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Prehistoric Plaque Reveals Plant Consumption

What’s now considered a weed was once a dietary staple for inhabitants of Al Khiday, Sudan

by Bethany Halford
July 21, 2014 | A version of this story appeared in Volume 92, Issue 29

Credit: Rickjpelleg/Wikimedia Commons
C. rotundus
Picture of Cyperus rotundus, a wild plant eaten by prehistoric people.
Credit: Rickjpelleg/Wikimedia Commons
C. rotundus

Whether our ancient ancestors ate wild plants before they practiced agriculture has been a mystery. Now, researchers have gathered evidence suggesting such flora was a dietary staple among prehistoric people. Researchers led by Karen Hardy of Spain’s Catalan Institution for Research & Advanced Studies examined the mineralized plaque known as dental calculus from ancient human teeth at the African prehistoric burial site of Al Khiday, Sudan. The researchers studied the teeth of 14 people from three time periods spanning 7,000 years. Hardy’s team extracted microfossils and chemical compounds from the teeth, analyzing the latter with gas chromatography/mass spectrometry (PLoS One 2014, DOI: 10.1371/journal.pone.0100808). In all samples, which included people from preagricultural and agricultural periods, the researchers found evidence of consumption of Cyperus rotundus. These days, C. rotundus is known as the world’s most costly weed, thanks to its ability to spread rapidly, infest crops, and reduce crop yields. “This plant is a good source of carbohydrates and has many useful medicinal and aromatic qualities,” the researchers note.


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