I was told once that in China, people squat a lot more than in the West. Both for toilet use, but also just for "sitting down" somewhere. Example: I was told that upon seeing a bench, whereas westerners would normally sit on it, a Chinese person will squat on it. This supposedly also makes their legs much stronger. Can anyone confirm this?
This is the stereotypical Asian squat. Interestingly, young children do it by default. I think we lose flexibility as we age. I can't squat back on my heels without straining my shin muscles to keep from falling backwards, but the more I do it, the easier it becomes.
It is certainly a lot healthier for your knees than squatting on the balls of your feet, if only because your knees stay roughly on the same vertical as your toes. This is old powerlifter wisdom, and anyone with a knee injury can tell you first-hand. I can't squat on the balls of my feet without my right knee squealing in pain. Squatting on my heels is, at least, tolerable.