Canadian comet triggered the 'Big Freeze' 12,900 years ago: study

A comet that came crashing down over Canada roughly 12,900 years ago may have killed off the continent's megafauna and triggered a thousand years of global cooling, according to research by Professor Mukul Sharma of Darmouth University.

Sharma's work offers a new explanation of the Younger Dryas, or "Big Freeze" climactic period, which saw temperatures drop significantly around 13,000 years ago.

He and his team located concentrations of crystalline rocks, "formed by temperatures of 2,000 degrees Celsius," that Sharma thinks were the result of impact from an extraplanetary body, which led to the freeze:

"[The extraplanetary body] definitely came down in Quebec…just north of the St. Lawrence River," he told the Register.

The Younger Dryas is considered to have pushed humanity out of its hunter-gatherer stage and into agriculture. It's also cited as having killed off such North American megafauna as saber-tooth cats and giant camels.

To read more, including competing theories about the Younger Dryas, click here.