Ancient stoners used wooden bowls. (Not the kind on pipes, either.)

Science News traces the history of highs to a Chinese site where 2,500-year-old tombside remains indicate that smoldering cannabis was stacked in wooden bowls for ritual inhalation – possibly to communicate with dead spirits:

Evidence of this practice comes from Jirzankal Cemetery in Central Asia’s Pamir Mountains, says a team led by archaeologist Yimin Yang of the University of Chinese Academy of Sciences in Beijing. Chemical residues on wooden burners unearthed in tombs there provide some of the oldest evidence to date of smoking or inhaling cannabis fumes, the researchers report online June 12 in Science Advances. Rituals aimed at communicating with the dead or a spirit world likely included cannabis smoking, the team speculates.

Cannabis remains of comparable age have been found in several other Central Asian tombs, including a site in Russia’s Altai Mountains located about 3,000 kilometers northwest of the Pamir Mountains. But the discoveries at Jirzankal Cemetery offer an unprecedented look at how cannabis was initially used as a mind-altering substance, the researchers say.

Crucially, high-elevation mountain passes of Central and East Asia, including the Pamir region, hosted trade routes of the early Silk Road, which linked China with West Asia and Europe, says archaeobotanist and study coauthor Robert Spengler of the Max Planck Institute for the Science of Human History in Jena, Germany. “Our study implies that knowledge of cannabis smoking and specific high-THC varieties of the cannabis plant were among the cultural traditions that spread along Silk Road exchange routes,” Spengler said at a June 11 news conference.

In support of the Pamir region as an ancient crossroads, earlier chemical analyses of human bones and teeth from Jirzankal Cemetery indicated that 10 of 34 individuals tested had grown up outside the area. Items placed in some Jirzankal tombs, such as silk fabrics from eastern China and a type of harp from West Asia, suggest that people from widespread cultures traveled to Central Asia.

Jirzankal Cemetery lies more than 3,000 meters above sea level. Black and white stone strips run across the site’s surface. Circular mounds of earth cover the tombs, which are lined by one or two rings of stones.

Yang’s team identified a chemical signature of cannabis on charred plant material from 10 wooden burners, or braziers, found in eight Jirzankal tombs. Chemical signs of an unusually high level of THC were found inside nine braziers and on two stones that had been heated and used to burn plants in the braziers.

Still, those ancient plants would have triggered less powerful psychoactive effects than present-day cannabis plants bred specifically for high THC levels, Spengler said.

You can read the Science Advances paper here.