When men collect wives – and keep them together under the one roof – it’s usually to do with extending power, influence and wealth, even if it’s just having more people working in the fields.
When women benefit from having multiple husbands – as they do in a number of cultures – the reasons are more desperate.
According to new paper, based on a 20-year research project set in a western Tanzanian village, women acquire new husbands as a way of buffering themselves against economic and social crises, and more effectively keeping their children alive.
If your husband isn’t bringing home the bacon…
“We can’t pin down the exact reasons for this finding, but our work … suggests that marrying multiply may be a wise strategy for women where the necessities of life are hard, and where men’s economic productivity and health can vary radically over their lifetime due to the challenging environmental conditions,” said the lead researcher, Monique Borgerhoff Mulder, a University of California, Davis, professor of anthropology.
According to a statement from the university, Dr Borgerhoff Mulder collected data on births, deaths, marriages and divorces of all households – nearly 2000 individuals – in the small village, at the north end of the Rukwa Valley, in an area adjacent to floodplains and woodlands now designated as Katavi National Park.
In their paper, published in Proceedings of the Royal Society, Biological Sciences, the authors paint a tough picture of life in this region:
“The modern administrative area of Mpimbwe is settled primarily by the Pimbwe and related Bantu groups. As erstwhile residents of what is now Katavi National Park, the Pimbwe have a history of extensive hunting and fishing that has become increasingly tenuous under twenty-first century conservation policies.
“Both men and women cultivate cassava and maize. Yields are unreliable owing to unpredictable rainfall, soil depletion, crop pests and theft. Men supplement farming with hunting, fishing and honey production; both men and women engage in off-farm activities like beer brewing, traditional medicine, and petty trade.
“The area has been poorly served administratively and in terms of infrastructure for the last 100 years.”
Where marriage really is what you make of it
Marriages, highly informal, are recognised when a couple decides to cohabit – and reproductive partnerships are almost always acknowledged as marriages.
But marriage here is a complicated and highly fluid concept – where “both sexes exploit the flexible norms allowing monogamy, serial polygyny (men with multiple wives), serial polyandry (women with multiple husbands), and concurrent polygyny to negotiate reproduction in an ecology with little infrastructure, poor food security, high disease burdens, and considerable material inequality.”
Working with the demographic data accrued by Borgerhoff Mulder, the study’s co-author, Dr Cody Ross – a postdoctoral fellow at the Max Planck Institute for Evolutionary Anthropology, Leipzig – found that women who moved from spouse to spouse tended to have more surviving children, controlling for the number of years they had been married.
Men by contrast, again controlling for their number of married years, tended to produce fewer surviving children with the individual women they married over their lives.
Success in life is measured in healthy children
“As evolutionary biologists we measure benefit in terms of numbers of surviving children produced – still a key currency in rural Africa,” Dr Borgerhoff Mulder explained.
In the paper she notes that it “bears emphasising that in many parts of rural Africa reproductive inequality among women emerges … more likely from direct competition among women for access to resources”.
These resources include high-quality spouses, multiple caretakers to help around the house and farm, and, at least in this particular cultural context, helpful in-laws, she said.
In the paper, she writes: “Our most parsimonious inference for the unusual patterning of spouse number on (reproductive success), with women benefiting more than men from multiple spouses… is that many Pimbwe women switch partners to improve their economic circumstances.”
The authors acknowledge that a level of speculation underpins their findings. But they note there are parallels in African ethnography:
“In Zambia women marry (and remarry) in search of supportive husbands, and in Malawi and Tanzania women use sexual relations to negotiate economic dependencies with multiple men.”