Gorillas beat their chests to communicate with each other, according to a new study. German scientists studied 25 gorillas in Africa. They found that male (雄性) gorillas tell others about their body size by beating chests. The bigger the gorillas are, the lower the sounds’ frequencies (频率) will be. Other gorillas can hear this. Bigger gorillas can stop smaller gorillas from trying to fight them by telling them that they’re bigger. This also helps them find mates (配偶) more easily, as bigger male gorillas are more attractive to female gorillas.