sábado, 8 de febrero de 2014

Near East crossroad of the Palaeolithic now questioned (Lebanon)

The Out-of-Africa model currently holds that anatomically modern humans (AMH) evolved and dispersed from Africa into Asia from about 50,000 years ago, and then continued on later into Europe. For this reason, palaeoanthropological evidence from the Near East assumes great importance, but remains of these early modern humans are extremely scarce.
Doubt over Palaeolithic migration route
The study published in PLOSone in September 2013  suggests they may have arrived in the Near East much later than previously theorised with a concurrent knock on effect that this region was not the single crossroads through which all early humans passed on their way to colonising the Eurasian landmass.
According to Dr Katerina Douka of the University of Oxford, who led the research, ‘Since the 1930s, many pre-historians have believed the Levant was a major strategic point for people moving from Africa into the Middle East and Europe ..and although it sounds a straightforward and obvious idea, these early humans didn’t necessarily follow the maps of today.’
If this new research is correct, the story may need to be rewritten about the early movement of our ancestors and exactly how they left Africa. Instead of colonising the Levant then moving into Europe, they may have first settled in the central Asian steppes before turning west.
Significant changes in human behaviour, cognition and innovation become sharply evident in the archaeological record of Eurasia at 45,000 years BP and demarcate the end of the Middle Palaeolithic and the onset of the Upper Palaeolithic period.

A key site

At the key site of Ksar Akil (Lebanon) ‘Egbert’, a now-lost AMH fossil and ‘Ethelruda’, a recently re-discovered fragmentary maxilla from the same site, are two rare examples where human fossils are directly linked with early Upper Palaeolithic archaeological assemblages and key to this new study.
Radiocarbon dates were taken from the contexts which Egbert and Ethelruda were recovered, as well as the levels above and below the findspots. In the absence of well-preserved organic materials, beads made from sea shells were used for the C14 dating, these items were used as adornments and are often considered a sign of complex symbolic behaviour akin to modern humans. It was impossible to date the remains directly as both of the individuals were missing and although part of Ethelruda‘s jawbone recently turned up the collagen had degraded too far to be used in the process.
Bayesian modelling allowed for the construction of a chronological framework for the Ksar Akil, which supported several conclusions. The model-generated age estimates place Egbert between 40.8–39.2 ka cal BP (68.2% prob.) and Ethelruda between 42.4–41.7 ka cal BP (68.2% prob.).
This showed that Egbert is of comparable age to the oldest directly-dated European AMH (Peştera cu Oase). Ethelruda is older, but no older than the modern human teeth from Cavallo in Italy.
The dating of the so-called “transitional” or Initial Upper Palaeolithic layers of the site may indicate that the passage from the Middle to Upper Palaeolithic at Ksar Akil, and possibly in the wider northern Levant, occurred later than previously estimated, casting some doubts on the assumed singular role of the region as a locus for human dispersals into Europe.

Central Asia and Siberia route

More research is required to examine other possible routes by which humans could have dispersed into Europe and Asia. The researcher is currently working on several projects in central Asia and Siberia – areas she thinks could form part of one such route.
When you look towards the East, there is mounting evidence for earlier colonisation with sites that are datable to older than than 50,000 years, which is unfortunately the absolute limit of how far back radiocarbon dating can be used.
Douka is working on a European Research Council-funded project (PalaeoChron) that uses another technique, known as optically-stimulated luminescence dating, which can go much further back into history – around half a million years.
She is convinced that anatomically modern humans had already populated central Asia and modern-day Russia before doubling back and colonising Europe in one or more waves of expansion.

Source: Past Horizons: http://www.pasthorizonspr.com/index.php/archives/02/2014/near-east-crossroad-of-the-palaeolithic-now-questioned

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