Has an extraterrestrial collision caused ice age animals to become extinct? An archaeologist at the University of South Carolina finds evidence in South Carolina to support a controversial theory.
The controversial theory, which suggests that an extraterrestrial body crashed on Earth almost 13,000 years ago, has caused the extinction of many large animals, and the likely decline in the population of early humans is gaining popularity from research sites around the world.
The Younger Dryas impact hypothesis, controversial since its presentation in 2007, suggests that the asteroid or comet hit Earth about 12,800 years ago, causing a period of extreme cooling that contributed to the extinction of over 35 megafauna species, including giant sloths, cats saber-teeth, mastodons and mammoths. This also coincides with a severe decline in early human populations such as the Clovis culture, and is thought to have caused massive fires that could block sunlight, causing "shock winter" at the end of the Pleistocene era.
In a new study published this week in Scientific reports, publication Nature, Archaeologist at the University of South Carolina Christopher Moore and 16 colleagues provide further evidence of a cosmic impact based on research at White Pond near Elgin, South Carolina. The study is based on similar findings of platinum peaks – an element associated with space objects such as asteroids or comets – in North America, Europe, western Asia, and more recently in Chile and South Africa.
"We are still finding evidence and expanding our geographical coverage. Over the past few years, there have been many articles with similar data from other sites that almost universally support the view that the existence of an extraterrestrial collision or comet explosion has caused the Younger Dryas climate event, "says Moore.
Moore was also the main author on a previous document documenting sites in North America in which platinum was found, and co-authored several other articles that document elevated levels of platinum in archaeological sites, including in Pilauco, Chile – the first discovery of evidence in the southern hemisphere.
"First, we thought it was an event in North America, and then in Europe and beyond, there was evidence that it was an event in the Northern Hemisphere. And now, thanks to research in Chile and South Africa, it looks like it was probably a global event, "he says.
In addition, a team of scientists found unusually high concentrations of platinum and iridium in the effluent sludge from a recently discovered crater in Greenland that could have been the point of impact. Although the crater has not yet been dated, Moore says there is a good chance that it could be the "smoking weapon" that scientists were looking to confirm the cosmic event. In addition, data from South America and other countries suggest that the event could have included many bumps and explosions around the world.
Although the brief return to the Ice Age during the Younger Dryas period has been well documented, the reasons for this phenomenon and the decline in human and animal populations remain unclear. The impact hypothesis has been proposed as a potential trigger for these sudden climate changes that lasted around 1,400 years.
The Younger Dryas event takes its name from the wild flower Dryas octopetala, which can tolerate cold conditions and suddenly became common in some parts of Europe 12,800 years ago. The Younger Dryas Impact hypothesis has become controversial, says Moore, because the all-encompassing theory that the cosmic impact caused cascading events leading to extinction was considered unbelievable by some scientists.
"It was bold in the sense that it tried to answer a lot of really difficult questions that people had struggled with for a long time with one blow," he says, adding that some researchers are still critical.
The conventional view is that the failure of ice icy dams has enabled the massive release of fresh water into the North Atlantic, affecting ocean circulation and causing the Earth to plunge into a cold climate. The Younger Dryas hypothesis simply claims that the cosmic impact was the trigger of the molten water pulse into the oceans.
During research at White Pond, South Carolina, Moore and his colleagues used a cylindrical core to extract sediment samples from under the pond. Samples, dated to the beginning of Younger Dryas with radiocarbon, contain a large platinum anomaly, consistent with findings from other places, says Moore. A large soot anomaly was also found in the cores from this place, indicating large-scale regional fires in the same time range.
In addition, it was found that fungal spores associated with the excrements of large herbivores decrease at the beginning of the younger Dryas period, suggesting a decline in the Ice Age megafauna since the impact.
"We speculate that the impact contributed to extinction, but that was not the only reason. It almost certainly contributed to human hunting as well as climate change, "says Moore. "Some of these animals survived this event, in some cases for centuries. However, spore data at White Pond and elsewhere suggests that some of them died extinct at the beginning of Younger Dryas, probably as a result of environmental disruptions caused by impact and climate change fires. "
Additional evidence found elsewhere to support extraterrestrial impact includes the discovery of molten glass, microscopic spherical particles and nanodiamonds, indicating the presence of sufficient heat and pressure to melt materials on the Earth's surface. Another indicator is the presence of iridium, an element associated with space objects, which scientists also discovered in the rock layers 65 million years ago before the impact that caused the extinction of the dinosaur.
Although no one knows for certain why the Clovis people and the iconic Ice Age beasts have disappeared, studies by Moore & # 39; and others provide important clues, as evidence supports the hypothesis of Younger Dryas.
"These are great debates that have been going on for a long time," says Moore. "Such things in science sometimes require a lot of time to be widely accepted. This was the case with the extinction of dinosaurs, when the idea was proposed that they were hit by a blow. It was the same with plate tectonics. But now these ideas are fully recognized science. "
Reference: "White Pond sediment cores in South Carolina contain a platinum anomaly, pyrogenic carbon peak and a drop in coprophilic spores at 12.8 ka" Christopher R. Moore, Mark J. Brooks, Albert C. Goodyear, Terry A. Ferguson, Angelina G Perrotti, Siddhartha Mitra, Ashlyn M. Listecki, Bailey C. King, David J. Mallinson, Chad S. Lane, Joshua D. Kapp, Allen West, David L. Carlson, Wendy S. Wolbach, Theodore R. Them II, M. Scott Harris and Sean Pyne-O & # 39; Donnell, October 22, 2019, Scientific reports.
DOI: 10.1038 / s41598-019-51552-8