The last universal common ancestor (LUCA) and the ancestors of archaea and bacteria were progenotes.

The tRNA split genes of Nanoarchaeum equitans and the Met-tRNA(fMet) → fMet-tRNA(fMet) pathway, identifiable as ancestral traits, and the late appearance of DNA are used to understand the evolutionary stage at which the progenote → genote transition took place. The arguments are such as to impose that not only was the last universal common ancestor (LUCA) a progenote, but the ancestors of Archaea and Bacteria were too. Therefore, the progenote → genote transition took place in a very advanced stage of the evolution of the tree of life, and only when the ancestors of Archaea and Bacteria were already defined. These conclusions are in disagreement with commonly held beliefs.