Graves J L
Department of Ecology and Evolutionary Biology, School of Biological Sciences, University of California, Irvine 92717.
Growth Dev Aging. 1993 Winter;57(4):233-49.
Dietary restriction increases life span in mammals. This essay connects the dietary restriction response to evolutionary life history theory and experiments related to it. Evolutionary biologists have shown mathematically that aging is an inevitable consequence of age-specific natural selection acting on species with somata separate from germ lines. Empirical tests of this prediction currently point to its general validity. Two specific genetic mechanisms are known which could underlie the evolution of aging under these conditions: age-specificity of gene effects and antagonistic pleiotropy between early and late ages. The antagonistic pleiotropy theory assumes that some genes with beneficial effects on early life fitness will have deleterious effects upon fitness in later life. Experimental work in insects, particularly selection experiments in Drosophila melanogaster, has tested these ideas. The negative genetic correlation between longevity and reproductive effort produced by selection has been shown to be paralleled, in some cases, by environmental manipulation. Thus the increase in life span caused by dietary restriction might be explained as an incidental consequence of lower reproductive effort. This response also could have been an adaptation that enhanced fitness in some species that faced uncertain food supplies, a condition that may have evolved independently in a wide variety of taxa. Several schools of research, besides that of the evolutionary biologists concerned with genetic correlations, have produced corroborations of this hypothesis in insects and mammals: the gerontological work on life span extension, reproductive physiologists concerned with factors that affect fertility, and various life history studies.
饮食限制可延长哺乳动物的寿命。本文将饮食限制反应与进化生命史理论及其相关实验联系起来。进化生物学家已通过数学证明，衰老对于体细胞与生殖细胞分离的物种而言，是年龄特异性自然选择的必然结果。目前，对这一预测的实证检验表明其普遍有效。已知有两种特定的遗传机制可能是这些条件下衰老进化的基础：基因效应的年龄特异性以及早期和晚期之间的拮抗多效性。拮抗多效性理论认为，一些对早期生命适应性有有益影响的基因，在后期生命中会对适应性产生有害影响。昆虫方面的实验工作，特别是黑腹果蝇的选择实验，已经对这些观点进行了检验。通过选择产生的寿命与繁殖力之间的负遗传相关性，在某些情况下已被证明与环境操纵情况相似。因此，饮食限制导致的寿命延长可能被解释为较低繁殖力的附带结果。这种反应也可能是一种适应性变化，它提高了一些面临不确定食物供应的物种的适应性，这种情况可能在广泛的分类群中独立进化。除了关注遗传相关性的进化生物学家之外，还有几个研究学派在昆虫和哺乳动物中证实了这一假设：关于寿命延长的老年学研究、关注影响生育力因素的生殖生理学家以及各种生命史研究。
