When women share a husband, physical fights between co-wives are common across cultures

A cross-cultural analysis of ethnographic records suggests that when women share a husband in polygynous marriages, physical fights between co-wives are common. Physical aggression was documented in most of the 19 cultures examined, providing evidence that women’s competition can include direct confrontation when the stakes are high, in contrast to the prevailing view that female rivalry is mostly indirect. The research was published in Evolution and Human Behavior.

What drives competition among women? Evolutionary theories have suggested that women avoid physical fights to protect their survival and the lives of their children, relying instead on indirect social tactics. For example, a theory called the “staying alive” hypothesis, proposed by psychologist Anne Campbell in a 1999 paper, suggested that natural selection favored risk-averse strategies in women because physical injury could severely harm the survival chances of their highly dependent infants.

Building on this idea, a 2013 review summarized the prevailing scientific view that women primarily compete for mates through indirect aggression, such as gossip and social exclusion, rather than physical fights. This aligns with a study covered by PsyPost in 2023, which found that women reported more envy toward well-off same-sex peers than men did and were more likely to engage in indirect competition such as gossip and spreading rumors.

However, anthropological surveys of polygynous marriages, in which a man has more than one wife at the same time, indicate a different pattern. When high-stakes resources and partners are on the line, direct physical conflict between women appears common. For instance, a 2005 cross-cultural study of polygynous societies found that co-wives routinely experience intense jealousy and often resort to verbal and physical violence when competing for their shared husband.

Maryanne L. Fisher of Saint Mary’s University in Canada set out to examine this dynamic systematically. She notes that much of the evidence for indirect competition comes from laboratory and survey studies of young women in Western countries competing over low or hypothetical stakes with rivals they did not know. In Fisher’s reading, the staying alive hypothesis was always conditional: women weigh the costs of physical risk more heavily than men, but direct aggression should become more likely when the payoff is high enough. She used co-wife arrangements as a test case, since co-wives compete repeatedly, over years, for resources that bear on their reproductive success and their children’s survival.

To explore how co-wives compete, Fisher analyzed ethnographic records, which are detailed written accounts by anthropologists and other observers who studied or lived among particular communities. The records came from the eHRAF World Cultures database, a comprehensive collection of cultural texts. She examined records from 19 distinct cultures spanning five major world regions (Africa, the Middle East, North America, South America, and Oceania), ranging from hunter-gatherer groups to intensive agricultural communities. Fisher coded the historical and cultural texts using a four-part system focused on the causes of co-wife competition, the modes of competition used, how conflicts were resolved, and what strategies were used to prevent disputes in the first place.

Fisher searched the database for records combining polygamy and wives with terms such as aggression, violent, and fight, and kept only records that directly described competition or conflict between co-wives. Three cultures turned up in the search but were excluded because their records described peaceful relations or no conflict between co-wives. Each remaining culture was coded for whether a given behavior was documented at all, so the percentages below reflect the share of cultures where a behavior appeared in the records, not how often it occurred. A second, independent coder applied the same scheme, and the two refined their definitions until they fully agreed.

The analysis indicates 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 percent). This included jealousy over sleeping arrangements, fear of being replaced, and competition for general affection. Competition over material resources, such as food, garden plots, livestock, and unequal distribution of resources to children, was the second most frequent cause, present in 7 of the 19 cultures (36.8 percent). Status competition, such as rivalry over who is senior wife, was a third cause, identified in 5 cultures (26.3 percent).

When looking at how women competed, direct physical aggression was the most frequently documented method. Fisher found explicit accounts of physical fighting in 12 of the 19 cultures (63.2 percent). This low-level direct combat included behaviors like hitting, biting, hair-pulling, and occasionally the use of objects like sticks or paddles, though a few accounts were more severe, including one in which a woman was knocked senseless and others describing fights that caused injury. Verbal aggression, such as face-to-face shouting matches, direct insults, and arguments, was documented in 10 cultures (52.6 percent).

Covert hostility, where women maintained an icy or deliberately hostile atmosphere without open fighting, appeared in 6 cultures (31.6 percent). Less common strategies included the use of supernatural means, such as curses or food pollution rituals, which were noted in 4 cultures (21.1 percent). Gossip and social exclusion, often considered classic indirect tactics, appeared in only 2 cultures. In a few cultures, competition took the form of property destruction, such as tearing a rival’s belongings or deliberately ruining her prepared food.

Because indirect tactics were split into many separate categories, Fisher also grouped them into a single category for a fairer comparison. Combined indirect aggression appeared in 9 to 11 of the 19 cultures (47 to 58 percent), depending on how broadly it was defined, compared with 12 cultures for physical aggression. Direct confrontation of any kind, physical or verbal, was documented in 14 cultures (73.7 percent).

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 between co-wives were handled. The most common resolutions, each documented in 9 of the 19 cultures (47.4 percent), 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. Less frequently, conflicts were arbitrated by community members, such as in-laws or neighbors, which happened in 8 cultures (42.1 percent). Only rarely were co-wives documented resolving a conflict through quiet negotiation among themselves.

Many societies also had arrangements that kept co-wives apart or reduced friction between them. The most common preventative measure was the spatial separation of wives, documented in 11 cultures (57.9 percent). This involved housing wives in separate dwellings, assigning them different cooking fires, or even placing them in completely different settlements, which Fisher interprets as a way of managing co-wife conflict.

Another common preventative strategy, found in 7 cultures (36.8 percent), was a cultural preference for marrying sisters, known as sororal polygyny. Ethnographic records often stated that men preferred sisters as co-wives because they tended to fight less than unrelated women. Evolutionary theory suggests that individuals are less likely to harm close genetic relatives because they share many of the same genes, meaning a sister’s reproductive success indirectly benefits the other sister. Fisher argues that the cross-cultural prevalence of this arrangement suggests societies implicitly recognize the volatility of non-kin co-wives and organize 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,” said Farid Pazhoohi, an interdisciplinary psychologist and researcher at the University of Plymouth who was not involved in the research.

Pazhoohi noted that the results should be viewed in their specific context. “[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, there are a few things to keep in mind. The study relied on a sample of 19 cultures, which limits how broadly the prevalence estimates can be generalized. Fisher also notes that the contrast with laboratory studies is suggestive rather than a direct test, since those studies differ from ethnographic records in their populations and methods. The sample was uneven as well: 13 of the 19 cultures were in the Americas, while Africa was represented by a single culture.

Pazhoohi also pointed out limitations in the study’s design. “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 said, referring to other factors that could explain the pattern.

“Furthermore, reducing complex cultural behaviors down to summary percentages and binary metrics (such as noting whether a behavior is simply present or absent) can conceal individual variations and local context,” Pazhoohi added. “Historical field notes are prone to reporting biases, meaning dramatic physical fights are much easier for ethnographers to record than covert hostility or quieter tensions.”

Fisher acknowledges this issue as well, noting that her search terms were geared toward overt conflict, so the prevalence of indirect tactics should be read as a minimum. The data also captured whether conflict occurred but not its intensity or duration. Future longitudinal research could show how verbal disputes escalate into physical fights and when these conflicts are successfully interrupted.

The study, “The battle of the brides: Co-wife competition and aggression across 19 cultures,” was authored by Maryanne L. Fisher.