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John Hawks
I think today's news about Toba volcanic shards in Pinnacle Point is really cool: "Humans thrived in South Africa through the Toba eruption about 74,000 years ago"
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John Hawks Mar 12
Replying to @johnhawks
I mean, we're talking about finding a few microscopic pieces of ancient glass from hundreds of kilograms of sediment. That's amazing!
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John Hawks Mar 12
Replying to @johnhawks
Many people may not realize that this kind of detective work is increasingly a routine feature of archaeology today. Ancient trace evidence has expanded our knowledge of human evolution!
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Michael Petraglia Mar 12
Replying to @johnhawks
I loved this title when you came out with it:
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John Hawks Mar 12
Replying to @MDPetraglia
I know! LOL. It's almost sad today in a way, because you just really want to be able to say something, anything about how such an observable event must have mattered.
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Michael Petraglia Mar 12
Replying to @johnhawks
It really is odd. And we have no evidence of massive extinctions in the proximal zone either.
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John Hawks Mar 12
Replying to @MDPetraglia
Well, I think there's a real opportunity now to revisit the relationships of paleoclimate and large/medium mammals. Where does climate matter, and where are species resilient?
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John Hawks Mar 12
Replying to @johnhawks
The Toba eruption was the largest event of the Pleistocene, but there were other big ones, too:
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Michael Petraglia Mar 12
Replying to @johnhawks @JulienLouys
Yes. But why creatures were so resilient to a super-eruption as shown by In SE Asia.
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John Hawks Mar 12
Replying to @johnhawks
Earth science has now invested a lot of interdisciplinary effort in cores, samples, and other evidence that has given us some great perspective on paleoclimates.
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Lee Drake Mar 12
Replying to @johnhawks @MDPetraglia
Climatic/environment processes (glaciation, deglaciation, freshwater Atlantic inputs, erosion) matter. Climatic/environmental events (eruption, earthquakes, storms) usually don’t.
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John Hawks Mar 12
Replying to @johnhawks
When you find that the most massive eruption in 2 million years had not even a hiccup's effect on human populations, that's pretty important.
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John Hawks Mar 12
Replying to @johnhawks
But Toba also shows how interdisciplinary science can go very wrong. It was 20 years ago that the idea of a Toba catastrophic bottleneck was first published.
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John Hawks Mar 12
Replying to @johnhawks
The idea was that genetic evidence for a bottleneck in the last 100,000 years might be explained by this volcano. It was a simple hypothesis, testable by multiple avenues of evidence.
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John Hawks Mar 12
Replying to @johnhawks
And within a short time, geneticists pointed out that the idea doesn't work. Human genes can't be explained by a bottleneck caused by a volcano. It didn't fit.
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SoggieBeastie Mar 12
Replying to @johnhawks
This is fascinating John. What is the current thinking on the causes of the bottleneck?
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John Hawks Mar 12
Replying to @johnhawks
The idea was based on a misunderstanding of genetics. But it just wouldn't die. Somehow grant reviewers never learned that the genetics didn't work.
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John Hawks Mar 12
Replying to @NessieforFM
In Africa, there's no good evidence for any bottleneck anymore. Out of Africa populations all show signs of a common bottleneck that probably reflects their founding from a small population.
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John Hawks Mar 12
Replying to @johnhawks
The irony is, I'm more excited about Toba now than I've ever been, just because it has given rise to renewed critical thinking about climate and resilience of human populations.
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SoggieBeastie Mar 12
Replying to @johnhawks
Ah, so no global bottleneck,. Thank you for taking the time to respond, that's most helpful.
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