Social influences on aging in a wild cooperative mammal

生物和医学科学研究的一个关键目标是理解为什么人口中有些人健康地进入老年，而另一些人则迅速衰退并过早死亡。对果蝇和小鼠等模型实验室生物的研究表明，随着年龄的增长，身体功能下降的速度，或衰老的速度，将取决于个体在整个生命周期中如何分配资源用于生存与繁殖，以及生长和发育过程中可用资源的数量和质量。在高度社会化或合作的动物中，这两个因素都强烈依赖于个体的社会地位及其与其他群体成员的互动。我们的研究将首次测试这些社会因素对一种高度社会化的哺乳动物——带状猫鼬的衰老率和生理衰老的影响，使用长期数据分析、行为实验和衰老的生理测量相结合。具体而言，我们将解决以下问题：(1)个人属性和社会因素（如帮助努力、主导地位和群体结构）的变化如何影响男性和女性的衰老率；(2)这些因素如何影响氧化应激的测量水平，氧化应激被认为是生理衰老的标志；(3)在发展过程中所获得的社会投资的变化如何影响成人的生存和状况？我们将通过大规模的野外实验来解决最后一个问题，在实验中，我们为幼崽提供生长所需的营养物质或抗氧化剂，以测试对成年状态、繁殖性能和氧化应激水平的下游影响。这项研究将产生重要的新信息，以了解影响社会脊椎动物自然种群变异、死亡率和生育力的主要因素，以及自然选择如何塑造生活在紧密家庭群体中的长寿动物的生活史进化，其中可能包括祖先人类。此外，我们的工作将为自然哺乳动物种群衰老的机制解释提供第一个测试，并为早期生活对成年健康特征的影响提供第一个实验测试。这些研究有望促进我们对进化过程和衰老的直接原因的理解。

A key goal of research in biological and medical science is to understand why some individuals in a population remain healthy into old age, whereas others decline rapidly and die early. Research on model laboratory organisms such as fruit flies and mice suggests that the rate of decline in bodily function with age, or the rate of senescence, will depend on how individuals allocate resources to survival versus reproduction across the lifespan, and on the quantity and quality of resources available during growth and development. In highly social or cooperative animals, both these factors are strongly dependent on an individual's social status and its interactions with other group members. Our research will test for the first time the influence of these social factors on rates of aging and physiological senescence in a highly social, mammal, the banded mongoose, using a combination of long-term data analysis, behavioural experiments and physiological measures of senescence. Specifically we will address questions: (1) how does variation in individual attributes and social factors (such as helping effort, dominance status, and group structure) influence rates of aging in males and females; (2) how do these factors influence measured levels of oxidative stress, a suggested marker of physiological senescence; and (3) how does variation in social investment received during development influence adult survival and condition? We will address the last question using a large-scale field experiment in which we provision pups with nutrients for growth or with antioxidants to test for downstream effects on adult condition, reproductive performance, and levels of oxidative stress. The research will generate important new information on the main factors influencing variation and mortality and fertility in natural populations of social vertebrates, and how natural selection shapes the evolution of life history in long-lived animals living in close-knit family groups, including, potentially, ancestral humans. In addition, our work will provide the first test of mechanistic explanations of senescence in a natural mammal population, and the first experimental test of early-life effects on adult fitness traits. These investigations promise to advance our understanding of the evolutionary processes and proximate causes of aging.