[oostevo]

I don't; it was just a thought experiment.

However, I did have someone with a Ph.D. in kinesiology (I think?) tell me that there's essentially no evidence of knee, hip, or back dysfunction in developing countries where people don't sit all day.

[corprew]

One of the interesting things you see in undeveloped countries is that people squat in a position that is hideously uncomfortable if you're used to using a chair.

Here's a somewhat nutty article on it called "third world squat": http://www.t-nation.com/free_online_article/sports_body_trai... but it is an actual thing that people and it makes for a different muscle development than chair-dwellers have.