Punctuated chirality.
Most biomolecules occur in mirror, or chiral, images of each other. However, life is homochiral: proteins contain almost exclusively L-amino acids, while only D-sugars appear in RNA and DNA. The mechanism behind this fundamental asymmetry of life remains an open problem. Coupling the spatiotemporal evolution of a general autocatalytic polymerization reaction network to external environmental effects, we show through a detailed statistical analysis that high intensity and long duration events may drive achiral initial conditions towards chirality. We argue that life's homochirality resulted from sequential chiral symmetry breaking triggered by environmental events, thus extending the theory of punctuated equilibrium to the prebiotic realm. Applying our arguments to other potentially life-bearing planetary platforms, we predict that a statistically representative sampling will be racemic on average.
Gleiser
Marcelo
M
Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755, USA. gleiserm@gmail.com
Thorarinson
Joel
J
Walker
Sara Imari
SI
D000596:Amino Acids / Q000737:chemistry; D019418:Evolution, Chemical; D000069497:Origin of Life; D013237:Stereoisomerism
D000596:Amino Acids