AMSTERDAM Chimpanzees drum with regular rhythm when they beat on tree trunks, a new study shows. Chimpanzees and humans last shared a common ancestor around 6 million years ago. Scientists suspect this ancient ancestor must have been a drummer, using beats to communicate . “Our ability to produce rhythm — and to use it in our social worlds — that seems to be something that predates humans being human,” said study co-author Cat Hobaiter, a University of St Andrews primatologist. Previous