Collaborative Research: Human Evolution, Rift Valley Environments and Orbitally Forced Climate Change

合作研究：人类进化、裂谷环境和轨道强迫气候变化

• 批准号: 0711371
• 负责人: John Kingston
• 金额: $ 10.15万
• 依托单位: Emory University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-15 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711371&HistoricalAwards=false
• 关键词: Collaborative; Research; Human; Evolution; Rift

Exploring the course of human evolution extends beyond the discovery and description of the fossils of early humans. To understand the evolutionary processes that led to key human features such as upright walking, a large brain, tool manufacture and use, and behavioral flexibility, it is necessary to develop a context for these innovations. What were the environmental forces that shaped and directed human evolution? Human evolution is a consequence of the interactions of early hominids with their physical and biological surroundings and there is a need to specifically reconstruct these parameters in association with discoveries of hominids. Documenting paleoenvironments at a relevant scale in the terrestrial record and developing causal links between evolution and environmental change, however, remains difficult. As a result, aspects of human evolution have been interpreted in the context of environmental data from the marine record, which provide a detailed record of large scale climatic change. This approach is valid only if links between global or regional phenomena and specific shifts in local hominid ecosystems can be demonstrated.This proposal seeks to address directly these issues by examining a series of environmental indicators to develop a high-resolution paleoenvironmental framework for a hominid-bearing sequence in the East African Rift Valley. This can then be linked to global climate changes. The work has at its focus a 2-3 million year old sedimentary sequence exposed in the Tugen Hills, a fault block within the rift valley near Lake Baringo in Kenya. This sequence exhibits abrupt and repeated cycling of major freshwater lake systems reflecting fluctuating climatic conditions. In recent research, this project has established a clear link between these short term oscillations (every 23 thousand yrs) and Milankovitch cycles that result from variations in the solar radiation received at the top of the atmosphere, controlled by variations in the geometry of the earth''s orbit. These changes represent the major driving force in the earth climate system through time, including glacial-interglacial cycles. Thirty-six vertebrate fossil localities, including three hominid sites, can be linked directly to this sequence, providing an opportunity to establish patterns of response by animals and vegetation to these short term shifts. This research represents the first attempt to develop multiple environmental and ecological indicators that can be linked directly to Milankovitch cycling in a terrestrial rift valley context. These data will be used to generate insights into the evolutionary response of hominid ecosystems to these pervasive climatic oscillations over the last six million years in Africa. While these data relate directly to fossil hominids and their vertebrate communities in the Baringo Basin, linking local ecological shifts with orbitally-forced patterns of insolation affords the prospect of extrapolating the affects of climatic oscillations on terrestrial ecosystems regionally in the past. With these data, we can begin to formulate high-resolution models for interpreting correlations between climate and human evolution, and elucidate the role of environmental change as a potential driving force in mammalian evolution in general and human evolution in particular. This research will foster highly interdisciplinary and collaborative studies, essential in developing perspectives of the multi-dimensional links between evolution and ecology. The project outlined here represents an ideal forum in which to generate and integrate research ideas cutting across traditionally disparate academic disciplines. The study will broaden opportunities and enable the participation of graduate students as well as research personnel from the National Museums of Kenya.

探索人类进化的过程不仅超出了对早期人类化石的发现和描述。为了了解导致人类关键特征的进化过程，例如直立的大脑，工具制造和使用以及行为灵活性，有必要为这些创新开发背景。塑造和指导人类进化的环境力量是什么？人类进化是早期人类与其物理和生物学环境的相互作用的结果，并且有必要专门地重建与人类发现的发现相关的这些参数。然而，在陆地记录中以相关规模记录古环境，并在进化与环境变化之间建立因果关系。结果，在海洋记录的环境数据的背景下，已经解释了人类进化的各个方面，这些方面提供了大规模气候变化的详细记录。仅当可以证明全球或区域现象之间的联系与本地人类生态系统的特定转变之间的联系时，这种方法才有效。该提案旨在通过检查一系列环境指标来直接解决这些问题，以开发高分辨率的古环境框架，以在东非Rift Valley中为人类实用序列开发出来的人性化序列。 然后，这可以与全球气候变化链接。这项工作的重点是在肯尼亚巴林戈湖附近的裂谷中的小丘陵中暴露了2至300万年历史的沉积序列。该序列表现出主要的淡水湖系统的突然和反复循环，反映了气候波动的波动。在最近的研究中，该项目已经建立了这些短期振荡（每23000年）与米兰科维奇周期之间的明确联系，这是由于大气顶部收到的太阳辐射的变化而导致的，并由地球轨道的几何形状的变化控制。这些变化代表了随着时间的流逝，包括冰川裂纹周期的主要驱动力。可以将36个脊椎动物化石所在地（包括三个原始地点）直接链接到该序列，从而提供了一个机会，可以建立动物和植被对这些短期转移的反应模式。这项研究是开发多种环境和生态指标的首次尝试，这些指标可以直接与陆地裂谷环境中的米兰科维奇自行车联系起来。这些数据将用于产生对在非洲过去600万年中人类生态系统对这些普遍气候振荡的进化反应的见解。尽管这些数据直接与Baringo盆地中的化石人类及其脊椎动物群落有关，但将局部生态转变与轨道造成的失去污染模式联系起来，可以推断出过去过去对地面生态系统区域区域区域性生态系统的气候振荡影响的前景。有了这些数据，我们可以开始制定高分辨率模型来解释气候与人类进化之间的相关性，并阐明环境变化作为哺乳动物进化中的潜在驱动力的作用，尤其是人类进化。这项研究将促进高度的跨学科和协作研究，这对于发展进化与生态学之间的多维联系的观点至关重要。此处概述的项目代表了一个理想的论坛，该论坛在其中生成和整合跨传统学科的研究思想。这项研究将扩大机会，并使研究生以及肯尼亚国家博物馆的研究人员参与。