I've been thinking about cancer. Maybe systems of replicators are prone to overdoing it by nature. The idea was that any universes compatible with life will also have spontaneous cancers because that's just what those universes do.

And then I learned the theory that many cancers are caused by undiscovered DNA-based viruses which tamper with the cell cycle to activate the replicative machinery that they need to make copies of their genome (HPV does this, and several others too). So then it was a switch: not an immutable feature of the universe, but caused by an agent.

But it's starting to look like viruses emerged independently more times than expected, so maybe it is more like "the universe just does that," and viruses are just cancers with a space program. Back to where I started.

I suppose some would see these loops as unproductive. "First principles" people. Descartes, etc. But I think that unresolvable why's like this are what understanding is made of.