They are falling. And getting hurt, seriously. Two did, not too long ago. In Jaipur. One in the bathroom. One, I believe, on one of the non existent sidewalks common to most of urban India. Others have fallen, too, family and friends, and broken bones. Those that fall are younger. Our world may be too flat. Maybe there is too much asphalt, concrete, carpet. Maybe we have forgotten how to balance ourselves. Some have deficiency of B12 our balance vitamin , a problem due to decreased absorption after age 60. Knee replacements nowadays also are common at 50. We are not as strong. We sit. Every chance we get. But not on the floor. In the car, at work, on the toilet we sit comfortably. Even at prayer meetings, disregarding tradition, more sit on chairs as getting up is too difficult. The problem likely is that the quadriceps or quads for short, the muscles in the front of our thighs that critically support and protect the knee, are weak. The knees bear more stress and wear out.