Do they live on the second floor?

So many assumptions are necessary for this type of research, particularly for the timing. Inferring such an early age depends on a "clock" that varies based on the stringency of purifying selection. I.e., it is only clock-like to the degree that competition and the level of biological systems integration were essentially static through time.

LUCA have 2600 genes ? How such thing can be even remotely called "first" ??

So weird to think we share a ancestor with mushrooms, trees and jellyfish.