Food Stuck in Teeth for 8,000 Years Alters View of Early Farming

Close on the heels of news about Ötzi the iceman's final meals come revelations about a diet even more ancient. New findings show that about 8,000 years ago, the inhabitants of the Nanchoc Valley in the lower Peruvian Andes were eating beans, peanuts, domesticated squash, and a fruit pod called pacay, whose sweet white lining Peruvians still enjoy today.

That comes as surprising news for anthropologists. Eight thousand years ago is back in the hazy dawn (or at least early morning) of agriculture, when people around the globe were just starting to figure out how to cultivate plants. Before the publication of this new evidence (last week in Proceedings of the National Academy of Sciences) researchers thought agriculture had taken another 2,000 years to develop in Peru.

How do you find out exactly when a people started eating peanuts and squash? If you're Dolores Piperno, of the Smithsonian Tropical Research Institute, and Tom Dillehay, of Vanderbilt University, you look at their teeth. Specifically at the calculus, which is that hardened plaque around your gumline that your dentist is always scolding you about. Tiny bits of food get caught up in that calcified bacterial sludge, where they can remain for millennia without disintegrating. And people like Dolores Piperno can identify them.

Piperno examined 39 teeth that date from a 1,000-year period at a Nanchoc archaeological site Dillehay had been working on. Her identification methods consisted of patiently training her microscope on grains of starch caught in the calculus. Despite being less than one-twentieth of a millimeter across, many of these grains were distinctive enough for Piperno to identify them to species. (It's not unlike the idea of using feather fragments to ID python meals: sounds logical but unimaginably hard.) Piperno could even tell that some of the food, particularly the beans, had been cooked before it was eaten. The cooked grains were gelatinous and matched the appearance of bean starch she had cooked in her laboratory for comparison.

Earlier archaeological work in the Nanchoc Valley had turned up evidence of people cultivating plants, but scientists weren't sure whether they had been used for food or other purposes. For instance, a squash plant might have been just as useful for gourds as for making baked squash for supper. The new work establishes that people had been eating their crops, and provides evidence that they already had a fairly diverse set of plants to cook with.

I like thinking of ancient people sitting around the Nanchoc Valley enjoying a stew of beans and peanuts and soft chunks of squash. Too often when I imagine early meals, it's depressing: grimy, shivering figures gnawing at barely warmed flesh, cracking their teeth on nuts or patiently chomping some gritty tuber into submission.

There's something comforting, too, about the thought that we're still enjoying these same plants today. I had a great lamb stew recently, with beans and potatoes stewed until they were creamy and infused with flavor. It's tempting to think the Nanchoc people ate something similar, perhaps watching the evening sun light up the Andes peaks and looking forward to a sweet dessert of pacay, nibbled from a pod and passed around the family circle.

Idyllic as it all sounds, there's one last lesson here: the importance of brushing your teeth. It's bad enough to walk around with bits of your last meal stuck in your teeth. You don't want to broadcast your lunch to people 8,000 years in the future, do you?