Alvergne Alexandra, Lummaa Virpi
School of Anthropology and Museum Ethnography, Oxford University, Oxford OX2 6PE, UK Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK Harris Manchester College, Oxford OX1 3TD, UK
Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
Proc Biol Sci. 2014 Dec 7;281(1796):20141733. doi: 10.1098/rspb.2014.1733.
The negative wealth-fertility relationship brought about by market integration remains a puzzle to classic evolutionary models. Evolutionary ecologists have argued that this phenomenon results from both stronger trade-offs between reproductive and socioeconomic success in the highest social classes and the comparison of groups rather than individuals. Indeed, studies in contemporary low fertility settings have typically used aggregated samples that may mask positive wealth-fertility relationships. Furthermore, while much evidence attests to trade-offs between reproductive and socioeconomic success, few studies have explicitly tested the idea that such constraints are intensified by market integration. Using data from Mongolia, a post-socialist nation that underwent mass privatization, we examine wealth-fertility relationships over time and across a rural-urban gradient. Among post-reproductive women, reproductive fitness is the lowest in urban areas, but increases with wealth in all regions. After liberalization, a demographic-economic paradox emerges in urban areas: while educational attainment negatively impacts female fertility in all regions, education uniquely provides socioeconomic benefits in urban contexts. As market integration progresses, socio-economic returns to education increase and women who limit their reproduction to pursue education get wealthier. The results support the view that selection favoured mechanisms that respond to opportunities for status enhancement rather than fertility maximization.
市场一体化所带来的负财富-生育关系仍然是经典进化模型中的一个难题。进化生态学家认为，这种现象源于最高社会阶层在生殖与社会经济成功之间更强的权衡取舍，以及群体而非个体之间的比较。的确，当代低生育率环境下的研究通常使用汇总样本，这可能掩盖了正财富-生育关系。此外，虽然有大量证据证明生殖与社会经济成功之间存在权衡取舍，但很少有研究明确检验这种限制会因市场一体化而加剧这一观点。我们利用经历大规模私有化的后社会主义国家蒙古的数据，研究了不同时间和城乡梯度上的财富-生育关系。在已过生育期的女性中，生殖健康在城市地区最低，但在所有地区都随财富增加而提高。自由化之后，城市地区出现了人口经济悖论：虽然教育程度在所有地区都会对女性生育产生负面影响，但教育在城市环境中独特地提供社会经济利益。随着市场一体化的推进，教育的社会经济回报增加，那些为追求教育而限制生育的女性变得更加富有。研究结果支持了这样一种观点，即选择有利于那些对地位提升机会而非生育最大化机会做出反应的机制。
