Social influences on aging in a wild cooperative mammal

生物和医学研究的一个关键目标是了解为什么一个群体中的一些人在老年时保持健康，而另一些人则迅速衰退和过早死亡。对果蝇和老鼠等模拟实验室生物的研究表明，身体机能随年龄下降的速度，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和繁殖，以及生长和发育期间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人的社会地位及其与其他群体成员的互动。我们的研究将使用长期数据分析、行为实验和衰老生理测量相结合的方法，首次测试这些社会因素对高度社会化的哺乳动物-带状猫鼬衰老速度和生理衰老的影响。具体来说，我们将解决以下问题：(1)个人属性和社会因素(如帮助努力、优势地位和群体结构)的变化如何影响男性和女性的老龄化速度；(2)这些因素如何影响氧化应激的测量水平，氧化应激是生理衰老的标记物；以及(3)在发育过程中接受的社会投资的变化如何影响成年人的生存和状况？我们将通过一个大规模的野外实验来解决最后一个问题，在这个实验中，我们为幼崽提供生长所需的营养物质或抗氧化剂，以测试下游对成年条件、繁殖性能和氧化应激水平的影响。这项研究将产生重要的新信息，涉及影响群居脊椎动物自然种群变异、死亡率和生育力的主要因素，以及自然选择如何影响生活在紧密家族群体中的长寿动物的生活史进化，包括潜在的祖先人类。此外，我们的工作将提供第一个关于自然哺乳动物种群衰老的机制解释的测试，以及第一个关于早期生命对成人健康特征影响的实验测试。这些研究有望促进我们对衰老的进化过程和直接原因的理解。

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.