SALT LAKE CITY, May 27 (UPI) — A group of U.S. scientists is criticizing a habitat claim involved in the discovery in Africa last year of a purported human ancestor nicknamed Ardi.
The fossil Ardipithecus ramidus — which was proclaimed Science magazine’s 2009 “Breakthrough of the Year” — is coming under fire by scientists who say there’s little evidence for her discoverers’ claims that there were dense woodlands at the African site where the creature lived 4.4 million years ago.
Instead, University of Utah Professor Thure Cerling, lead author of a critique appearing as a technical comment in the May 28 issue of Science magazine, said, “There is abundant evidence for open savanna habitats.”
The scientists — eight geologists and an anthropologist from seven universities — said the distinction is important because the claim Ardi lived in woodlands and forest patches was used as an argument against a longstanding theory of human evolution known as the savanna hypothesis.
The researchers said that hypothesis holds an expansion of savannas — grassy plains dotted with trees and shrubs — prompted apelike human ancestors to descend from the trees and start walking upright to find food more efficiently or to reach other trees for shelter or resources.
The critique concludes Ardi most likely lived in a tree or bush savanna with 5 percent to 25 percent of the area covered by trees or shrubs, not the minimum 60 percent to meet the definition of a closed-canopy woodland.
“Our conclusion is that much of the evidence … should be interpreted as a savanna environment, therefore (the) rejection of the savanna hypothesis is incorrect,” Cerling said.
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