From club-wielding carnivorous cavemen to harvesters cooking barley porridge, the Neanderthal image certainly has come a long way. Now, a new study of ancient feces yields the first direct evidence that they had varied diet: meat heavy yes, but with plant tissue from tubers, berries, and nuts on the side.
Previous work with isotopes of bone fragments, dentition analyses, and plant microfossils discovered in Neanderthal teeth have suggested that our prehistoric cousins ate an assortment of foods. But maybe the plants came from the stomach contents of their prey, or perhaps the plants got stuck when they used their teeth as tools for biting. For instance, just last week, we learned that Neanderthals may have used their teeth as a “third hand” for gripping objects, leaving their two hands free.
So, a team led by Ainara Sistiaga from the University of La Laguna in Spain looked for a more direct approach. Working in El Salt in Alicante, Spain -- a Middle Paleolithic Neanderthal site dating back 50,000 years -- the researchers identified human fecal remains among varying layers of soil and ash. They used a technique usually reserved for detecting gut bacteria (and hence feces) in drinking water.
Poo is “the perfect evidence,” Sistiaga explains to BBC. “If you find it in the feces, you are sure that it was ingested.” They scooped up about 10 grams of the sediment, ground it into a powder, and used multiple solvents to extractall the organic matter. Then they analyzed each sample of excrement for metabolized versions of animal-derived cholesterol, as well as a cholesterol-like compound found in plants, called phytosterol. All five of the samples showed signs of meat consumption, although two of them showed traces of plant matter -- the first direct evidence that Neanderthals may have enjoyed an omnivorous diet. The work was reported in PLoS ONE this week.
Here are some photos of slightly burned fossilized feces (or coprolites) that were found near fire pits (which weren’t active when the feces were deposited, naturally). The fluorescence in the bottom picture indicates high phosphate content.
Even though the plant biomarker was found in just two samples, that still indicates that substantial helpings of plant matter were ingested. Gram for gram, there’s more cholesterol in meat than there is phytosterol in plants, so it would take a significant plant intake to produce even a small amount of metabolized phytosterol, Sistiaga explains. Neanderthals probably ate what was available to them during different situations, seasons, and climates.
The traditional view of our extinct cousins is that they depended too much on meat, Science reports, whereas modern humans are more versatile, surviving on a broad spectrum of edibles. “It’s important to understand all aspects of why humanity has come to dominate the planet the way it does,” study coauthor Roger Summons of MIT says in a news release. “A lot of that has to do with improved nutrition over time.”
Images: B. Galván and PLOS ONE/Creative Commons