Department of Functional Ecology, Alfred Wegner Institute for Polar and Marine Research, Bremerhaven, Germany.
Gerontology. 2013;59(3):261-6. doi: 10.1159/000345331. Epub 2012 Dec 18.
Longevity and ageing are two sides of a coin, leaving the question open as to which one is the cause and which one the effect. At the individual level, the physiological rate of ageing determines the length of life (= individual longevity, as long as death results from old age and not from disease or other impacts). Individual longevity depends on the direct influence of environmental conditions with respect to nutrition, and the possibility for and timing of reproduction, as well as on the energetic costs animals invest in behavioural and physiological stress defence. All these environmental effectors influence hormonal and cellular signalling pathways that modify the individual physiological condition, the reproductive strategy, and the rate of ageing. At the species level, longevity (= maximum lifespan) is the result of an evolutionary process and, thus, largely determined by the species' behavioural and physiological adaptations to its ecological niche. Specifically, reproductive and breeding strategies have to be optimized in relation to local environmental conditions in different habitats. As a result of adaptive and evolutionary processes, species longevity is genetically underpinned, not necessarily by a few ageing genes, but by an evolutionary process that has hierarchically shaped and optimized species genomes to function in a specific niche or environmental system. Importantly, investigations and reviews attempting to unravel the mechanistic basis of the ageing process need to differentiate clearly between the evolutionary process shaping longevity at the species level and the regulatory mechanisms that alter the individual rate of ageing.
长寿和衰老犹如一枚硬币的两面，究竟是哪一个是因，哪一个是果，尚无定论。从个体水平来看，衰老的生理速度决定了寿命的长短（只要死亡是由衰老引起，而不是由疾病或其他因素引起）。个体的寿命取决于环境条件对营养的直接影响，以及繁殖的可能性和时机，还取决于动物在行为和生理应激防御方面投入的能量成本。所有这些环境影响因素都影响着激素和细胞信号通路，从而改变个体的生理状况、生殖策略和衰老速度。在物种水平上，长寿（最大寿命）是进化过程的结果，因此在很大程度上取决于物种对其生态位的行为和生理适应。具体而言，繁殖和繁殖策略必须针对不同栖息地的当地环境条件进行优化。由于适应和进化过程，物种的长寿是由遗传决定的，不一定是由少数衰老基因决定，而是由一个进化过程决定的，这个进化过程分层塑造和优化了物种基因组，使其在特定的小生境或环境系统中发挥功能。重要的是，试图揭示衰老过程的机制基础的研究和综述需要清楚地区分塑造物种长寿的进化过程和改变个体衰老速度的调节机制。
