An analysis of ancient DNA entrapped in Neanderthal dental calculus (calcified dental plaque) has revealed the complexity of Neanderthal behavior, including dietary differences between Neanderthal groups and knowledge of medication.

“Dental plaque traps microorganisms 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 Dr. Laura Weyrich, a researcher at the University of Adelaide and lead author of the study, published in the journal Nature.

“Genetic analysis of that DNA ‘locked-up’ in plaque, represents a unique window into Neanderthal lifestyle — revealing new details of what they ate, what their health was like and how the environment impacted their behavior.”

Dr. Weyrich and co-authors analyzed and compared dental plaque samples (42,000-50,000 years old) from four Neanderthals found at the cave sites of Spy in Belgium and El Sidrón in northern Spain.

“At Spy cave, Neanderthal diet was heavily meat based and included woolly rhinoceros and wild sheep (mouflon), characteristic of a steppe environment,” the researchers said.

“In contrast, no meat was detected in the diet of Neanderthals from El Sidrón cave, and dietary components of edible mushrooms (Schizophyllum commune), pine nuts (Pinus koraiensis), and forest moss (Physcomitrella patens) reflected forest gathering.”

“Differences in diet were also linked to an overall shift in the oral bacterial community (microbiota) and suggested that meat consumption contributed to substantial variation within Neanderthal microbiota.”

“We were surprised not to find any remains of meat in El Sidrón Neanderthals, given that they were thought to be predominantly meat eaters,” said co-author Dr. Antonio Rosas, from Spain’s National Natural Science Museum.

“However, we have found evidence they enjoyed a varied diet including a wide range of plants. What’s more, some of these plants may well have been cooked before being eaten.”

One of the most surprising finds was in an El Sidrón Neanderthal, who suffered from a dental abscess visible on the jawbone.

The plaque showed that he also had an intestinal parasite (Enterocytozoon bieneusi) that causes acute diarrhea, so clearly he was quite sick.

He was eating western balsam-poplar (Populus trichocarpa), which contains the pain killer salicylic acid (the active ingredient of aspirin), and we could also detect a natural antibiotic mould (Penicillium) 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,” Dr. Weyrich said.

“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.”

The Neanderthal plaque also allowed reconstruction of the oldest microbial genome yet sequenced — Methanobrevibacter oralis, a commensal that can be associated with gum disease.

Remarkably, the genome sequence suggests Neanderthals and humans were swapping pathogens as recently as 180,000 years ago, long after the divergence of the two species.

The researchers also noted how rapidly the oral microbial community has altered 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 El Sidrón Neanderthals grouping with chimpanzees and our forager ancestors in Africa.

In contrast, Spy Neanderthal bacteria were similar to early hunter gatherers, and quite 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 co-author Prof. Keith Dobney, from 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.”

“This extraordinary window on the past is providing us with new ways to explore and understand our evolutionary history through the microorganisms that lived in us and with us.”

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Laura S. Weyrich et al. Neanderthal behaviour, diet, and disease inferred from ancient DNA in dental calculus. Nature, published online March 8, 2017; doi: 10.1038/nature21674