Weak neutral currents and the origin of biomolecular chirality

It has long been known that Earth's biochemistry is overwhelmingly dissymmetric or chiral1–4. In model chemical systems5–7 that spontaneously evolve to a state dominated by either the L or the D enantiomer, parity violation in β-decay and that attributable to weak neutral currents (WNC) in molecules8,9 is thought to be too small to have any significant influence on the emergent chirality10,11. Other conceivable systematic chiral influences are generally even weaker12–14. We show here that there is a simple and extremely sensitive mechanism by which a minute but systematic chiral interaction, no stronger than the WNC interaction in amino acids, can, over a period of ∼15,000 yr, determine which enantiomer will dominate. Such a mechanism is especially interesting when considering the origins of terrestrial biochemistry, particularly in view of the work by Mason and Tranter15, who found that it is the terrestrially dominant L amino acids that are favoured by the WNC interaction.