This is a look at tree rings, which is known as "dendrochronology". Some years after learning about it in college, I had the opportunity to try to use it to date trees near my home. I took many photos of stumps, counted rings, and compared them. I was disappointed that I couldn't date trees by their rings. That made me come to doubt that a major scientific study that used dendrochronology to make a "calendar" of 12,000 years couldn't be right.This...