DAVID W. BALL

Recently, Agnieszka Wo¡os and colleagues published a study that dramatically complicated the picture of prebiotic chemistry (Science, vol. 369, eaaw1955 [2020]), starting with just six fundamental building blocks—but also demonstrated the synthesis of dozens of known biotic molecules, some by multiple pathways and many in as few as three steps.

The authors used a desktop computer and defined six simple substances thought to be prevalent in prebiotic conditions.

The authors used a desktop computer and defined six simple substances thought to be prevalent in prebiotic conditions—methane, ammonia, water, hydrogen cyanide, nitrogen, and hydrogen sulfide—using SMARTS, a coding method used to describe molecules so they can be manipulated by a computer. They then allowed the computer to apply a set of 614 well-known chemical reactions (which they called “transforms”) that change the molecules at a carbon, oxygen, nitrogen, sulfur, or phosphorus atom. These transforms also consider the acidity (from highly acidic to highly basic), the presence of known metallic catalysts (especially copper, zinc, and manganese), the presence of other inorganic reactants (phosphates, acids, and bases), and known reaction yields (from trace to >80 percent yield). They let the computer program run the reactions on the initial starting materials, then took the products of that first iteration (Generation 1 products, or G1) and re-reacted them with the same set of 614 reactions to generate G2, then took the G2 products and reacted them, and so forth. The paper describes their results and directs readers to additional materials available online.