Socioecological factors and patterns of growth and development in two gorilla species

人类进化研究的一个核心挑战是了解现代人类生活史的独特特征是何时、如何以及在什么样的社会和生态背景下进化的，包括我们断奶的早期年龄、长期缓慢的儿童生长期和第一次繁殖的晚期年龄。 我们生活史中的这些关键要素被认为是人类认知和行为进化的关键转变的基础。 我们的近亲，类人猿，为研究人类生活史进化提供了重要的比较，但目前关于它们身体生长模式的知识绝大多数仍然来自圈养研究和黑猩猩。该项目使用非侵入性方法研究两个长期研究野生大猩猩种群的生长和发育，现有数据很少。这项研究的结果将大大推进我们对类人猿比较发展的理解，并将为现代人类生活史进化起源的基本问题提供重要信息。 此外，该研究将产生一个有价值的新数据集，供多个学科的研究人员使用，并支持灵长类动物保护、学生培训、研究基础设施和国际合作方面的重要努力。这项研究采用了一种新的组合的非侵入性的方法来整合形态，生理和行为数据，以产生一个全面的了解的方式，观察到的生活史和社会生态学的差异与变化的物理个体发育内和生态不同的野生大猩猩种群之间的相互作用。从Karisoke山地大猩猩收集的数据（N=115; 0-18岁，基于当前人口统计学，N=80）包括形态生长和发育指标（牙齿出现，线性身体尺寸，通过尿肌酐的肌肉质量），母体和后代能量学和饮食（尿C-肽，哺乳率和分娩持续时间，饮食组成和营养成分），母体优势地位和产次，以及其他行为指标（例如，活动预算、每日旅行距离）和健康。这些数据将与从该研究中心自然积累的骨骼样本中确定的牙齿和躯体生长测量结果相结合。 野生西部低地大猩猩的比较形态和行为数据来自刚果共和国的Mbeli Bai研究（N=140; 0-18岁，N=50）。 该项目旨在：1）提供已知年龄的野生山地大猩猩身体个体发育的第一个数据，并测试影响山地大猩猩和西部大猩猩之间发育和生活史变化的假设社会生态因素; 2）测试母体能量、营养和其他对山地大猩猩后代牙齿和身体发育变化的影响; 3）检验山地大猩猩形态发育指标与关键行为和生殖生活史指标之间的关系;以及4）测试从骨骼遗骸评估的发育里程碑的时间是否与从相同群体的存活成员确定的时间显著不同。 结果将产生一个更全面的了解如何以及为什么牙齿，躯体，生殖和行为的里程碑在密切相关的类人猿类群的共同变化，并通过阐明如何在生活史中的个体变异可能介导的后代的生长，提高我们的理解生殖（因此，进化）个体发育变异的结果。 此外，通过生成这些现存种群的发育和生活史的综合模型，并测试我们从相关骨骼组合中推断生活史的准确性，我们的结果预计将为在化石背景下研究生活史的方法提供重要信息。

A central challenge in human evolutionary studies is to understand when, how and in what social and ecological context unique features of modern human life history evolved, including our early age at weaning, prolonged period of slow childhood growth, and late age at first reproduction. These key elements of our life histories are proposed underlie key shifts in human cognitive and behavioral evolution. Our closest living relatives, the great apes, provide critical comparisons for investigating human life history evolution, but current knowledge of their physical growth patterns remains overwhelmingly derived from captive studies and from chimpanzees. This project uses non-invasive methods to study growth and development in two long-term study populations of wild gorillas, for which there are very few existing data. The outcome of this research will significantly advance our understanding of comparative great ape development and will critically inform fundamental questions about the evolutionary origins of modern human life history. In addition, the research will result in a valuable new dataset of interest to researchers across several disciplines, and support important efforts in primate conservation, student training, research infrastructure, and international collaboration. This research employs a novel combination of non-invasive methods to integrate morphological, physiological, and behavioral data to generate a comprehensive understanding of the manner in which observed differences in life history and socioecology interact with variation in physical ontogeny within and among ecologically distinct populations of wild gorillas. Data to be collected from Karisoke mountain gorillas (N=115; 0-18 years, N=80 based on current demographics) include measures of morphological growth and development (dental emergence, linear body dimensions, muscle mass via urinary creatinine), maternal and offspring energetics and diet (urinary C-peptide, suckling rate and bout duration, diet composition and nutritional content), maternal dominance status and parity, and other measures of behavior (e.g., activity budgets, daily travel distance) and health. These data will be partnered with measures of dental and somatic growth determined from a naturally accumulated skeletal sample at this site. Comparative morphological and behavioral data for wild western lowland gorillas are from the Mbeli Bai Study, Republic of Congo (N=140; 0-18 years, N=50). The project aims to: 1) provide the first data on physical ontogeny in wild mountain gorillas of known age, and test hypothesized socioecological factors influencing variation in development and life history between mountain and western gorillas; 2) test maternal energetics, nutrition and other effects on variation in offspring dental and somatic development within mountain gorillas; 3) test relationships between measures of morphological development and key behavioral and reproductive life history measures in mountain gorillas; and 4) test whether the timing of developmental milestones assessed from skeletal remains differs significantly from those determined from surviving members of the same population. Results will yield a more comprehensive understanding of how and why dental, somatic, reproductive, and behavioral milestones co-vary in closely-related great ape taxa, and by shedding light on how individual variability in life history may be mediated by offspring growth, improve our understanding of reproductive (and thus, evolutionary) outcomes of ontogenetic variation. Further, by generating a comprehensive model of development and life history in these extant populations, and testing the accuracy of our life history inferences from an associated skeletal assemblage, our results are expected to significantly inform approaches to studying life history in fossil contexts.