also, how long does it stay emerged

Was it this billion years or that billion years

probability of our experience matching another planet’s experience in the same time frame is low

There haven't been that many billion-year periods. The big bang was 13.7 billion years ago.

Emergence of eukaryotes specifically entailed aerobic respiration of the mitochondria, which was a massive increase of chemical energy (when glucose and oxygen are present).

Chloroplasts enabled direct harvest of photons from our parent star.

We are actually older than the plants.

These are going to leave a signature in the gas of an exoplanet, if they happen.

Oxygen on our planet was a wasteproduct of life before life learned how to use it.

If some planet had oxygen rich atmosphere from the get go it might have sped up the evolution of life by a billion years or few.

> but the mitochondria and plastids of eukaryotes took a very long time to emerge.

Not an expert, but mitochondria didn't "emerge." Mitochondria co-evolved as bacteria, merged and became organelles through complex protein-import machinery and insertion into inner membranes of protein carriers for extracting energy for the host cell.

You are talking about different semantics. You're talking about a merge in the context of a mechanical process, and they are talking about emergence in the context of speciation. There's no reason to expect the verb to be the same if the subject is different.

There are not "different semantics." There is semantics. It's a mass noun and singular. If you're attempting to hand wave by calling my comment a semantic argument, and therefore insignificant, then you are simply incorrect. Semantics are of vital importance to language and communication. Without semantics, no one would have any idea what anyone else was saying. And my use of "merge" was a pun. Woosh!

I'll try to be helpful and not combative.

I think it is a matter of semantics because it seemed like you have a different understanding of the meaning of the word emerge then the person you are responding to. Within the context of the original post, the word emerge has nothing to do with the physical location of mitochondria and the eukaryotic cell. Instead, the meaning of emergence was to come into existence from non-existence. That is to say, your objection relies on a different semantic understanding of the word used. It is unclear to me if you don't understand this meaning or if you understand it but disagree with others using it.

Similarly, I would argue that a "mitochondria" not living in a parent so is not a mitochondria at all. Again, this is a matter of semantics. It relies on the meaning of the word mitochondria and how it is defined.

Bay way of comparison, is a person who buys a house homeless or a homeowner? Are humans prototocells because our evolutionary history can be traced back to them?

1) A thing can have a different name depending on where it is - for example, "power converter mounting bolt" and "control panel cover fastening bolt" might both be M8 bolts, and interchangeable. This isn't any sort of fallacy.

2) In any case, mitochondria have evolved, and are now distinct species from their ancestors that cannot survive outside the cell.

3) Fittingly, a spade is pointed, while a shovel is square tipped.

There were no eukaryotes... and then there were.

This was the ignition of complex, multicellular biology. What else could explain it?

I will admit that I thought they were closer to the Cambrian Explosion. This is much farther away than I thought.

"Eukaryotes emerged approximately 2.2 billion years ago, during the Proterozoic eon, likely as flagellated phagotrophs."

https://en.m.wikipedia.org/wiki/Eukaryote

fungi, farming before they were even fungi.