No evidence that polygynous marriage is a harmful cultural practice in northern Tanzania
David W. Lawson a,1, Susan James b, Esther Ngadaya c, Bernard Ngowi c, Sayoki G. M. Mfinanga c, and Monique Borgerhoff Mulder b,d
aDepartment of Population Health, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, United Kingdom;
bSavannas Forever Tanzania, Arusha, Tanzania;
cNational Institute for Medical Research, Muhimbili Medical Research Centre, Dar es Salaam, 11101, Tanzania;
dDepartment of Anthropology, University of California, Davis, CA 95616
Edited by James Holland Jones, Stanford University, Stanford, CA, and accepted by the Editorial Board September 23, 2015 (received for review May 14, 2015)
Significance
Polygynous marriage is commonly regarded as a harmful cultural practice, detrimental to women and children at the individual and group level. We present counterevidence that polygyny is often positively associated with food security and child health within communities and that, although polygyny and health are negatively associated at the group level, such differences are accounted for by alternative socioecological factors. These results support models of polygyny based on female choice and suggest that, in some contexts, prohibiting polygyny could be costly for women and children by restricting marital options. Our study highlights the dangers of naive analyses of aggregated population data and the importance of considering locally realizable alternatives and context dependency when considering the health implications of cultural practices.
Abstract
Polygyny is cross-culturally common and a topic of considerable academic and policy interest, often deemed a harmful cultural practice serving the interests of men contrary to those of women and children. Supporting this view, large-scale studies of national African demographic surveys consistently demonstrate that poor child health outcomes are concentrated in polygynous households. Negative population-level associations between polygyny and well-being have also been reported, consistent with the hypothesis that modern transitions to socially imposed monogamy are driven by cultural group selection. We challenge the consensus view that polygyny is harmful, drawing on multilevel data from 56 ethnically diverse Tanzanian villages. We first demonstrate the vulnerability of aggregated data to confounding between ecological and individual determinants of health; while across villages polygyny is associated with poor child health and low food security, such relationships are absent or reversed within villages, particularly when children and fathers are coresident. We then provide data indicating that the costs of sharing a husband are offset by greater wealth (land and livestock) of polygynous households. These results are consistent with models of polygyny based on female choice. Finally, we show that village-level negative associations between polygyny prevalence, food security, and child health are fully accounted for by underlying differences in ecological vulnerability (rainfall) and socioeconomic marginalization (access to education). We highlight the need for improved, culturally sensitive measurement tools and appropriate scales of analysis in studies of polygyny and other purportedly harmful practices and discuss the relevance of our results to theoretical accounts of marriage and contemporary population policy.
evolutionary anthropology public health family structure child health food security
Footnotes
1To whom correspondence should be addressed. Email: david.lawson{at}lshtm.ac.uk.
Author contributions: D.W.L., S.J., E.N., B.N., S.G.M.M., and M.B.M. designed research; D.W.L. analyzed data; D.W.L. and M.B.M. wrote the paper; and S.J., E.N., B.N., and S.G.M.M. collected data.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. J.H.J. is a Guest Editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1507151112/-/DCSupplemental.
Freely available online through the PNAS open access option.
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