To me, this is a question for the next generation of primatologists. It may be an answerable question for the program the Max Planck Institute is attempting, which would attempt to study all chimpanzee groups cultural behaviours using motion-sensor camera traps. However, at the moment it is really not well understood how culture diffuses between chimpanzee groups. In fact, this is quickly becoming a contentious issue between anthropologists and psychologists. Psychologists claim that we cannot be sure that chimpanzees are as complex culturally as anthropologists claim until we know that their cultures diffuse and are transmitted in the same way that human culture diffuses and is transmitted. They claim that until we understand this, it is possible that what we are observing are simply products of ecology, genetics, and random chance.