Yerkes National Primate Research Center, Emory University, Atlanta, Ga 30329, USA.
Gerontology. 2010;56(1):73-9. doi: 10.1159/000236045. Epub 2009 Sep 3.
Women experience more years of vigorous life after ovulation has ceased than do females of other primate species. Is this an epiphenomenon of the greater life expectancy humans have enjoyed in the past century or so, or is long post-menopausal survival the result of an evolutionary selection process? Recent research implies the latter: Long post-menopausal survival came about through natural selection. One prominent line of thought explaining this selection process is the grandmother hypothesis.
To evaluate the implications of the hypothesis for non-human primate studies of aging and cognition.
The author presents a synopsis of the hypothesis, evaluates the uniqueness of the 'grandmother effect' to humans, and discusses its implications for non-human primate models of cognitive aging.
The hypothesis contends that, in past epochs, women who remained vigorous beyond their fertile years may have enhanced their reproductive success by providing care for their grandchildren. This care would have enabled their daughters to resume reproduction sooner, endowing them with greater lifetime fertility. Genes of grandmothers possessing such old-age vigor would be more likely to persist in subsequent generations. Is midlife menopause a uniquely human phenomenon, or does the chimpanzee, our closest primate relative, also display this trait? If so, we might expect a grandmother effect in this species as well. However, female chimpanzees continue to cycle until near the end of their maximum life span of about 60 years.
Long survival beyond fertility and a long life expectancy are distinctive human adaptations. The robustness of ancestral human grandmothers necessarily included resistance to cognitive decline through preservation of functions present in many primates but also development of processes of social cognition unique to our species. Cognitive traits such as language and social cognitive functions may function in our species in particular as mechanisms to compensate for age-related decline. This has significant implications for research in which non-human primates are considered as models of human cognitive aging; it also means that some processes can be studied only in humans.
与其他灵长类动物相比，女性在绝经后仍能拥有更多年的活跃期。这是过去一个多世纪人类寿命延长带来的附带现象，还是绝经后长寿是进化选择的结果？最近的研究表明，后一种情况居多：绝经后长寿是自然选择的结果。有一个突出的观点认为，这种选择过程与祖母假说有关。
评估该假说对衰老和认知的非人类灵长类动物研究的影响。
作者介绍了该假说的概要，评估了“祖母效应”对人类的独特性，并讨论了其对非人类灵长类动物认知衰老模型的影响。
该假说认为，在过去的时代，那些在生育期后仍然保持活力的女性可能通过照顾孙辈来提高自己的生殖成功率。这种照顾使她们的女儿能够更早地恢复生育，从而使她们拥有更大的终身生育能力。具有这种老年活力的祖母的基因更有可能在后代中延续。绝经是人类独有的现象，还是我们最接近的灵长类近亲黑猩猩也有这种特征？如果是这样，我们可能也会在这个物种中看到祖母效应。然而，雌性黑猩猩在接近其 60 岁左右的最大寿命结束前仍在循环。
绝经后长寿和预期寿命长是人类独特的适应。远古人类祖母的活力必然包括通过保留许多灵长类动物共有的功能来抵抗认知能力下降，以及发展出我们人类特有的社会认知过程。语言和社会认知等认知特征可能在我们的物种中具有特定的功能，作为补偿与年龄相关的衰退的机制。这对将非人类灵长类动物视为人类认知衰老模型的研究具有重要意义；这也意味着有些过程只能在人类中进行研究。
