This is sort of a joke.
We all know not to take too seriously the 'no disease and dying of old age' thing, its nice and all, but biologically impossible. So here's a place to talk about it if you so desire. (Who'd be interested anyway unless you're an extreme nerd? :B )
Biologically speaking though you need bacteria in an environment, it helps your body function and do certain things. You have to have plant cells, animal cells, and bacteria, and therefore, you also need to have a body decompose after the person dies, assuming they dont get eaten and are lucky enough to leave a corpse behind in the first place (interesting idea, would a corpse not degrade in felarya if there's no disease?).
So, by definition there has to be diseases for felarya to function naturally.
Of course Felarya operates on a totally different level of existence than we understand. I will reiterate this is a joke thread - that's why I put it in the off-topic thread and not in general discussions.
I just say its fun to think about. Though aging is a different problem than diseases.
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Also another silly idea!
If you take a person's soul and bind it to a corpse you get a lich. You're technically not raising the dead, bringing people back to life (well, not the normal way you'd think of), so if you did that, suddenly felarya gets a 403 error? X3