Uriah

Other than maybe Jews or Parsis no one is truly adapted to city life, because high mortality from diseases made old cities population sinks. The active community life and cooperative agriculture in rural villages though produced much the same effect.

Feudal communities were practically states within themselves. Because lands and animals were communally owned, they were jealously guarded and interlopers were automatically assumed to be thieves. A peasant spent his whole life in a glorified pen.

Agricultural life in mountains resembled feudalism in that it required constant cooperative activity and geography naturally restricted movement in much the same sense feudal lords did: you only have so far to wander when boxed in mountains.

Peasant life was a thresher. The people who couldn’t cut it were partly those who couldn’t meet the physical demands without succumbing to exhaustion and infection, but also those who felt penned in, who dreamed of what life would be like on the other side of the mountain.

Okay, so life was stressful, but what does that have to do with skull shape? Why do different species of domesticated animals invariably end up with short, broad skulls?

Two researchers at Harvard made note that in animal studies high levels of glucocorticoids inhibit the outward development of the upper jaw. They decided to measure if the same relationship between skull form and stress reactivity occurred in humans: https://sci-hub.se/https://srcd.onlinelibrary.wiley.com/doi/abs/10.1111/j.1467-8624.1995.tb00950.x …

I suspect that the outward development of the jaw is paralleled by outward development of the shoulders because brachycephalized people are usually quite broad, and outside of cold mountains, long limbed in the sense of the stereotypical “European supermodel”.