Posted on 28/01/2011
Jebel Faya rockshelter from above, showing eboulis blocks from roof collapse and the location of excavation trenches
An international team of scientists – including Dr Simon Armitage from Royal Holloway, University of London – have rejected the existing view that modern humans left Africa around 70,000 years ago. Their discovery of ancient artefacts reveal that humans left Africa at least 50,000 years earlier than previously suggested and were, in fact, present in eastern Arabia as early as 125,000 years ago.
These ‘anatomically modern’ humans – you and me – had evolved in Africa about 200,000 years ago and subsequently populated the rest of the world. “These findings will stimulate a re-evaluation of the means by which modern humans became a global species,” says Dr Armitage from the Department of Geography.
The new study, published today (28 January) in the journal Science, reports findings from an eight year archaeological excavation at Jebel Faya in the United Arab Emirates.
The researchers analysed the Palaeolithic stone tools found at the site and discovered that they were technologically similar to tools produced by early modern humans in east Africa, but very different from those produced to the north, in the Levant and the mountains of Iran. This suggested that early modern humans migrated into Arabia directly from Africa and not via the Nile Valley and the Near East as is usually suggested.
The direct route from east Africa to Jebel Faya crosses the southern Red Sea and the flat, waterless Nejd Plateau of the southern Arabian interior, both of which represent major obstacles to human migration. However, Professor Adrian Parker of Oxford Brookes University studied sea-level and climate change records for the region and concluded that the direct migration route may have been passable for brief periods in the past. During Ice Ages, large amounts of water are stored on land as ice, causing global sea-levels to fall. At these times, the Bab al-Mandab seaway of the southern Red Sea narrows considerably, making it easier to cross.
Natural climate changes at the end of Ice Ages cause rainfall over the Nejd Plateau to increase, making the area habitable. Professor Parker explains: “By 130,000 years ago, sea-level was still about 100m lower than at present while the Nejd Plateau was already passable. There was a brief period where modern humans may have been able to use the direct route from east Africa to Jebel Faya.”
Dr Armitage calculated the age of the stone tools at Jebel Faya using a technique called luminescence dating. His ages revealed that modern humans were at Jebel Faya by around 125,000 years ago, immediately after the period in which the Bab al-Mandab seaway and Nejd Plateau were passable.
“Archaeology without ages is like a jigsaw with the interlocking edges removed – you have lots of individual pieces of information but you can’t fit them together to produce the big picture,” he says. “At Jebel Faya, the ages reveal a fascinating picture in which modern humans migrated out of Africa much earlier than previously thought, helped by global fluctuations in sea-level and climate change in the Arabian peninsula.”