AI-rewritten: This is a summary of an article from Ars Technica, rewritten by AI (Qwen, running locally) to make it easier to read. The facts come from the original article – read it for the full story.

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Life relies on molecules with "handedness," known as chirality, where left- and right-handed forms are mirror images. While most chemical reactions create a 50-50 mix of these forms, living organisms use only one type. Key enzymes in life fail to work if presented with the wrong handedness because they are sculpted by evolution to fit specific chemicals. This creates a challenge for origin-of-life research: explaining how a world starting with an even mix produced organisms using only one form.

The 2021 Nobel Prize in Chemistry was awarded to Henri Kagan and Kenso Soai for discovering reactions that can produce large excesses of a single chiral form. Kagan found that using a chiral catalyst, where one form is more active than the other, could lead to much higher levels of a single chirality in the product. He identified three different reactions by the mid-1960s that demonstrated this behavior in the real world.

Soai discovered a reaction where the product itself acts as a catalyst to boost the formation of more molecules of the same chirality. Starting with a tiny excess of 0.00005 percent, he found that after several rounds of reactions, the excess rose to over 99 percent. His work showed how a slight initial difference could be amplified into dominance through self-catalysis or inhibition of the opposite form.

These discoveries have immense practical applications in pharmaceuticals, where the wrong chiral form can be inactive or harmful. While these reactions were not demonstrated with biomolecules, they show that small excesses of chiral forms may be common in nature. Scientists believe these small differences helped push the emergence of life along a pathway leading to the exclusive chemistry seen today.