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Comment by thelittleone | Hacker News Reader

This make me curious about mutations and human evolution.

By 50 years of age she has past her (natural) maternal age. So it's not like women with that mutation would bear more children.

How would such a mutation help her lineage? But that same question, more broadly, how do mutations that benefit people past their child bearing age factor into human evolution?

I suppose mentally healthy grandparents are able to spend more time with grandchildren freeing up the parents to be more productive. They can also pass down wisdom, techniques that could benefit grandchild.

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> How would such a mutation help her lineage? But that same question, more broadly, how do mutations that benefit people past their child bearing age factor into human evolution?

To oversimplify a bit, you can think of most mutations as neutral, in terms of reproductive fitness. People (and populations) accumulate them all the time, just by chance. Occasionally, one that was previous neutral becomes beneficial when the environment changes - say, when it confers immunity to a virus, or helps with synthesizing an amino acid that's in short supply. This is why having a big population with lots of variation is beneficial and why bottlenecks hurt the viability of a species.

I remember reading something where they explained that cultures where they kept the grandmothers around tended to have better outcome for both the mother and the baby when their daughters gave birth.

It isn't really surprising, when you think of it, and it's probably just one of many examples where aging better, past child bearing age, improves the chances of a lineage.

Your last paragraph is likely the crux of it. When people die “young” in low information societies, received wisdom has tremendous survival value.

It doesn't, that's why not everybody has that gene; if Alzheimers was something you developed as a teen, I'm sure that mutation would spread and soon everybody would have it.

Maybe we could use that gene in the future on patients at the onset of regular Alzheimers.

It would be interesting to see if, in a few thousands years, these traits do somehow manage to get passed down. There is a good chance that traits that help with things like Alzheimer's wouldn't be as likely to get passed down because of reasons you've mentioned. Or we might be able to treat it with other therapies as science outpaces evolution as far as longevity goes.

Humans are in a very unique place with our sentient minds and understanding of the world. It'd be nice if we could compare ourselves to other species, but we haven't found any yet, and they're likely to be billions of light years away, or extinct, or both.

I agree.

One thing that strikes me is how many go undocumented - including mutations that cause HIV immunity.

I think it's incredibly interesting that perhaps 5000 years from now some mutations would be well established - but that we aren't aware of now (as they happen).

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