Whether you are right-handed or left-handed, your body uses left-handed amino acids to build proteins and right-handed sugars in DNA. What does that mean? This molecular “handedness,” known as chirality, means molecules exist as mirror images—left- and right-handed versions of the same molecule. Practically all of life’s amino acids are left-handed, and its sugars are right-handed. Why? Scientists don’t know. No natural process explains this bias because in nature the mixture is generally 50:50.
This chirality matters for drugs. One chiral form may treat disease while the other may be inert or even toxic. Historically, drugmakers produced racemic (50:50) mixtures, sometimes causing unwanted side effects. Thalidomide is an example, with one handedness (enantiomer) causing birth defects. However, even if this drug is homochiral (single-handed), it can become racemic in the body.
The 2026 Nobel Prize in Chemistry honored Henri Kagan (Paris-Sud University) and Kenso Soai (Tokyo University of Science) for developing “asymmetric catalysis,” enabling the selective synthesis of homochiral (single-handed) molecules. Kagan pioneered chiral catalysis in the 1960s, and Soai refined it in 2003. Their work enabled the pharmaceutical industry to produce homochiral drugs. For example, Eli Lilly produced a left-handed cough suppressant, Novrad, and a right-handed version called Darvon, an opioid painkiller. The molecules (and their names) are mirror images of each other.
The work of Kagan and Soai solved “how” to make single-handed drugs—not “why” life itself is homochiral. That remains unexplained. In nature, molecules exist as mirror images in roughly equal numbers. That means the formation of life from non-living matter (abiogenesis) faces a paradox. Random chemistry yields equal left- and right-handed forms, yet life requires near-perfect homochirality to fold functional proteins and replicate DNA. No known natural mechanism can do that. Is it reasonable to suggest that an external influence, an intelligent agent, was involved? We think this is another indicator that life is not an accident but God’s creation.
— Roland Earnst © 2026
Reference: smithsonianmag.com