Why is civilization the way it is? What caused humans to build societies? Could it have been different?
The philosophical answers to these questions may be beyond our reach, but scientifically speaking, the answer might be “a ginormous comet”, according to a new paper published in the journal Earth-Science Reviews.
About 14,500 years ago, the Earth started to heat up. The ice sheets that had rendered much of the Northern hemisphere uninhabitable for millennia began to retreat, and humans started their migration across Eurasia and into the Americas.
Then, around 13,000 years ago, it stopped. Temperatures across the Northern hemisphere dropped back to near-glacial conditions, and it happened at a rate faster even than today’s man-made climate change. The “Younger Dryas” – a period named for a flower that flourished during the colder conditions – had started, and it would be a whole millennium before the climate returned to normal.
But the climate wasn’t the only thing to experience a major change around this time. Human populations in the “fertile crescent” of southwest Asia – including modern-day Egypt, Iraq, and Lebanon – started to settle for the first time and switched from hunter-gatherer lifestyles to agriculture-based societies. Meanwhile, the Clovis people of North America seem to have disappeared completely. And across the planet, plants and animals went extinct on a massive scale.
But precisely what caused this global change is something that science has yet to conclusively discover. One of the most controversial suggestions, however, says that it was triggered when Earth was struck by fragments of an enormous comet that pummeled North and South America, Europe, and Asia. First seriously proposed in 2007, the theory has been hotly debated from both sides as fresh evidence has continued to emerge through the years to support (or oppose) it.
A University of Edinburgh team set out to review this evidence and make an assessment on the likelihood of the Younger Dryas Impact Hypothesis, as it’s known, being correct. Their conclusion: it’s pretty darn likely, actually.
“[A] large body of evidence supports the theory that a comet struck around 13,000 years ago,” the researchers confirmed in a statement, with “excess levels of platinum, signs of materials melted at extremely high temperatures and the detection of nanodiamonds known to exist inside comets and form during high-energy explosions”
The data that the team says strongly supports the theory was taken from across four continents. Geological data came from North America and Greenland particularly, where the biggest comet fragments were thought to hit, while study lead author Martin Sweatman pointed out one especially intriguing piece of anthropological evidence.
“This major cosmic catastrophe seems to have been memorialised on the giant stone pillars of Göbekli Tepe, possibly the ‘World’s first temple‘,” he commented, “which is linked with the origin of civilisation in the Fertile Crescent of southwest Asia. Did civilisation, therefore, begin with a bang?”
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