Madrigal Lorena, Meléndez-Obando Mauricio
Department of Anthropology, University of South Florida, Tampa, FL 33617, USA.
Am J Phys Anthropol. 2008 Jun;136(2):223-9. doi: 10.1002/ajpa.20798.
The evolution of postmenopausal longevity in human females has been the subject of debate. Specifically, there is disagreement about whether the evolution of the trait should be understood as an adaptive or a neutral process, and if the former, what the selective mechanism is. There are two main adaptive proposals to explain the evolution of postreproductive longevity: the grandmother and the mother hypotheses. The grandmother hypothesis proposes that postreproductive longevity evolved because it is selectively advantageous for females to stop reproducing and to help raise their grandchildren. The mother hypothesis states that postmenopausal longevity evolved because it is advantageous for women to cease reproduction and concentrate their resources and energy in raising the children already produced. In this article, we test the mother and the grandmother hypotheses with a historical data set from which we bootstrapped random samples of women from different families who lived from the 1500s to the 1900s in the central valley of Costa Rica. We also compute the heritability of longevity, which allows us to determine if genes involved in longevity are nearly fixed in this population. Here we show that although longevity positively affects a woman's fertility, it negatively affects her daughter's fertility; for this reason, the heritability of longevity is unexpectedly high. Our data provide strong grounds for questioning the universality of the grandmother hypothesis and for supporting the mother hypothesis as a likely explanation for the evolution of human postreproductive longevity.
人类女性绝经后长寿的演变一直是争论的焦点。具体而言，对于该特征的演变应被理解为适应性过程还是中性过程，以及如果是前者，其选择机制是什么，存在不同意见。有两种主要的适应性观点来解释生殖后长寿的演变：祖母假说和母亲假说。祖母假说认为，生殖后长寿的进化是因为女性停止生育并帮助抚养孙辈具有选择优势。母亲假说指出，绝经后长寿的进化是因为女性停止生育并将资源和精力集中在抚养已生育的子女上是有利的。在本文中，我们使用一个历史数据集对母亲假说和祖母假说进行了检验，我们从该数据集中对15世纪至19世纪生活在哥斯达黎加中央山谷不同家庭的女性进行了随机抽样自展。我们还计算了长寿的遗传力，这使我们能够确定与长寿相关的基因在该人群中是否几乎固定。我们在此表明，虽然长寿对女性的生育能力有积极影响，但对其女儿的生育能力有负面影响；因此，长寿的遗传力出乎意料地高。我们的数据为质疑祖母假说的普遍性以及支持母亲假说作为人类生殖后长寿演变的一种可能解释提供了有力依据。
