Andrew Sullivan blogged about the recent discovery of new endogenous cannabinoids: put simply, our brains make our own weed.

It’s been years since the cannabinoid receptors, the receptors that react to THC and other similar drugs, in our brain were discovered and any scientist would be able to predict that our brains would create neurotransmitters that use these receptors. Maybe we hadn’t found any of the endogenous form yet, so this might be a new discovery but it’s certainly not surprising. If our brain has a receptor for a certain type of neurotransmitter, it’s almost a given that our brain produces neurotransmitters that those receptors will receive. Our brain doesn’t have random receptors in the hopes that the body it’s in will take those chemicals in. It only accepts what it expects to accept; the fact that there are other chemicals which can mimic, or block, those neurotransmitters is just a bonus.