When we’re talking to another person, we probably wouldn’t leave without saying goodbye; that would just be impolite. Apes seem to do something similar, researchers report in a study, in which they documented apes purposefully using signals to start and then end interactions — a behavior not seen outside of the human species until now. They also found that the social and power dynamics between the interacting apes affected the communication efforts used, which the researchers say mirrors patterns similar to human politeness.