Chest Beating

Chest beating, in male gorillas, is a bit of a cinema stereotype. Studies have, however, now been carried out on 6 male Mountain gorillas in Rwanda's Volcanoes National Park, to determining its function ( https://www.theguardian.com/science/2021/apr/08/gorilla-beat-chest-signal-size-avoid-fight-with-rival-researchers-say). The Primatologists, doing this study, used 2 green lasers, so they could accurately determine the width of each male's back. Chest beating seems to provide 'honest information' (the animal can't cheat because chests of different size produce different sounds) about the likely strength of the male. Chest beating appears to stop males getting into potentially damaging fights with bigger, stronger opponents.