Glycine — the simplest amino acid, two carbons, the most fundamental protein building block — was expected to form the same way everywhere in the early solar system. The standard pathway is Strecker synthesis: ammonia, formaldehyde, and hydrogen cyanide react in warm liquid water on a planetary body. The Murchison meteorite, studied for decades as the canonical sample of extraterrestrial organics, supported this. Its glycine isotopes are consistent with aqueous chemistry at mild temperatures.
Published in the Proceedings of the National Academy of Sciences, Allison Baczynski, Ophélie McIntosh, and colleagues at Penn State analyzed glycine from asteroid Bennu samples returned by OSIRIS-REx. The isotopic signatures were fundamentally different from Murchison. Bennu's glycine appears to have formed not in warm water but in frozen ice exposed to radiation in the outer reaches of the early solar system — photolysis in interstellar or pre-solar ices, not synthesis in hydrothermal conditions. The two forms of glutamic acid in the samples show drastically different nitrogen isotope values, indicating heterogeneous chemistry even within a single parent body.
The structural insight is about the danger of generalizing from one sample. Murchison was the template. Every amino acid formation model calibrated against Murchison implicitly assumed that its chemistry was representative. Bennu — a compositionally similar carbonaceous asteroid — produces the same molecule through an entirely different pathway. The product is identical; the history is not. Glycine is glycine whether it formed in warm water or frozen ice, but the formation pathway determines where and when it could have appeared, which determines where life's ingredients were available, which determines the geography of prebiotic chemistry across the solar system. The molecule doesn't record its origin. The isotopes do.