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Comment by xenadu02 | Hacker News Reader

Almost certainly not; improved memory is absolutely something evolution would select for in primates, especially humans.

Most mouse models don't replicate in other animals either.

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You have to live to reproductive age for your genes to carry on. So a genetic difference that improves outcome for adults, but harms children won't be carried on as often (per other comments, this one may improve memory--in mice--but has negative effects related to resisting common diseases like the flu). On the other hand, genes related to cancer perpetuate because their impact often is felt after primary reproductive age (at least historical reproductive age, since we've started having children later in life over the last century).

Additionally, nothing has to be selected (evolutionarily speaking). It's a stochastic process. We could be one base-pair swap away from perpetual youth, and never see it because it just doesn't happen (or when it did happen they died from other circumstances before reproducing sufficiently to spread the genes wide enough to be useful).

Well, yes and no. We each have 3.2 billion bases and about roughly 100 mutations each, over 100 billion people who've ever lived. That's about 3000 mutations per base pair, so if the eternal-youth mutation was indeed a single base-pair swap away, thousands of people would already have been born with it. Of those, we could expect some decent fraction to have had children. Given that eternal youth confers a staggering reproductive advantage, and we don't have it, it's safe to say that if it exists at all, it's more than a base-pair swap away.

>improved memory is absolutely something evolution would select for in primates, especially humans.

What if it makes people more scared, because they can remember past experiences better. This could lead to less procreation and thus inverse selection pressure.

Only because a trait is superficially good it doesn't mean nature would select for it.

Why would a memory enhancing drug only increase rememberance of negative memories and not the positive and loving ones? Such people could become more active, motivated and procreating more because life seemed more motivating for them because they remembered all the good from the past also?

it would increase both, but negative ones can have bad, debilitating consequences in life (cue PTSD, phobias)

That's not the point, I was just giving an example. It could have millions of effects and whether evolutionary selection would favor these genes is not trivial.

> Why would a memory enhancing drug only increase rememberance of negative memories and not the positive and loving ones?

There's a psychological phenomenon:

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

That a trait is preferable and not developed can never be an indicator of what a gene is for. The fact that I didn't evolve to fly doesn't mean I don't have the potential genes for that. There's also far less natural selection in evolution than we think. Evolution overwhelmingly happens in relatively short time periods, after which stability seems to take over. This is at odds with the natural selection principle as the primary driver of evolution. Also, most DNA-sharing between organisms happens horizontally, not top down (think single cell organisms). There's really much more that we don't know than what we know here.

HIV related dementia is a thing. This method might be able to alleviate it

https://www.mdmag.com/medical-news/breakthrough-discovery-in...

I agree, super memory is not necessarily a good thing

Sure but selection only works on events that have happened. Loss of function isn't that common especially if the benefit of the gene is resistance to flu, which is far more important than improved memory on an evolutionary scale. Purging selection trumps almost anything more rational.

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