Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Despite centuries of recreational use of cannabis, it is only relatively recently that its mechanisms of action, and the existence of endogenous cannabinoids, have been discovered. In this Timeline article, Raphael Mechoulam and colleagues discuss early research on the plant cannabinoids and speculate on the directions this research might take in the future.