Toba super-volcano catastrophe idea 'dismissed'

BBC News ^ | Jonathan Amos

[SunkenCiv]

The idea that humans nearly became extinct 75,000 ago because of a super-volcano eruption is not supported by new data from Africa, scientists say.

In the past, it has been proposed that the so-called Toba event plunged the world into a volcanic winter, killing animal and plant life and squeezing our species to a few thousand individuals.

An Oxford University-led team examined ancient sediments in Lake Malawi for traces of this climate catastrophe.

It could find none...

Researchers estimate some 2,000-3,000 cubic kilometres of rock and ash were thrown from the volcano when it blew its top on what is now the Indonesian island of Sumatra.

Much of that debris landed close by, piling hundreds of metres deep in places. But a lot of it would also have gone into the high atmosphere, blocking out sunlight and cooling the planet. Sulphurous gases emitted in the eruption would have compounded this effect...

They identified tiny glass shards mixed in with the muds almost 30m below the lake bed. The shards represent small fragments of magma ejected from a volcano that have "frozen" in flight.

"They're smaller than the diameter of a human hair, less than 100 microns in size," explains Dr Lane. "We find them by sieving the sediments in a very long process that goes through every centimetre of core." Chemical analysis ties the fragments to the Toba eruption.

Re-timed droughts

The shards are present only in traces, but indicate the eruption spewed ash much further than previously thought -- about twice the distance recorded in other studies.

But the investigation finds no changes in the composition of the sediments that would indicate a significant dip in temperatures in East Africa concurrent with the Toba eruption.

[SunkenCiv]

Toba traces: The volcanic glass fragments are thinner than human hair

[SunkenCiv]

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[SunkenCiv]

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[cripplecreek]

It would just about have to be something environmental. To me it seems unlikely that disease would spread very effectively among the people unless there was a lot more interaction than we’ve imagined.

Maybe a disease that jumped from a migratory species.

[muawiyah]

humans habitually swap the girls off to the neighbrs ~ and that ripples on down the line transporting genes from one side of the continent to the other even as the tribe as a whole moves in a completely different direction.

It's quite possible we'll never learn the reality of 'out of Africa' ~

[blam]

"They're smaller than the diameter of a human hair, less than 100 microns in size"

An average Caucasian hair is right at 100 microns in diameter. The hair of all other races are larger.

Now, Toba is a neat story and one fun to reckon with.

I've had my own doubts too when I first read about the Hobbits on Flores Island (very near to Toba) and their dating to 80,000+ years. They would have had to survive the Toba eruption too...so...

[cripplecreek]

Good point about marriage.

Or they could have all become socialists and died out naturally. Socialism does seem to be a civilization killer.

[bigheadfred]

Or they could have all become socialists and died out naturally.

I can't tell you this for a fact and only because I haven't done it (yet) but dying under socialism seems most unnatural.

[Theoria]

'The idea that humans nearly became extinct 75,000 ago because of a super-volcano eruption is not supported by new data from Africa, scientists say.'

Tell that to the Atlanteans.

[Theoria]

'The idea that humans nearly became extinct 75,000 ago because of a super-volcano eruption is not supported by new data from Africa, scientists say.'

Tell that to the Atlanteans.

[djf]

I’m very skeptical that it didn’t happen.

I’ve seen LOTS of confirming evidence using different disciplines.

The volcanic glass sediments match the sea-floor core sample data (which is a wealth of info by itself).

Something happened about 75,000 years ago. And except for the very central tropics, worldwide temps fell by 10 degrees Celsius for almost a thousand years!

[SunkenCiv]

Thanks blam.

[SunkenCiv]

Thanks cc.

[Tilted Irish Kilt]

djf~:” Something happened about 75,000 years ago. And except for the very central tropics, worldwide temps fell by 10 degrees Celsius for almost a thousand years!”

If my calculations are correct , I believe that the reported “ 10 degrees Celsius” for 1,000 years would compute to a 50 º temperature change in Fahrenheit.
If that would be occurring for 1,000 years , that would represent a short ‘ ice age’ , I believe .

[gleeaikin]

Prevailing winds being what they are, the Toba ask would probably have moved toward the east, and landed on Africa after much dispersion. Nevertheless, I am sure that world hominid populations took a significant hit after Toba, although probably less in parts of Africa. I have noticed that while there were a number of finds dated before that period, there was something of a gap until 10 to 20,000 years after Toba.

