Gibbons can communicate with each other and have an extensive vocabulary

FOR MOST of history we have been firmly convinced that we are completely different to animals. This has been reinforced by various theologies — in the Christian world it’s expressed by the idea that mankind was created as an image of God.

This conviction started to erode around a century and a half ago. Evolutionary theory suggested that we developed from animals and might have more in common with them than we realise. The progress of science since then has proceeded to chip away at our notion of our own uniqueness.

But one point of difference that we have clung to with something approaching desperation is the notion that we are special because we have language and can use it to communicate with each other in a way that no other living creature can.