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 in 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.
Esteban Sarmiento of the Human
Evolution Foundation in East Brunswick, New Jersey, wrote in the new analysis
that he's not convinced Ardi belongs on the evolutionary tree branch leading to
modern humans.
He thinks it came along earlier, before that human
branch split off from the ancestors of chimps and gorillas.
The
anatomical features of teeth, the skull and elsewhere that experts cited just
don't make a convincing case for membership on the human branch, he argued.
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