[michaelochurch]

I'm very skeptical.

Aging isn't there because our genes "need" it. It's there because our genes don't need long lifespans. The gain in reproductive viability that we'd get with a >60 year natural lifespan just isn't enough to justify the constraint that a much longer (or indefinite) lifespan would impose on our genetic "search space". We can live forever and be simple, or we can be complex and get a job done and die.

There probably is some anti-fragility in us. I don't buy the LNT threshold of radiation, for example. All that said, I'm not sure that hormesis is useful as a general concept. There are mild stressors (such as cold, when prepared and for short duration) that turn out to have positive effects, but there are a great number of stressors that seem to have no positive effects, whether you're talking about biological agents (e.g. cadmium, lead) or psychological experiences (e.g. rape, war).

[dvanduzer]

Can you translate that for someone who skimmed to "weight on belly versus weight in backpack" ?

[thret]

Natural selection only molds us up to the point where we procreate and ensure the survival of our offspring. After that (say age 50), we're winging it.

Mild stressors that would occur naturally - physical exertion, exposure, hunger; it is perfectly logical that natural selection would favour those who handle these circumstances well.

[ak39]

I like that ... "winging it" after 50. :-) Made me chuckle. I agree with it.

I have a (an emotional) problem with that number though, being acutely aware and sensitive to ageism or age-related relegation of human functions and roles in society. I have a problem with any number for that matter. 50 is too low, and any number will always be too low, the way I see it if you incorporate Dawkins' idea of the Selfish Gene into the mix. I would argue that sticking around "to ensure the survival of our offspring" (as you put it) for the human species is significantly more important than any other species on the planet.

Turtles don't need this survival strategy. Lay eggs (procreate) and chuck - that form of hormesis aggressively weeds out the weak members of the species from the ones laying eggs for the next generation. While chimps, elephants and whales may also need to "stick around longer" for their young - relatively, the human is by far an incredible outlier in this regard. Not only do adults have to stick around for their kids well into the young's teen years, but elders too have to stick around for the group or for the clan. This last point is important to understand the relationship between the survival success of the species and an imagined age cutoff for "usefulness" (that contributes to the success of the species) of any one member of the species. The individual has extended roles beyond just his/her offspring. His/her role in the clan's survival success mattered too.

Recent discoveries of hominid fossils suggest that as early as Erectus, "humans" have been keeping their elders alive! :-) Evidence of a toothless skulls suggest that able members of the group may have been keeping the elder alive by chewing for her. But for what?? Could it be to access knowledge of poisoned berries to avoid, or hunting methods to teach or ... stay at home creche for the kids while able-bodied adults went out for hunting??

Again, I don't think I needed to respond to your point necessarily ... you're right for the most part.

[pavel_lishin]

> 50 is too low, and any number will always be too low, the way I see it if you incorporate Dawkins' idea of the Selfish Gene into the mix. I would argue that sticking around "to ensure the survival of our offspring" (as you put it) for the human species is significantly more important than any other species on the planet.

I see what you mean, but with every generation of your offspring, you're less and less vital to their survival - your children and grandchildren can care for your great-grandchildren as well; there's more redundancy there, so no individual is as crucial.

[exratione]

Counterpoint: the grandmother hypothesis.

https://en.wikipedia.org/wiki/Grandmother_hypothesis

[Retra]

Of course, menopause needn't be an adaptation, but a side-effect of some other adaptation. (Even that is pushing it, since it is hard to talk about evolution without using language of agency.) The point is: if you do not have actual information about how and when this evolved, you have nothing to stand on.