In 1952 on the island of Koshima, a primatologist was leaving sweet potatoes on the shore for the monkeys to eat. One smart monkey, a one and a half year old named Imo, began washing the sand off her potatoes in a brook. You can imagine how much better this insight on her part made the potatoes taste! Next, Imo's playmate was observed washing potatoes. Then her mother, then another peer. In four years, three more of her relatives and four members of another macaque group were washing their food. The primatologist realized he was watching the way new ideas spread in society! Infants in the next generation saw their mothers washing potatoes, and virtually all the next generation, both male and female, grew up washing their food, but not the older males! Older males were resistant to the new idea, refusing to wash their food even when older females made the change. It was as if a new idea from a female, or perhaps a lower-ranking member of macaque society, were rejected by older males even though it was a good idea. They seemed to choose eating sand rather than admitting Imo was smarter than they were.