Department of Psychology, University of Michigan, Ann Arbor, MI, USA.
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA.
Mol Ecol. 2017 Jun;26(12):3090-3092. doi: 10.1111/mec.14129.
There is tremendous diversity in ageing rates and lifespan not only among taxa but within species, and particularly between the sexes. Women often live longer than men, and considerable research on this topic has revealed some of the potential biological, psychological and cultural causes of sex differences in human ageing and lifespan. However, sex differences in lifespan are widespread in nonhuman animals suggesting biology plays a prominent role in variation in ageing and lifespan. Recently, evolutionary biologists have borrowed techniques from biomedicine to identify whether similar mechanisms causing or contributing to variation in ageing and lifespan in humans and laboratory animals also operate in wild animals. Telomeres are repetitive noncoding DNA sequences capping the ends of chromosomes that are important for chromosomal stability but that can shorten during normal cell division and exposure to stress. Telomere shortening is hypothesized to directly contribute to the ageing process as once telomeres shorten to some length, the cells stop dividing and die. Men tend to have shorter telomeres and faster rates of telomere attrition with age than women, suggesting one possible biological cause of sex differences in lifespan. In this issue of Molecular Ecology, Watson et al. () show that telomere lengths in wild Soay sheep are similar between females and males near the beginning of life but quickly diverge with age because males but not females showed reduced telomere lengths at older ages. The authors further show that some of the observed sex difference in telomere lengths in old age may be due to male investment in horn growth earlier in life, suggesting that sexually dimorphic allocation to traits involved in sexual selection might underlie sex differences in telomere attrition. This study provides a rare example of how biological mechanisms potentially contributing to sex differences in lifespan in humans may also operate in free-living animals. However, future studies using a longitudinal approach are necessary to confirm these observations and identify the ultimate and proximate causes of any sex differences in telomere lengths. Collaborations between evolutionary biologists and gerontologists are especially needed to identify whether telomere lengths have a causal role in ageing, particularly in natural conditions, and whether this directly contributes to sex differences in lifespan.
衰老速度和寿命不仅在不同物种之间存在巨大差异，而且在同一物种内，尤其是在性别之间也存在巨大差异。女性通常比男性长寿，并且针对这一主题的大量研究揭示了导致人类衰老和寿命性别差异的一些潜在生物学、心理学和文化原因。然而，非人类动物的寿命性别差异广泛存在，这表明生物学在衰老和寿命的变化中起着突出的作用。最近，进化生物学家从生物医学中借鉴技术，以确定导致或促成人类和实验室动物衰老和寿命变化的类似机制是否也在野生动物中起作用。端粒是位于染色体末端的重复非编码 DNA 序列，对于染色体的稳定性很重要，但在正常细胞分裂和暴露于应激时会缩短。端粒缩短被假设直接导致衰老过程，因为一旦端粒缩短到一定长度，细胞停止分裂并死亡。与女性相比，男性的端粒较短，端粒随年龄的增长而磨损的速度也较快，这表明端粒长度的性别差异可能是寿命性别差异的一个潜在生物学原因。在本期《分子生态学》中，Watson 等人（）表明，在生命初期，野生斯澳羊的雌性和雄性的端粒长度相似，但随着年龄的增长迅速分化，因为雄性而不是雌性在老年时显示出端粒长度降低。作者进一步表明，老年时观察到的端粒长度的一些性别差异可能是由于雄性在生命早期对角生长的投资所致，这表明参与性选择的特征的性二态分配可能是端粒磨损性别差异的基础。这项研究提供了一个罕见的例子，说明可能导致人类寿命性别差异的生物学机制也可能在自由生活的动物中起作用。然而，未来使用纵向方法的研究是必要的，以确认这些观察结果，并确定端粒长度任何性别差异的最终和近端原因。进化生物学家和老年学家之间的合作尤为必要，以确定端粒长度是否在衰老中起因果作用，特别是在自然条件下，以及这是否直接导致寿命的性别差异。
