TEMPO, MODE, THE PROGENOTE, AND THE UNIVERSAL ROOT

Early cellular evolution differed in both mode and tempo from the cont emporary process. If modern lineages first began to diverge when the p henotype-genotype coupling was still poorly articulated, then we might be able to learn something about the evolution of that coupling throu gh comparing the molecular biologies of living organisms. The issue is whether the last common ancestor of all life, the cenancestor, was a primitive entity, a progenote, with a more rudimentary genetic informa tion-transfer system. Thinking on this issue is still unsettled. Much depends on the placement of the root of the universal tree and on whet her or not lateral transfer renders such rooting meaningless.