Which Way did Humans Travel ‘Out of Africa’?
It is a widely held and scientifically viable belief that humans originated in sub-Saharan Africa some 150 to 200 thousand years ago. However our migration away from there, to populate immediate areas and, later, the world, is not so easily ascertained.
Archaeological evidence has thrown up question marks for previous explanations. Tracking mitochondrial DNA has shown travel patterns across the entire planet. But no one migration explanation has been able to properly explain all the evidence.
Now a team led by the University of Bristol has published a paper in this week’s edition of Proceedings of the National Academy of Sciences, which presents a new theory for our most likely route out of sub-Saharan Africa.
Looking at a map of Africa, sub-Saharan Africa is everything that is not the Sahara Desert. A massive expanse, the Sahara is the planet’s largest hot desert (second largest desert after Antarctica). To travel across it to where humans ended up is a massive challenge today, let alone hundreds of thousands of years ago.
But the team from Bristol University has suggested that wetter conditions existed much further north than previously believed. As a result, a wet corridor through Libya might have existed, allowing for early human migrations to avoid dying in what we know as today’s Sahara.
"Space-born radar images showed fossil river channels crossing the Sahara in Libya, flowing north from the central Saharan watershed all the way to the Mediterranean,” said Anne Osborne, lead author on the paper. “Using geochemical analyses, we demonstrate that these channels were active during the last interglacial period. This provides an important water course across this otherwise arid region."
The researchers traced the isotopic composition of snail shells taken from two sites in the fossil river channels and from shells of planktonic microfossils in the Mediterranean. Despite being hundreds of kilometers from the volcanic rocks in the mountains of the Saharan watershed, previously believed to the limit of the wet region in our early ancestors time, these shells had a distinctly volcanic signature that could only be explained by water flowing from the volcanic mountains.
Dr Derek Vance, senior author on the paper, added: "The study shows, for the first time, that monsoon rains fed rivers that extended from the Saharan watershed, across the northern Sahara, to the Mediterranean Sea. These corridors rivalled the Nile Valley as potential routes for early modern human migrations to the Mediterranean shores."
Posted by Josh Hill.
http://www.eurekalert.org/pub_releases/2008-10/uob-ww101308.php
Images: A map showing the sample locations mentioned here, plus other images of the Sahara, can be downloaded from here: https://www.bris.ac.uk/fluff/u/inclel/hLpdnnvzzmnVVGYNlnETAAy1/
The article and related research is truly interesting.
However there is NO evidence that the sub-Sahara populations had mass migrations to Europe.
If that happened there were 'heavy reasons' to do that.
Some have infered that the climatic changes and related desertification were the main reasons for those populations or big groups to migrate to north.
The natural pathway however was unlikely the MED sea.
NO cruiser velles existed in those days.
Migration was through the Suez canal (that likely was NOT xisting in those days) to Naer Asia (Iraq),India and central Asian areas where DNA of actual men has recently been found to be at all similar-identical to that of old African humans.
If the straits of Dardanelli was viable in those remote days some gropus may be ended to east European areas.
BUT again this is 'pure inference ...while Neanderthal remnants have been found throughout Europe....and these are facts.
NO we do not have any answer YET to this fascinating question : 'How - when the Sapiens appeared in Europe'???
Posted by: claudio | October 19, 2008 at 01:34 AM
Why doesn't this scientist calculate that the sea levels was different at 150 to 200 thousand years ago?
Different sea levels at this time should also mean that the rain falls at different parts of the world than today.
Couldn't Sahara at this time have been a tropical paradise?
Some other scientists have found fossils in Sahara that suggest that!
Doesn't scientist read others scientist studies?
Posted by: Gagarin Miljkovich | October 19, 2008 at 06:19 PM