Neanderthals reveal their diet with oldest excrement

I would like to picture the first discovery of Neanderthal poop as a moment worthy of a National Geographic special. The plucky archaeologist sits covered in dust, patiently chipping away at the bottom of a pit, when a familiar shape starts to take form. She whisks a brush back and forth. A breathless narrator whispers, “She’s found it. After all these years.”

That’s how I imagined it. But in reality ancient poop is most likely to get squashed flat if it’s preserved at all, just an organic smear buried in the dirt. When geoarchaeologist Ainara Sistiaga found the first remains of Neanderthal dung at the El Salt site in southern Spain, she tells me, it appeared not as a fossilized lump but as peaks representing chemicals on an instrument’s readout.

“I didn’t know it was there at first,” says Sistiaga. She was a Ph.D. student at MIT, working at the Spanish site and looking for chemical traces of cooked food in the fire pits of Neanderthals that lived 40,000 to 60,000 years ago.

But in the remains of these cooking pits, resting on layers of sediment, charcoal and ash, Sistiaga and her colleagues hit a different kind of jackpot: Neanderthal excrement. Telltale molecules called sterols and stanols are found in fecal material, and in particular the ratios of certain types of chemicals in a group of lipids called 5β-stanols indicate human feces.

Scientists have used these biomarkers, as they’re known, to study fecal pollution in waterways and even to study the diets and population movements of ancient Romans and Native Americans. But never before has anyone found or tried to study such old poop from humans or their close relatives, the Neanderthals.

The Neanderthals at El Salt were omnivores, Sistiaga and colleagues report June 25 in PLOS ONE. They consumed mostly meat, but ate at least some veggies too. One of the compounds found at high levels, coprostanol, comes from the breakdown of cholesterol by microbes in the gut and is a good indicator of meat in the diet. Another, called 5β-stigmastanol, was found in one of five fecal samples and is made during the digestion of plants.

El Salt is a fascinating place to study ancient diets, says Sistiaga, who is now at the University of La Laguna in Tenerife, Spain. The site, which is still being excavated, includes numerous cooking pits or fireplaces, plus butchered animal bones, Neanderthal teeth and stone tools that show Neanderthals occupied the site off and on over thousands of years.

The five fecal fossils, or coprolites as archaeologists call them, turned up in fireplaces at the site. “They wouldn’t be preserved if the fires were active,” Sistiaga says; they would have burned up. The Neanderthals probably deposited them in fire pits that hadn’t been used for a while, perhaps converting old pits into handy latrines. Sistiaga says that where the coprolites turned up — above buried ashes but without new sediments in between — suggests that the cooking pits had not been abandoned for very long, at least not long enough for new sediments to have formed.

As for what was on the Neanderthal dinner plate, there’s been plenty of controversy. Long thought to be mainly top-level carnivores, the emerging picture is that Neanderthals gathered and even cooked a range of plants. Tiny plant fossils turned up in some of their massive tartar buildup, though as I wrote last year anthropologists have also suggested some of the plant material might have come from Neanderthals eating herbivores, including their plant-filled stomach contents.

Much hay has also been made about translating what our ancestors ate into a rational healthy diet for today. (For an interesting overview of some of the recent research and the battle over the ills of carbs versus fats, see this recent article in Aeon.) The upshot, as I see it, is that the tide is rolling against the low-fat diets of the past couple decades and toward blaming more of our dietary woes on carbohydrates, especially the refined and processed varieties like those that make up my beloved croissants. Green vegetables, the one thing it’s hard to get people to eat if they have lots of choices, remain beyond reproach.

Those who consider themselves to be paleodieters of one variety or another (and there are many varieties) generally hold as a premise the human body has been poorly equipped by our evolutionary ancestors to handle high loads of carbs. In some cases paleodieters even eschew anything that a perceived Paleo Man would not have had access to. If our Neanderthal cousins at El Salt are any indication, this means eating a lot of cooked deer and goat. I certainly don’t know what the optimal human diet is at this point, but I will quote Sistiaga: “We are not living the way they were.”

To learn more about how the human diet evolved, Sistiaga and her colleagues are next aiming even further back, to the 2-million-year-old human ancestors at the Olduvai Gorge in Tanzania. By looking for traces of ancient feces there and by analyzing the fecal fingerprints of wild gorillas and chimps in Uganda, they hope to help piece together the story of diet’s evolution.

Follow me on Twitter: @GoryErika