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Thursday, June 22, 2017

Fossils cast doubt on human lineage originating in Africa

http://www.reuters.com/article/us-science-fossils-idUSKBN18I2HX

Fossils from Greece and Bulgaria of an ape-like creature that lived 7.2
million years ago may fundamentally alter the understanding of human
origins, casting doubt on the view that the evolutionary lineage that led
to people arose in Africa.

Scientists said on Monday the creature, known as Graecopithecus freybergi
and known only from a lower jawbone and an isolated tooth, may be the
oldest-known member of the human lineage that began after an evolutionary
split from the line that led to chimpanzees, our closest cousins.

The jawbone, which included teeth, was unearthed in 1944 in Athens. The
premolar was found in south-central Bulgaria in 2009. The researchers
examined them using sophisticated new techniques including CT scans and
established their age by dating the sedimentary rock in which they were
found.

They found dental root development that possessed telltale human
characteristics not seen in chimps and their ancestors, placing
Graecopithecus within the human lineage, known as hominins. Until now, the
oldest-known hominin was Sahelanthropus, which lived 6-7 million years ago
in Chad.

The scientific consensus long has been that hominins originated in Africa.
Considering the Graecopithecus fossils hail from the Balkans, the eastern
Mediterranean may have given rise to the human lineage, the researchers
said.

The findings in no way call into question that our species, Homo sapiens,
first appeared in Africa about 200,000 years ago and later migrated to
other parts of the world, the researchers said.

"Our species evolved in Africa. Our lineage may not have," said
paleoanthropologist Madelaine Böhme of Germany's University of Tübingen,
adding that the findings "may change radically our understanding of early
human/hominin origin."

Homo sapiens is only the latest in a long evolutionary hominin line that
began with overwhelmingly ape-like species, followed by a succession of
species acquiring more and more human traits over time.

University of Toronto paleoanthropologist David Begun said the possibility
that the evolutionary split occurred outside Africa is not incongruent
with later hominin species arising there.

"We know that many of the mammals of Africa did in fact originate in
Eurasia and dispersed into Africa at around the time Graecopithecus
lived," Begun said. "So why not Graecopithecus as well?"

Graecopithecus is a mysterious species because its fossils are so sparse.
It was roughly the size of a female chimp and dwelled in a relatively dry
mixed woodland-grassland environment, similar to today's African savanna,
alongside antelopes, giraffes, rhinos, elephants, hyenas and warthogs.

The findings were published in the journal PLOS ONE.







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