Wednesday, June 13, 2007

Exploding mammoths update New Theory on Old Debate: Comet Killed the Mammoth
For decades, scientists have debated whether the giant, elephant-like beasts were driven to extinction by the arrival of overzealous human hunters or by global warming at the end of the Pleistocene era, the last great Ice Age. Some say it was a combination of the two.

Recently, a group of more than two dozen scientists offered a new explanation. They have found signs that a comet -- or multiple fragments of one -- exploded over Canada about 12,900 years ago with the force equivalent to millions of nuclear weapons. That unleashed, they said, a tremendous shock wave that destroyed much of what was in its path and ignited wildfires across North America.

It also mentions other research indicating that there were two groups of mammoth, one that went extinct 50k years ago, and the ones that continued on until the Holocene. They argue that this would not be the cause -- sort of, because they argue that without it, there would still be mammoths -- but one of several:
"Our theory is that if this event had not happened, that mammoths would still most likely -- not certainly, but most likely -- be wandering around North America now," said Allen West, a retired geophysicist who is a leader of the research team. "Almost certainly, humans hunting animals can have a major effect on populations. It seems like there was, in a sense, a perfect storm going on -- of overkill, the comet, climate change, possibly disease. I don't think this theory negates any of the other theories. It's just one more of a mix of things that were absolutely lethal to these animals."

So why'd they go extinct in Europe, too?

At any rate, some of the abstracts are up at the AGU web site, though it requires some searching.