Reproductive conflict and the separation of reproductive generations in humans
Reproductive conflict and the separation of reproductive generations in humans
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DOI：
10.1073/pnas.0711911105
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发表时间：
2008-04-08
影响因子：
11.1
通讯作者：
Johnstone, Rufus A.
中科院分区：
文献类型：
--
作者：
Cant, Michael A.;Johnstone, Rufus A.
人类生活史上一个持久的谜题是，为什么女性在中年停止生育。选择有利于繁殖后的生存，因为年长的雌性可以帮助它们的后代繁殖。但是，亲人选择的帮助健康的收益似乎不足以超过继续繁殖的潜在好处。那么，为什么女性一开始就停止生育呢？在这里，我们认为人类提前停止生殖是几代人之间生殖竞争的结果，我们提出了一个如何解决这种竞争的简单候选模型。我们表明，在表现出生殖后寿命的灵长类动物中，人类在世代之间表现出极低程度的生殖重叠。人类女性生殖系统的迅速衰老恰逢在自然生育人口中，妇女预计将面临来自下一代繁殖雌性的生殖竞争的年龄。有几条证据表明，在祖先原始人中，年轻一代通常由移民女性组成。在这种情况下，预计家庭内部的亲缘关系不对称将使年轻女性在与年长女性的生育冲突中获得决定性优势。一个既考虑了生育竞争的代价，又考虑了当奶奶的好处的模型，可以解释人类停止生殖的时间，因此可以更好地理解更年期的演变。
An enduring puzzle of human life history is why women cease reproduction midway through life. Selection can favor postreproductive survival because older females can help their offspring to reproduce. But the kin-selected fitness gains of helping appear insufficient to outweigh the potential benefits of continued reproduction. Why then do women cease reproduction in the first place? Here, we suggest that early reproductive cessation in humans is the outcome of reproductive competition between generations, and we present a simple candidate model of how this competition will be resolved. We show that among primates exhibiting a postreproductive life span, humans exhibit an extraordinarily low degree of reproductive overlap between generations. The rapid senescence of the human female reproductive system coincides with the age at which, in natural fertility populations, women are expected to encounter reproductive competition from breeding females of the next generation. Several lines of evidence suggest that in ancestral hominids, this younger generation typically comprised immigrant females. In these circumstances, relatedness asymmetries within families are predicted to give younger females a decisive advantage in reproductive conflict with older females. A model incorporating both the costs of reproductive competition and the benefits of grandmothering can account for the timing of reproductive cessation in humans and so offers an improved understanding of the evolution of menopause.