Doctoral Dissertation Improvement Grant: Experimental Determination of Tooth Mineralization Patterns in Ungulates for Application to Paleoseasonality Reconstruction

博士论文改进资助：有蹄类动物牙齿矿化模式的实验测定，用于古季节性重建

• 批准号: 1247426
• 负责人: Tanya Smith
• 金额: $ 3.36万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-12-15 至 2014-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1247426&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Improvement; Grant; Experimental

Scholars have been debating the conditions that led to the evolution of humans' large brains and unique behaviors, including complex stone tool use and language, for more than a century. One influential theory proposes that these features emerged in response to seasonal resource availability in Africa over the last five million years. Geological and paleontological data suggest that changing rainfall patterns might have produced more arid African ecosystems and novel foraging behaviors, although approaches for documenting ancient precipitation patterns remain rudimentary. Under the direction of Dr. Tanya Smith, Daniel Green aims to improve methods of seasonal reconstruction with new laboratory techniques and experimentation, facilitating research on ancient climate change during key periods in human evolution.Climatic patterns may be reconstructed through chemical analysis of teeth, which record environmental chemistry during formation and remain unchanged after death and fossilization. Tooth increments, analogous to rings in trees, form every day during childhood from ingested minerals that are in equilibrium with local water sources. As seasons pass, the composition of isotopes (atomic variants) change, and teeth record these changes. Importantly, isotopes in teeth record seasonal changes that can be related to time markers, facilitating precise estimates of environmental change. This project will improve climate reconstruction by precisely mapping the geometry and timing of tooth mineralization. A combination of cutting-edge synchrotron imaging and scanning electron microscopy of developing sheep teeth will yield mineral density change over time. This project then tests these results using animals subject to an isotopic water switch, experimentally demonstrating the relationship between tooth chemistry and changes in water that approximates seasonal variation.Ultimately, a concrete understanding of how environmentally sensitive minerals are added to teeth will improve seasonal reconstruction, and will allow one to investigate if marked climatic change accompanied the development of unique human anatomy and behaviors. This project will train graduate and undergraduate students, and enhance collaborations with scholars in Europe and Africa. Results of this research will be broadly disseminated in professional journals and meetings, and presented to public audiences.

一个多世纪以来，学者们一直在争论导致人类大大脑和独特行为（包括复杂的石器使用和语言）进化的条件。一种有影响力的理论认为，这些特征的出现是为了应对过去五百万年非洲的季节性资源可用性。地质和古生物学数据表明，降雨模式的变化可能产生了更加干旱的非洲生态系统和新的觅食行为，尽管记录古代降水模式的方法仍然很初级。在 Tanya Smith 博士的指导下，Daniel Green 旨在通过新的实验室技术和实验改进季节性重建方法，促进对人类进化关键时期古代气候变化的研究。气候模式可以通过牙齿的化学分析来重建，牙齿记录了形成过程中的环境化学，并在死亡和石化后保持不变。牙齿的生长，类似于树木的年轮，是在童年时期每天通过摄入与当地水源保持平衡的矿物质而形成的。随着季节的流逝，同位素（原子变体）的组成发生变化，牙齿记录了这些变化。重要的是，牙齿中的同位素记录了与时间标记相关的季节变化，有助于精确估计环境变化。该项目将通过精确绘制牙齿矿化的几何形状和时间来改善气候重建。将尖端同步加速器成像和发育中的羊牙齿的扫描电子显微镜相结合，将产生矿物质密度随时间的变化。然后，该项目使用接受同位素水转换的动物测试这些结果，通过实验证明牙齿化学与近似季节性变化的水变化之间的关系。最终，对如何将环境敏感矿物质添加到牙齿中的具体了解将改善季节性重建，并使人们能够调查显着的气候变化是否伴随着独特的人体解剖学和行为的发展。该项目将培训研究生和本科生，并加强与欧洲和非洲学者的合作。这项研究的结果将在专业期刊和会议上广泛传播，并向公众展示。