historycircus

There is a whole branch of anthropology dedicated to answering the very question you have just posed. Here are some books that look at the issues of exchange/trade economics that have been helpful to me - you'll have to read them and decide for yourself:

Maurice Godelier, "The Mental and the Material."

Maurice Godelier, "The Enigma of the Gift."

Claude Meillaseaux [sic], "Maidens, Meal, and Money."

Claude Meillaseaux [sic], "The Anthropology of Slavery."

Marshall Sahlins, "Tribesmen."

Marshall Sahlins, "Stone Age Economics."

Maurice Bloch, "Cultural Materialsim."

William Rosebury,"Anthropologies and Histories."

Arjun Appadurai, "The Social Life of Things."

Annette B. Weiner "Inalienable Possessions."

If you can wade through that stuff, and then want more, just let me know.