Well, one feature of sedentary life is stable burial practices, with strata (sometimes graveyards: often, bodies were buried in the floors of their home). So you could see the change over time there, associated with a particular type of settlement. I think there is likely less evidence for the HG “norms”, but again, the situation of the burial often gives you a good idea about the lifestyle of the person.
I agree it gives you some idea. Those ideas might become a little less distinct and more fanciful as millennia pass. In medicine, you can sometimes come up with a bunch of numbers, which is one thing. It is something else to believe these numbers apply everywhere and not just to one place or population. This was a major problem with Covid reporting, research and remedies.
We can do isotope analysis of bones and teeth and form a pretty good picture of what that person’s diet was like. It’s not just speculating on skeletal height vs some abstract theory of dietary change. It’s correlation of two measurables.
The reason correlation is not causation is in part because of the possible confounding conditions mentioned - and my list is very incomplete. Still, it is impressive they can get as far as correlating even these two variables and it does lend credence to your point. If modern archeologists believe it probably they have reason.
Sure, but note that some of your confounding conditions are directly tied to the change in lifestyle - note that “change in diet” isn’t all the model talks about, it’s more “change in lifestyle” overall, including changes in food preparation, changes in activity and mobility, etc .) And others, like climate, are controlled for by studying contemporaneous foragers vs farmers in the same region.
They’re not just saying “eating more grains leads to smaller physique”, it’s “taking up farming leads to smaller physique” and one of the ways we identify farmers is through isotope analysis.
Just to add, we’ve actually dug up a lot of skeletons, so measuring the difference is statistically valid in many locations.