A clip from a BBC documentary, “Cannabis, the Evil Weed?  This short explains the endocannabinoid system in humans. The endocannabinoid system, discovered in 1989, is a set of receptors in which the only substance that you put in your body that reacts with them is cannabis. Our body produces anandamide, runner’s high, which is identical to cannabis. The endocannabinoid system is the messenger between our immune and central nervous systems. Researchers are finding that we need cannabis as a supplement when our body is ill or stressed.

http://www.youtube.com/watch?v=hpV6licCOMw