Here’s how cannabis use became prohibited—and the science of its biological, psychological, and social effects. At the 1998 Winter Olympics in Nagano, Japan, snowboarding made its debut as an Olympic sport. No longer relegated to the fringes, snowboarders took to the snow-capped peaks of Mount Yakebitai, and 26-year-old Canadian Ross Rebagliati rose to global fame. But shortly after he won gold in the giant slalom event, a drug test revealed 17.8 nanograms per milliliter of…