ROBERT SIEGEL, HOST:
One of the hinge points in human history was the invention of agriculture. It led to large communities, monumental architecture and complex societies. Not bad. The downside was tooth decay. Switching from hunting and gathering to eating grains and starches brought about the age of cavities. At least that's what a lot of people thought. NPR's Christopher Joyce reports on a breakthrough in dental history, a discovery which suggest that even before agriculture, what hunter-gatherers ate could rot their teeth.
CHRISTOPHER JOYCE, BYLINE: There's a cave in Morocco - the Cave of the Pigeons, it's called - where ancient people lived and died between 12,000 and 15,000 years ago. These were hunters and gatherers. They didn't grow stuff. And what was astonishing to scientists who've studied the cave people was the condition of their teeth.
LOUISE HUMPHREY: Basically, nearly everybody in the population had caries.
JOYCE: Caries, or tooth decay. Louise Humphrey, who's a paleoanthropologist with the Natural History Museum in London, says 94 percent of the people she found in the cave had serious tooth decay.
HUMPHREY: I was quite surprised by that. I haven't seen that extent of caries in other ancient populations.
JOYCE: Sure, life was brutal and short for Stone Age folks, what with saber-toothed cats, parasites, and not an aspirin anywhere. But at least the paleo diet was supposed to be good for the teeth: meat, tubers, berries, maybe some primitive vegetables and very few carbs. Carbohydrates turn sugary in your mouth, then bacteria turn that into enamel-eating acid. But apparently these ancient people had a thing for acorns.
HUMPHREY: Acorns are high in carbohydrates. They also have quite a sticky texture. So they would have adhered easily to the teeth.
JOYCE: Yes, these people did eat meat and snails apparently, but also a lot of acorns, judging by the debris they left behind. Without toothbrushes, without dental floss, that diet rotted their teeth.
HUMPHREY: They were eating on the roots of their teeth. I think they would have been in pain.
JOYCE: Humphrey says this is the earliest case of widespread dental caries ever seen by thousands of years. It contradicts the idea that agriculture ushered in tooth decay and that the so-called paleo diet is inherently healthy. When it came to cuisine, she says Paleolithic people were simply opportunistic.
HUMPHREY: There's not one kind of paleo diet. I think wherever people lived, they had to make best of the wild food resources available to them.
JOYCE: In this case, Humphrey believes, ground acorn patties.
Have you tried them out?
HUMPHREY: No, but I would like to. I imagine that they would be something like sweet chestnuts.
JOYCE: Kind of like the Twinkies of the Paleolithic. The research appears in the Proceedings of the National Academy of Sciences. Christopher Joyce, NPR News.