> It is interesting to note that all higher lifeforms have evolved to die (presumably to avoid out-competing their descendants).
I need a source on that, because for the most part that's not how evolution works.
At the point of reproduction, the moment genes are passed on, the paternal time of death isn't "known" to natural selection. Generally speaking, there really is no way to put pressure on death like you suggested. Except maybe for some group selection mechanics, where scientific consensus would be far from settled, and it wouldn't qualify for any statement on "all higher lifeforms", anyway.
What's true tho, evolution doesn't care too much about your survival after reproduction, either. So, eg. some early in life adaptations may increase your chances of death later in life - live fast, die young.
But that's really different than saying death has this evolutionary purpose like you suggested. Complicated things just fall apart at some point. That's so much a fact, that large animals like whales and elephants actually do need "anti-cancer" adaptations to bring their plenty of cells into reproductive age.
Also, I think people may be prone to an anachronistic fallacy in regard to dying here. See, 1 in 5 people will die because of cancer, it's a pretty "natural" thing in our lives, but.... human cancer rates are actually mostly down to environmental and lifestyle factors. Before civilization and industrialization cancer was rare. Yes, people live longer to see it happen, but for example lung cancer is almost always attributable to some hazard exposure. Smoking increases your risk by 2000% (!), yet most smokers won't get lung cancer - lung cancer is that rare!
Alcohol, houses on radon soil, highly processed food, VOCs, hexavalent chromium, heavy metals, estrogenic plasticizer, asbestos, sedentary lives, obesity, microplastic, nanoparticles, ... stress. We could have cashed in on maternal and child mortality to fix our stats, but hey: you win, you lose.
The mechanism has not evolved to "curtail life". The changes that happen in the body with activation of the HPA axis and SNS are beneficial in times of stress. They shift glucose towards the muscles, reduce energy use by the digestive system a, and shift the immune system towards innate immunity in order to deal with immediate threats to the body.
I don’t think anything evolved to die. Dying is a prerequisite to evolution. If every individual were to survive, the gene pool would not converge towards more advantageous adaptations. The word “advantageous” means more apt to survive.
> Dying is a prerequisite to evolution. If every individual were to survive, the gene pool would not converge towards more advantageous adaptations.
This is kinda wrong. Reproduction is the perquisite for evolution. Evolution does not care much about your "survival" as a whole, especially after you reproduced. In "Survival of the fittest", you can better think of survival on the level of genes, not individuals, for the most part.
Aging doesn't seem to be inevitable: some animal species live for very long times even hundreds of years. And yet we have a predetermined lifespan far below that. Seems as though that's an purposeful systematic difference etween species that control how long each generation survive before death.
This might be more philosophical, but here’s how I think about. Would love to hear your take on it.
Before life, there was only death. At some point, something life-like sprung into existence, and soon died. And then it happened again. At some point it was able to reproduce, and then died.
Death is the default. It was always there. Some things managed to cheat it long enough to reproduce. Those things are alive.
This is why I don’t see that organisms evolved to die. The very first life-like things were dying, before they had the ability to reproduce.
Apoptosis happens at a cellular level and is controlled by higher systems such as cytokines. You haven't evolved to die, but your cells have evolved to die when instructed to.
From this perspective, mechanisms that prolong life in favourable circumstances but curtail in difficult times, make sense.