Recognizing one another
One of the most important pieces of information it transmits is identity. We take it for granted that all our faces are very different from one another yet this is a very unusual characteristic among animals. If individuals are to cooperate in an organised team in which each person has their own responsibility then it is crucial for those taking part to be able to distinguish one from another immediately. Many social animals, such as hyenas and wolves, distinguish each other by smell. Human's sense of smell, however, is much less well-developed than their sight, so recognition should be based on the shape of the face.