Origins of Homochirality

Origins of Life and Evolution of Biospheres

, Volume 38, Issue 6, pp 499-508

First online:

Punctuated Chirality

  • Marcelo GleiserAffiliated withDepartment of Physics and Astronomy, Dartmouth College Email author 
  • , Joel ThorarinsonAffiliated withDepartment of Physics and Astronomy, Dartmouth College
  • , Sara Imari WalkerAffiliated withDepartment of Physics and Astronomy, Dartmouth College

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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.


Homochirality Prebiotic chemistry Origin of life Early planetary environments