[PaulDavisThe1st]

I haven't measured my blood oxygen, alas.

I've been here 4+ years now, and other than being 4 years older and just coming out of a sedentary 3 year period, I notice zero effects of living (and running, cycling, swimming, hiking) at altitude. Can't say any more than that really.

[refulgentis]

Hmmm, given that...it does seem to me the initial claim is likely to be true.

I know you said that it has to vary between multiple individuals at altitude, but it's unclear to me why.

Don't we just have to show some individuals don't ever get back up to the same blood oxygen levels?

[PaulDavisThe1st]

Well, another comment here from a guy of Sammi ancestry notes potential polymorphism in GHC1 as possible (and likely) partial explanation.

I would imagine that there are a variety of potential genetic differences that could generate a wide range of altitude-adaptation differences.