London School of Hygiene & Tropical Medicine

Polygyny - a marriage system where men can have multiple wives - may provide women with superior food security and health for their children, according to new research published in the Proceedings of the National Academy of Sciences.

Research led by Dr David Lawson at the London School of Hygiene & Tropical Medicine compared polygynous and monogamous households in 56 villages in northern Tanzania, where polygyny is widespread among certain ethnic groups, including the Maasai.

When comparing households within individual villages, polygynous households often had better access to food and healthier children. Polygynous households also owned more cattle and farmed more land than monogamous households. These findings support anthropological accounts of marriage indicating that polygyny can be in a woman's strategic interest when women depend on men for resources.

Dr Lawson, Lecturer in Population Health at the School, said: "Polygyny is often considered to be a harmful cultural practice, detrimental to the well-being of women and children. However our findings reveal that the costs of sharing a husband can be offset by equal or greater resource access than could otherwise be obtained via monogamy in some settings."

Consistent with prior research, the study found that polygyny was associated with low food security and poor child health when looking at data across all villages. However, this pattern was accounted for by the tendency of polygyny to be most common in ecologically vulnerable and marginalised ethnic groups.

Dr Lawson added: "Our study suggests that highly polygynous, predominantly Maasai, villages do poorly not because of polygyny, but because of vulnerability to drought, low service provision and broader socio-political disadvantages."

Tanzania faces a high burden of food insecurity and malnutrition; 45% of children are stunted (low height for their age, indicating chronic malnutrition with long term impacts on physical and cognitive development). Previous research by Dr Lawson and colleagues reported that Tanzanian Maasai children do particularly poorly, with nearly 60% experiencing stunting.

The United Nations states that polygyny contravenes a woman's right to equality with men and can have such serious emotional and financial consequences for her and her dependents that such marriages ought to be discouraged and prohibited.

However, the researchers highlight the importance of local context in studying the health implications of cultural practices, and suggest that in some settings, prohibiting polygyny could be disadvantageous to women by restricting their marriage options.

The study is limited to food security and health, and cannot tell us about the wider potential for polygyny to cause harm. The researchers also note that polygyny was only associated with superior outcomes when fathers and children where co-resident. This suggests that any potential benefits of sharing a husband may be limited to the primary wife within a polygynous marriage.

The study was supported by funding from the UK Medical Research Council and Department for International Development. The research was conducted in partnership with Savannas Forever Tanzania, the National Institute for Medical Research in Tanzania, and the University of California, Davis.

Publication:

• David W. Lawson, Susan James, Esther Ngadaya, Bernard Ngowi, Sayoki G. M. Mfinanga, Monique Borgerhoff Mulder. No evidence that polygynous marriage is a harmful cultural practice in northern Tanzania. PNAS. DOI: 10.1073/pnas.150715111.