I suspected that you guys could make this thread more interesting.

Some people believe that Cain and Abel is a later version of the Sumerian myth "Dumuzid and Enkimudu" (by the way, that website is fantastic!), where Inana, the Sumerian goddess of fertility, wants to marry the farmer Enkimudu, as opposed to the brother who wants her to marry the sheperd Dumuzid. Dumuzid eventually convinces her to marry him.

This version (if the two stories are related) is different from the Hebrew one in that Dumuzid and Enkimudu remain the best of friends after the dispute.