Did you know that in orangutan, a raspberry is used to indicate play. It's one of over sixty signals that orangutans use to communicate.

They can make loud calls that travel across miles of rain forest as well as quieter sounds such as "kiss squeak" when they're disturbed, and "grumph" when they are fearful. They also use visual signs such as pointing, rocking their body, waving, and banging on objects.

Are they using gestures to represent words?

No, orangutan communication is more like charades. They have certain gestures to initiate interactions, request or share objects, prompt joint movement, or to cause another individual to move back or stop their action.

Research also found they can be persistent and elaborate on their signals if they don't think another ape, or person, understands them.

How did the researchers find that out?

Scientists had two types of food, one the orangutans liked, the other they didn't. They allowed each ape to ask for the preferred food with a signal.

In some instances, the researcher gave them the preferred food, in other instances the researcher played dumb, giving them half of the preferred food or only undesirable food. They recorded how each orangutan responded.

Signaling

When apes received preferred food, they stopped signaling in most cases.

When they received part of the preferred food, they would repeat the first signal several times. When they were given only undesirable food, they would use a new signal.

Read More: Orangutan pantomime: elaborating the message (Biology letters)