Mind altering substances are very important to humanity, and have been used for thousands of years. I researched opium quite extensively for one of my works, but alcohol and nightshade have also been used (in the European Neolithic). Alcohol and nightshade should be okay to include (herbs), but I suspect opium would have to go into the (much anticipated) realism DLC, due to the silly ratings systems. These drugs could have been for relaxing, as well as medicine or spiritual.
Does anyone know any other Neolithic drugs used?