Skip to comments.Late Pleostocene Human Population Bottlenecks. . . (Toba)
Posted on 12/16/2005 11:33:44 AM PST by blam
Professor Stanley H. Ambrose Department of Anthropology, University Of Illinois, Urbana, USA
Extract from "Journey of Human Evolution"  34, 623-651
The last glacial period was preceded by 1000 years of the coldest temperatures of the Late Pleistocene, apparently caused by the eruption of the Mount Toba volcano. The six year long volcanic winter and 1000-year-long instant Ice Age that followed Mount Toba's eruption may have decimated Modern Man's entire population. Genetic evidence suggests that Human population size fell to about 10,000 adults between 50 and 100 thousand years ago. The survivors from this global catastrophy would have found refuge in isolated tropical pockets, mainly in Equatorial Africa. Populations living in Europe and northern China would have been completely eliminated by the reduction of the summer temperatures by as much as 12 degrees centigrade.
Volcanic winter and instant Ice Age may help resolve the central but unstated paradox of the recent African origin of Humankind: if we are all so recently "Out of Africa", why do we not all look more African?
Because the volcanic winter and instant Ice Age would have reduced populations levels low enough for founder effects, genetic drift and local adaptations to produce rapid changes in the surviving populations, causing the peoples of the world to look so different today. In other words, Toba may have caused Modern Races to differentiate abruptly only 70,000 years ago, rather than gradually over one million years.
The Mount Toba eruption is dated to approximately 71,000 years ago. Volcanic ash from Mount Toba can be traced north-west across India, where a widespread terrestrial marker bed exists of primary and reworked airfall ash, in beds that are commonly 1 to 3, and occasionally 6 meters [18 feet] thick.
Tambora, the largest known historic eruption, displaced 20 cubic kilometres of ash. Mount Toba produced 800 cubic kilometres.* It was therefore forty times larger than the largest eruption of the last two centuries and apparently the second largest known explosive eruption over the last 450 million years.
*Mount St Helens produced a tiny 0.2 cubic kilometres.
Volcanic Winter, and Differentiation of Modern Humans
Mount Toba's eruption is marked by a 6 year period during which the largest amount of volcanic sulphur was deposited in the past 110,000 years. This dramatic event was followed by 1000 years of the lowest ice core oxygen isotope ratios of the last glacial period. In other words, for 1000 years immediately following the eruption, the earth witnessed temperatures colder than during the Last Glacial Maximum at 18-21,000 years ago.
For the volcanic aerosols to be effectively distributed around the earth, the plume from the volcanic eruptions must reach the stratosphere, a height greater than 17 kilometres. Mount Toba's plume probably reached twice this height. Most solar energy falls at low latitudes between the Tropics of Cancer and Capricorn, so eruptions that happen near the Equator cause much more substantial cooling due to the reflection of solar energy. Toba lies 2 degrees north of the Equator, on the Island Sumatra.
The reduction in atmospheric visibility due to volcanic ash and dust particles is relatively short-lived, about three to six months. Longer-term global climatic cooling is caused by the highly reflective sulphuric acid haze, which stays suspended in the upper atmosphere for several years.
Ice core evidence implicates Mount Toba as the cause of coldest millennium of the late Pleistocene. It shows that this eruption injected more sulphur that remained in the atmosphere fo a longer time [six years] than any other volcanic eruption in the last 110,000 years. This may have caused nearly complete deforestation of southeast Asia, and at the same time to have lowered sea surface temperatures by 3 to 3.5 degrees centigrade for several years.
If Tambora caused the " The year without a summer" in 1816, Mount Toba could have been responsible for six years of relentless volcanic winter, thus causing a massive deforestation, a disastrous famine for all living creatures, and a near extinction of Humankind.
The Volcanic Winter/Weak Garden of Eden model proposed in this paper. Population subdivision due to dispersal within African and other continents during the early Late Pleistocene is followed by bottlenecks caused by volcanic winter, resulting from the eruption of Toba, 71 ka. The bottleneck may have lasted either 1000 years, during the hyper-cold stadial period between Dansgaard-Oeschlger events 19 and 20, or 10ka, during oxygen isotope stage 4. Population bottlenecks and releases are both sychronous. More individuals survived in Africa because tropical refugia were largest there, resulting in greater genetic diversity in Africa.
