Did early Earth have all the chemical elements and molecules needed to "build" life under the right conditions? Or were some vital ingredients added by comets and/or meteors? Scientists have long been split on this one.
A new experiment gives a strong, though not conclusive, indication that Earth could indeed have been the crucible of life without cosmic help. A simulated lighting storm in a re-created primordial atmosphere - an experiment first performed in 1953, but now informed by a much better idea of what the planet was like in those days - produced a "soup" of amino acids necessary for life. Chemist Jeffrey Bada, whose team at the Scripps Institution of Oceanography performed the experiment, says, "Maybe we're over-optimistic, but I think this is a paradigm shift."