I happily grant much of what you’re saying; I think the difference here in my view is that you can define groups in one way, and find that _other things_ can be predicted. No one said, “we will define African Americans by whether or not they have problems with high sodium causing heart issues” and then determined that African Americans have this medical problem. Race is certainly a suboptimal way to predict this medical problem; much better to have statistically determined genetic markers, or better yet, a complete rendering of the mechanisms of action. But we don’t.

I’m all for “variation with groups is larger than variation between groups”, both as a literal reality and also as a practical answer to the question of how do I go through the world without being a jerk to people.

Racial categories are squishy and permeable. So are ideas of species, sub species. They’re useful tools with sharp limitations. Again, some people certainly oversell the utility of the tools, often for malign ends. But it doesn’t mean it’s an entirely bankrupt view

The following is a response to only your first paragraph:

Huh? If the distributions of bone densities among “people you would visually identify as ‘race X’ ” and “people you would visually identify as ‘race Y’ ” differ, then knowing that an individual would be someone you would visually identify as ‘race X’, gives you some amount of statistical information about their bone density.

I guess you just mean that you can’t make any high-confidence statements that are substantially different than if you didn’t have that information?

Small note on second paragraph: I don’t think the racial categories in question are even half-biblical? I mean, I know in the Old Testament there are lots of things referring to e.g. edomites, or Amalekites, etc. , but I don’t think these are really like, “races”, and I can’t think of anything that really supports the idea of a fixed set of racial categories. But perhaps I’m forgetting/missing something.

that is a wonderful word, thanks

Are you positing a close ancestral link between Africans and Australian natives, say closer than between either and northwestern Europeans?