Earlier quoted context omitted.
I am not too sure we know how Cyanobacteria arose (I did my Ph.D. on them) nor how mitochondria arose. Given how rampant horizontal gene transfer is I doubt we ever will. I think the most interest question in this early biology is why LUCA is so complex [1]. We have a massive gap between abiotic processes and the first organism we know anything about. What happened. 1. https://en.wikipedia.org/wiki/Last_universal_anc…
Thanks. There are some hints to "why" on the page you link to: "Before high fidelity replication, organisms could not be easily mapped on a phylogenetic tree. Not to be confused with the Ur-organism, however, the LUCA lived after the genetic code and at least some rudimentary early form of molecular proofreading had already evolved. It was not the very first cell, but rather, the one whose descendents survived beyond…
This is a really good question. It is possible that some of these primitive lifeforms still exist (deep underground would be my best guess) but for technical reasons we can’t easily find them.
We have two basic ways of find living microorganisms: 1. We can either grow them in culture, or 2. We can look for genetic markers that can be amplified using techniques like PCR. If these primitive micro-organisms grow slowly (say divide once a year) then we will never find them in culture (we already know the microorganisms that live deep underground grow at this sort of speed). The genetic marker approach requires that the primitive organism have the same genes as all modern organisms (ribosomes normally). If they don’t have these genes then we won’t find them using our current approaches - they could be there and we just miss them.
If I was Bill Gates rich I would spend some of my money sponsoring deep earth microbiologists to look for cells that appear to be maintaining an energy gradient, but which don’t have ribosomes.