Bahamas Coral Reef Chart
BLOMBOS CAVE : 77,0000 YEARS OLD
Small and portable, this red ochre stone is engraved with what must be "tally" marks. It is one of two such stones recently found in the Blombos Cave in South Africa and have been dated as being 77,000 years old, making them the oldest form of recorded counting ever found.
The stone is worn which probably indicated that it was constantly handled over a period of time, how long is impossible to tell. It looks as though the stone has been reused at least once before as the lighter marks appear to have been erased rather than worn away naturally.
If the dating is accurate this stone was used 5000 years before the Mount Toba eruption of 71,000 years ago. The evidence from the Toba eruption indicates that the world's population of Modern Man was reduced to a total of around 10,000 adults.
I expect that we'll eventually find that humans were stranded in South America during the Volcano Winter caused by the Toba explosion and were not re-united with the world's other humans until thousands of years later.
I grabbed Kwares Erupt program.
Tried to simulate Toba.
To get the amount of volcanic gunk to erupt that Toba did, you have to simulate an eruption lasting over one year.
Toba erupted its load in less than that.
I have heard speculation that during the last third or so of the last great ice age, worldwide population fell to the 10-20K range.
I guess we're talking about 12-15 K years ago.
Last I checked, ice was water.
I seem to recall Toba was a Caldera.. like the one sitting under Yellowstone... does Kwares Erupt even have the capacity to simulate a Caldera eruption?
I think you're thinking of the Last Glacial Maximum(LGM), 18-23,000 years ago. That was an extremely cold period and this Journey Of Mankind shows an extreme shrinkage of humans worldwide during that period. I've not seen any population figures associated with that period though.
Yes. Super Volcano status.
I've seen some discussion on up-grading the Thera eruption some...not to super volcano status though.
The above looks like a moderne style menorah. Very nice design.
Placemark, I look forward to reading this.
i have a question for you...how does the author know that those lines on the rock are tally marks and not just the grooves left when someone sharpened a stick or arrow head on that rock?
Stones used for sharpening tend to have more, and deeper scratches, and they are generally more central. Sometimes they have a single deep "V"-shaped groove.
This stone matches the world-wide pattern you find with non-sharpening (i.e., ceremonial, counting, etc.) stones.
Check out a book title "Patterns that Connect: Social Symbolism in Ancient & Tribal Art" by Schuster and Carpenter for illustrations.
Proud member of Haplogroup G2 :^)
Yes, but only up to a point.
Whew! I was hoping you'd step forward and answer that one, lol.
ping for great discussion topic
Looking back into the program, it simulates only two types of caldera, Valles type, and Mazama type.
"i have a question for you...how does the author know that those lines on the rock are tally marks and not just the grooves left when someone sharpened a stick or arrow head on that rock?"
Sharpening stones do not have regular geometric patterns on them. A stone used for sharpening wooden tools generally has a single groove in it, making it easier to put a point on a wooden shaft.
Arrow heads are made by flaking, not grinding, so they're irrelevant. Ground stones, such as some other common tools were ground on a large stone, which will have fairly large depressions, not lines, worn into it.
Well you have at least described a few things that it isn't. I see your point on arrow heads. Are they all made only by chipping? What about bone? Is it possible they were sharpening bone and the lines cross because they switched from the left hand to the right hand? If it is a numbering system...what number is it? How do you prove that those triangles were used as a counting system? How do you know that someone wasn't trying to groove scales on a rock that looked like a fish? It is interesting...I just don't understand how archaelogists say things with such certainty some times.
"Well you have at least described a few things that it isn't. I see your point on arrow heads. Are they all made only by chipping? What about bone? Is it possible they were sharpening bone and the lines cross because they switched from the left hand to the right hand? If it is a numbering system...what number is it? How do you prove that those triangles were used as a counting system? How do you know that someone wasn't trying to groove scales on a rock that looked like a fish? It is interesting...I just don't understand how archaelogists say things with such certainty some times."
I can't fully answer your question. I'm not an archaeologist. But tally stones are pretty common items, archaeology speaking. I assume that they've been related to some form of tallying or counting based on other information.
I don't normally just automatically reject something just because I don't have all the information myself. If a journal article refers to an object by its use, then I assume they have reason to do so.
If I waited until I researched everything that interests me somewhat, I'd have to drop a lot of things from my life. So, I generally work with what the specialists in an field have to say. If they're wrong, then I'll find some other explanation at another time.
