Neanderthals clubbed their way to the top of an ancient food chain, slaying caribou and mammoths. But a peek inside their prehistoric poop reveals that the meat-loving early humans may have also enjoyed some salad on the side.
Researchers excavating a site in southern Spain where Neanderthals lived 50,000 years ago were initially looking for remnants of food in fireplaces. Then they stumbled upon tiny bits of poop — which turned out to be the oldest fecal matter from a human relation ever discovered.
Ainara Sistiaga, a paleoarchaeologist with the Massachusetts Institute of Technology who led the excavation, tells The Salt that what surprised her team even more was the contents of the poop.
When they analyzed poop from the site, called El Salt, under a microscope, they saw cholesterol-like compounds called phytosterols, which come from plants. The feces also contained a lot of animal-derived cholesterol — confirming they were also chowing down on meat.
"This opens a new window into Neanderthal diet because it's the first time we actually know what they digested and consumed," Sistiaga says. The findings appeared Wednesday in the journal PLOS One.
For years, scientists assumed our early ancestors were carnivores. According to that theory, Neanderthals saw plants merely as part of the terrain, or perhaps as tools, but certainly not as food. Until a couple of decades ago, there was little hard evidence of an omnivorous Neanderthal.
One study found fossilized bits of plant stuck between the teeth of a Neanderthal. That study, Sistiaga points out, did not confirm the Neanderthals' taste for plants because she says they could have used their mouths as a third hand to hold the plant and use it as a tool. Or the plant material could have come from the entrails of an animal they'd eaten, she says.
The scientists who previously tackled this debate on the side of the omnivorous Neanderthal say that the new findings help make the case.
"It shows that from the mouth to the end point, you consistently have plant material," says Stephen Buckley, an archaeological chemist at the University of York, who previously found plant material in Neanderthal teeth. "This paper makes it extremely difficult for people who want to maintain the idea that Neanderthals only ate meat to do so."
His views are echoed by Alison Brooks, paleoanthropologist at The George Washington University in Washington, D.C. She tells The Salt that the new work by Sistiaga puts "another nail in the Neanderthal carnivore coffin."
But Brooks also raises some questions about the team's methods for determining who — or what — produced the poop. She says it's possible the poop came from another omnivorous mammal, such as a wolf, bear or Macaque monkey.
"I don't know what humans are doing defecating in a fireplace, but you could see a wolf doing that," says Brooks.
But Sistiaga says that certain mammal carnivores such as wolves and lions can be ruled out because their quick digestive systems prevent them from converting cholesterol into coprostanol, a compound found in the feces. She also says that chimps and gorillas have closer cholesterol-to-coprostanol ratios to herbivores, so that rules them out, and there is currently no evidence of other primates in the area where the site is.
Her next steps are to further excavate El Salt and unearth more ancient clues to piece together what made up the Neanderthals' dinner plate.