Human fossils hint at new species
24 Mar,BBC
The remains of what may be a previously unknown human species have
been identified in southern China.The bones, which represent at least
five individuals, have been dated to between 11,500 and 14,500 years
ago.But scientists are calling them simply the Red Deer Cave people,
after one of the sites where they were unearthed.
The team has told the PLoS One journal that far more detailed
analysis of the fossils is required before they can be ascribed to a new
human lineage."We're trying to be very careful at this stage about
definitely classifying them," said study co-leader Darren Curnoe from
the University of New South Wales, Australia."One of the reasons for
that is that in the science of human evolution or palaeoanthropology, we
presently don't have a generally agreed, biological definition for our
own species (Homo sapiens), believe it or not. And so this is a highly
contentious area," he told BBC News.
Much of the material has been in Chinese collections for some time
but has only recently been subjected to intense investigation.The
remains of some of the individuals come from Maludong (or Red Deer
Cave), near the city of Mengzi in Yunnan Province. A further skeleton
was discovered at Longlin, in neighbouring Guangxi Province.The skulls
and teeth from the two locations are very similar to each other,
suggesting they are from the same population.
But their features are quite distinct from what you might call a
fully modern human, says the team. Instead, the Red Deer Cave people
have a mix of archaic and modern characteristics.In general, the
individuals had rounded brain cases with prominent brow ridges. Their
skull bones were quite thick. Their faces were quite short and flat and
tucked under the brain, and they had broad noses.
Their jaws jutted forward but they lacked a modern-human-like chin.
Computed Tomography (X-ray) scans of their brain cavities indicate they
had modern-looking frontal lobes but quite archaic-looking anterior, or
parietal, lobes. They also had large molar teeth.Dr Curnoe and
colleagues put forward two possible scenarios in their PLoS One paper
for the origin of the Red Deer Cave population.One posits that they
represent a very early migration of a primitive-looking Homo sapiens
that lived separately from other forms in Asia before dying out.
Another possibility contends that they were indeed a distinct Homo
species that evolved in Asia and lived alongside our own kind until
remarkably recently.A third scenario being suggested by scientists not
connected with the research is that the Red Deer Cave people could be
hybrids."It's possible these were modern humans who inter-mixed or bred
with archaic humans that were around at the time," explained Dr Isabelle
De Groote, a palaeoanthropologist from London's Natural History Museum.
"The other option is that they evolved these more primitive features
independently because of genetic drift or isolation, or in a response to
an environmental pressure such as climate."Dr Curnoe agreed all this was
"certainly possible".Attempts are being made to extract DNA from the
remains. This could yield information about interbreeding, just as
genetic studies have on the closely related human species - the
Neanderthals and an enigmatic group of people from Siberia known as the
Denisovans.
Whatever their true place in the Homo family tree, the Red Deer
People are an important find simply because of the dearth of well dated,
well described specimens from this part of the world.And their
unearthing all adds to the fascinating and increasingly complex story of
human migration and development."The Red Deer People were living at what
was a really interesting time in China, during what we call the
epipalaeolithic or the end of the Stone Age," says Dr Curnoe.
"Not far from Longlin, there are quite well known archaeological
sites where some of the very earliest evidence for the epipalaeolithic
in East Asia has been found.
"These were occupied by very modern looking people who are already
starting to make ceramics - pottery - to store food. And they're already
harvesting from the landscape wild rice. There was an economic
transition going on from full-blown foraging and gathering towards
agriculture."Quite how the Red Deer People fit into this picture is
unclear. The research team is promising to report further investigations
into some of the stone tools and cultural artefacts discovered at the
dig sites.The co-leader on the project is Professor Ji Xueping of the
Yunnan Institute of Cultural Relics and Archaeology.
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