Debunking Toba Catastrophe Theory

One of the most popular posts here is Tim Jones’ post, published almost 11 years ago on the Toba Eruption. Toba Catastrophe Theory was proposed first by Stanley Ambrose. Henry Harpending popularized it. In a nutshell, a genetic bottleneck has been observed in Homo sapiens occurring approx. 70,000 years ago that temporally correlated with a massive eruption of a volcano whose caldera is now Lake Toba in Sumatra.

Toba is thought to be the greatest known volcano to erupt. It is believed to have been 19 times more powerful than Mt. St. Helens. The ash that covered the skies is thought to have made the world 7 degrees colder. Over 90% of humans at the time are thought to have died, leading to a bottleneck of only 10,000 or so people to survive.

The density of plotted finds across the upper LBSR, ALBS, and SADBS at PP5-6. This figure shows the distribution of plotted archaeological and faunal materials at PP5-6. Each dark grey point represents a single artefact, bone or shell. The yellow dots are sediment samples collected for analysis. The white dashes indicate the extent of the stratigraphic aggregate indicated as LBSR, ALBS or SADBS on the right. See Supplementary Videos 1–4 for 3D renderings of these data
The density of plotted finds across the upper LBSR, ALBS, and SADBS at PP5-6. This figure shows the distribution of plotted archaeological and faunal materials at PP5-6. Each dark grey point represents a single artefact, bone or shell. The yellow dots are sediment samples collected for analysis. The white dashes indicate the extent of the stratigraphic aggregate indicated as LBSR, ALBS or SADBS on the right. See Supplementary Videos 1–4 for 3D renderings of these data

Last week’s Nature published a paper looking at two human sites located in the tip of South Africa, and ultimately debunks the claim. One site, an open campsite (Vleesbaai Area B (VBB)) and another more sheltered alcove (Pinnacle Point Site 5-6 (PP5-6)) housed humans during the Toba eruption. Looking at each strata of earth and analyzing exactly what these humans trashed before, during and after the catastrophic eruption the researchers were able to see a representation on human activity. The eruption of Toba left a signature layer of sediment that correlated with other known Toba sediment deposits.

Curiously, the group saw that these people who survived the eruption left behind more trash after the eruption than before it. That is counterintuitive. Putting aside the assumption that sites like this would be demolished during a catastrophic volcanic winter. But the contrary happened at VBB and PP5-6. Instead, these sites grew, they ate more, they invented new tools… The archaeological record at these sites prevaled despite the eruption.

It is possible these places were a refuge. But that also doesn’t correlate to any other animal, plant or other hominin bottlenecks of the same time. We know other animals and plants thrived, so why didn’t 90% of other species die?

So what exactly, caused the genetic population bottleneck? Founder effect, possibly. As  humans migrated, they became less dense. Smaller groups with less diversity entered Eurasia, and that became more pronounced as they wandered farther East. Those who remained in Africa remained more diverse.

 

3 thoughts on “Debunking Toba Catastrophe Theory

  1. Clear signs of climate refugees from Eurasia moving into Sub-Saharan Africa via the Bab-el-Mandab Straights. We have a sudden increase in activity at sites, accompanied by new technologies, change in culture and additional mtDNA and Y-Chromosomal haplogroups. While Sub-Saharan Africa was not significantly impacted, it is known the cloud from Toba encircled the Northern Hemisphere. Modern humans in Eurasia would not have been doing very well at all.

    It is shortly after Toba that the first arrowheads appear in the African record, Eurasian refugees entering Africa with this advanced technology would have been unstoppable if resited (especially with all hell raging behind them). Most likely they would have been quickly welcomed rather than opposed by people with nothing more than stone axes. We know today that South Africa was not the only region with modern humans at the time Toba exploded, they were spread from the Levant to Southeast Asia.

    I have written on this in my book, but it has not dawned on the scientific community just yet how elegant this solution is for the anomalous evidence.

  2. Coastal areas are refuges from inhospitable interiors. During long droughts in California the population moved to the coastal areas for food and fog captured water. It is likely the interiors were similarly less habitable after this event, too & related people and refugees naturally congregated where resources were available.

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