Science: Looking for Signs of Life

Clues are found in rocks, a meteorite and space

How —and when —did life begin? Cyril Ponnamperuma, 55, a Ceylon-born geochemist at the University of Maryland, has been seeking answers to this question for much of his career. He has created precursors of life in laboratory simulations of the earth's primitive atmosphere and while with NASA in 1970, identified amino acids (the building blocks of protein) in the Murchison meteorite, which had fallen in Australia a year earlier. Last week, at a meeting of the American Chemical Society in Washington, Ponnamperuma presented three new pieces of evidence that the processes leading to...