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出来的，包括我们断奶的早期、儿童生长缓慢的长时期和首次繁殖的较晚年龄。我们生命历史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。我们现存的近亲——类人猿，为研究人类的生活史进化提供了重要的比较，但目前对它们身体发育模式的了解，绝大多数还是来自圈养研究和黑猩猩。本项目采用非侵入性方法对两个长期研究的野生大猩猩种群进行生长发育研究，这两个种群的现有数据很少。这项研究的结果将极大地促进我们对比较类人猿发展的理解，并将批判性地告知有关现代人类生活史进化起源的基本问题。此外，这项研究将为多个学科的研究人员提供一个有价值的新数据集，并为灵长类动物保护、学生培训、研究基础设施和国际合作提供重要支持。本研究采用一种新颖的非侵入性方法组合，将形态学、生理学和行为学数据整合在一起，以全面了解在不同生态的野生大猩猩种群内部和种群之间，观察到的生活史和社会生态学差异与生理个体发生变化的相互作用方式。Karisoke山地大猩猩(N=115；0-18岁，N=80，基于当前人口统计学)包括形态生长和发育的测量（牙齿出现，线性身体尺寸，通过尿肌酐获得的肌肉质量），母亲和后代的能量和饮食（尿c肽，哺乳率和持续时间，饮食组成和营养成分），母亲的优势地位和胎次，以及其他行为测量（例如活动预算，每日旅行距离）和健康。这些数据将与从该地点自然积累的骨骼样本中确定的牙齿和躯体生长测量相结合。西部低地野生大猩猩的形态和行为比较数据来自刚果共和国Mbeli Bai研究（N=140； 0-18岁，N=50）。该项目旨在：1)首次提供已知年龄野生山地大猩猩身体发育的数据，验证影响山地大猩猩和西部大猩猩发育和生活史差异的社会生态因素；2)考察母性能量、营养等对山地大猩猩子代牙体发育变异的影响；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；4)测试从骨骼遗骸中评估的发育里程碑的时间是否与从同一种群的幸存成员中确定的时间有显著差异。研究结果将使我们更全面地了解亲缘关系密切的类人猿类群中牙齿、躯体、生殖和行为里程碑是如何以及为什么共同变化的，并揭示生命史中的个体差异是如何由后代生长介导的，从而提高我们对个体发生变异的生殖（以及进化）结果的理解。此外，通过生成这些现存种群的发育和生活史的综合模型，并从相关的骨骼组合中测试我们的生活史推断的准确性，我们的结果有望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.