From ABC News in Science, 26 June 2014:
The oldest known samples of Neanderthal faeces have revealed these early humans actually enjoyed some salad with their steak.
The findings, published today in PLoS ONE, challenge the image of Neanderthals as unrepentant carnivores, and the theory that their high meat intake may have contributed to their extinction.
Researchers from Spain and the US were able to distinguish the tiny faecal samples from the surrounding sediment by microscopic features that were similar to some previously observed in fossilised human faeces.
The 50,000 year-old samples also contained the remains of parasite eggs known to occur in humans.
Analysis of five faecal samples showed that at least two contained significant levels of two compounds — 5 beta-stigmastanol and 5 beta-epistigmastanol — that are produced by the breakdown of phytosterol, the plant version of cholesterol.
“We are sure that these compounds come from the diet because it is impossible for a human to produce these,” says lead author Ainara Sistiaga, visiting researcher at the Massachusetts Institute of Technology and PhD candidate at the University of La Laguna, Spain.
The researchers used the ratio of other dietary metabolites in the fossilised samples to confirm that the samples were indeed human and not from other animals that might have browsed in the area.
While they could not identify the specific foods eaten, the researchers note that animal remains suggest Neanderthals hunted deer and horses. Sistiaga says evidence from other studies suggest the presence of berries, nuts and tubers but “we cannot say anything about what kind of plants were actually eaten.”
The finding brings new information to an ongoing debate about whether Neanderthals included vegetables in their diet.
Previous studies of Neanderthal bones, which looked at the carbon and nitrogen isotopes, suggested a wholly carnivorous diet. However other studies of microfossils found embedded in Neanderthal teeth point to a diet much higher in plant matter.
However Sistiaga says both methods have their limitations because they rely on indirect evidence of dietary habits.
“The microfossils are trapped in the teeth in the mouth, but we cannot assume these microfossils come from a plant that they were actually eating because sometimes these [prehistoric humans] use the mouth as a tool,” Sistiaga says.
Similarly, the isotopic analysis is restricted to protein, which is abundant in meat but present only in small quantities in plant matter.
“We have obtained the first direct evidence of animal and plant intake by Neanderthals based on identification of human faecal biomarkers in archaeological sediments,” write the authors. Read more.