What if life began not in the famous warm primordial soup, but in primordial ice? (Ooh, that's much better--now Darwinian evolution doesn't disagree with the Second Law of Thermodynamics quite so much.)
...Douglas Fox describes a series of experiments seeking to confirm this hypothesis in the face of considerable skepticism. Opponents argue that ice slows the rate of chemical reactions to a point where life couldn't develop. The lower the temperature, the lower the chances that chemicals would randomly collide and form into the first basic self-reproducing structures -- called RNA -- from which all life (supposedly) evolved. Plus, that reaction would need liquid. As a result, the conventional candidates for life's birthplace have been warm, wet places such as tropical ponds or boiling volcanic vents.
But ice has some qualities that might outweigh these disadvantages as an incubator for life. Even at very cold temperatures, small amounts of water can persist in ice. Conveniently, the water is trapped in tiny compartments, which would serve as millions of test tubes, each with a different RNA experiment. What's more, while freezing slows most chemical reactions, it speeds up a few that could have served as stepping-stones to life. (What about the rest?)
Some studies have corroborated some of those claims, one of them a 25-year-old experiment by Stanley Miller, who died last year after a lifetime studying the chemical origins of life. (Um, I believe he just 'created' some amino acids; the rest can form only under nearly opposite conditions.) Another experiment has shown that ice actually helps RNA form into chains.
Even if the ice theory is correct, it doesn't rule out the possibility that a primordial soup also gave birth to life on Earth. (Or divine creation? No, no, science *can't* *intersect* with the supernatural at all...) But it does have implications for life on other planets. It would allow for the possibility that life has formed on cold places like Mars or Europa, a moon orbiting Jupiter.
Wednesday, January 16, 2008
The Informed Reader (B16, second item, subscription required) scoops February's Discover. Bold parenthetical material mine.