Thread: electron spin may explain molecular handedness

CharlesMullins2 posted a thread on May 16 pointing readers to a line of quantum-biology research that asks whether electron spin helped set life’s molecular handedness billions of years ago. The thread’s core claim matches a live debate in the literature over homochirality — the fact that biology overwhelmingly uses left-handed amino acids and right-handed sugars. A 2022 paper by S. Furkan Ozturk and Dimitar D. Sasselov argued that spin-polarized electrons could have acted as symmetry-breaking agents in prebiotic chemistry. An April 22, 2026 Science Advances paper by Yossi Paltiel, Ron Naaman and co-authors pushed the argument further by reporting a dynamic spin-based asymmetry between mirror-image molecules. ### What exactly is the mystery these papers are trying to solve? Life’s basic building blocks come in mirror-image forms called enantiomers, and modern biology overwhelmingly picks one version over the other. The 2022 PNAS paper states that amino acids and sugars are chiral and that modern life “selectively uses only one of the enantiomers,” calling the origin of that symmetry breaking a major open problem in origin-of-life research. The Kavli Foundation’s 2024 profile of Ozturk says living systems predominantly use one handed form of amino acids and that DNA sugars are right-handed. (pmc.ncbi.nlm.nih.gov) Louis Pasteur first noted molecular handedness in 1848, according to the Kavli Foundation profile. The same profile says the question has remained central because biology is unusually strict about chirality at the molecular level. ### How does electron spin enter a chemistry problem? The 2022 PNAS paper proposed spin-polarized electrons as possible chiral symmetry-breaking agents. (pmc.ncbi.nlm.nih.gov) Ozturk and Sasselov wrote that the mechanism would rely on the chiral-induced spin selectivity, or CISS, effect — a coupling between electron spin and molecular chirality observed at room temperature in earlier experiments. CISS describes a result in which chiral molecules preferentially transmit or interact with electrons of one spin orientation. (kavlifoundation.org) A 2018 Science paper reported enantioselective interactions between chiral molecules and magnetized substrates mediated by spin-specific interactions, while a 2023 Science Advances paper reported about 60% enantiomeric excess in crystallizing the RNA precursor ribo-aminooxazoline on magnetite surfaces. (pmc.ncbi.nlm.nih.gov) ### What did the 2022 prebiotic-lake model actually propose? Ozturk and Sasselov’s 2022 paper proposed shallow closed-basin lakes on early Earth as a plausible setting. The paper says ultraviolet light in the 200- to 300-nanometer range striking magnetite deposits could eject hydrated spin-polarized electrons, and those electrons could drive reduction reactions whose kinetics differ between mirror-image molecules. (science.org) Magnetite is central in that model because the authors argued sedimentary deposits would have been common in such lakes. Their paper presents the idea as a hypothesis and estimate, not as a direct reconstruction of what happened on early Earth. ### What changed with the April 2026 paper? Yossi Paltiel of Hebrew University and Ron Naaman of the Weizmann Institute led the April 22, 2026 study in Science Advances. (pmc.ncbi.nlm.nih.gov) According to the paper abstract and institutional summaries, the team combined direct measurements, theory and ab initio calculations to show that dynamic spin processes in chiral molecules can produce different efficiencies for spin-related phenomena in mirror-image molecules. The paper’s title is “Dynamic breaking of mirror symmetry in spin-dependent electron transport through chiral media causes enantiomeric excesses.” The authors say the effect appears in dynamic processes such as electron transport and interactions with magnetic environments, rather than in static equilibrium properties. ### Does this mean the origin of homochirality is solved? The 2026 Science Advances paper says its findings “may provide an explanation” for specific homochirality in nature. (science.org) That wording is narrower than a definitive claim, and the 2022 PNAS paper likewise framed its lake-and-magnetite scenario as a hypothesis about a plausible prebiotic environment. A 2025 Nature Reviews Materials article described CISS as a promising tool for controlling spin properties, while noting that the effect’s underlying mechanism has remained an active research problem. (science.org) That leaves the thread’s main point intact: there is a real research program linking electron spin and chirality, but the field is still testing mechanisms rather than closing the case. ### Where can readers check the underlying papers? (science.org) The 2022 PNAS paper by S. Furkan Ozturk and Dimitar D. Sasselov is available through PubMed Central under the title “On the origins of life’s homochirality: Inducing enantiomeric excess with spin-polarized electrons.” The April 22, 2026 Science Advances paper by Yossi Paltiel, Ron Naaman and co-authors is titled “Dynamic breaking of mirror symmetry in spin-dependent electron transport through chiral media causes enantiomeric excesses,” and supplementary materials are also posted by Science. (nature.com) (pmc.ncbi.nlm.nih.gov)