Researchers report paleoclimate records in Africa that link a drying climate with technological and evolutionary changes among hominins. Fossils, artifacts, and cores have been used to support theories of links between environmental change in Africa and human evolution, but the evidence is derived from sites too distant from one another to establish firm correlations. R. Bernhart Owen and colleagues analyzed sedimentary cores from Lake Magadi in Kenya that provide a multiproxy record of climate extending back to around 1 million years. Beginning around 575,000 years ago, the lake began a long-term drying trend indicated by a progression toward saline and alkaline water. The trend was punctuated by wet-dry cycles but became arid between 525,000 and 400,000 years ago and after around 350,000 years ago. The early aridification of Lake Magadi occurred concurrently with extinctions of large grazing mammals in the nearby Olorgesailie Basin, and also spanned the time-period between the last known samples of Acheulean style stone tools in the region, around 500,000 years ago, and the first known Middle Stone Age artifacts, which appear by 320,000 years ago. According to the authors, stresses associated with variable and drying climates may have acted as selective factors among early hominins and spurred migration and intermixing with other groups to exchange resources and advance hominin evolution toward modern human populations.
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Article #18-01357: "Progressive aridification in East Africa over the last half million years and implications for human evolution," by Richard Bernhart Owen et al .
MEDIA CONTACTS: Richard Bernhart Owen, Hong Kong Baptist University, Kowloon, HONG KONG; e-mail: owen@hkbu.edu.hk ; Andy Cohen, University of Arizona, Tucson, AZ; tel: 520-471-2625; e-mail: cohen@email.arizona.edu
Proceedings of the National Academy of Sciences