State Key Laboratory of Grassland Agro-ecosystem, College of Ecology, Lanzhou University, Lanzhou, People's Republic of China.
Department of Anthropology, University College London, London, UK.
Proc Biol Sci. 2023 Mar 29;290(1995):20230159. doi: 10.1098/rspb.2023.0159. Epub 2023 Mar 22.
Humans exhibit a broad range of post-marital residence patterns and there is growing recognition that post-marital residence predicts women's reproductive success; however, the nature of the relationship is probably dependent on whether co-resident kin are cooperators or competitors. Here, we explore this relationship in a Tibetan population, where couples practice a mixture of post-marital residence patterns, co-residing in the same village with the wife's parents, the husband's parents or endogamously with both sets of parents. Using detailed demographic data from 17 villages we find that women who live with only their own parents have an earlier age at first birth (AFB) and age at last birth (ALB) than women who live with only their parents-in-law. Women who co-reside with both sets of parents have the earliest AFB and ALB. However, those with co-resident older siblings postponed reproduction, suggestive of competition-related delay. Shifts to earlier reproductive timing were also observed in relation to the imposition of family planning policies, in line with Fisherian expectations. Our study provides evidence of the costs and benefits to women's direct fitness of co-residing with different kin, against a backdrop of adaptive responses to cultural constraints on completed fertility.
人类表现出广泛的婚后居住模式，越来越多的人认识到婚后居住可以预测女性的生殖成功；然而，这种关系的性质可能取决于同居亲属是合作者还是竞争者。在这里，我们在一个藏族人群中探索了这种关系，在这个人群中，夫妻实行混合的婚后居住模式，与妻子的父母、丈夫的父母或与双方父母在同一个村庄居住。我们利用来自 17 个村庄的详细人口统计数据发现，与只有自己父母居住的女性相比，只与自己公婆居住的女性初育年龄（AFB）和最后生育年龄（ALB）更早。与双方父母共同居住的女性初育年龄和最后生育年龄最早。然而，那些与年长的兄弟姐妹共同居住的女性则推迟了生育，这表明存在与竞争相关的延迟。与计划生育政策的实施有关的生育时间提前的转变也与费希尔的预期一致。我们的研究提供了证据，证明了女性与不同亲属同居对其直接适合度的成本和收益，这是对完成生育能力的文化限制的适应性反应的背景下得出的。
