Skip to comments.Ancient drought 'changed history'
Posted on 12/08/2005 3:58:46 AM PST by TigerLikesRooster
Ancient drought 'changed history'
The evidence comes from sediments drilled up from the beds of Lake Malawi and Tanganyika in East Africa, and from Lake Bosumtwi in Ghana.
It shows equatorial Africa experienced a prolonged period of drought.
It is possible, scientists say, this was the reason some of the first humans left Africa to populate the globe.
Certainly, those who remained on the continent at that time would have had to be extremely resilient to make it through such hard times.
"This was a profound impact on the landscape," said Christopher Scholz, from Syracuse University, US.
"So it must have had a major impact, not just on humans but on all species in equatorial Africa at this time."
Dr Scholz presented data from the drilling project here at the Fall Meeting of the American Geophysical Union.
The cores reveal that prior to 75,000 years ago, Lake Malawi, which is currently an inland sea some 550km long and 700m deep, was reduced to a couple of pools no more than 10km across and 200m deep.
Only a prolonged continent-wide drought could have had this effect. What makes the timing so fascinating is that it ties in with the "Eve hypothesis" of human evolution.
Genetic studies suggest modern human society is descended from a group of around 10,000 individuals who lived in East Africa at the time of this crisis.
Immediately after its end, human populations started to expand rapidly - and many of our ancestors began moving out of Africa and into the Middle East, Asia and Europe.
Scientists are increasingly convinced that tragedies in the deep past have shaped human evolution.
The intriguing thought is that we owe our existence to a small band of survivors who clung on to life during a crisis of epic proportions or who simply decided they had to move to find water.
"And, also, there may be a connection with the exodus of early modern humans out of Africa and this climatic release.
"There's been recognition that speciation of hominids is controlled by environmental factors - whether that's long-term changes in aridfication in Africa or perhaps the dramatic increase in variability in environmental conditions, such as in precipitation, temperature, and so forth."
Out of Africa, Ping!
Is it possibly to truly "change history" as the headline states?
I guess we can't blame this on global warming or Bush. Never mind, the dems will think of something around that.
I guess this is why you see so many Wildebeast in American, they all migrated out of Africa because if this drought, right? Changing history isn't possible unless you are a Democrat or a communist. History is what it is, the drought happened therefore it is the history of that time.
What about all those time travelers with their Mr. Fusion-equipped SUVs that will be going back there to cause Global Warming®? I guess you aren't aware that Bushco (with KKKarl Rove as the CEO) is developing time travel technology. It's true, I will see it on the Internet as soon as I hit the "Post" button.
If history only goes back about 5000 years, what history was there to change?
It should have been "natural history," not human history.
You can "revise" history.
Rather than "changing" history, this looks more like it "rerouted" it.
This was covered pretty well in a PBS documentary (Nova, I think) that focussed on the back-tracking of human history via the Y chromosome. However, IIRC, they felt the drought, due to an Ice Age, was comewhat more recent than 70,000 years.
Evolution in Your FaceLake Victoria, Africa's largest lake, is home to more than 300 species of cichlids. These fish, which are popular in aquariums, are deep-bodied and have one nostril, rather than the usual two, on each side of the head. Seismic profiles and cores of the lake taken by a team headed by Thomas C. Johnson of the University of Minnesota, reveal that the lake dried up completely about 12,400 years ago. This means that the rate of speciation of cichlid fishes has been extremely rapid: something on average of one new species every 40 years!
by Patrick Huyghe
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Alternatively, it could mean there was a residual reservoir of cichlid fishes, of which the researches are currrently unaware.
Especialy so, since that would help explain where the fish came from in the first place, if the lake actually "completely" dried up. 300 species don't come from no ancestral population, but could easily come for a remnant pool of 300 ancestral species.
In Texas a species of snail darter (minnow) located in the San Marcos went on the endangered species list and caused about 5 Billion dollars in changes to the Texas water plans.
Strangely enough, these springs went completely dry during the lenghty drought of the 50s--and no one has successfully explained how these snail darters survived to become a listed species in the 80s.
I agree. Probably Toba. I've seen estimates as low as 2,000 for the worldwide human population after Toba. Most are closer to 5,000 with some ranging up to 10,000. Even so, not many people for the whole world.
The Last Glacial Maximum(LGM) 18-23,000 years ago thinned out the human population dramatically too.
I'm a proud member of Haplogroup G2
See my post #24. It may have been the Last Glacial Maximum, the coldest period of the Ice Age.
Or that fishy Gramma had been drinking wacky juice and squirted out ALL these critters herself!
(This assumin' is FUN! I'll have to do it more often!)
I'da moved South!!!
Glaciers locking up all the water so that streams and lakes go dry.....
Yes, but much more than that. The glaciers suck the moisture out of the air, which is how they grow. The area along the face of a giant glacier can be as dry as a desert.
I thought only historians and politicians could do that. : )
The PBS program I referred to was talking about a drought and drop in sea-level that resulted from an Ice Age, when glaciers bound up a great deal of the water in the atmosphere and the oceans, forcing those in interior Africa like the clicking bushmen we are descended from to move.
Coitenly. The archive's an archive after all...
How'd we ever get from NW to GW???
Seems to me, if it gets too warm, all we gotta do is pop of a few nukes!!
Al Gore just called. Turns out it was Global Warming that caused this. As the inventor off the internet, Al proclaims that this was a precursor event to show how bad things could get...
Unfortunately the oral history of the local inhabitants failed to carry the message accurately to the present day.(/sarc)
"The last glacial maximum 18,000 to 23,000 years ago."
There were a number of major volcanic events from 28 kya to 22 kya, that appeared to cause a stepwise decrease in temperatures. The one for 22,000 years ago was Mt. Sakura-jima in Japan. It left a crater 15 miles in diameter, which is now a great bay with a much smaller volcano of the same name on one side. I would love to get time and size data on a few other possible major volcanic events for that period.
|GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach|
Just updating the GGG info, not sending a general distribution.12,400 years ago? Hydrologic cycle came to a screeching whoa for some reason, hmm, what could it have been?Evolution in Your FaceLake Victoria, Africa's largest lake, is home to more than 300 species of cichlids. These fish, which are popular in aquariums, are deep-bodied and have one nostril, rather than the usual two, on each side of the head. Seismic profiles and cores of the lake taken by a team headed by Thomas C. Johnson of the University of Minnesota, reveal that the lake dried up completely about 12,400 years ago. This means that the rate of speciation of cichlid fishes has been extremely rapid: something on average of one new species every 40 years!
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