(I’m not actually sure if e.g. median income is positively associated with elevation in the US, since a bunch of those people are “ski bums” working a series of seasonal jobs at ski resorts, white water rafting companies, etc. I used the word class because I think those people are still disproportionately drawing from upper-class cultures and probably have high education on average, and there are definitely a lot of rich people hanging around as well, and the latter are more likely to live closer to the resorts. Mean income is definitely higher in those areas, though.)
That’s a really neat set of data in that blog post which I will have to go over in more detail later. The effect size doesn’t seem to be that large to me, but maybe I don’t have a good intuition for birth weight; 100 g = 0.2 pounds corresponds to 4% of the low range of what is considered healthy in European babies. And that’s over a fairly wide elevation range of 3,300 feet. So I would be surprised if that could explain the very large difference in adult average BMI, but I could also be totally wrong about how fetal weight translates to adult weight. Given the limitations of “controlling for observables” I’m also still leaning towards selection effects, but the close linear relationship does cast doubt on that idea. I think it casts doubt on the pollution hypothesis too, FWIW, since there’s no way that’s cleanly linear, and it probably fits better with hypoxia but still not perfectly, since air pressure decreases sublinearly with elevation.
(I’m not actually sure if e.g. median income is positively associated with elevation in the US, since a bunch of those people are “ski bums” working a series of seasonal jobs at ski resorts, white water rafting companies, etc. I used the word class because I think those people are still disproportionately drawing from upper-class cultures and probably have high education on average, and there are definitely a lot of rich people hanging around as well, and the latter are more likely to live closer to the resorts. Mean income is definitely higher in those areas, though.)
That’s a really neat set of data in that blog post which I will have to go over in more detail later. The effect size doesn’t seem to be that large to me, but maybe I don’t have a good intuition for birth weight; 100 g = 0.2 pounds corresponds to 4% of the low range of what is considered healthy in European babies. And that’s over a fairly wide elevation range of 3,300 feet. So I would be surprised if that could explain the very large difference in adult average BMI, but I could also be totally wrong about how fetal weight translates to adult weight. Given the limitations of “controlling for observables” I’m also still leaning towards selection effects, but the close linear relationship does cast doubt on that idea. I think it casts doubt on the pollution hypothesis too, FWIW, since there’s no way that’s cleanly linear, and it probably fits better with hypoxia but still not perfectly, since air pressure decreases sublinearly with elevation.