Maternal longevity and the sex of offspring in pre-industrial Sweden
Maternal longevity and the sex of offspring in pre-industrial Sweden
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DOI：
10.1080/03014460701517215
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发表时间：
2007-01-01
影响因子：
1.7
通讯作者：
Wallace, Bjorn
中科院分区：
文献类型：
--
作者：
Cesarini, David;Lindqvist, Erik;Wallace, Bjorn
背景：Helle等人（2000）。在工业化前的人类中，儿子缩短了母亲的寿命。《科学》（Science）杂志，296,1985)认为，在前工业社会，生儿子会降低母亲的寿命，因为生儿子的生理成本更高，而且在生男孩的母亲身上观察到睾丸激素水平升高。目的：本研究使用更全面的数据集检验了这一假设，并评估了以前研究中使用的统计方法的优点，以确定在母亲老年寿命方面生儿子的成本。研究对象和方法：Helle et al.（2002）的分析。在工业化前的人类中，儿子缩短了母亲的寿命。科学296,1085)通过使用一个相当大的前工业化瑞典妇女数据集进行扩展，并仔细考虑了样本选择的方法问题和省略变量偏差。我们认为，以前的文献低估了由于未观察到的健康异质性，量化平价和寿命之间权衡的困难。然而，在限制较少的假设下，人们可以估计出儿子对固定家庭规模的边际影响。结果：没有证据表明生儿子会有负面的相对影响。尽管研究人群很贫穷，但也没有发现任何证据支持文献中其他地方提出的男性偏向的家庭内部资源竞争假说。这些结果在广泛的规格测试中是可靠的。结论：未能重现早期的发现，而且这一研究领域的研究似乎继续产生相互矛盾的结果，因此在讨论和评估结果时要非常谨慎。很可能，儿子的负面影响，如果存在的话，只是在尚未完全了解的条件下表现出来。我们还认为，之前关于这一主题的文献并没有充分认识到与省略变量偏差和样本选择相关的推理问题。
Background: Helle et al. (2000. Sons reduced maternal longevity in preindustrial humans. Science, 296, 1085) argued that giving birth to sons reduced maternal longevity in pre-industrial societies due to higher physiological costs of bearing sons and the elevated testosterone levels observed in mothers carrying male foetuses.Aim: The present study examined this hypothesis using a more comprehensive dataset and evaluated the merits of the statistical approach used in previous studies to identify the cost of giving birth to sons in terms of maternal old-age longevity.Subjects and methods: The analysis in Helle et al. (2002. Sons reduced maternal longevity in preindustrial humans. Science 296, 1085) was extended by using a considerably larger dataset of preindustrial Swedish women, and with careful consideration paid to methodological problems of sample selection and omitted variable bias. We argue that the previous literature has underestimated the difficulties in quantifying the trade-off between parity and longevity due to unobserved heterogeneity in health. However, under less restrictive assumptions, one can estimate the marginal impact of a son for a fixed family size.Results: No evidence was found of a negative relative impact of sons. Neither was any evidence found in favour of the male-biased intra-household resource competition hypothesis proposed elsewhere in the literature, despite the poverty of the study population. These results are robust to a wide range of specifications tested.Conclusion: The failure to reproduce earlier findings and the fact that studies in this area of research seem to continue to yield conflicting results warrant much caution in discussing and evaluating results. It is likely that the negative effect of sons, if it existed, only manifested itself under conditions that are not yet fully understood. We also argue that the previous literature on this topic has not fully acknowledged the inference problems associated with omitted variable bias and sample selection.