In a museum about the history of Tokyo, I saw an exhibit that showed a typical Tokyo home from hundreds of years ago. It contained an elaborate good-luck charm next to the shrine. I realized that good-luck charms can be explained by my theory of human evolution as another example of behavior — along with art, ceremonies, and gift-giving norms – that long ago supported technical progress. This particular good-luck charm was hard to make. Because people wanted them, they bought them. This helped support skilled craftsmen, who were the ones who made technical progress. Along the same lines, ceremonies usually involve lots of high-end hard-to-make stuff, such as fine clothes.
Visiting distant big cities has taught me a lot about human nature. The big examples are the Shangri-La Diet (Paris) and the umami hypothesis (a earlier Tokyo visit led me to make a lot of miso soup, which had surprising effects). Trips to Antigua (single words make it easy to trade), Toronto (gifts support technical progress), and now Tokyo (again) helped me think about human evolution.