Cannabis smoking began in China at least 2,500 years ago, according to new research.
Traces of THC – the psychoactive chemical in cannabis – have been found in wooden incense burners dating back to the first millennium BC.
The vessels were in an ancient tomb dug up at a spectacular mountain range near the Himalayas dubbed ‘the roof of the world’. It is the first evidence of the recreational use of marijuana.
The smoke would have got mourners high during funeral rituals, say scientists.
Co-author Professor Nicole Boivin, director of the Max Planck Institute for the Science of Human History in Germany, said: “The findings support the idea cannabis plants were first used for their psychoactive compounds in the mountainous regions of eastern Central Asia, thereafter spreading to other regions of the world.”
Weed has been around for thousands of years but most early civilisations used it as a herbal remedy.
Remnants have been found in ancient Egypt and at other sites. Little is known about how it became one of the most widely used mind-altering drugs in the world today.
The study, published in the journal Science Advances, shows prehistoric people at the Jirzankal Cemetery in the eastern Pamirs were deliberately selecting the most powerful plants.
It used a scanning technique called gas chromatography-mass spectrometry to isolate and identify compounds preserved in the burners.
To the international team’s surprise, these were an exact match to the chemical signature of cannabis.
Moreover, they indicated a higher level of THC than is normally found in wild marijuana.
The findings shed fresh light on one of the most infamous plants on the planet with rapidly changing legislation surrounding its legalisation, said the researchers.
Prof Boivin said: “Given the modern political climate surrounding the use of cannabis, archaeological studies like this can help us to understand the origins of contemporary cultural practice and belief structures – which, in turn, can inform policy.”
It’s known cannabis was grown in east Asia for the oily seeds and fibre from at least 4000 BC. But these varieties had low levels of THC.
So it’s been a long-standing mystery as to when and where the psychoactive compounds were first recognised.
Dr Robert Spengler, also of the Max Planck Institute for the Science of Human History, said: “Modern perspectives on cannabis vary tremendously cross-culturally, but it is clear that the plant has a long history of human use, medicinally, ritually, and recreationally, over countless millennia.”
Many historians place the origins of cannabis smoking on the ancient Central Asian steppes.
But these arguments rely solely on a passage from a single ancient text from the late first millennium BC, written by the Greek historian Herodotus.
So archaeologists have long sought to identify concrete evidence for cannabis smoking in Eurasia.
The breakthrough came after the burners were unearthed during an excavation expedition to the mountains by members of the Chinese Academy of Social Sciences.
It corroborates other early evidence for cannabis from burials further north, in the Xinjiang region of China and in the Altai Mountains of Russia.
Some of the skeletons recovered from the site, situated in western China, have features that resemble those of modern people further west in Central Asia.
Objects found in the burials also appear to link this population to peoples further west in the mountain foothills of Inner Asia.
Additionally, stable isotope studies on the human bones from the cemetery show that not all of the people buried there grew up locally.
The data fits with the notion that the high mountain passes of Central and Eastern Asia played a key role in early trans-Eurasian exchange.
Indeed, the remote region may have sat astride a key ancient trade route of the Silk Road – once the single most important route for cultural spread in the ancient world.
Dr Spengler, the lead archaeobotanist on the study, said: “The exchange routes of the early Silk Road functioned more like the spokes of a wagon wheel than a long-distance road, placing Central Asia at the heart of the ancient world.
“Our study implies knowledge of cannabis smoking and specific high-chemical-producing varieties of the cannabis plant were among the cultural traditions that spread along these exchange routes.”
People sought and later cultivated more psychoactive varieties of cannabis for use in burial rituals. One theory is cannabis plants will produce greater quantities of active compounds in response to increased UV radiation and other stressors related to growing at higher elevations.
So nomadic people may have discovered more potent wild plants there – and initiated a new kind of use of the plant. While cannabis is used primarily as a recreational drug or for medical applications now, it may have been used rather differently in the past.
The evidence from Jirzankal suggests cannabis was being burned at rituals commemorating the dead.
They buried their kin in tombs over which they created circular mounds, stone rings and striped patterns using black and white stones.
Whether cannabis also had other uses in society is unclear, though it seems likely that the plant’s ability to treat a variety of illnesses and symptoms was recognised early on.
Co-author Dr Yimin Yang, of the University of the Chinese Academy of Sciences in Beijing, added: “This study of ancient cannabis use helps us understand early human cultural practices, and speaks to the intuitive human awareness of natural phytochemicals in plants.”