Questions raised about 'Ardi' as man's ancestor
news.yahoo.com
By MALCOLM RITTER, AP Science Writer Malcolm Ritter, Ap Science Writer – Thu May 27, 2:38 pm ET
NEW YORK – Last fall, a fossil skeleton named "Ardi" shook up the field of human evolution. Now, some scientists are raising doubts about what exactly the creature from Ethiopia was and what kind of landscape it inhabited.
New critiques question whether Ardi really belongs on the human branch of the evolutionary tree, and whether it really lived in woodlands. That second question has implications for theories about what kind of environment spurred early human evolution.
The new work is being published by the journal Science, which last year declared the original presentation of the 4.4 million-year-old fossil to be the magazine's breakthrough of the year.
Ardi, short for Ardipithecus ramidus, is a million years older than the famous "Lucy" fossil. Last October, it was hailed as a window on early human evolution.
Researchers concluded that "Ardi" walked upright rather than on its knuckles like chimps, for example, and that it lived in woodlands rather than open grasslands. It didn't look much like today's chimps, our closest living relatives, even though it was closer than Lucy to the common ancestor of humans and chimps.
Such questioning isn't unusual; big scientific discoveries are typically greeted that way. Until more scientists can study the fossil and other work can be done, broad consensus may be elusive. The 2003 discovery of diminutive fossil "hobbits" in Indonesia, for example, has spurred a long-running debate about whether the hobbits were a separate species or not.
Tim White of the University of California, Berkeley, one of the scientists who described Ardi last year in Science, said he isn't surprised by this week's debate.
"It was completely expected," he said. "Any time you have something that is as different as Ardi, you're probably going to have it."
Esteban Sarmiento of the Human Evolution Foundation in East Brunswick, N.J., wrote in the new analysis that he's not convinced Ardi belongs on the evolutionary tree branch leading to modern humans.
Instead, he said in an interview, he thinks it came along earlier, before that human branch split off from the ancestors of chimps and gorillas.
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