Posted on 08/30/2007 10:15:20 AM PDT by blam
Source: Geological Society of America
Date: August 30, 2007
Migration of Early Humans From Africa Aided By Wet Weather
Science Daily The African origin of early modern humans 200,000--150,000 years ago is now well documented, with archaeological data suggesting that a major migration from tropical east Africa to the Levant took place between 130,000 and 100,000 years ago via the presently hyper-arid Saharan-Arabian desert.
This migration was dependent on the occurrence of wetter climate in the region. Whereas there is good evidence that the southern and central Saharan-Arabian desert experienced increased monsoon precipitation during this period, no unequivocal evidence has been found for a corresponding rainfall increase in the northern part of the migration corridor, including the Sinai-Negev land bridge between Africa and Asia.
Passage through this "bottleneck" region would have been dependent on the development of suitable climate conditions.
Vaks et al. present a reconstruction of paleoclimate in the Negev Desert based on absolute uranium series dating of carbonate cave deposits (speleothems). Speleothems only form when rainwater enters the groundwater system and vegetation grows above a cave.
Today the climate in the Negev Desert is very arid and speleothems do not form, but their presence in a number of caves clearly indicates that conditions were wetter in the past. Vaks et al. dated 33 speleothem samples from five caves in the central and southern Negev Desert.
The ages of these speleothems show that the last main period of increased rainfall occurred between 140,000 and 110,000 years ago. The climate during this time consisted of episodic wet events that enabled the deserts of the northeastern Sahara, Sinai, and the Negev to become more hospitable for the movement of early modern humans.
The simultaneous occurrence of wet periods in the northern and southern parts of Saharan-Arabian desert could have led to the disappearance of the desert barrier between central Africa and the Levant.
The humid period in the Negev Desert between 140,000 and 110,000 years ago was preceded and followed by essentially unbroken arid conditions; thus creating a climatic "window" for early modern human migration to the Levant. Vaks et al.'s study suggest that climate change had an important limiting role in the timing of dispersal of early modern humans out of Africa.
Reference: Desert speleothems reveal climatic window for African exodus of early modern humans, Anton Vaks, Hebrew University, Institute of Earth Sciences, Edmond Safra Givat Ram Campus, Jerusalem 91904, Israel; et al. pages 831-834.
Note: This story has been adapted from a news release issued by Geological Society of America.
GGG Ping.
And global warming...
So, we are all descendants of wetblacks?.........
Of Africa - make sure you check the right box on your next minority only scholarship, set aside and quota job...
I thought everyone knew the forbidden zone was once a paradise!
When the census comes I check three boxes, white/caucasian, Asian, and white/hispanic.................
YEC INTREP
If we rule out boredom and wanderlust in these early men we must consider food shortages and inclement climate conditions.
Why leave a virtual paradise where the food grows on trees and bushes, the forest floor makes a comfortable bed, the water runs clear and plentiful and time clocks are millenia in the unanticipated future?
i still like how they open.....
the origin of early humans in africa...blah blah blah...is well documented. huh how about a theory?
when you build your house of cards on sand....
I dunno, I wonder why Peary and Byrd explored the arctic, Admunsen the antarctic, why Hillary climbed Everest, why Burton explored the source of the Nile and why Stanley looked for Livingston...because it was there?
One more reason. Why did the early Europeans leave for America?
Persecution.
Those places in Africa from where humans spread, humans still live, don't they? Maybe the ones that left, were chased away.
Uh, right, and the earth is still just 6,000 years old according to the Bible...
So, it looks to be a long time until the Negev is once more "The Land of Milk and Honey".
Totally out of the question — the earliest man had no knowledge of his whereabouts or that there was even a larger world out there.
As foragers they likey traveled only as far as daylight would allow a roundtrip.
That’s what they get for coming down out of the safety of the trees.
Again, unless the ones that stayed behind, hadn't chased the "foragers" away, in the first place.
Persecution still is an excellent motivator for abandoning known lands for newer ones.
“Out of Africa” is being proven false, one new discovery at a time.
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