How Do Vervet Monkey Grunts Act Like Words?

Jared Diamond says vervet monkey grunts function as words. Each grunt names a different danger, and the other monkeys answer with a matching move.

Bird songs already carry a lot of information, and similar studies followed in monkeys. A husband and wife at UCLA later moved to Pennsylvania. They did the vervet monkey work. Vervet monkeys make grunts, and the pair thought some of the grunts sound a little different, so they recorded the grunts and played them back. Some grunts made the monkeys look up. Some made them look down. Some made them prop themselves up. One grunt means eagle. When a vervet monkey gives the eagle grunt, the others look up. Another grunt means python. When they hear python, they look down in the grass. Another grunt means leopard. When they hear leopard, they scramble up a tree.

The calls carry the same kind of information already found in bird songs, now carried by monkey grunts. A short sound stands for one animal and tells the group where to look.