A favorable climate
If early modern humans were on the verge of leaving Africa today, the Arabian Peninsula would not likely be the most enticing route. The current global climate is currently vastly different than it was 200,000 to 130,000 years ago. As a global ice age locked up much of the Earth's water in frigid poles, sea levels receded, narrowing straights practically down to large lakes. By the end of the glacial period, water levels in the Red Sea would have been more than 100 meters lower than they are currently.
As the glaciers began to thaw, weather patterns would have shifted, bringing the Indian monsoon system to drench Arabia with rains, bringing with them greenery and freshwater lakes and rivers. This transitional time, Adrian Parker, also of Royal Holloway and a member of the research group, explained on the Wednesday conference call, was the chance climatic opening during which it made sense for H. sapiens to endeavor crossing the then-small sea.
"This led to a brief window of time when sea levels were still low, and Arabia experienced a wetter climate," Parker said.
After the makers of the C group of tools arrived in Arabia, continued glacial melting would have raised sea levels again, making more trans–Red Sea trips less likely. But, Uerpmann noted, "another window opened shortly after this event, increasing monsoon during the full interglacial enabled hunter–gatherers to cross the desert separating south[ern] Arabia from southeast[ern] Arabia. A drop in sea level during the subsequent cooler period provided an opportunity to reach parts of Mesopotamia, extending much farther into what is now the Persian Gulf and the Iranian coast—and the Indian subcontinent could be reached [from there]."
The climatic conditions so favorable to human expansion did not last indefinitely. The Jebel Faya archaeological site has yielded evidence from the Neolithic, Bronze and Iron ages as well, but the trail of artifacts has a gaping hole between 38,000 and 10,000 years ago when the area would have once again become desertlike.
The Paleolithic period climatic cycles' influence on early human dispersal likely have many more discoveries to divulge. The lowering and rising of seas and the shifting of precipitation patterns "happened many times during the Quaternary [period], and this leaves a lot of possibilities for human migrations," Uerpmann said. "And keeping this in mind might change our view completely."
Subscription Center
See what we're tweeting about
15 Comments
Add CommentAs I understand, fossilization most often occurs in very specific conditions - usually, I think, flowing water repeatedly overlaying a carcass with sediments. If so, environments that do not contain these conditions may not produce any fossils, regardless of any species populations that may exist there.
Reply | Report Abuse | Link to thisIn this case, fossil finds do not provide any representative sampling of resident population geographical distributions, and the absence of fossil evidence does not indicate any absence of population residency.
A fascinating article that tantalises with an exciting vista of earlier human migration. But a lot more evidence will be needed to confirm if this is the case and people need to remain open minded and wait for that evidence.
Reply | Report Abuse | Link to thisWOW! I've never seen anything quite that ignorant or offensive posted here. There is only ONE species of human extant on earth now. If you don't believe me ask geneticists. No one human being is more than a fraction of one percent different than another genetically. Not only are we one species but we've got remarkably low genetic diversity for a species as numerous as we are. Written large? We're inbred as all get out. Modern human populations went through what's called a genetic bottleneck sometime in the last 80 thousand years or so. That means we nearly became extinct at some point in the relatively recent past. Every man woman and child alive today is descended from a group that was probably no larger than a couple thousand people possibly as small as 250.
Reply | Report Abuse | Link to thisThe great variety of surface variation in people is just that. Surface variation. While there are definitely some genetic distinctions from one geographical region to another and some of those distinctions are functionally important (IE specific mutations that confer resistance to parasites or the ability to digest milk into adulthood) none is sufficient to qualify any other group of humans on planet earth as a separate species. No matter how you slice it the differences are ridiculously tiny. There is more genetic variation from two different chimpanzee troops a couple miles apart in africa (Members of the same species, I might add) than there is in the entirety of humanity.
I strongly suggest you do a bit more reading... Maybe something not on a conspiracy website.
I will grant you one and only one point. Some of the differences in humans that occur regionally can be medically significant if current data are to be trusted, but again this doesn't pass muster in the big picture as a reason to define any group as being a separate species.
