Jeffrey L. Bada, 67, is the distinguished professor of marine chemistry at the University of California, San Diego. He studies how life began. We spoke for an hour during the American Association for the Advancement of Science’s annual meeting in San Diego last winter and again this month by telephone. An edited version of the two conversations follows:
Q. HAVE YOU ALWAYS BEEN INTERESTED IN THE CHEMISTRY OF LIFE?
A. No. When I started in graduate school in 1965, I had ideas about becoming a theoretical chemist, applying quantum mechanics to chemistry. But when I arrived at U.C.S.D., I met Stanley Miller, who’d been a student of Nobel Prize-winning chemist Harold Urey. In 1953, they completed the classic experiment on the chemical origins of life. They’d taken gases present on the early Earth like methane, ammonia and hydrogen and applied a spark discharge to them, to mimic lightning. From that, they produced amino acids, the compounds that make up the proteins in all living organisms. It was a stunning discovery. So when I met Stanley, I was hooked. I switched my thesis to work with him. My Ph.D. idea was to move the spark discharge experiment a step forward by studying amino acid stability.
Q. WHY WAS STABILITY IMPORTANT TO UNDERSTAND?
A. Because, in the turbulent environment of the early Earth, if an amino acid had been too unstable it would have decomposed. There would have never been enough of it to make up what we call “the prebiotic soup,” the molecular ingredients of life. So I suggested this one set of reactions that might constrain their decomposition, and then, in the lab, we did an experiment, which worked the first time we tried it. We were able to show some of the conditions that would allow amino acids to exist for longer time periods. And this allowed us to understand what types of amino acids may have been present on the baby Earth.