Mortality is absolutely a feature of evolution. Sticking around after you reproduce and helping your offspring is great, but beyond some point you've done what you can to improve the viability of your offspring and are just competing with them for resources.
Meh, I disagree. It is not a feature of evolution, it is completely accidental.
Evolution doesn't give a damn about any of that at all. All that it is doing is selecting for survival and reproduction. Things find a niche that allow them to survive and reproduce, if they only need to live days like a fly, or a hundred years like some lobsters, turtles, birds, and even hundreds or possibly thousands like some trees[0] are able to do, they will go ahead and do that.
What happens is old ones that become weakened die from predation, or reduced hunting capacity, or some kind of senescence from something like molting, cell division, disease or injury.
Typically, reproduction can happen relatively quickly so there isn't much selection pressure towards extremely long lives in general. Some things are able to live incredibly long, but that again is mostly an accident. Either for or against, evolution doesn't favor anything but enough, after that--its gravy.
The thing about humans is that we are the ultimate generalist in the evolutionary kingdom. We can work in any niche, we could probably live on a scorching Venus in small numbers for a while--who knows?
Communication has allowed us to find survival traits in the knowledge of our elders, stories, and later in societies and writing and large scale organization. Now that we have evolved science and soon, if we slide through the filter, post-industrial technology, we might just find that our selection pressure leads up to increased lifespans, or at least the possibility. We certainly have the urge here and there ...
Perhaps it would enable us to colonize extrasolar planets, or maybe gain a perspective of scale that allows us to break free of the local minimum of the economics that is fossil fuel usage, planetary destruction events, knowledge transfer, or just plain ole' happiness, if living a long time somehow turns out granting us that. Can always pull the plug (in the space suit's oxygen tank or perhaps space-narcotic micro-drip injector) if it turns out to be terrible.
Just because it's a feature of evolution doesn't mean we shouldn't try to stop it. Evolution does not care about how you or your offspring feel. Literally the only thing evolution cares about is achieving cancerous growth at all costs. I don't think that's a worthy goal.
*Achieving exponential growth until we as a species reach our environment’s resource limit, and then a plateau, not a crash; Evolution’s “goal” then is to try to ensure the survival of the species.
Indeed, survival of the species with no regard to the happiness of the members therein. I think we can do better ourselves at this point, which would be in itself arguably part of evolution.
