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

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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.