Reporting from Wounded Knee

You’d assume that osteoarthritis of the knee would be caused by wear and tear. But if that were true, wouldn’t we see a lot more knee arthritis in the bones of those who lived back when humans were a lot more physically active? Well, it turns out that our knees have it a lot worse than our ancestors. And that higher rate holds “even after scientists corrected for body mass and age. So there’s apparently something else driving the increase in knee arthritis.”