Doctoral Dissertation Research: Weaned Age Variation and Trace Element Distributions in Primate Teeth

对于我们的人类祖先来说，更早断奶可能有助于更高的繁殖成功率和人口增长。然而，这种适应性转变的进化背景尚不完全清楚，部分原因在于从化石记录中获取断奶证据的方法限制。这个博士论文项目将分析保存在野生山地大猩猩牙齿中的化学特征，以确定这些特征与断奶和社会生态因素之间的关系。这个项目的发现可以作为将这种方法应用于人类化石记录的基础。该项目将包括对学生的科学培训和指导，包括来自STEM领域中代表性不足的群体的个人。它还将加强研究合作，支持公共科学宣传和教育，并为正在进行的灵长类动物保护工作提供信息。研究人员将测试一种正在开发的方法，该方法通过牙齿中钙标准化锶和钡的分布来重建生命早期饮食转变的时间，并调查来自卢旺达火山国家公园的维龙加山地大猩猩的一个完整记录的野生种群的断奶年龄变化。研究山地大猩猩食物资源的化学特征，为解释其牙釉质和牙本质中钡、锶强度的变化提供依据。根据微量元素分析估计的断奶年龄将与野生山地大猩猩饮食和哺乳的纵向记录进行比较。将解决以下问题：1)牙齿中的微量元素分布与哺乳行为观察和确定断奶年龄的其他指标（例如，出生间隔）的对应程度如何？2)在野生山地大猩猩种群中，断奶的化学特征是如何变化的？从这一人群中收集个体的行为和化学数据的能力代表了一个独特的机会，可以测试一种新兴的方法，以恢复人类化石记录中相对高分辨率的断奶证据。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

For our human ancestors, a shift toward earlier age at weaning may have contributed to higher reproductive success and population growth. However, the evolutionary context of this adaptive shift is not fully understood, in part because of methodological constraints in obtaining evidence of weaning from the fossil record. This doctoral dissertation project will analyze chemical signatures preserved in the teeth of wild mountain gorillas to determine how those signatures may be related to weaning and socioecological factors. Findings from this project could then serve as a foundation for applying this approach to the human fossil record. This project will include scientific training and mentorship of students, including individuals from groups underrepresented in STEM fields. It will also bolster research collaborations, support public science outreach and education, and inform ongoing primate conservation efforts. The investigators will test a developing method for reconstructing the timing of early-life dietary transitions from the distribution of calcium-normalized strontium and barium intensities in teeth, and to investigate weaning age variation within a single well-documented wild population of Virunga mountain gorillas from Volcanoes National Park in Rwanda. The chemical signature of mountain gorilla food resources will be characterized in order to provide a context for interpreting variation in enamel and dentine barium and strontium intensities. Estimated weaned age from trace element analysis will then be compared to longitudinal records on wild mountain gorilla diet and suckling. The following questions will be addressed: 1) How well do trace element distributions in teeth correspond to behavioral observations of suckling and other metrics for determining weaning age (e.g., interbirth interval)? and 2) How does the weaning chemical signature vary within a wild mountain gorilla population? The ability to partner behavioral and chemical data from individuals in this population represents a unique opportunity to test an emerging methodology for recovering relatively high resolution evidence of weaning in the human fossil record.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.