Sunday, May 24, 2009

Life Could Have Survived Earth's Late Heavy Bombardment

"Life Could Have Survived Earth's Early Bombardment"
LiveScience (May 20, 2009)

"An asteroid bombardment of Earth nearly 4 billion years ago may have actually been a boon to early life on the planet, instead of wiping it out or preventing it from originating, a new study suggests.

"Asteroids, comets and other impactors from space have been suggested as the causes behind some of the world's great mass extinctions, including the disappearance of the dinosaurs...."

"...the new study uses a computer model to show it would have melted only a fraction of Earth's crust, and that microbes - if any existed in the first 500 million years or so of Earth's existence - could well have survived in subsurface habitats, insulated from the destruction.

" 'These new results push back the possible beginnings of life on Earth to well before the bombardment period 3.9 billion years ago,' said CU-Boulder Research Associate Oleg Abramov...."

The researcher's model had survivors on Earth, even when they had ten times as many asteroids hitting Earth.

The article points out that some microbes, like those found in Yellowstone National Park's hydrothermal vents, live at temperatures around 250 degrees Fahrenheit (at above-sea-level pressure, of course). Individual species, like koalas or green-cheeked parrots, may disappear with the slightest breath of change.

The possibility that organisms could have survived the Early Bombardment is important. "...'Exactly when life originated on Earth is a hotly debated topic," says NASA's Astrobiology Discipline Scientist Michael H. New. 'These findings are significant because they indicate life could have begun well before the [Late Heavy Bombardment], during the so-called Hadean Eon of Earth's history 3.8 billion to 4.5 billion years ago.' "

'Life,' though, seems to be a great deal more durable. Take the cockroach, for example. Cockroaches were around when more appealing creatures like the triceratops came in. And, they kept nibbling their way through Earth's history long after the triceratops left life's stage.

Don't get me wrong: I think koalas are cute, and don't think it's smart to strip-mine a nature preserve. But I'm also aware here on Earth, change happens.

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