I still think it’s super weird that it looks exactly like an EM image, but is generated. Anyway, good to know!

There are some very important differences between Archaea and Bacteria, in membrane composition and in the nucleic acid replication and protein synthesis mechanisms, but there are several hypotheses about how these differences could have evolved and there is not enough evidence yet to be sure which of them is true, i.e. whether the distinctive membranes, ribosomes and certain enzymes of Archaea have never been like those of Bacteria, or they have evolved from those of Bacteria.

The eukaryotes are hybrids, mainly between some Archaea and some bacteria (the ancestors of mitochondria). It is not completely certain whether the ancestor of the eukaryotes from Archaea belonged to a branch that was sister to all still existing Archaea or only of one branch of Archaea, but here the evidence makes it very likely that the ancestor of the eukaryotes belonged to an interior branch that was nested within the existing Archaea, i.e. it was sister to only one branch of the present Archaea.

In the history of life, there have been many events of hybridization between very distant living beings, so the tree of evolution is only approximately a tree, while actually being a more general directed graph. A part of these events have been the results of symbiosis, the most frequent cases being of symbiosis with some phototrophic organism able to capture solar light or with some bacteria able to consume some unusual substance from the environment.

Other such hybridization events have been with viruses, when the genes for some enzymes have been transferred permanently from viruses to their hosts and they have been retained, presumably for being better than the versions used by the hosts for the same function, previously. Even vertebrates and humans have a small fraction of their genome that originates from viruses.

For example, suppose horizontal gene transfer occurs from organism X to organism Y. Does that mean Y is now a branch of X?

* Does it depend on how much was transferred?

* Does it matter only if the specific sequence was passed down? If so, how much mutation is too much mutation?

* What if the same end-result occurred through a retrovirus instead of a plasmid. Is the virus an ancestor too?

* What if the swap was simultaneous and bidirectional?

* What about transitive links to organisms W, V, U that did the same?

* Are mitochondria "us" yet? If so, are we the ancestors if they redevelop enough machinery to "escape"?

etc.

https://www.ofb.net/~jlm/virus.html

More because it's funny than that it matters.

Hunters hunt as much as they can. Wolves regularly kill 10 or 20 sheep while eating one if they get the chance. Foxes do similar stuff with chickens. Nature is brutal and without empathy.

If we do find another earth-like planet within travel distance (impossible afaik but let's suspend disbelief for a moment), how do we determine whether it's worth colonising? And how to we measure it?

"The resources on this planet will last 15.6B person-years which means if we send 5 million people there over time, we will have to prepare for their evacuation in ??? years"?

Obviously totally moot if Earth's resources aren't going to last that long, but just had that thought bubble up.

We know for a fact that earth is doomed, on top of our own continuous efforts to kill ourselves off. No not recent climate change type of doomed, but the evolution of our sun is continuously pushing the habitable zone outwards. We might be able to deal with that particular annoyance by hiding underground when it becomes an emergency in half a billion years or so, but our utopia won't be as utopic anymore.

Eventually however, the sun will balloon to a red giant at which point we better have a plan in place other than staying on this planet.