Title: Rain or Shine: hominin evolution and dispersal in response to environmental shifts – insights from a ~620 kyr climate record from Lake Chew Bahir in eastern Africa

Authors: Asfawossen Asrat^1,2, Verena Foerster³, Henry Lamb^4,5, Frank Schaebitz³, Martin H. Trauth⁶

Affiliations: (the affiliations of the co-authors will be provided at a later stage)
¹School of Earth Sciences and Engineering, Botswana International University of Science and Technology, Palapye, Botswana; E-mail: kassayea@biust.ac.bw
²School of Earth Sciences, Addis Ababa University, Addis Ababa, Ethiopia
³Institute of Geography Education, University of Cologne, Cologne, Germany
⁴Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, UK
⁵Botany Department, School of Natural Science, Trinity College Dublin, Ireland
⁶Institute of Geosciences, University of Potsdam, Potsdam, Germany

Abstract: The East African Rift System (EARS) has long been recognized as a hotspot of hominin evolution. Since the discovery of some iconic Upper Miocene–Pleistocene hominid and anatomically modern human fossils in the 1960s and 1970s, the region has become a focus of substantial paleoanthropological and archaeological research. With the discovery of more hominin fossils and cultural remains, the focus of research in the region progressively developed towards constraining the environmental context of hominin evolution and dispersal. The role of climate variability in human evolution and dispersal has become an overarching theme. However, long and continuous paleoenvironmental records from the region were lacking, hindering the establishment of the regional environmental context. The Chew Bahir Drilling Project (CBDP), part of the Hominin Sites and Paleolakes Drilling Project (HSPDP) initiated in the late 2000s,  made a major breakthrough by providing a ~620 kyr environmental record. This record spans the period of key events in hominin evolution and their cultural transformation including the separation of modern human ancestors from archaic hominin groups and the subsequent appearance of anatomically modern humans as well as global dispersal of Homo sapiens. 

The Chew Bahir climate record shows a complex relationship between climate variability and hominin evolution. Stable humid conditions between 620–275 kyrs BP favoured high anatomical diversity of hominins while more arid and pronounced climate variability between 275–60 kyrs BP coincided with the appearance of H. sapiens in the region accompanied by habitat transformation, and key human cultural innovations. Global human dispersal after 60 kyrs BP occurred during regionally dry but pronounced, high frequency climate cyclicity between arid and humid phases. In this plenary, this complex relationship between climate variability and hominin evolution will be discussed with particular emphasis on the response of human societies to shifting climate regimes.

Biography: Asfawossen Asrat is Professor of Geology at the School of Earth Sciences and Engineering of the Botswana International University of Science and Technology in Botswana and the School of Earth Sciences of the Addis Ababa University in Ethiopia. He received his PhD from the University of Nancy in France, and he is a geochemist and petrologist by training. His main research focus is Quaternary paleoenvironmental and paleoclimate reconstruction of eastern Africa. He worked on various archives, particularly on lake sediments and speleothems, using geochemical and stable isotope proxies. He has been leading and participating in several successful lake drilling projects in Ethiopia during the last two decades, including leading the ICDP-sponsored Chew Bahir Drilling Project in southern Ethiopia, as part of the Hominid Sites and Paleolakes Drilling Project (HSPDP) in eastern Africa. His research aims at understanding the impact of climate variability on human evolution, expansion and innovation.