2,800-year-old hair reveals cannabis use

The discovery was made at the Tunnug 1 burial mound in southern Siberia, where archaeologists recovered more than 1,400 cannabis seeds alongside exceptionally well-preserved human remains. Chemical analysis of the hair detected cannabinol, a compound produced when THC, the main psychoactive substance in cannabis, oxidises. The researchers also found weaker chemical signatures consistent with THC itself.

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The findings provide the earliest securely dated direct evidence supporting the use of cannabis for its mind-altering effects.

– We have long known that people cultivated hemp for oil and fibres used for food, textiles and ropes, among other things. However, there is very little early archaeological evidence regarding how or when humans began using cannabis for its psychoactive effects. This is precisely why the discovery in Siberia is so significant, says Natalia Riabogina, archaeobotanist at the Department of Historical Studies, University of Gothenburg.

Seeds provide new clues

As an archaeobotanist, Natalia Riabogina studies pollen and botanical remains recovered from archaeological sites. Her contribution to the study, published in Science on 5 November, has primarily involved developing a strategy and methodology for recovering and analysing archaeobotanical remains.

One particularly interesting aspect of the discovery is the exceptionally well-preserved cannabis seeds. Their size and physical characteristics suggest that they came from wild or wild-like plants rather than varieties cultivated for oil and fibres.

– What makes this discovery unique is that we not only have direct evidence of cannabis being used for its psychoactive effects, but also the seeds themselves. They allow us to investigate how plants used for their psychoactive properties differed from those cultivated for oil and fibre, says Natalia Riabogina.

May have been part of burial rituals

The burial mound was constructed by the Scythians, nomadic pastoralists who lived in the region. The large quantities of cannabis seeds found in the graves suggest that the plant may have held particular significance in burial ceremonies.

In ritual burial practices, it is common to include objects and symbols that were significant during a person's lifetime and served to demonstrate their status.

– The seeds could represent either a valuable offering to the deceased or a component of a shamanic ritual accompanying the burial and the sacrifice of horses. Hemp was the only plant the Scythians placed in the graves at this site, and that was no coincidence. In this respect, this burial mound is unique, says Natalia Riabogina.

However, the archaeological evidence cannot establish exactly how the individuals consumed cannabis. One possibility is that they inhaled smoke from the plant. At other archaeological sites in Central Asia, researchers have discovered censers dating from several centuries later that contained chemical traces of cannabis.

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Seven years of research behind the discovery

Work on the study has spanned more than seven years. In 2019, Natalia Riabogina contacted archaeologists from St Petersburg who were conducting excavations in Tuva, a region in southern Siberia. Together, they developed a strategy and methodology for recovering archaeobotanical remains from the burial mound.

This is a complex and time-consuming process, as even minute plant remains must be carefully recovered. During the COVID-19 pandemic, Natalia Riabogina continued to discuss the sampling procedures with the excavation team remotely. The material was subsequently processed and analysed in laboratories in collaboration with international research colleagues.

The exceptional preservation conditions in the burial mound proved crucial. The waterlogged, frozen ground had protected seeds, hair, skin and textiles for almost three millennia. Under normal circumstances, only bones and teeth, if anything, would remain after such a long time.

– Neither my colleagues nor I had any specific plans to study cannabis. It was an accidental discovery, which we then subjected to a comprehensive analysis. I am glad that we joined forces and pooled our resources to conduct this study, says Natalia Riabogina.

The research team now hopes to gather more data to investigate the process of cannabis domestication in ancient times and assess the role the plant played in ancient societies' rituals.

Text: Johanna Hillgren

Contact:
Natalia Riabogina, Mail: natalia.riabogina@gu.se