No evidence that polygynous marriage is a harmful cultural practice in northern Tanzania

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 R ecent years have witnessed growing recognition of the importance of gender in all aspects of international development (1). This shift includes domestic and international efforts to abolish so-called "harmful cultural practices," a term used to describe practices of, typically nonwestern, cultures deemed detrimental to well-being, most often with regard to women and children (SI Text). Most attention has focused on female genital cutting and on child and forced marriage (2, 3). In many policyorientated texts, this label is also given to polygynous marriage (hereafter polygyny). For example, the United Nations Convention on the Elimination of All Forms of Discrimination Against Women states that polygyny "contravene[s] 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" (2). Such statements are frequently presented as stylized facts and made without discussion of supporting evidence. However, a recent spate of articles, mostly based on large-scale African Demographic and Health ...

What do men want? Re-examining whether men benefit from higher fertility than is optimal for women

“…It is worth noting that polygyny could empower women by increasing their mating options [27]i.e. they can choose to be the only wife of a poorer man, or share a wealthier man with co-wives-and recent research questions the causal role of polygyny in lowering women's fitness outcomes like child health [29]. However, inter-male competition for wives in these contexts tends to lead to younger ages at marriage for women, and less autonomy for them in such relationships with larger age gaps [13].…”

Are wives and daughters disadvantaged in polygynous households? A case study of the Arsi Oromo of Ethiopia

“…Polygyny, the marriage practice where men are allowed to marry multiple wives, exists in circa 80% of human societies (Murdock & White, 1969) and its consequences for women and children has been subject to much debate (Borgerhoff Mulder, 1992;Fortunato, 2015;Gibson & Mace, 2007;Hadley, 2005;Henrich, Boyd, & Richerson, 2012;Lawson et al, 2015;Sellen, 1999;Strassmann, 1997;Strassmann & Gillespie, 2002;Winking, Stieglitz, Kurten, Kaplan, & Gurven, 2013). While the benefits of polygyny to men include both a larger family size and labour participation from multiple wives (Luttbeg, Borgerhoff Mulder, & Mangel, 2000), the benefits to women of sharing a husband with other wives are less evident.…”

“…This is important because results based on an overall population may obscure the true consequences of alternative marital strategies for individual women. For example, among the Kenyan Kipsigis negative associations with polygyny were found only in the poorest households (Borgerhoff Mulder, 1997) and in a study from Tanzania, Lawson et al (2015) report that child health is only negatively associated with polygyny in female-headed households. But there may also be heterogeneity within households.…”

Reply to Rieger and Wagner: Context matters when studying purportedly harmful cultural practices

“…First, Rieger and Wagner (1) argue that our (2) demonstration that polygyny predicts higher child weight-for-height z-scores (WHZ) in two out of three ethnic groups practicing polygyny should be disregarded because of inadequacies of this measure. We defend our use of WHZ because: (i) although no measure is perfect, many studies unequivocally confirm that WHZ is a useful indicator of acute malnutrition, highly predictive of child mortality (3); and (ii) regardless of construct validity, WHZ scores have guided the international development sector for decades, our primary audience in addressing claims that polygyny is universally harmful.…”

“…Africa is a diverse continent and polygyny a diverse institution, encompassing variable norms of residence, resource sharing, and spousal recruitment (5). A true understanding of polygyny can only be gained by acknowledging this diversity and designing analyses that take context into account (2).…”