PHI-
Early
Walkers
study of a fossil thigh bone
Anewshows that walking upright may
have already been old hat six million
years ago. Researchers led by Penn
State anthropologist Robert Eckhardt
analyzed CAT scans of a fragment of
the left femur of Orrorin tugenensis, a
chimpanzee-size creature whose place
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o
A CATscan of a thighboneshows that
Orrorinwalked upright.
six-million-year-old
on the hominid family tree has been the
subject of controversy since its discovery in the hills of western Kenya nearly
four years ago ("Ancient Ancestors?"
September/October 2Ó01).According to
Eckhardt, the CAT scans reveal the
internal structure of the bone "is considerably closer to an upright bipedal
human than to a chimpanzee," suggesting that Orrorin walked on two feet.
"We don't know what Orrorin looked
like," says Eckhardt. "We don't have a
crystal ball. But by the time you see
structural changes in the bones like this,
there has been some behavioral change.
This is solid evidence for bipedalism,
dated to six million years ago." The new
analysis bolsters the case that Orrorin is
an ancestral hominid, but other
researchers point to features like
Orrorins teeth, which are more apelike,
as evidence that the species may be
more closely related to chimpanzees.
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Archaeology * November/December 2004