What I don't do is assume the information is incorrect, based on nothing but my very limited personal knowledge. I do know about some toolmaking items, since I have a small collection of my own. Beyond that, I pay attention to the experts.
Given how benign nature has been over the last 20,000 years, people forget how awful things can get. All it would take is another of these things to wake up, and there goes civilization down the drain for another hundred centuries.
I didn't assume anything. All I did was ask a simple question about the process that archaeologists use to verify the statements that they make. Is it a theory? Are there similar stones being used by indigenous people today? There is a difference between asking someone to describe how they came to a conclusion and just outright dismissing something. Since you said yourself that you are no expert in archaeology perhaps we should leave the question for someone that is. The question was intended to help me understand how much of archaeology is based on science and what part is pure hypothesis.
Archaeologists deal with patterns and extrapolate from the known to the unknown. Many peoples studied by anthropologists used counting devices, and some are similar to those seen in the past (by archaeologists).
Archaeologists also do replication, and study how various items are made. Projectile points are a good example. I had a course in grad school titled "Lithic Technology" in which we learned to make points of various kinds and studied the debitage which resulted. (Some of us called it elementary finger-bleeding.)
In an earlier post, I recommended the book by Schuster and Carpenter titled "Patterns that Connect." That book is somewhat expensive, but is available at many libraries. Their larger multi-volume set is available at some libraries. In these volumes you will see literally thousands of examples of art from around the world. That is part of the archaeological "database" that lets us make educated guesses about artifacts when them appear in other contexts.
Archaeology is not as easy as it looks, and most of its practitioners are always studying and learning.
Bump for later read...
I think archaeology is fascinating. It is almost like building a case based on circumstantial evidence. I was reading online somewhere about the distinctly negroid features in some of the mayan carvings as well as what looks like an elephant trunk which obviously begs the question where the hell did they run into an elephant? The author was theorizing that there may have been ancient trade routes that were far more developed than previously thought based on various similarities between artifacts from different countries. Pretty cool stuff.
Yup. That's just one of a number of things that could happen. After studying the effects of asteroid and comet impacts onto the earth I'm convinced that catastrophies through out history/prehistory have had a major effect on who we are.
We do appear to be in a quiet period presently for worldwide affecting events.
Chaac upon Temple
Chaac is featured again in the Puuc style. This face is part of the Temple of the Magician at Uxmal, a major Puuc city. The face of Chaac appears repeatedly down the sides of the stairway on the temple's western side. Because of the relatively dry nature of the northern Maya Lowlands in Yucatán, rain was a much higher demand than in the wetter highlands in the south. Therefore the price for rain was higher - during times of drought, more sacrifices to Chaac would be performed or the Maya would begin to pray to even more rain deities if necessary.
Isn't it weird how it bears a resemblance to an elephant or the Hindu God Vishnu?
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Another view including frontal face shot..
Arrows are a late invention many thousands of years later than that stone.
Toba near-extinction ping...
Looking at the stone and living in the mountains, I would have thought it was a map to some important deposit like salt or flint. Go over so may mountains, etc.
Thanks for the ping. The highs and lows on the temperature chart illustrate the fact there have been many extinctions -- but some living things have survived each extinction. Not gradual evolution, but flourishing intervals punctuated by massive extinctions caused by impacts and also by volcanos. Perhaps the axiom should be modified from "survival of the fittest" to include "survival of the luckiest."
18 meters of ash is incredible.
I wonder how future generations of mankind could cope with that type of devastation? I think we could -- if enough science types survived the initial chaos.
Another thought - would this not have caused massive extinctions among non-human animals, as well?
Humans and mastodons did coexist in the Americas -- I have no idea when.
I bet they were conservatives. Liberals ("give me half your pie, because I didn't make one") came later, after the conservatives rebuilt the world.
Thanks for this very interesting post. These folks doing the genetic marker tracking are doing great work. It is interesting to note that, if traces of hominid occupation of North America can be traced a far back a 35,000 years, This means that these early people traveled fast, far, and wide. Simply amazing.
"I expect that we'll eventually find that humans were stranded in South America during the Volcano Winter caused by the Toba explosion and were not re-united with the world's other humans until thousands of years later."
From my post #2.
ping for Toba and super caldera research
I think ice is considered a mineral whereas water is considered a liquid. I believe in the context of the possible flood, the writers were considering water as a liquid. Also it is pretty tough to float an ark on ice.
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