The wise man points at the moon and the madman looks at the finger

Jean-Louis Dessalles proposes a third very attractive hypothesis. He noticed that the little human being, even before being able to talk, have a trend to point with their finger, i.e. sharing information. It's not the case with animals.
An experience illustrates this:
Some food is hidden under one bowl and nothing under another: showing the right bowl to a chimp does not incite him to get the food whereas going towards the right bowl incites the animal to go and get the food. On the contrary the child will understand the information just by being pointed the right bowl.
The difference is that the animal does not generally integrate in its communication the given information which does not expect a return. Communication helps to show physical strength, sexual attraction but not things useless to the communicator.
Man also communicates this way, but he will also add information without expecting other information back. Doing that, he's gonna show others the qualities which make him worth joining the groupe (self-abnegation, altruism, sincerity...).