Scientists say analysis of some of the oldest preserved human feces ever found supports the view the Neanderthal diet was at least partly a vegetarian one.
The 50,000-year-old feces show evidence they ate berries, nuts and tubers in addition to meat, and that the role meat played in their diet has probably been overestimated, said the researchers excavating at a dig site known as El Salt in Spain.
Feces is "the perfect evidence" of an omnivorous diet, said study first author Ainara Sistiaga of the University of La Laguna on the Canary Islands, "because you're sure [of what] was consumed."
"If you find it in the feces, you are sure that it was ingested," she said. "This molecular fossil is perfect to try to know the proportion of both food sources in a Neanderthal meal."
Samples collected from the known Neanderthal habitation site on Spain's Mediterranean coast were analyzed at a laboratory at the Massachusetts Institute of Technology.
While the chemical makeup showed meat digestion was dominant, there were also significant traces of plant-derived material, suggesting a "significant intake of plants," Sistiaga said.
Still, the study authors said, the findings don't suggest the Neanderthals had anything approaching a balanced diet, since all evidence suggests meat was the dominant food source for the ancient species, relatives of modern humans.
Neanderthals lived throughout Europe and in central and southwestern Asia from around 200,000 to 28,000 years ago.
Although they successfully coexisted with modern humans for some time, they eventually went extinct, and some scientists have theorized their meat-heavy diet may have been a factor, making Neanderthals less successful in adapting to changing climate conditions and disappearing food sources.
"It's important to understand all aspects of why humanity has come to dominate the planet the way it does," said study co-author Roger Summons, an MIT geobiology professor. "A lot of that has to do with improved nutrition over time."
The new research is a "hugely welcome addition" to the study of the Neanderthal diet, said archaeologist Stephen Buckley of Britain's University of York, who previously had discovered evidence of plant matter in fossilized Neanderthal teeth.
"The start point, the teeth, and the end point, the feces, show the same thing," Buckley said. "The evidence is clear at both ends, if you like."
