- WASHINGTON (Reuters) - A
tiny pre-human who lived more than 900,000 years ago in what is now Kenya
may have been a "short experiment" in evolution that never quite
made it, scientists said on Thursday.
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- The little skull clearly belongs to an adult and was
found last summer at a site where much larger hominids classified as Homo
erectus lived, said Richard Potts of the Smithsonian Institution and colleagues.
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- He or she died on a volcanic ridge, perhaps mauled by
a lion or other carnivore, Potts said.
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- It is the smallest adult fossil found dating back to
the time of Homo erectus, the species of pre-human that dominated between
500,000 and 1.7 million years ago, Potts' team writes in Friday's issue
of the journal Science.
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- Potts believes the fossil find shows that early humans
lived in little groups that became separate and distinct for a while, and
then came together every few thousand years or so, swapping genes and then
parting ways again.
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- "On occasion, they became isolated for a while,
possibly hundreds of generations, and so developed their own unique combination
of features," Potts said in an e-mail.
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- But dramatic climate and environmental changes known
to have occurred during those times forced groups to move together again,
and perhaps drove some into extinction.
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- Perhaps there were lots of "short experiments"
-- species that never really quite made it, Potts said.
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- "In this light, I would see the hominid population
at Olorgesailie as part of a single, highly variable species, with both
large and small (possibly male/female) adults."
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- VIOLENT DEATH
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- This particular early human was found in an area that
would have been a volcanic ridge 900,000 years ago. Potts' team is working,
as anthropologists often do, from fragments of skull -- and guessing what
the rest of the creature looked like.
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- It had carnivore bite marks on the left brow ridge, Potts
said. "Quite possibly this is how the individual died. It was walking
along or near the volcanic ridge leading up to the highlands (a safer nighttime
place to be than by the water's edge in the lowland) and it didn't quite
make it."
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- Remains of large tools have been found in the area, where
Potts and colleagues have worked for years.
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- "The entire area was a grassy plain, filled with
grazing zebra and very large grass-eating baboons, along with grazing elephants
and huge pigs," Potts said.
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- "The toolmakers made extensive use of the volcanic
rocks up on Mount Olorgesailie and surrounding highlands -- we've identified
14 different types of volcanic rocks that they chipped into handaxes."
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- Homo erectus remains have been found in parts of Africa,
southern Europe and Asia. These hominids made tools and lived in groups,
but anthropologists are trying to figure out whether there were separate
species or sub-species among the group.
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- This particular individual will be difficult to classify,
Potts said.
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- "It's really too hard to say what species it is,
if you happen to think there were multiple species around at the time.
I certainly used to think so," he said.
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- He has compared the skulls of fossils found from other
hominids that lived around the same time, including Homo antecessor from
Atapuerca in Spain or Homo cepranensis, from Ceprano, Italy.
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- "I find the variability in the skulls (and parts
of skulls) impossible to divide neatly into separate lineages that stay
consistently identifiable over any length of time, like Homo erectus in
Asia does," Potts said.
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