Temperature charts show a significant drop after Toba in a downward slope that is already noticeable. That being the case, Flores would have been larger because sea water levels would have been lower than today and grown as temperatures continued to drop. If they exploited seafood resources both animal and vegetable, they would not have starved, even if land resources had taken a significant hit.

For another interesting survival story, check out the Kow hominids in Australia. Apparently they were killed off around 12,000 years ago. In the Koch brothers exhibit of skulls and what they show about evolution, a Kow skull is identified as Homo Sapien. It is at the far right of the exhibit wall and in the lower area. However after looking at it very carefully, it seemed to me to have more Heidelbergensis characteristics than either Homo or Neanderthal. This could mean that these hominids arrived in Australia several ice age cycles ago when water was low, but were killed off by the arrival of the current native Australians who arrived around 40,000 years ago.

Here is a link with a long article about the Kow Swamp Homo argument. It even mentions the possibility of a Heidelberg or late Solo relationship.
http://www.canovan.com/HumanOrigin/kow/kowswamp.htm

Here is another find of non modern Australians. http://austhrutime.com/wlh-50.htm

Having read several other articles about this it seems that archaeologists in Australia are having the same problem with wanting to look at new data as we have seen in US regarding the “nothing before Clovis” mind set, or the failure to search under water for ice age shoreline cultural remnants.

[djf]

I would call it that. But I think the data they rely on for long-term climatology is not fine enough to show it. The Vostok data shows a major glacial maximum about 115,000 yrs ago, I’m not sure of Toba shows up.

[JimSEA]

Flores Island combines well with the current idea that the Bottlenecks were, in fact, the effects of relatively large migrations out of Africa. I’ve read that also that human tool kits have been found in India immediately on top of the Toba ash.

I’m sure something else will soon come along to again turn things upside down.

[muawiyah]

or ~ Toba was so huge it just flumed most of the debris into outer space!

That stuff would still be coming back

Should still be detectable.

[PIF]

If I might add my 2 cents:

While everyone is looking at the impressive release of rock and aerosols for the Bottleneck, I think there is an overlooked factor which may be the real culprit: Tsunami.

Tsunamis come in two versions: the first is uplift or subsidence - which was the 2004 variety - creates a rolling ocean wave like as a storm at sea.

The energy released by the uplift is dissipated and dispersed over a wide area. Toss a rock in a bathtub filled with water. The ripple is the wave, and while large were the rock entered the water, the wave becomes small at the edge as the energy dissipates.

The 2004 tsunami, centered near Toba, caused massive loss of life where the wave came ashore, but only went ashore as far as the energy would push it.

The second tsunami version is collapse - when rock collapses into or under the ocean. This version makes a standing wave.

Standing wave tsunamis, unlike their cousin rolling wave tsunamis, builds to a height in direct proportion to the falling distance and mass of the collapsing formation. The farther it falls, the larger the formation, the larger the wave created. The energy here is massive. Slide a bucket of rocks down the side of the bathtub and the wave created continues at the same height until it reaches the opposite end of the tub.

The only real world example I know of this sort is a bay in Alaska - there is a video of this taken by a crabber. The far wall of the bay collapsed creating a standing wave which scoured the bay down to bedrock of everything up to the height of the wave.

Another predicted wave could be created by the collapse of the west side of the Canary Islands. This wave could be from several thousand feet to three miles high and hit the East Coast of the US stopping only at the top of the Allegheny Mountains. Everything below the mountain tops would simply be gone - like it never existed.

It is possible that the initial stage Toba eruption pushed massive amounts of material into the ocean before the finial stage of the eruption. No matter what happened in the later stages of the eruption, the standing wave tsunami would have been created and traveling outward at whatever height it was until the wave met some formation taller that it was. Everything below that would have be erased - including all the people living below the height of the wave in all the lands bordering the Indian Ocean.

I don't know if there is any evidence for this, nor if anyone has looked.

Another thing this climate change researcher overlooked is the effect of inhalation of those volcanic glass particles - inhaling glass particles will cause hemorrhaging in the lungs and death.

“... it's just too simplistic ...” And why does every explanation have to be complex to be true, Ms Lane?
Her specialty: Tephrochronology: a geochronological technique that uses discrete layers of tephra —volcanic ash from a single eruption—to create a chronological framework ...

[lepton]

F= C*1.8 + 32
10°C equals a total of 50°F

DF = DC * 1.8
A change of 10°C equals a change of 18°F