behavior. A drug's ability to affect the neural systems related to dopamine production has now become the defining characteristic of drugs with serious abuse potential. The discovery of a previously unknown system of cannabinoid neural transmitters is profound. While century-old questions such as why marijuana is nontoxic are finally being answered, new fascinating questions are emerging. In the words of Israeli researcher Raphael Mechoulam, the man who first isolated the structure of THC, "Why do we have cannabinoid receptors?"...
