Did Only 6,000 Humans Really Survive the Toba Eruption?

[DoggerDan]

Just heard this line on a TV show that's been known to mix fact and fiction. When they do mention facts, however, they've always been reliable.

They said 75,000 years ago there was a horrific ice age and that only 6,000 people survived.

Is this true? I spent the last half hour browsing the Internet, but couldn't find historic population data or curves.

 

[jackmell]

That's a lower-limit on what some feel was a drastic reduction in population at that time. Can't comment on the details without reviewing. You can do that.

 

[skeptic2]

What was the name of the show and what network was it on?

 

[jackmell]

Here's a reference:

http://news.bbc.co.uk/2/hi/science/nature/166869.stm

Just google "Near extinction of humans"

 

[DoggerDan]

Here's a reference:

http://news.bbc.co.uk/2/hi/science/nature/166869.stm

Just google "Near extinction of humans"

I think that's it. The dates and numbers vary a bit, but not much, less than a factor of two, so it's within parameters.

So how does it feel to have passed through an evolutionary recent geological or biological bottleneck? Feels good! Yee-hah! We made it!

So, why the long face?

Question is: What's next? Do we do it, or screw it?

 

[Ryan_m_b]

This was the http://en.wikipedia.org/wiki/Toba_catastrophe_theory" that some estimates suggest took humans down to just 1000 breeding pairs.

 

[Andre]

The Toba event may be seen ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/chem/volcano.txt like this:

• DATA:
  
  age (yr) total sulfate (ppb) volcanic sulfate
  
  70895.50- 190.90- 0
  70923.50- 235.20- 0
  70977.50- 265.06- 17
  71004.50- 244.01- 1
  71031.50- 264.88- 61
  71058.50- 639.71- 466
  71085.50- 127.22- 0
  71112.50- 94.42- 0
  71139.50- 138.78- 57
  71166.50- 85.60- 9
  71193.00- 66.05- 0
  71219.00- 64.47- 0
  71245.00- 48.89- 0
  ..

It's certainly the biggest spike by far, but a few thousand years earlier than other datings

That result would not support the idea of a millenium scale return to glacial conditions. Also the impact on populations -obviously significant- but probably purely theoretically, a hypothesis waiting for supporting evidence. Here is some work: http://www.sciencedirect.com/science/article/pii/S1040618211005362

 

[Astronuc]

Genetic evidence suggests that Human population size fell to about 10,000 adults between 50 and 100 thousand years ago.

Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans.
by Professor Stanley H. Ambrose,
Department of Anthropology, University Of Illinois, Urbana, USA
Extract from "Journal of Human Evolution" [1998] 34, 623-651

http://www.bradshawfoundation.com/stanley_ambrose.php (this site seems a bit too commercial for my taste, but interest stuff to look at)

 

[Evo]

I've found several studies that show near extiction ~1 million years and ~70,000 years ago.

This article mentions both.

http://www.scientificamerican.com/article.cfm?id=early-human-population-size-genetic-diversity

 

[Andre]

Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans.
by Professor Stanley H. Ambrose,
Department of Anthropology, University Of Illinois, Urbana, USA
Extract from "Journal of Human Evolution" [1998] 34, 623-651

http://www.bradshawfoundation.com/stanley_ambrose.php (this site seems a bit too commercial for my taste, but interest stuff to look at)

Maybe the site is not devoid of some bias. But maybe we should take a closer look at this. Notice that it's published in 1998, saying:

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.

using this to illustrate:

Now the ice cores was a big project in the 1980s and most publications came in the 1990s, so in 1998, maybe they could also have shown this:

source

see that in the timeframe if the Toba event (71-75 ky) there is the Dansgaard Oeschger cycle #20, which roughly looks like all another cycles. Can anybody justify that this particular cycle was caused by the Toba event? It occurs that the "1000 years of the lowest ice core oxygen isotope ratios" is a bit hard to substantiate. Obviously science moves fast enough to supersede hypotheses like that, which may be treated elsewhere as rock solid facts.

Also my aforementioned recent http://www.sciencedirect.com/science/article/pii/S1040618211005362 (behind pay wall) gives a comprehensive over view of the presence of hominidae in India, mentioning areas with a constant presence from the early Pleistocene until now with no evidence of absence after Toba. Also it does not attempt to estimate the number of casualties and again, it seems that any number of survivors of the event are estimates not based on any evidence.