Similarly, many people past their childhood years couldn't imagine climbing a tree, stating that they're too old to be physically capable of doing so. Yet if you climbed a tree every day of your life, I suspect it would be routinely easy well into your 30s and 40s.
It's not age by itself that's at fault, it's the avoidance of certain physical movements that atrophies our abilities, caused by things like chairs and taboos about child vs adult behavior.
I suspect this is similar to going to the floor regularily.
On the other hand, we're still growing taller...
I will easily sit on a rock while hiking (better than the dusty or wet ground) but at home happily sit on the floor to read, talk, play etc. How do non-floor-sitters play with their small kids? Peoples' physiology is the same, but they have adapted their environment -- I presume there is some mechanism or affordance for this that I am not aware of. (Oh, and I use a chair when using my laptop, like now).
> Deep squatting is favored by people in Southeast Asia, Africa, and Latin America,
My mother has never talked about her childhood in WWII very much but one observation she has made several times over the years how distinctive it was to her that the Japanese soldiers would squat in a group for hours having a meal, or meeting, or just relaxing. Out of perversity I taught myself to do that as a kid but never developed the strength to do it for an extended period and now cannot do it at all, though I am seemingly quite flexible and strong.
In 15 minutes I would just give up and either standup or lay flat on the floor. I can stand up all day but sit on the floor for 15 minutes is awful.
https://www.amazon.com/Structures-Everyday-Life-Civilization...