Table manners are as old as human society itself, the reason being that no human society can exist without them. The active sharing of food — not consuming all the food we find on the spot, but carrying some back home and then giving it out systematically — is believed, even nowadays, to lie at the root of what makes us different from animals. Birds, dogs, and hyenas carry home food for their young until they are ready to find for themselves, and chimpanzees may even demand and receive pieces of meat from other adults in their group. (Chimpanzees apparently exhibit this behaviour only on the occasions when they consume meat; their main, vegetable diet they almost invariably eat where they find it, without sharing.)
→Table manners are something that can differentiate humans and chimpanzees.