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 Scientists said on Thursday an analysis of fossil hand bones of
the species Australopithecus africanus that lived in southern Africa
about 3 million to 2 million years ago indicated this human
forerunner could use its hands in ways very much like modern people.
This species, known for its mix of ape-like and human-like
characteristics, possessed the uniquely human ability to have a
power-squeeze grip as needed to wield a hammer and a forceful
precision grip as used to turn a key, the study showed.
"Forceful precision grips have been linked specifically to stone
tool use and tool making, and so it is possible that
Australopithecus africanus was using stone tools as well," said
Tracy Kivell of Britain's University of Kent, who helped lead the
study published in the journal Science with fellow University of
Kent paleoanthropologist Matthew Skinner.
 This species appeared roughly a half million years before the first
evidence of stone tools. The traditional view of scientists is that
a species called Homo habilis that appeared about 2.4 million years
ago was the pioneer in stone tool use in the human lineage.
The scientists examined trabecular bone - the internal spongy
structure of bones - in chimpanzees and other apes, modern people,
and extinct species in the human lineage including Neanderthals as
well as Australopithecus.
Trabecular bone changes throughout an individual's lifetime in
response to how the bone is being used. Because of this, trabecular
bone reflects how an individual actually employed their joints and
hands.
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The scientists found a distinctive asymmetric pattern in the
distribution of trabecular bone in the modern human hand that
reflects people's ability to forcefully oppose the thumb to the pads
of the fingers for forceful precision grip.
The same human-like pattern appeared not only in Neanderthals, known
as proficient tool users, and early members of our own species,
which first appeared some 200,000 years ago, but also in the much
older Australopithecus africanus.
This pattern was absent in chimpanzees, our closest genetic cousin
whose last common ancestor with humans lived roughly 7 million years
ago, and other apes.
"This evidence suggests that species of Australopithecus were more
human-like in their behavior than we previously thought and that we
should concentrate our efforts on finding evidence for tools that
they might have been using, whether made out of stone, wood or
bone," Skinner said.
(Reporting by Will Dunham; Editing by Sandra Maler)
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