Depending on your point of view, it is either a sign of science?s boundless optimism or its utter lack of hubris that scientists today hope to solve the puzzle of how life began. Until this century, that sort of question was commonly regarded as out of bounds. In 1863, Charles Darwin commented that it was a futile exercise to try to apply scientific thought to this origin of origins, when the first living things took shape on a hitherto lifeless planet. Eight years later he had relented somewhat, musing on whether life might have begun in some ?warm little pond? spiced with simple organic chemicals.
But where on Earth do you find the building blocks for the molecules of life on a planet that is just a mass of rock and water? We are so used to the idea of an Earth crammed with life in every niche that it is hard to picture the barren world of four billion years ago, when the seas were newly formed and the planet itself was a mere half a billion years old. Somehow, this world spawned the proteins and nucleic acids (DNA and RNA) that are the distinguishing molecular fingerprints of life.
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