We often think that when a wild mountain gorilla beats his chest, it means he is angry, and you’d better get out of his way. But it is really just his way of either showing off, getting rid of anxiety, or merely just staying in contact with his family. Craig Sholley, the explore team's guide to the gorilla population of Rwanda, explains the nuances of gorilla communication, from the "belch vocalization" of a content silverback to the angry "pig grunt" of a female feeling threatened on her own turf.