Terrestrial climate and ecosystem dynamics in SE Africa during the emergence, persistence and extinction of archaic hominids in the late Pliocene and early Pleistocene based on cores from IODP Expedition 361

为了详细了解上新世晚期至更新世早期东南非洲的陆地生态系统和气候演变，从而了解古代原始人类演变的外在边界条件，该项目的目标是在IODP站点U1478（莫桑比克海峡）生成4-2 Ma和（作为本后续提案中的一个新要素）2- 0.8Ma时间段的新陆地植被记录。从方法上讲，将通过基于孢粉学（花粉和孢子丰度，以及基于花粉的气候重建）、元素地球化学（XRF扫描）和有机生物标志物（δ 13 Cwax、δDwax、TEX 86）分析的综合方法实现项目目标。迄今为止（即，经过15个项目月的研究，第一至第三工作包取得了以下成果：（一）过去4 Ma的连续X射线荧光光谱记录，用于通过旋回地层学建立年龄模型，并能够重建控制U1478站点沉积物元素含量的过程;（ii）连续的花粉记录从4到2马在轨道尺度的分辨率，这是增加了定量花粉为基础的气候重建。项目第一阶段最重要的发现包括在c处植被基本重组的证据。2.8它的标志是从稀树草原到fynbos生物群落的更替，与上新世晚期的早期北方半球冰川事件同时代。第三个项目年将致力于第4工作包，将产生：㈠ 4-2 Ma间隔的叶蜡δ 13 C记录，这将使人们能够深入了解东南非洲C3和C4植物的分布，因此，这将是限制原始人类进化关键间隔期间降水量变化幅度的关键; ㈡ 2-0.8 Ma间隔的新的轨道尺度分辨率花粉记录，结合从站点U1478和附近岩芯MD 96 -2048获得的花粉数据，将产生自上新世以来东南非洲以外第一个连续的轨道尺度分辨率花粉记录;项目成果综述。总之，孢粉学和元素地球化学代用数据的整合将允许详细评估林波波河流域的生态系统和气候变化的特征，时间，幅度和克里思，从而在“人类的摇篮”地区，上新世以来。因此，不仅有可能澄清特别强烈的环境变化的间隔是否与原始人类出现和灭绝的步骤相吻合，而且还可以确定这种变化的确切性质。这些信息将为正在进行的关于环境强迫与人类进化之间潜在因果关系的讨论提供新的思路。

To gain detailed insight into the terrestrial ecosystem and climate evolution – and thus the extrinsic boundary conditions for the evolution of archaic hominids – in SE Africa during the late Pliocene to early Pleistocene, the project aims to generate new terrestrial vegetation records for the intervals 4–2 Ma and (as a new element within this follow-up proposal) 2–0.8 Ma at IODP Site U1478 (Mozambique Channel). Methodologically, the project goal will be reached through an integrated approach based on palynological (pollen and spore abundances, and pollen-based climate reconstructions), element- geochemical (XRF scanning) and organic biomarker (δ13Cwax, δDwax, TEX86) analyses of material from the splice of Site U1478. To date (i.e., after 15 project months), Work Packages 1 to 3 have yielded: (i) a continuous XRF record for the past 4 Ma that was used for age-model development by means of cyclostratigraphy, and has also enabled the reconstruction of processes controlling the elemental content of the sediments at Site U1478; (ii) a continuous pollen record from 4 to 2 Ma at orbital-scale resolution, which is augmented by quantitative pollen-based climate reconstructions. The most important finding within the first project phase comprises evidence for a fundamental reorganization in vegetation at c. 2.8 Ma; it is marked by a turnover from savanna to fynbos biomes, coeval with the early Northern Hemisphere glaciation events of the late Pliocene. The third project year will be dedicated to Work Package 4 that will yield: (i) a leaf-wax δ13C record for the 4–2 Ma interval, which will allow insight into the distribution of C3 and C4 plants in SE Africa and, hence, will be pivotal in constraining the magnitude of precipitation change during critical intervals of hominid evolution; (ii) a new orbital-scale resolution pollen record for the 2–0.8 Ma interval, which in combination with the already available pollen data from Site U1478 and nearby core MD96-2048 will yield the first, continuous pollen record off SE Africa since the Pliocene at orbital-scale resolution; (iii) a synthesis of the project results. In summary, the integration of palynological and element geochemical proxy data will allow detailed assessment of the character, timing, magnitude, and tempo of ecosystem and climate variability in the Limpopo River catchment, and thus in the ‘Cradle of Humankind’ region, since the Pliocene. As such, it will become possible not only to clarify whether intervals of particularly strong environmental change coincided with steps in hominid emergence and extinction, but also to identify the exact nature of this change. This information will shed new light on the ongoing discussion on potential causal links between environmental forcing and human evolution.