From an evolutionary standpoint, individuality, self-awareness, and self-serving behavior all appear to be by-products of our species' tremendous dependence on learning.  Learning, by its very nature, is a differentiating and individuating experience.  No two individuals can possibly share exactly the same set of experiences over the courseof their lives, and since eperience shapes both our values and our perceptions of ourselves, a highly developed awareness of self and self-serving behavior become unavoidable.  This does not prevent us from cooperationg with one another since most of us discover in infancy and early childhood that the benefits of cooperation usaully exceed the costs.  Thus, enlightened self-interest ensures a substantial amount of cooperation in every human society (1991, p. 26).