Georgia. Theory says this group evolved further in central Eurasia and
then returned to Africa to become Homo erectus.
September 9, 2009
A skull that rewrites the history of man
By Steve Connor, Science Editor
It has long been agreed that Africa was the sole cradle of human
evolution. Then these bones were found in Georgia...
The conventional view of human evolution and how early man colonised
the world has been thrown into doubt by a series of stunning
palaeontological discoveries suggesting that Africa was not the sole
cradle of humankind. Scientists have found a handful of ancient human
skulls at an archaeological site two hours from the Georgian capital,
Tbilisi, that suggest a Eurasian chapter in the long evolutionary
story of man.
The skulls, jawbones and fragments of limb bones suggest that our
ancient human ancestors migrated out of Africa far earlier than
previously thought and spent a long evolutionary interlude in Eurasia
- before moving back into Africa to complete the story of man.
Experts believe fossilised bones unearthed at the medieval village of
Dmanisi in the foothills of the Caucuses, and dated to about 1.8
million years ago, are the oldest indisputable remains of humans
discovered outside of Africa.
But what has really excited the researchers is the discovery that
these early humans (or "hominins") are far more primitive-looking than
the Homo erectus humans that were, until now, believed to be the first
people to migrate out of Africa about 1 million years ago.
The Dmanisi people had brains that were about 40 per cent smaller than
those of Homo erectus and they were much shorter in stature than
classical H. erectus skeletons, according to Professor David
Lordkipanidze, general director of the Georgia National Museum.
"Before our findings, the prevailing view was that humans came out of
Africa almost 1 million years ago, that they already had sophisticated
stone tools, and that their body anatomy was quite advanced in terms
of brain capacity and limb proportions. But what we are finding is
quite different," Professor Lordkipanidze said.
"The Dmanisi hominins are the earliest representatives of our own
genus - Homo - outside Africa, and they represent the most primitive
population of the species Homo erectus to date. They might be
ancestral to all later Homo erectus populations, which would suggest a
Eurasian origin of Homo erectus."
Speaking at the British Science Festival in Guildford, where he gave
the British Council lecture, Professor Lordkipanidze raised the
prospect that Homo erectus may have evolved in Eurasia from the more
primitive-looking Dmanisi population and then migrated back to Africa
to eventually give rise to our own species, Homo sapiens - modern man.
"The question is whether Homo erectus originated in Africa or Eurasia,
and if in Eurasia, did we have vice-versa migration? This idea looked
very stupid a few years ago, but today it seems not so stupid," he
told the festival.
The scientists have discovered a total of five skulls and a solitary
jawbone. It is clear that they had relatively small brains, almost a
third of the size of modern humans. "They are quite small. Their lower
limbs are very human and their upper limbs are still quite archaic and
they had very primitive stone tools," Professor Lordkipanidze said.
"Their brain capacity is about 600 cubic centimetres. The prevailing
view before this discovery was that the humans who first left Africa
had a brain size of about 1,000 cubic centimetres."
The only human fossil to predate the Dmanisi specimens are of an
archaic species Homo habilis, or "handy man", found only in Africa,
which used simple stone tools and lived between about 2.5 million and
1.6 million years ago.
"I'd have to say, if we'd found the Dmanisi fossils 40 years ago, they
would have been classified as Homo habilis because of the small brain
size. Their brow ridges are not as thick as classical Homo erectus,
but their teeth are more H. erectus like," Professor Lordkipanidze
said. "All these finds show that the ancestors of these people were
much more primitive than we thought. I don't think that we were so
lucky as to have found the first travellers out of Africa. Georgia is
the cradle of the first Europeans, I would say," he told the meeting.
"What we learnt from the Dmanisi fossils is that they are quite small
- between 1.44 metres to 1.5 metres tall. What is interesting is that
their lower limbs, their tibia bones, are very human-like so it seems
they were very good runners," he said.
He added: "In regards to the question of which came first, enlarged
brain size or bipedalism, maybe indirectly this information calls us
to think that body anatomy was more important than brain size. While
the Dmanisi people were almost modern in their body proportions, and
were highly efficient walkers and runners, their arms moved in a
different way, and their brains were tiny compared to ours.
"Nevertheless, they were sophisticated tool makers with high social
and cognitive skills," he told the science festival, which is run by
the British Science Association.
One of the five skulls is of a person who lost all his or her teeth
during their lifetime but had still survived for many years despite
being completely toothless. This suggests some kind of social
organisation based on mutual care, Professor Lordkipanidze said.
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