The Effects of Climate Change on Early Human Evolution

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A new paper in Nature Ecology and Evolution, one of the world's top ecology journals, examines the relationships between early human evolution and the decline of forest ecosystems in East Africa over the past 6 million years.  

Jason Kamilar, professor of anthropology at UMass Amherst and a co-author of Long-term biotic homogenization in the East African Rift System over the last 6 million years of hominin evolution, said that the research team examined the changing distribution of large mammals and found that regional species assemblages became more similar over time. “This was largely driven by grazers (grass feeders) becoming more widespread and forest-dwelling fruit and leaf eating mammals going extinct,” noted Kamilar. This change in the distribution of mammal species, coupled with the increase in the mammal assemblage similarity, may be due to habitat change: the fossil record shows an expansion of grassland ecosystems, with extinctions of forest-dwelling mammals and an increase of grazing mammals as their range expanded.

“Our results help us understand the evolution of early human ancestors, who were more reliant on trees for their survival and who likely met the fate of other mammal species by going extinct when forests and other wooded habitats declined due to climate change,” said Kamilar. 

The paper’s lead author, John Rowan, began this work as a postdoctoral researcher with Kamilar’s Comparative Primatology Lab at UMass Amherst. Rowan is currently an assistant professor in the Department of Archaeology at the University of Cambridge (UK). The research was funded by National Science Foundation grants awarded to Kamilar (BCS #1551799) and co-author Kaye Reed (BCS #1551810) of Arizona State University.