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OMDURMAN, Sudan: An international team of researchers has found new evidence that prehistoric ancestors had a detailed understanding of plants long before the development of agriculture. By extracting chemical compounds and microfossils from dental calculus—calcified dental plaque—from ancient teeth, the researchers were able to provide an entirely new perspective on our ancestors’ diets.
The research suggests that purple nut sedge, today regarded as a nuisance weed, formed an important part of the prehistoric diet and that prehistoric people living in Central Sudan may have understood both the nutritional and medicinal qualities of this and other plants.
The research, led by the Universitat Autònoma de Barcelona (UAB) and the University of York, was conducted at Al Khiday, a prehistoric site on the White Nile in Central Sudan. It demonstrates that for at least 7,000 years, starting before the development of agriculture and continuing after agricultural plants were also available, the people of Al Khiday ate the plant purple nut sedge. The plant is a good source of carbohydrates, and has many useful medicinal and aromatic qualities.
Lead author Dr Karen Hardy, a Catalan Institute for Research and Advanced Studies Research Professor at the UAB and an honorary research associate at the University of York, said: “Purple nut sedge is today considered to be a scourge in tropical and sub-tropical regions and has been called the world’s most expensive weed due to the difficulties and high costs of eradication from agricultural areas. By extracting material from samples of ancient dental calculus we have found that rather than being a nuisance in the past, its value as a food, and possibly its abundant medicinal qualities were known. More recently, it was also used by the ancient Egyptians as perfume and as medicine.”
“We also discovered that these people ate several other plants and we found traces of smoke, evidence for cooking, and for chewing plant fibres to prepare raw materials. These small biographical details add to the growing evidence that prehistoric people had a detailed understanding of plants long before the development of agriculture.”
Al Khiday is a complex of five archaeological sites that lie 25 km south of the city of Omdurman. One of the sites is predominantly a burial ground of the pre-Mesolithic, Neolithic and Late Meroitic periods. As a multiperiod cemetery, it gave the researchers a useful long-term perspective on the material recovered.
The researchers found ingestion of the purple nut sedge in both pre-agricultural and agricultural periods. They suggest that the plant’s ability to inhibit Streptococcus mutans, a bacterium that contributes to tooth decay, may have contributed to the unexpectedly low level of cavities found in the agricultural population.
“The development of studies on chemical compounds and microfossils extracted from dental calculus will help to counterbalance the dominant focus on meat and protein that has been a feature of pre-agricultural dietary interpretation, up until now,” Hardy stated. “The new access to plants ingested, which is provided by dental calculus analysis, will increase, if not revolutionise, the perception of ecological knowledge and use of plants among earlier prehistoric and pre-agrarian populations.”
The study, titled “Dental calculus reveals unique insights into food items, cooking and plant processing in prehistoric central Sudan”, was published online on 16 July in the PLOS ONEjournal.
