A new study of dental calculus extracted from archaeological remains from the multi-period Sudanese site of Al Khiday has revealed insights into the consumption, cooking and processing of plants from the pre-Mesolithic, Neolithic and Late Meroitic age.1

Morphological analysis of materials sampled from calculus provided evidence for cooking and smoke inhalation, with 'char markers' such as charcoal and soot, and combustion markers, such as fluoranthene and pyrene, consistent with exposure to fire. Starch granules found in three Neolithic samples were enlarged and cracked, indicative of roasting.

Perhaps most interesting are chemical profiles in remains across the three periods that point towards the ingestion of Cyperus rotundus tubers in the pre-agricultural and agricultural period: a time span of more than 7,000 years. C. rotundus, more commonly known as 'purple nut sedge', has been dubbed the 'world's most expensive weed', despite its aromatic and medicinal properties. This suggests our ancient ancestors had greater ecological knowledge than previously thought. Other dental evidence alludes to the use of teeth as a third hand to process plant material for use in other items, suggesting C. rotundus was not just used for food.

While meat and protein have been the focus of pre-agricultural dietary interpretation up to this point, this new research provides an argument for varied uses of plants in earlier prehistoric populations and the need for a revolutionised perception of the ecological knowledge of our ancient predecessors.