Medical marijuana was legalized in the state of Colorado in 2000. Twelve years later, voters approved recreational marijuana throughout the state. As a result, Coloradans have been inundated with information about both the merits, and the pitfalls, of marijuana use. But according to author Hampton Sides, the science around marijuana is not where it needs to be to answer many of the questions surrounding the drug. His article, "High Science," is the June cover story of National Geographic magazine. In it, Sides reports on marijuana research happening around the world. He spoke with Ryan Warner.