How long could a 'normal' human lifespan get with selective breeding?

[bup]

@astro

Socially it doesn’t strike me as a particularly good idea to have a society top heavy with “vigorous” old people. Vigorous old people are still old people with their attendant physical compromises, and there’s a limit to how many older people society can support and still be economically competitive.

So then we’re back to decreeing the minimum age at which one can reproduce, and hoping that’s correlated to longevity.

I suppose some club could start that only accepts people with long-lived parents and grandparents, and whose members agree to only find mates within the group, and who agree to only have children when both partners are at least 40.

Then you elongate life proportionately, and the percentage of old people who have physical compromises remains constant. And your descendants get longer carefree years - after childhood but before having kids.

[Chronos]

Wouldn’t a “vigorous old person”, by definition, be one without the attendant physical compromises normal to a person of their age?

[Skald_the_Rhymer]

@jayjay

Robert Heinlein, in his Future History timeline, created an organization called the Howard Families (after millionaire Ira Howard, who founded and endowed it), for the purpose of lengthening human lifespan. IIRC, the criteria to be a member were that all certain recent ancestors (great-grandparents, I think) had to have lived past a certain age, though I don’t remember the exact details. I’d think that would be a first step, assuming that aging is influenced by genetics (the length of your telomeres, for example).

It’s worth noting that the Howards owe much of their longevity to a factor that cannot be explained simply through selective breeding: Lazarus Long’s longevity. In Time Enough For Love, either Ira or Justin notes that Lazarus lived too long before his first rejuvenation for the breeding to have been the most important factor; he was only a third- or fourth-generation Howard, and no one else of his generation came close to matching his longevity.

[Chronos]

One presumes that the genes for a Lazarus Long had been floating around for a while, and that there had probably been similarly long-living folks before him (and in fact he claims to have met some of them, though who knows if he was being truthful), but that it was only with the establishment of the Howard Foundation that anyone was able to notice people like him.

Still, though, as of Methuselah’s Children, there are plenty of 150+ year old Howards who aren’t descended from L. L., so it would appear that the program was a success even without his genetic influence.

[astro]

@Chronos

Wouldn’t a “vigorous old person”, by definition, be one without the attendant physical compromises normal to a person of their age?

You can physical compromises and still be vigorous. I’m thinking of myself as an example. I’m 51 and physically I’m quite strong and can lift weights that most younger men could not manage, however I still have aches and pains “attendant” with my age, and I’m not going to kid myself that I have the physical stamina I did when I was 25 or 30. If we needed to go to war fielding an army of 50 to 60 somethings, even in good shape, would not be something I would want to contemplate.