The menus of millennia past can be tough to crack, especially when it comes to fruits and vegetables. For archaeologists studying a prehistoric site in Sudan, dental plaque provided a hint.
"When you eat, you get this kind of film of dental plaque over your teeth," says Karen Hardy, an archaeologist with the Catalan Institute for Research and Advanced Studies at the Universitat Autnoma de Barcelona.
"If you don't clean it off, it mixes up with bits of food and it gets stuck in this area below the gum," she says. "It can calcify within about two weeks, and once it's calcified it's very hard."
That plaque is so hard that it lasts thousands of years. And since Prehistoric folk were not known for their flossing habits, the plaque that survived them can serve as a kind of scrapbook for what they ate and breathed.
Hardy and her colleagues were studying skeletons from Al Khiday in Central Sudan, a burial site that was used between around 2,000 and 9,000 years ago, since before the advent of farming in the area.
Using a few isotope and chemical analysis techniques, Hardy says they found "all sorts of different things" in the teeth of 19 individuals, things like sand, dirt, pollen, plant fibers — even evidence of carbon, from breathing smoke from a fire.
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