Cannabis sativa is one of two main varieties smoked today. It diverged from cannabis indica more than 1 million years agoBildagentur-online/Getty Images

It’s the kind of question that might be raised in a smoky room, as the asker flicks back the wheel on a lighter, about to hold the flame to a joint: Where did weed even come from? Not the marijuana dispensary down the street or that guy your cousin goes to – but long, long before that?

Pinning down precisely when cannabis evolved is tricky business because the plant’s iconic leaves …

 Cannabis was one of the first crops that humans cultivated about 12,000 years ago. But medicinal and psychoactive uses are much more recent  Read More