Ancient DNA found in the dental plaque of Neanderthals—our nearest extinct relative—has revealed new information about their behavior, diet, and evolutionary history, including their use of plant-based medicine to treat pain and illness, according to an international research team led by the University of Adelaide’s Australian Centre for Ancient DNA (ACAD) and Dental School, along with the University of Liverpool.
“Dental plaque traps micro-organisms that lived in the mouth and pathogens found in the respiratory and gastrointestinal tract, as well as bits of food stuck in the teeth, preserving the DNA for thousands of years,” said lead author Laura Weyrich, PhD, and ARC Discovery Early Career Research Fellow with ACAD.
“Genetic analysis of that DNA locked up in plaque represents a unique window in Neanderthal lifestyle, revealing new details of what they ate, what their health was like, and how the environment impacted their behavior,” said Weyrich.
The researchers analyzed and compared dental plaque samples from 4 Neanderthals found at the cave sites of Spy in Belgium and El Sidrón in Spain. These samples range from 42,000 to around 50,000 years old and are the oldest dental plaque ever to be genetically analyzed.
“We found that the Neanderthals from Spy Cave consumed woolly rhinoceros and European wild sheep, supplemented with wild mushrooms,” said Alan Cooper, PhD, director of ACAD. “Those from El Sidrón Cave on the other hand showed no evidence of meat consumption but appeared instead to have a largely vegetarian diet, comprising nuts, moss, mushrooms, and tree bark, showing quite different lifestyles between the 2 groups.”
One of the Neanderthals from El Sidrón had suffered from a dental abscess visible on the jawbone. The plaque also showed that he had an intestinal parasite that causes acute diarrhea, indicating he was sick. The Neanderthal was eating poplar, which includes salicylic acid—a painkiller and the active ingredient in aspirin. Plus, the sample revealed Penicillium, a natural antibiotic mold not seen in the other specimens.
“Apparently, Neanderthals possessed a good knowledge of medicinal plants and their various anti-inflammatory and pain-relieving properties and seem to be self-medicating,” said Cooper. “The use of antibiotics would be very surprising, as this is more than 40,000 years before we developed penicillin. Certainly our findings contrast markedly with the rather simplistic view of our ancient relatives in popular imagination.”
Neanderthals and humans also shared several disease-causing microbes, including the bacteria that cause dental caries and gum disease. The Neanderthal plaque allowed reconstruction of the oldest microbial genome yet sequenced: Methanobrevibacter oralis, a commensal that can be associated with gum disease. The genome sequence suggests Neanderthals and humans were swapping pathogens as recently as 180,000 years ago, long after the divergence of the 2 species.
Also, the team noted how rapidly the oral microbial community has changed in recent history. The composition of the oral bacterial population in Neanderthals and both ancient and modern humans correlated closely with the amount of meat in the diet, with the Spanish Neanderthals grouping with chimpanzees and mankind’s forager ancestors in Africa. In contrast, the Belgian Neanderthal bacteria resembled early hunter gatherers and close to modern humans and early farmers.
“Not only can we now access direct evidence of what our ancestors were eating, but differences in diet and lifestyle also seem to be reflected in the commensal bacteria that lived in the mouths of both Neanderthals and modern humans,” said Keith Dobney, PhD, of the University of Liverpool.
“Major changes in what we eat have, however, significantly altered the balance of these microbial communities over thousands of years, which in turn continue to have fundamental consequences for our own health and well-being,” Dobney said. “This extraordinary window on the past is providing us with new ways to explore and understand our evolutionary history through the micro-organisms that lived in us and with us.”
The study, “Neanderthal Behaviour, Diet, and Disease Inferred from Ancient DNA in Dental Calculus,” was published by Nature.