Archaeologists have found the oldest evidence to date of humans using cannabis for psychoactive purposes, inside a tomb dating back about 3,000 years, according to a new study published in the scientific journal Science on Thursday.
The study's lead researcher, Gino Caspari, a researcher at the Swiss University of Bern, told CNN that his team found preserved hemp seeds and human hair inside a huge tomb belonging to an elite in southern Siberia.
He added: "There is a lot of speculation about the use of narcotic plants in prehistoric times, but this discovery proves that these speculations are based on actual evidence."
The cemetery is located in the Aweik Valley, and contains the remains of a number of figures who enjoyed a high social status. Caspari and his colleagues have been working at the site since 2017, when they found evidence indicating that the tomb dates back about 2,800 years, that is, to the earliest stages of the Scythian era.
“These were nomadic Bedouins who rode horses and were famous for their skill in shooting from their backs, in addition to their luxurious gold possessions,” Caspary said.
At the site, Caspari and his colleagues noticed small black dots inside the grave, and were able to determine that they were hemp seeds. They eventually collected more than 1,400 seeds and used radiocarbon dating to determine they date back about 2,800 years.
The researchers also found preserved human hair, which they analyzed using mass spectrometry.
“It is very rare to find preserved plant remains dating back about 3,000 years, as they are usually difficult to preserve,” Caspary told CNN.
He added: "It is even rarer to find them alongside soft human tissue, such as hair, which allows us to actually test for the use of someone who died 3,000 years ago."
The analysis revealed the presence of tetrahydrocannabinol (THC), known as delta-9-tetrahydrocannabinol, which is the main compound responsible for the psychoactive effects of cannabis, as well as cannabinol, a chemical compound that forms when THC is exposed to the air.
“It was a really amazing moment,” Caspary said, describing the discovery, adding that this discovery enhances our understanding of the history of cannabis use.
So far, scientists have found evidence suggesting that hemp was cultivated in East Asia at least 6,000 years ago, likely to take advantage of its oil-rich seeds, according to a statement from the researchers.
Evidence has also previously been found indicating the use of the plant for its effects on the mind about 2,500 years ago, including ritual practices in Central Asia, according to the statement.
“The use of cannabis in this cemetery should be viewed within a ritual context, and may have been linked to shamanic beliefs,” Caspari told CNN, adding, “Given that we found dozens of sacrificial horses, as well as the possibility of human sacrifices, cannabis may also have been used to sedate the victims before they were subjected to something horrific, but we cannot prove that.”
He continued: "We know little about the ancient cultural history of this important crop, coincidentally. For example, we are not even sure what wild hemp actually looks like."
“We now have evidence of cannabis being used for its psychoactive effects on the Eurasian continent at least 3,000 years ago, and it appears that it was then spreading from China to Europe,” Caspary said.
He added: "We believe that this discovery constitutes a historical and cultural reference for current discussions regarding the legalization of the use of this plant and its medicinal benefits."
Caspari explained that the research team is currently working on analyzing the ancient DNA sequences of the seeds found at the site, noting that “finding well-preserved plant DNA is even rarer than finding plant remains, and this is the oldest preserved cannabis DNA to date.”
"Over the next few years, our team will likely rewrite part of the history of cannabis domestication," he added.
For his part, Roger Forshaw, honorary lecturer in biomedical Egyptology at the University of Manchester in England, who was not involved in the study, told CNN that the research “provides interesting insights into the use of cannabis in Early Iron Age societies in Central Asia, a practice for which direct archaeological evidence has rarely been found previously.”
Finding chemical traces of cannabis in the hair “provides direct molecular evidence of its use, and supports the hypothesis of its use as part of burial rituals,” Forshaw said.
He added: "Although we cannot be certain how this plant was used or what specific role it played in burial rituals, this discovery greatly enhances our understanding of the use of psychoactive plants in ancient societies."
