New evidence from South Africa is adding further credence to the idea that a large asteroid or comet struck Earth during the Pleistocene — an event that possibly triggered the extinction of many large animals while also disrupting human populations at a global scale.
Along with locations in North and South America, Greenland, Western Europe and the Middle East, we can now add southern Africa to the list of places where scientists have uncovered evidence of a calamitous event that happened 12,800 years ago.
New research published this week in the science journal Palaeontologia Africana describes the presence of excessive platinum in sedimentary material extracted from a site in South Africa dating back to this period.
Meteorites are packed with platinum, and an impact with a sufficiently large, disintegrating object would’ve spread platinum across the globe, according to the research team, led by Francis Thackeray of the Evolutionary Studies Institute at the University of the Witwatersrand in South Africa.
This evidence of a 12,800-year-old platinum spike in Africa is the first to be found on the continent, and it’s yet further evidence in support of the Younger Dryas Impact Hypothesis.
According to this theory, either a comet or asteroid struck Earth during the Pleistocene, triggering an impact winter that saw temperatures plummet around the globe. The associated loss of plant life lead to the extinction of many large animal species, along with possible disruptions to human populations around the world.
Thackeray, along with co-authors Philip Pieterse from the University of Johannesburg and Louis Scott from the University of the Free State, uncovered the platinum spike in ancient peat deposits at the Wonderkrater site in South Africa’s Limpopo Province.
“Our finding at least partially supports the highly controversial Younger Dryas Impact Hypothesis,” explained Thackeray in a press release.
“We seriously need to explore the view that an asteroid impact somewhere on Earth may have caused climate change on a global scale, and contributed to some extent to the process of extinctions of large animals at the end of the Pleistocene, after the last ice age.”
Indeed, the time of the alleged impact coincides with the disappearance of many animal species around the planet. Africa was no exception, as the Young Dryas period (12,800 to 11,500 years ago) was when several species, including giant buffalos, zebras, and wildebeest, went extinct.
At the same time, there’s evidence from this period that human populations might have also suffered. The Clovis people of North America, for example, were suddenly producing fewer stone tools during this period, and a similar drop in stone tool production has been documented among the Robberg culture of southern Africa.
“We cannot be certain, but a cosmic impact could have affected humans as a result of local changes in environment and the availability of food resources, associated with sudden climate change,” said Thackeray.
The new paper also describes the discovery of ancient pollen at Wonderkrater that also dates back to the Young Dryas period. Chemical analysis of this fossilised pollen points to temperature declines, which nicely coincide with a similar cooling period in the Northern Hemisphere.
Allen West, a retired American geologist who studies the Younger Dryas Impact Hypothesis, said the new paper is important “because it suggests that the Younger Dryas impact event had global effects.”
Previously, scientists “knew that it affected nearly all of the Northern Hemisphere, but not the South,” he wrote to Gizmodo. “Then, recently, another study was published showing a platinum peak at Pilauco, Chile, indicating that South America was affected. Now, we know that southern Africa was affected as well, nearly 8,000 kilometers [5,000 miles] away from the nearest similar site in Syria, making this a global event.”
It’s important to point out that the Younger Dryas Impact Hypothesis is a highly controversial idea, given the lack of evidence. Critics have said an “an age discrepancy” exists “between different sites where proposed impact markers have been found, and that much of the evidence, such as magnetic microspherules, nanodiamonds, shocked quartz, and other minerals, are ambiguous in nature and open to interpretation. It also doesn’t help that an associated impact crater hasn’t been linked to the supposed event.
That said, a fascinating discovery from 2018 revealed the presence of a hidden impact crater beneath the Hiawatha Glacier in Greenland.
This crater measures around 31 kilometres wide, and it struck the Earth at some point between 3 million and 12,000 years ago. This could very well be the impact crater from the Young Dryas event, but more evidence is needed. When Gizmodo covered the discovery of this crater last year, we asked Nicolaj Larsen, an Aarhus University geologist who contributed to the discovery, to explain the rather sizeable dating discrepancy:
It is correct that the crater is not well dated, but there’s good evidence that it is geologically young, that is, it formed within the last 2 to 3 million years, and most likely it is as young as the last Ice Age [which ended around 12,000 years ago]. We are currently trying to come up with ideas on how to date the impact. One idea is to drill through the ice and get bedrock samples that can be used for numerical dating.
Nailing down a tighter date would be helpful as far as the Younger Dryas Impact Hypothesis is concerned. Unsurprisingly, Thackeray already has eyes on this crater, saying “it might possibly have been the very place where a large meteorite struck the planet Earth 12,800 years ago,” and that a meteorite of this size would have mostly certainly resulted in “global consequences.”
So, still no sure-fire confirmation that Earth got hit back then, but this possibility continues to intrigue.