Tuesday, August 14, 2007

The ice bug cometh

According to a new study by Rutgers scientists, DNA, long frozen in glaciers, may return to life as the glaciers melt.

The scientists melted five samples of ice ranging in age from 100,000 to 8 million years to find microorganisms trapped inside. Life in the oldest ice samples grew very slowly, doubling only every 70 days. But life in the newest samples doubled every couple of days.

They discovered the math behind the difference: It seems that – at least in the polar regions of Earth – DNA literally has a half-life of 1.1 million years. That is, every 1.1 million years a piece of DNA will lose half its base pairs: DNA from the oldest samples had on average just 210 base pairs, while the newest samples had over 20,000 pairs. And the less DNA, the harder it is to reproduce.

The scientists suggest that, given the extremely high cosmic radiation flux in space, it is highly unlikely that life on Earth could have been seeded by genetic material external to this solar system; it would never have survived the trip.

There is little concern that the ancient life will pose any danger. But who really knows? Could global warming’s biggest threat actually be from life unleashed from our past?

I wouldn’t be too concerned. We’re probably still our own worst enemy.

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