The 2026 Nobel Prize in Chemistry was awarded Wednesday to French chemist Henri B. Kagan and Japanese chemist Kenso Soai, whose experiments offered an answer to one of chemistry's oldest riddles: how the molecules of life came to exist in only one of their two mirror-image forms.
The Royal Swedish Academy of Sciences cited the pair "for the discovery of non-linear effects and autocatalysis in asymmetric organic synthesis." They will split the prize money of 12 million Swedish kronor equally.
The puzzle
Many molecules come in left- and right-handed versions that mirror each other the way a pair of hands does. Chemists call this property chirality. Living things are strikingly selective about it. The amino acids that build proteins, for instance, show up in cells in only one of their two forms, and the same is true of the sugars in DNA. Scientists call this preference homochirality.
In the lab, though, reactions that make chiral molecules normally produce a roughly 50-50 mix of both versions. That gap left researchers wondering for more than a century how nature ended up so lopsided, and how chemists could reliably make just the version they want.
What the laureates did
According to the Nobel committee, Kagan, born in 1930 and a professor emeritus at what was Université Paris-Sud, took the first big step in 1986. He found a way to steer reactions so they produced a larger excess of one mirror-image form than chemists had believed possible.
Soai, born in Hiroshima in 1950 and a professor emeritus at Tokyo University of Science, built on that. He described a candidate reaction in 1995, and by 2003 he had shown a reaction in which only one of the two possible forms came out. The committee said no one other than life itself had achieved that before. The trick relies on autocatalysis, in which a reaction's own product speeds up the making of more of itself, so a small head start for one version can snowball.
The work fulfilled conditions laid out in a 1953 theoretical paper by British physicist Charles Frank, who sketched how a self-reinforcing reaction could, in principle, lead to homochirality.
Why it matters
The distinction is far from academic. In medicine, one mirror image of a drug molecule can treat a disease while the other does nothing or causes harm. The BBC pointed to thalidomide, the 1950s morning-sickness drug whose two forms behaved very differently in the body, as a tragic example. The Nobel committee said the laureates' discoveries have become decisive for chemists designing reactions used in pharmaceutical manufacturing, as well as for flavors, scents and new materials.
Committee chair Heiner Linke called the reactions the two developed "spectacular." Speaking to the Nobel press conference by phone, Soai said it was "one of the most exciting days of my life," the BBC reported.
This year's Nobel announcements run from Oct. 5 through Oct. 12.