Mystery still shrouds much of the story of our origins, but new Arizona State University (ASU) research sheds new light on why we first emerged where and when we did. Around 2.8 million years ago our genus, Homo, could have emerged in a valley in Ethiopia. It was a time of change on that Earth long ago; it appears forest landscapes altered into grassy ones where our ancient ancestors lived.
Back in 2013 an ASU team discovered a jawbone with teeth at Ledi-Geraru, and the incredible find is the oldest evidence of Homo we’ve yet found and dates back around 2.8 million years. The find was 400,000 years older than other fossils we’d discovered to that point. Building on that discovery, ASU scientists hoped to answer two questions: why did humans emerge in Ethiopia’s lower Awash Valley, and why did they emerge at that point in time?
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Animal fossils help scientists recreate the conditions of the past – what they ate help indicate the environment in those days. Scientists discovered that the animals found with the 2.8 million-year-old Homo fed on grass, seeming to support the guesses of many in the scientific community humanity emerged as grassy environments were spreading in a period of global cooling. According to IBTimes UK, the landscape in which early humans lived would have been similar to today’s Serengeti region.
Scientist Joshua Robinson said evidence had hinted at the connection between the emergence of humans and the spread of those grassy, open environments, “but, until now, we had not direct environmental data for the origins of Homo now that it’s been pushed back in time.”
The 2.8 million date is also incredibly important for the fossil record. The famous Lucy fossil (Australopithecus), which dates to around 3.2 million years ago, was found just around 18 miles west of ASU’s 2013 discovery. But the geological sequence ended around 2.95 million years ago, until the recent findings. ASU researcher John Rowan said although Lucy’s species endured many environmental changes, it appears they didn’t last through the ancient climate change as open environments spread. The diet of early humans was still very similar to what Lucy would have consumed, however.
The ASU research was published online this week in Nature Ecology & Evolution. Four ASU scientists worked on the study with one geoscientist from the University of South Florida.
Via Arizona State University and IBTimes UK
Images via Kaye Reed/Phys.org and Josh Robinson/Arizona State University