Evidence supports theory that humans evolved in grasslands

JUNE 11, 2016

by Chuck Bednar

Researchers from the Columbia University Lamont-Doherty Earth Observatory have discovered new evidence to support the theory that key human traits, including large brains and the ability to walk on two legs, evolved as our ancestors adapted to living in open grasslands.

Writing in a special human-evolution issue of the journal Proceedings of the National Academy of Sciences, postdoctoral research scientist Kevin Uno and his colleagues found a 24 million year old vegetation record buried deep within seabed sediments off the coast of eastern Africa.

This vegetation is the longest and most complete record of ancient plant life discovered to date in the purported birthplace of humanity, modern-day Kenya and Ethiopia, the researchers noted in a statement. It also indicates that between 24 million and 10 million years ago, well before the first human ancestors arose, the region was dominated by woodlands with few grasses.

That all changed due to a dramatic shift in climate, and within a few million years time, grasses became dominant – a trend that continued throughout the entire course of  human evolution, Uno and his colleagues said. As our ancestors adapted to these changes, they evolved physically, their diets became more flexible, and their social structures grew in complexity.

Genetic evidence suggests that early hominids first split from other apes between six and seven million years ago, and many scientists believe that it was the shift from dense forests to savannas in eastern Africa that served as the catalyst for their eventual development into modern humans. The new study indicates that the rise of grasslands had a tremendous impact on hominins.

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