Borate Minerals Stabilize Ribose

Evidence for an “RNA world, ” an episode of life on Earth during which RNA was the only genet-ically encoded component of biological catalysts, is found in the ribosome (1), catalytic RNA mol-ecules (2), and contemporary metabolism (3). That RNA could form spontaneously and persist under prebiotic conditions has been doubted, however (4, 5). Ribose and its sister pentoses (arabinose, xylose, and lyxose) are made under alkaline conditions from simple organic precur-sors (formaldehyde and glycolaldehyde) (6) known in interstellar space and presumably avail-able on early Earth (7). Pentoses do not accumu-late under these conditions, however; they rapidly decompose in a “browning ” reaction to generat