Most biomolecules occur in mirror, or chiral, images of each
other. However, life is homochiral: proteins contain almost exclusively
levorotatory (L) amino acids, while only dextrorotatory (R) 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.
Reference: Marcelo Gleiser, Joel Thorarinson, Sara Imari Walker: arXiv:0802.1446
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