RNA and Protein: A Match made in the Hadean

Life is diverse, but core biochemistry is not. Despite the immense organismal variety of the Tree of Life—tigers and butterflies, thermophiles and metal-respiring microbes—fundamental biochemistry and biophysics have remained nearly unchanged for ~4 billion years. All life employs the same polypeptide and ribose–phosphate backbones, the same limited monomer sets, the same ribosome, genetic code, and essential metal ions. Fundamental physical-chemical principles unite all biochemistry: all polymer synthesis occurs exclusively through dehydration condensation, bioenergetics depends on water as a nucleophile, biopolymers organization arises largely from the hydrophobic effect, all universal biopolymers fold and assemble and by so doing resist hydrolysis.

Understanding this conservatism requires distinguishing which biochemical features are physically constrained, which are thermodynamically inevitable, and which are historically contingent. I will present our recent results on the origins and evolution of the translation system and on experimental chemical evolution, discussing the essential physical and chemical properties of polynucleotides and polypeptides. Our guiding principle is that biochemistry and biophysics are understood most clearly in light of evolution.