The dilemma surrounding the place of evolution of the cannabis plant has been a topic of immense interest lately.
A recent analysis of ancient pollen suggests it evolved some 3 kilometers above sea level on the Tibetan Plateau. Interestingly, this site is only a few hundred kilometers from a cave that researchers lately announced was once home to our ancient Denisovan cousins.
While cannabis seeds are a rich source of proteins and fatty acids, the fiber from the stems of the cannabis plant can be spun into yarn and converted into textiles; its flower, though, is the source of all the cannabinoids, and thus it shouldn’t come as a surprise if we tell you the drug has been in use for at least the last 2700 years.
For the analysis, John McPartland, along with his colleagues, at the University of Vermont went thoroughly through the already existing scientific studies to pick out geological and archaeological sites across Asia where cannabis pollen has been found.
The researchers said that identifying cannabis pollen is a hard task since it looks identical to the pollen of a closely associated plant named the common hop. The latter is reportedly used for flavoring beer.
However, McPartland and his teammates are of the view that, despite the aforesaid obstacle, it is possible to find which species the pollen belongs to by considering the other pollen present at a given site- cannabis lives on open grassy steppes, thus its pollen usually occurs with the pollen of steppe plants. The common hop, though, grows mostly in woodlands, so its pollen generally occurs with tree pollen.
Applying this rationale, the researchers saw that the earliest occurrence of cannabis pollen in the archaeological record is in northern China and southern Russia. Further studying the distribution of the pollen, the team deduced that cannabis probably emerged on the Tibetan Plateau in the vicinity of Qinghai Lake, about 3200 meters above sea level.
Notably, cannabis thrives in arid, steppe-like environments and it was the formation of the Tibetan Plateau that led to the spread of those conditions in Asia.
The Tibetan Plateau formed because of the collision between the Indian and Asian landmasses, so in a way, we can thank plate tectonics for the evolution of cannabis, says McPartland.
Robert Clarke of BioAgronomics Group Consultants, Los Angeles, however, is critical of the presumption made by the researchers. He said that trees may grow on the banks of rivers in steppe environments, therefore cannabis and tree pollen can co-exist.
According to Jean-Jacques Hublin at the Max Planck Institute for Evolutionary Anthropology, Germany, who has had the opportunity to analyze the Baishiya Karst Cave material, the Earth was deep in an ice age 160,000 years ago. “We don’t yet know whether cannabis continued to grow on the Tibetan Plateau during such harsh conditions,” he was quoted as saying.
