How life came to use only one molecular handedness
In plain words
Many biological molecules come in mirror-image forms, yet life uses only left-handed amino acids and right-handed sugars. Whether this choice was set by a physical bias or by chance, and how it was amplified to purity, is unknown.
Precise statement
Identify the symmetry-breaking event (a deterministic bias such as weak-interaction parity violation, circularly polarized light, or spin-polarized electrons from magnetic minerals; or spontaneous symmetry breaking) and the amplification mechanism (autocatalysis, crystallization, polymerization selectivity) that took a near-racemic prebiotic pool to enantiomeric excess $\mathrm{ee} > 0.99$ in nucleotides and amino acids. Answer: a demonstrated, prebiotically plausible pathway.
What would settle it
A laboratory sequence under plausible early-Earth conditions that produces enantiopure nucleotide and amino-acid building blocks from racemic or near-racemic feedstocks.
Status in the literature
Since 2023, spin-selective crystallization of an RNA precursor on magnetite surfaces has been proposed as a route (arXiv 2303.01394); its sufficiency and geological plausibility remain under discussion, to this survey's knowledge.
Related problems
- More general than Can parity violation bias the homochirality of biological molecules?
- More general than Prebiotic transfer of chiral bias from sugars to amino acids