Darwinian threshold

[3] The Last Universal Common Ancestor is often considered to be an already complex organism with a DNA-based genome, a complex informational flow and an efficient metabolism, but some authors, like Carl Woese, believe instead that the LUCA was not a discrete entity but rather a diverse community of cells that survived and evolved as a biological unit.

[1] These organisms or biological entities, these progenotes (or ribocytes), had RNA as informational molecule instead of DNA.

It is hypothesized that structured tRNAs could have provided amino acids during a process called self-translation of a single extended tRNA strand.

Therefore, it is assumed that there existed a community of sub-systems that started to cooperate collectively and culminated in the LUCA.

[6] Carl Woese thought that even during the era around the origin of the LUCA, the root and the first branches were very blurred since the cells were not very well defined yet and HGT was still quite important.