Exploring the impacts of past environments and climates on the initial dispersal of humans out of Africa

Project Abstract

Scientists continue to debate the onset and development of hominin migration events throughout the East African Rift System. Recent archaeological discoveries reveal that Homo sapiens initially emerged in north Africa, 300ka. From this initial emergence, sapiens migrated throughout north and sub-Saharan Africa, up the Levantine corridor, and into Eurasia between 50 to 120ka. Variations in climatic and environmental conditions are often inferred to be the catalysts of these migrations, yet the precise context of these dispersals remain unclear. There are two schools of thought on the matter: warm and wet conditions could have facilitated the earliest migration of Homo sapiens approximately 90 to 120ka, or an unusually cold and dry period between 55 to 65ka brought about the initial out-of-Africa event.

A lack of land-based records hinders this debate. What were the Late Pleistocene paleoenvironmental and paleoclimatic conditions like on land? How did these conditions cause our ancestors to disperse out of Africa? Answers to these questions may lie in the paleosols (fossilized soils) of Gona, Ethiopia, an area with one of the most established archaeological records in the East African Rift System.

This area contains Late Pleistocene paleosol deposits, which are a reservoir of biogeochemical dynamics that can be related to the surrounding environment. Thus, these paleosols are an ideal archive for reconstructing the paleoenvironment associated with Gona’s hominin fossil sites. To answer the questions above, I would like to characterize the bulk and stable isotope geochemistry of these terrestrial paleosols in Gona’s sedimentary record.

Establishing a stable isotopic geochemical record of oxygen and carbon isotopes from soil carbonates of the Late Pleistocene in Gona will allow us to reconstruct changes in Late Pleistocene temperature and vegetation over time. The terrestrial isotopic data will then be compared with data from the established archaeological record at Gona to determine when archaeological and hominin fossil sites occur more frequently in the local environmental record - during wetter or drier intervals - and under what type of vegetation.

I will characterize the paleosols associated with soil carbonates using bulk geochemical signals of drainage, where mass-balance of geochemical depth trends in paleosols will be used to reconstruct dominant weathering trends and changes throughout the Late Pleistocene. When compared with the terrestrial stable isotopic data, I can see if poorly-drained paleosols/environments at Gona are linked to changes in isotope geochemistry and whether these changes can be correlated to any patterns in local archaeological and hominin fossil records.

This project will produce a comprehensive Late Pleistocene record of paleoenvironmental and paleoclimatic change at Gona, which in turn will provide a much-needed baseline of comparison to already established genetic and marine-based records. Land-based records will help us determine to what degree the local/regional environment and climate drove the initial out-of-Africa migration. Furthermore, it will shed light upon the climatic intervals where migration events were likely to occur.

Conference

N/A

Funding Type

Research Grant

Academic College

Jesse D. Jones College of Science, Engineering and Technology

Area/Major/Minor

Earth and Environmental Sciences, Watershed Science Concentration

Degree

MS in Earth and Environmental Sciences

Classification

Graduate

Name

Gary Stinchcomb

Academic College

Jesse D. Jones College of Science, Engineering and Technology

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