping arrangements, fear of being replaced, and general affection were all included in this category. Competition over material resources, such as food, garden plots, livestock or unequal distribution of resources to children, was the second most common cause, present in seven cultures (36.8 per cent). Status competition, including rivalry over who is the senior wife, appeared in five cultures (26.3 per cent).
When it came to how women competed, direct physical aggression was the most frequently documented method. Explicit accounts of physical fighting appeared in 12 of the 19 cultures (63.2 per cent), ranging from low‑level exchanges such as hitting or hair-pulling to occasions where objects were used or injuries occurred. Verbal aggression—shouting matches and direct insults—was reported in 10 cultures (52.6 per cent).
Covert hostility—an icy or deliberately hostile atmosphere without open fighting—appeared in six cultures (31.6 per cent). Less common strategies included supernatural means, such as curses or food‑pollution rituals, noted in four cultures (21.1 per cent). Gossip and social exclusion, often thought of as classic indirect tactics, appeared in only two cultures. In a few cultures, competition took the form of property destruction.
Because indirect tactics were divided into many subcategories, Fisher also grouped them into a single indirect-aggression category for fairer comparison. Combined indirect aggression appeared in nine to 11 of the 19 cultures (47 to 58 per cent), depending on how broadly defined, versus 12 cultures with direct aggression. Direct confrontation of any kind, whether physical or verbal, was documented in 14 cultures.
The findings suggest that physical confrontation is a common element of co-wife rivalry, occurring alongside indirect strategies rather than replacing them.
The study also looked at how disputes were resolved. The most common outcomes were the husband intervening to arbitrate or separate the wives and the permanent dissolution of the relationship, such as a wife fleeing or being expelled, each documented in nine cultures (47.4 per cent). Community arbitration by in‑laws or neighbours occurred in eight cultures (42.1 per cent). Quiet negotiation between the co-wives themselves was rarely observed.
Many societies also employed preventative measures to keep co-wives apart or reduce friction. Spatial separation of wives—housing them in separate dwellings or settlements—was the most common strategy, found in 11 cultures (57.9 per cent). Another preventative approach, found in seven cultures (36.8 per cent), was sororal polygyny, the favouring of sisters as co-wives. Ethnographic records often note that men preferred sisters because sisters tend to fight less than unrelated women; Fisher argues the cross-cultural prevalence of this arrangement suggests societies organise households to deter anticipated conflict.
“ This study provides a valuable cross-cultural perspective by reviewing 19 different cultures, challenging the lab-based view that women’s competition is always indirect,” remarked Farid Pazhoohi, an interdisciplinary psychologist at the University of Plymouth who was not involved in the research. He added that the results should be interpreted carefully. “[W]hile readers might mistakenly interpret this as proof that women are universally violent, the findings instead point to a flexible strategy where women use direct aggression when the stakes are high enough to outweigh the risks,” he told PsyPost.
As with all research, the study has limitations. Fisher notes the sample of 19 cultures limits broad generalisations, and the contrast with laboratory studies is suggestive rather than a direct test. The sample is uneven, with 13 of the cultures in the Americas and Africa represented by only a single culture.
Pazhoohi highlighted further caveats. “Because it relies on second-hand ethnographic records, observational secondary data is inherently less informative for pinning down strict causal relationships. While we can spot broad patterns, we cannot isolate direct cause-and-effect or rule out hidden confounders.” He also cautioned that reducing complex cultural behaviours to summary percentages can mask local variation, and that historical field notes may reflect reporting biases.
Fisher acknowledges these issues, noting that her search terms targeted overt conflict and that the prevalence of indirect tactics should be read as a minimum. The study records whether conflict occurred but not its intensity or duration, leaving room for future longitudinal work to explore escalation and interruption.
The study is titled The battle of the brides: Co-wife competition and aggression across 19 cultures and was authored by Maryanne L. Fisher.
