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.
Is your argument based on population pressures or simple malevolence?
Both, but the latter factor to a somewhat greater extent than the former.
All of N. African continent once had a wetter climate. Bones of non-desert animals have been found there.
Remember the recent theory about the Sphinx showing unmistakable signs of weathering from water?
REDATING THE GREAT SPHINX OF GIZA
by Dr. Robert M. Schoch © 1992
" If the Great Sphinx of Giza was weathered heavily, and at an early period in its existence, by precipitation, this suggests that it initially may have been carved prior to the last great period of major precipitation in this part of the Nile Valley. Egypt was subjected to erratic floods and what is sometimes referred to as the "Nabtian Pluvial" (a period of relatively heavy rainfall) from 12,000 or 10,000 to about 5,000 years ago; and it has been suggested that there were sporadic but relatively heavy rains during the Fourth Millennium (4000 to 3000 B.C.), and a less and climate along the Nile as late as 2350 B.C. (with relatively wetter conditions and unusually high Nile inundations recorded sporadically during historical times).[10] "
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First historical example of white flight.
Wadi Bakht A long wadi along the south-eastern side of the Gilf Kebir. A large dune blocked the wadi near it's middle, forming an extensive lake behind the sand dam. Unlike Ard al Akhdar, the dune is still present, and the lakebed is uneroded, as if it were drained just a few weeks ago. The shores and lakebed are littered with the traces of the prehistoric inhabitants.
Brilliant — not
Give it a rest
I guess they wrote travelogues.
The African origin of early modern humans is increasingly disputed. "News" like this just looks like desperation to hold on to a sacred old theory in danger of losing out to new discoveries.
But it’s *dry* heat...
....................
SUPERCROC "SuperCroc" Fossil Found in Sahara
and we all know how corcodiles LOVE *dry* heat!
“The African origin of early modern humans is increasingly disputed.”
By whom, in which journals, at which institutions, and based on what evidence?
New Fossil Study Rejects “Eve Theory” And Supports Diverse Ancestry Of Modern Humans
The ancestors of modern humans came from many different regions of the world, not just a single area, according to a University of Michigan study published in the current (Jan. 12) issue of Science. The study, by U-M anthropologist Milford H. Wolpoff and colleagues, is one of just a few to base its controversial conclusion about the origin of the human species on a comparison of actual human fossils-—early modern and archaic fossil skulls from around the world...
http://www.sciencedaily.com/releases/2001/01/010111194453.htm
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Hidden in General Chat already. Someone sure doesn’t want anyone to see science stuff on FR.
Disregard, I was wrong. Meant to post on the DNA found in chewing of leaves thread.
It’s inevitable that the global warming propaganda follows the same path of development. :’)
Science topics are supposed to be posted in Chat (which is where the Topics selector has headings like “Astronomy” and “Science”) — FreeRepublic is primarily a political site.
In the early era of modern humans between 120-200kya they were already evolved to jog over 50 miles a day on a near perpetual basis and swim large channels separating the east coast beaches in the region where all existing evidence suggests they lived. A long period of good weather and rainfall to the immediate north of their domain would simply give them expanded room to explore.
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