Eighty percent of North Americans have X-ray evidence of osteoarthritis by age 65, and sixty percent have significant joint pain. A recent study compared the size of knee cartilage in: 176 skeletons of people who lived from 6000 to 300 years ago (from U.S. museums)
 1581 skeletons of people who died between 1905 and 1940, during the early industrial era
819 skeletons of people who died between 1976 and 2015 during the modern post-industrial era They found that the incidence of knee osteoarthritis (loss of cartilage) has risen at a frightening rate over the last 50 years, reflecting changes from active agrarian or industrial lifestyles to a post-industrial society in which most people do not do a lot of physical labor and gain too much weight (Proc Nat Acad Sci, August 29, 2017;114(35):9332-9336)….