Non-verbal communication is important to human communication. Think about how different it can be talking to someone on the telephone from speaking face-to-face. Communication is two-way, so we adapt our communication (verbal and non-verbal) depending on the other person’s response. If someone isn’t engaging with you, such as smiling at your jokes, then you might tone down the humour, if you want to encourage someone to keep talking you might smile or nod your head.
A recent study looked at the reactions of two chimpanzees (who have been trained in language) to communicate with a human to find hidden food. The chimpanzees increased their use of non-verbal communication, such as pointing, when the human approaches the food, thus meaning the food is found quicker. This study suggests that the use of non-verbal cues in response to an action is likely to have been important in the development of human language.