An international team of archaeologists has discovered the earliest evidence of humans processing plants for food found anywhere in the world. The findings are reported in the journal Nature Plants.
Exceptionally preserved archaeobotanical remains from the Takarkori rock shelter, Tadrart Acacus, Libya, dating from 7500 to 4200 BC: a – inflorescence of Typha (Late Acacus 3, c. 6800 BC); b – syconium of Ficus sp. (Late Acacus 2, 7500 BC); c – galbulus of Cupressus (Middle Pastoral 2); d – spikelet of Tragus (Middle Pastoral 2, 4200 BC); e – legumes of Cassia (Early Pastoral 1, 6350 BC); f – fruit of Balanites aegyptica (Late Acacus 3, 6800 BC); g – spikelet of Dactyloctenium aegyptium and a detailed image of the grain (Middle Pastoral 2, 4200 BC). Image credit: Julie Dunne et al, doi: 10.1038/nplants.2016.194.
The team, led by University of Bristol Professor Richard Evershed, studied unglazed pottery dating from more than 10,000 years ago, from two sites in the Libyan Sahara.
“We reveal the earliest direct evidence for plant processing in pottery globally, from the sites of Takarkori and Uan Afuda in the Libyan Sahara, dated to 8200–6400 BC,” the scientists said.
“Characteristic carbon number distributions and 13C values for plant wax-derived n-alkanes and alkanoic acids indicate sustained and systematic processing of C3/C4 grasses and aquatic plants, gathered from the savannahs and lakes in the Early to Middle Holocene green Sahara.”
Ancient cooking would have initially involved the use of fires or pits and the invention of ceramic cooking vessels led to an expansion of food preparation techniques. Cooking would have allowed the consumption of previously unpalatable or even toxic foodstuffs and would also have increased the availability of new energy sources.
Remarkably, until now, evidence of cooking plants in early prehistoric cooking vessels has been lacking.
Prof. Evershed and co-authors detected lipid residues of foodstuffs preserved within the fabric of unglazed cooking pots.
Over half of the vessels studied were found to have been used for processing plants based on the identification of diagnostic plant oil and wax compounds.
“The finding of extensive plant wax and oil residues in early prehistoric pottery provides us with an entirely different picture of the way early pottery was used in the Sahara compared to other regions in the ancient world,” Prof. Evershed said.
“Our new evidence fits beautifully with the theories proposing very different patterns of plant and animal domestication in Africa and Europe/Eurasia.”
Detailed analyses of the molecular and stable isotope compositions showed a broad range of plants were processed, including grains, the leafy parts of terrestrial plants, and most unusually, aquatic plants.
The interpretations of the chemical signatures obtained from the pottery are supported by abundant plant remains preserved in remarkable condition due to the arid desert environment at the sites.
The plant chemical signatures from the Saharan pottery show that the processing of plants was practiced for over 4,000 years, indicating the importance of plants to the ancient people of the prehistoric Sahara.
“Until now, the importance of plants in prehistoric diets has been under-recognized but this work clearly demonstrates the importance of plants as a reliable dietary resource,” said study lead author Dr. Julie Dunne, also from the University of Bristol, UK.
“These findings also emphasize the sophistication of these early hunter-gatherers in their utilization of a broad range of plant types, and the ability to boil them for long periods of time in newly invented ceramic vessels would have significantly increased the range of plants prehistoric people could eat.”
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Julie Dunne et al. 2016. Earliest direct evidence of plant processing in prehistoric Saharan pottery. Nature Plants 3, article number: 16194; doi: 10.1038/nplants.2016.194
