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Diamonds & Extinction

August 6, 2009

What really killed North America’s large mammals at the end of the last ice age?


Tracking a mammoth killer. I’m Bob Hirshon and this is Science Update.

It’s widely believed that many large North American mammals, such as mammoths, horses and camels went extinct around 13,000 years ago because of overhunting by humans. But a new discovery in the Channel Island off the coast of California suggests that an impact from a comet may have also been to blame. University of Oregon geoarchaeologist Douglas Kennett and his team unearthed billions of tiny diamonds with a distinctive crystalline structure in a layer of sediment dating to this period.

DOUGLAS KENNETT (University of Oregon):
They’ve only been identified in impact craters and inside of meteorites, so we think that this is a fairly strong indicator of some kind of a cosmic impact.

He says a catastrophic cosmic impact would have killed many humans, too, and he notes that the archaeological record is rather quiet for at least 500 years following the proposed impact date. I’m Bob Hirshon, for AAAS, the science society.