At Twycross Zoo, primatologist Dr. Katja Liebal is investigating the methods of communication chimps choose amongst themselves.

Although chimps can't speak, they use a range of gestures and facial expressions as a way of communicating.

Chimps don't need language in their environment because they have a very complex communicative system based on nonverbal communication.

By observing many different groups of chimpanzees, Katja hopes to compile the world's first chimp dictionary.

The Twycross chimps are a useful group to study.

There's an ongoing power struggle between the dominant male Kip and a young teenage challenger named Peter.

Fights between the pair are commonplace.

The tension is producing a rich and varied array of chimp communication across the whole group.

The first gesture noticed by Katja comes as a direct result of the fight.

Peter is spotted making a facial expression that signifies fear.

The corners of the mouth are really withdrawn, and you can see the teeth.

They also do this when they scream, so it can be slightly open.

Chimps also have a facial expression for playfulness.

The mouth is open and the teeth are still covered with the lips.

It would be like this, so this would be a play face.

In this interaction, we can see Kip and William are chasing around, and you can see that it's a playful interaction because William actually has a play face.

But chimps gestures can be far more subtle than mere facial expressions.

Immediately after their fight, Peter taps Kip lightly on the shoulder.

It's "Chimp" for saying, "Sorry!"

The individual that lost the fight will approach the more dominant one, and will extend its arm to ask for reconciliation, so this is an expression of submissive behavior.

The chimps also show such communications as displaying, which means, "I'm the boss,"

pouting, which means, "give me some food please,"

grooming, which means, "I am your friend and supporter."

Pretending to bite means, "I'm enjoying this play fight."

All of these behaviors reinforce social bonds, communicate feelings, and establish who is in charge of the group.

They even perform actions that seem... all too human.

But while chimps across the world only have a limited repertoire of vocalizations, they constantly invent and share new gestures with each other.

One theory basically is that they imitate gestures from each other.

They learned their gestures by interacting with others.

The theory that chimps imitate each other's gestures has led some primatologist to believe that this behavior may have also been present in the ancient ancestors of humans,

and may have led to the languages that we all use today.