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Toba Supereruption Didn’t Cause Volcanic Winter
74,000 years ago, the Toba supereruption caused spectacular destruction on the island of Sumatra. It has been hypothesised that the eruption triggered a six-year long volcanic winter in East Africa, in turn causing the human population in the region to plummet.
New research from the University of Arizona has looked at the effect of the eruption on East Africa. The findings disagree with the Toba Catastrophe Hypothesis, finding no evidence of severe ecological disruption following the eruption.
“This is the first research that provides direct evidence for the effects of the Toba eruption on vegetation just before and just after the eruption,” said lead author Chad L. Yost, a doctoral candidate in the UA Department of Geosciences. “The Toba eruption had no significant negative impact on vegetation growing in East Africa.”
Yost and colleagues studied microscopic bits of plants preserved in two sediment cores from Lake Malawi, the southernmost of the East African Rift Lakes. They analysed samples taken from roughly every 8.5 years over a period beginning approximately 100 years before the eruption and ending 200 years later.
“It is surprising,” Yost said. “You would have expected severe cooling based on the size of the Toba eruption–yet that’s not what we see.”
According to Yost, if the region had experienced the multi-year cooling suggested in the Toba Catastrophe Hypothesis, the cores would have evidence of a massive die-off of the region’s vegetation at all elevations. However, the team only found some die-off in mountain plants just after the eruption, and no die-off in lower elevation plants.
Part of the Toba Catastrophe Hypothesis says the eruption caused human populations to shrink. However, according to Yost, all known archaeological evidence of human habitation in the region is found at low elevations.
“We know anatomically modern humans were living within 50 kilometers of Lake Malawi,” Yost said. “People would have been able to travel to habitats and lower elevations that had little to no cooling effect from the Toba eruption,” he said.
Co-author Andrew S. Cohen, UA Distinguished Professor of Geosciences, said: “That a singular event in Earth history 75,000 years ago caused human populations in the cradle of humankind to drop is not a tenable idea.”
The research has been published in the Journal of Human Evolution.
First Briton had “Dark to Black Skin”
Scientists have carried out the first ever full DNA analysis of Britain’s oldest modern human specimen, revealing that 10,000-year-old Cheddar Man likely had “dark to black skin”, blue eyes and dark curly hair.
“Generally people would be very surprised to see what Cheddar Man – an individual from 10,000 years ago – looked like,” Dr Selina Brace, an ancient DNA researcher who contributed to the work at the Natural History Museum, told The Independent.
The fossil of Cheddar Man was first discovered in 1903 in Gough’s Cave in Somerset. He lived shortly after the first settlers crossed from continental Europe to Britain at the end of the last ice age. The new revelations, made through genetic analysis of Cheddar Man’s bones, show that the genes for lighter skin became widespread in European populations later than traditionally thought.
Tom Booth, an archaeologist at the Natural History Museum who worked on the project, told the Guardian: “It really shows up that these imaginary racial categories that we have are really very modern constructions, or very recent constructions, that really are not applicable to the past at all.”
The key to the surprising discovery was genetic markers that showed skin pigmentation usually associated with sub-Saharan Africa.
Dr Brace told The Independent: “It’s kind of surprising, because you would have thought [light skin] would have come more quickly as people are moving into these different climates. But in fact what we think is they had a very meat and fish-rich diet, so it was quite likely they were getting their vitamin D from there.”
Featured image: Replica of drawing of lions painted in the Chauvet Cave. Art in the cave has been identified as created by early modern humans.]]>