Achilles and Ajax Gambling, from a black figure amphora.

All gambling must have had divinatory origins, since the random (which is to say, undirected by humans) nature of the acts would have been considered indicative of the will of the Fates. Where the ancients speak off the casting of lots, they were probably refering to a kind of divination based upon the throwing down of sticks of differing lengths, as in oriental modes of fortune-telling, and then interpreting the patterns according a prescribed set of rules or formations, similar to the I Ching. Getting the short straw must have had a peculiarly unfavorable meaning. Card games are, of course, derived from Tarot, which came from Egypt. Back to the future.