Cannabis Evolved High Up on the Tibetan Plateau, Says New Study

The search for cannabis’ origins has reached a new high. Analysis of ancient pollen now suggests the plant evolved two miles above sea level on the Tibetan Plateau. 

While the plant’s Asian roots have been known for centuries, a more exact location of its beginnings has remained a mystery. 

Setting out to fill this gap in the cannabis family tree, researchers from the University of Vermont scoured through scientific studies dating back to the 1930s to find the dig sites across Asia where cannabis pollen fossils have been found.

But identifying cannabis from pollen fossils isn’t as easy as recognizing the plant itself. The pollen of Asian cannabis is remarkably similar in appearance to the pollen of another plant, the common hop, which diverged from cannabis around 28 million years ago. It’s this similarity between the two plants’ pollen that has thwarted many previous attempts to pinpoint the popular plant’s beginnings. 

To get around this issue, the Vermont team first analyzed the pollen of other plant species found in the archaeological sites. 

Because "cannabis flourishes in steppe - an open, treeless habitat," according to the researchers, its pollen is usually found beside the pollen of grasses. The hop plant, on the other hand, grows mostly in woodlands, where its pollen mixes with tree pollen. 

Using this logic, the research team determined that cannabis probably emerged 28 million years ago on the north-eastern side of the Tibetan Plateau near Qinghai Lake, which stands 3260 meters above sea level. 

Over the millennia, the plant would spread west to Europe and east into Asia, where it first appears in the archaeological record 10,000 ago as a food crop in Okinoshima, Japan.