For the record ethical and moral people don't need a reason to avoid bigotry and racism. No justification is necessary for what is clearly ugly and wrong.
Man, the trolls come out of the woodwork on this site. Must mean SCIAM is doing a good job. The whack jobs feel threatened. Yeah I know calling them whack jobs isn't productive, but I'm having a mental health moment.
Reply | Report Abuse | Link to thisAnyway, outstanding article. :-)
Don't feed the trolls guys ......... Come on ! :)
Reply | Report Abuse | Link to thisIt is an indication of migration of a small group from Mars when Mars was alive and human beings were at the height of their civilization. Some clues may come from Mars after Russia is successful in their piloted mission to Moon.
Reply | Report Abuse | Link to thisdebu, I truly hope that was in jest. Otherwise I can't imagine why someone of your mental capacity is reading the Sci-Am website.
Reply | Report Abuse | Link to thisI agree Doug, Deb is wrong. Those artifacts are actually much older than thought. They were made by an advanced group of velociraptors, right before the big asteroid hit. Real question is, did they make it into space and survive? Think 'greys'. Note that there is no fossil evidence of H. Sapiens. Other question is: Is my theory more entertaining than Deb's? By the way, it is an interesting article.
Reply | Report Abuse | Link to thisI think this advanced group of people left some behind!
Reply | Report Abuse | Link to thisSpiff
Dispersal occurs in animal populations. Whenever a barrier can be overcome by a breeding pair or more, successful dispersal has happened.
Reply | Report Abuse | Link to thisWhat is called paleolithic includes groups of hominins that broke stone into useful tools. Paleontologists can discriminate among the techniques with which tools were made. These tools look and are described as requiring complex work.
An important point is that finders have proxy dated and found the approximate age of the tool leavers. At that time the Sahara and the Arabian deserts were quite different in climate.
It is doubtful that any significant number of preagrarian people were slaves. Expect hunters to eat meat. Hunter-gathers had to range within territories that were sufficient in size to thrive, and bringing slaves just increases mouths to feed. I leave you with a more obvious use for strangers with whom one disputes.
Significantly larger brains than our averages, were the norm until the agrarian revolution. Some theories associate larger brains with decreased disposition to subservience.
Consider that nation-states, and city-states, and their practices would be highly unlikely, as the characteristics of hunter-gatherers are individualistic relative to almost all present cultures, with bands being less than 20-30, only visiting others for short periods. The others with whom they visited were likely related, and friendly, as foot locomotion prevents breeding populations from distant travel and raiding.
Point? Commentators must look beyond their own biases.
Dominance has specific meanings in various fields of inquiry, and the pretension of dominance to which some commentators appear to adhere, is extremely temporary in a species that continually reforms coalitions in which individuals achieve social dominance.
To use resources is not dominance, but a characteristic of individuals and populations. The results of overblooming species tend to hold the seeds of their collapse.
Like other readers, I am curious as to the reasons for that population bottleneck which occurred after the period of this finding. Dispersed populations, if too thinned by a catastrophic or demographic effect, might find it hard to reconnect, and a cascade of loss occurs.
This tool in the picture, look to me like Homoerictus tools
Reply | Report Abuse | Link to thisThe tool in the picture look to me like Homoerectus tools
Reply | Report Abuse | Link to thisCan any one please tell 'why the migration along Nile is discarded and a coastal route is preferred'. Is it not a river route more vegetated and easy to get food? The earliest human being born and lived inland,is it not natural will be afraid of the vast expanse of water of the sea? Not that in this travel he had to cross long expanse of water to reach the Arabian peninsula as the sea level was very much low.
Reply | Report Abuse | Link to thisV.K.GUPTAN vkguptan@hotmail.com
I believe that most of human history is under water and once the means to study these artifacts happens the results will require rewriting the history books.It is quite possible that a number of very advanced civilizations have existed in the past 50,000 years.
Reply | Report Abuse | Link to this