The Cosmochemical Record of Carbonaceous Meteorites: An Evolutionary Story

Abstract

This account traces a lecture given to El Colegio Nacional last March during a Conference “On the origin of life on the Earth” organized to celebrate Darwin’s Bicentennial. It reports on the extraterrestrial organic materials found in carbon-containing meteorites, their composition, likely origin and possible prebiotic contribution to early terrestrial environments. Overall, this abiotic chemistry displaysstructures as diverse as kerogen-like macromolecules and simpler soluble compounds, such as amino acids, amines and polyols, and show an isotopic composition that verifies their extraterrestrial origin and lineage to cosmochemical synthetic regimes. Some meteoritic compounds have identical counterpart in the biosphere and encourage the proposal that their exogenous delivery to the early Earth might havefostered molecular evolution. Particularly suggestive in this regard are the unique l-asymmetry of a number of amino acids in some meteorites as well as the rich and almost exclusively water-soluble compositions discovered for other meteorite types.