Hominids, geology, geochronology, and isotope ecology in the Omo-Turkana Basin, East Africa

人类的进化史具有广泛的学术和公共利益。 东非的奥莫-图尔卡纳盆地包含最连续的含人地层序列，因此对古人类学具有特殊重要性。 在这个盆地里，有许多关于人类进化的基本问题的答案，但要把答案拼凑起来，往往需要精确地确定化石和我们祖先的其他痕迹的年代。这些灰烬的地球化学“指纹”可以确定许多时间线，氩年代测定法被用来确定许多这些灰烬的年龄，从而确定人类化石的年龄。 盆地中广泛的暴露使这些喷发的顺序得以确定;反过来，这些喷发可以与东非的其他化石遗址相关联，并允许在某些时间间隔内详细比较遥远的遗址。 然后，这项研究将整理大量的灰烬，以确定人类进化的详细历史。 沿着这些灰烬的是记录气候和生态信息的土壤层;对土壤碳酸盐的稳定同位素研究将有助于对东非热带草原生态系统的发展进行全面研究，并可以在人类进化的背景下加以解释。 Omo-Turkana盆地和埃塞俄比亚Awash盆地的火山灰之间的详细相关性将允许对两个地区的生态系统进行比较，以回答两个地区是否以相同的方式行事。 对化石哺乳动物牙釉质的稳定同位素研究显示了某些食物的饮食选择和可用性;综合起来，它们可以用来确定该地区在过去400万年或更长时间内的古干旱。 因此，本研究将使用火山灰的相关性，这些灰烬的年代测定和同位素研究来了解伴随人类进化的气候和生态变化。 对Omo-Turkana和Awash地区的气候和生态事件进行比较将解决环境变化与人类进化之间的关系问题。 该项目将为美国、肯尼亚和埃塞俄比亚的学生和科学家提供培训。 它将为至少8名研究生和16名本科生提供研究机会;其中许多本科生将参加国际实地考察。 未来教师的培训将来自年度实地课程;这些学生将来自美国各地的几所大学以及选定的外国机构。 这种由美国、肯尼亚和埃塞俄比亚科学家参与的多国团队合作将加深他们之间的理解，并将为未来的科学家提供一批可以合作的人才。 重要的是，只能在实地有效传播的知识将传递给至少三个不同国家的年轻科学家。 最后，该项目将为非洲的古生态学研究提供重要的同位素框架，并建立一个420万至1万年前广泛分布的火山灰层数据库。

The evolutionary history of humans is of broad academic and public interest. The Omo-Turkana Basin in East Africa contains the most continuous sequence of hominin-bearing strata and is therefore of special importance to paleoanthropology. Within this basin lie many answers to fundamental questions about human evolution, but piecing together the answers often requires precise determination of dates of fossils and other traces of our ancestry.The basin has recorded the succession of volcanic eruptions in the East African Rift; geochemical "fingerprinting" of these ashes allows many time lines to be identified and potassium-argon dating is used to determine the ages of many of these ashes and hence of hominin fossils. The extensive exposures in the basin allows the order of these eruptions to be determined; in turn these can be correlated to other fossil sites in East Africa and allows distant sites to be compared in detail at certain time intervals. This study will then put in order the multitude of ashes that allow detailed histories of human evolution to be determined. Along with these ashes are soil horizons that record climate and ecological information; stable isotope studies of soil carbonates will allow a comprehensive study of the development of savanna ecosystems in East Africa and can be interpreted in the context of human evolution. The detailed correlations of volcanic ashes between sites in the Omo-Turkana Basin and the Awash Basin in Ethiopia will allow comparison of the ecosystems in the two regions to answer whether or not both regions were behaving in the same way. Stable isotopes studies of tooth enamel from fossil mammals shows the diet choices and availabilities of certain foods; taken together, they can be used to determine the paleo-aridity of the region over the last 4 million years or more. Thus, this study will use correlation of volcanic ashes, dating of those ashes, and isotope studies to understand the changes in climate and ecology that accompany human evolution. Comparison of climatic and ecologic events in the Omo-Turkana and Awash regions will address the problem of the relationship between environmental change and human evolution. The environmental context of human evolution will be put firmly in place.This project will provide training for American, Kenyan, and Ethiopian students and scientists. It will provide research opportunities for at least 8 graduate and 16 undergraduate students; many of these undergraduates will participate in international fieldwork. Training of future teachers will come about from the annual field course; these students will be from several universities from across the USA as well as from selected foreign institutions. This multi-national teamwork with participation of American, Kenyan, and Ethiopian scientists will deepen understanding between them, and will provide a cadre of individuals with whom future scientists can work. Importantly, knowledge that can only be effectively transmitted in the field will be passed on to younger scientists of at least three different nations. Finally, this project will provide an important isotopic framework for African studies of paleoecology, and a database of widespread volcanic ash layers over the time period from 4.2 to 0.01 million years ago.