Resolving the timescale of south-central African palaeoenvironments and their impact on human behaviour and evolution

时间决定一切：准确的地质记录年代测定对于理解地球的历史是必不可少的，但超过放射性碳测年(约5万年)的限制，物质的年代测定变得困难。第四纪(过去约260万年)提供了丰富的古环境记录，对于检验气候模型预测未来气候变化的有效性至关重要。然而，由于缺乏年代学，氨基酸年代学严重不足；氨基酸测年的最新进展可以克服这一僵局。氨基酸年代学使用生物矿物(如贝壳、牙齿)中蛋白质随时间的分解。我们最近的突破是分离被包裹的蛋白质，这种蛋白质表现为一个封闭的系统，在3000万年的时间里既不会丢失产物，也不会获得反应物。这为陆地沉积物提供了一个极其强大的测年工具。通过专注于一系列不同的生物矿物(软体动物、介形动物、釉质等)，本博士将利用这些进展来制定南部非洲的年表，该地区拥有丰富但未被充分研究的更新世古气候记录，也是全面了解人类进化的关键地区。超出了现有其他测年方法的范围，这将使古环境记录受到限制，也使我们能够研究人类与不断变化的环境之间的相互作用。目的1)通过高温动力学实验测试生物矿物的晶体内蛋白质降解(ICPD)2)测试沉积中的化石。4)利用这一框架，开发更新世的区域古环境记录，为该区域的动物群演化和行为变化提供背景。该项目(设在约克大学NERC认可的氨基酸设施)将涉及多学科培训；学生将获得最先进的分析方法开发技术以及实地工作和采样方法的经验。监督小组结合了地质年代学和分析化学(Penkman；York)、南部非洲旧石器时代考古学和古环境(Barham；利物浦)以及使用多种化石替代品进行古生态重建(White，自然历史博物馆)方面的专业知识。技术培训将包括色谱学、测年方法、古气候、软骨病学和旧石器时代考古学。

Timing is everything: accurate dating of the geological record is essential to understand our planet's history, but beyond the limit of radiocarbon dating (~50,000 years) material becomes difficult to date. The Quaternary period (the last ~2.6 million years) provides a rich palaeoenvironmental record vital for testing the usefulness of climate models to predict future climate change. However it is severely underused because of a lack of chronology; recent advances in amino acid dating can overcome this impasse.Amino acid geochronology uses the time-dependent breakdown of proteins in biominerals (e.g. shells, teeth). Our recent breakthrough has been to isolate entrapped proteins, which behave as a closed system, neither losing products nor gaining reactants over >30 million years. This provides an extremely powerful dating tool for terrestrial deposits. By focusing on a range of different biominerals (molluscs, ostracods, enamel etc.), this PhD will exploit these advances to develop a chronology for southern Africa, a region with a rich but understudied Pleistocene palaeoclimate record and a critical area for a full understanding of human evolution. Stretching beyond the range of the other dating methods available, this will enable the palaeoenvironmental record to be constrained, also allowing us to study the interactions between humans and the changing environment.Objectives1) Test biominerals for intra-crystalline protein degradation (IcPD) through high temperature kinetic experiments.2) Test fossils in deposits of well-constrained age. 3) Develop an IcPD dating framework for southern-central Africa.4) Using this, develop a regional palaeoenvironmental record for the Pleistocene, providing the context for faunal evolution and behavioural changes in this region.The project (based in the NERC-recognised amino acid facility at the University of York) will involve multidisciplinary training; the student will gain hands-on expertise in state-of-the-art techniques for analytical method development as well as experience of fieldwork and sampling approaches. The supervisory team combines expertise in geochronology and analytical chemistry (Penkman; York), southern African Palaeolithic archaeology and palaeoenvironments (Barham; Liverpool) & palaeoecological reconstructions using multiple fossil proxies (White, Natural History Museum). Training in techniques will include chromatography, dating methods, palaeoclimate, malacology and Palaeolithic archaeology.