Key phases of human evolution coincide with flickers in eastern Africa's climate

The project explores the youngest chapter in human evolution by analyzing lacustrine sediments in close vicinity to paleo-anthropological key sites in eastern Africa using scientific deep drilling. The research endeavor included more than 22 researchers from 19 institutions in 6 countries, and was led by Dr. Verena Foerster at the University of Cologne's Institute of Geography Education. The article "Pleistocene climate variability in eastern Africa influenced hominin evolution" has now appeared in Nature Geoscience.

Despite more than half a century of hominin fossil discoveries in eastern Africa, the regional environmental context of the evolution and dispersal of modern humans and their ancestors is not well established. Particularly for the Pleistocene (or Ice Age) between 2,580,000 to 11,700 years ago, there are no continuous high-resolution paleo-environmental records available for the African continent.

The research team extracted two continuous 280-meter sediment cores from the Chew Bahir Basin in southern Ethiopia, an area where early humans lived and developed during the Pleistocene. Chew Bahir is very remotely situated in a deep tectonic basement in close vicinity to the Turkana area and the Omo-Kibish, key paleo-anthropological and .

The cores yielded the most complete record for such a long period ever extracted in the area, revealing how different climates influenced the biological and cultural transformation of humans inhabiting the region.

Chew Bahir coring site, extracting a liner full of recovered sediment material from the 280-m-long core: the day shift trying to pull the liner out with combined forces. Credit: Frank Schaebitz

Scientific deep drilling operations in Chew Bahir, southern Ethiopia, during night shift and with remote thunder storms. Credit: Annett Junginger

The Chew Bahir science camp: 'Chew Bahir city', 3 km from the drill site. Credit: Verena Foerster