It’s a fun little thought experiment to imagine the beginnings of the marijuana plant. The why, how, and where of it all. Why would a plant evolve into something that, when smoked, would make humans feel the way it does? And where did this whole thing start?

A new study published on Friday answers at least the “where” question.

It had been thought that Central Asia was the source where weed sprung, but the study published in Science Advances was able to trace the source back to Eastern Asia, around 12,000 years ago. At the time, it was used more for medicine and fiber than getting high.

It then took about 8,000 years before cannabis spread to other areas of the world, in particular Europe and the Middle East. That’s when it gained popularity by getting people high.

What’s interesting is that the study’s authors were able to trace all marijuana variations to one single source in East Asia, probably northwestern China. This would mean one region’s climate and land were the ideal conditions to evolve marijuana as we know it. After that, the plant spread, since one of its reasons for popularity is its ability to grow anywhere.

The authors of the study found that the samples of wild varieties were “historical escapes from domesticated forms,” proving the single origin location theory. They claim that any purely wild marijuana variations have gone extinct.

Read the study here.

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