The research, led by the universities of Adelaide and Liverpool, provides the first genetic proof of these habits, thanks to the analysis of ancient DNA conserved in the dental plaque - the oldest to be analysed so far - of four individuals discovered at the European sites of Spy in Belgium and El Sidrón in Spain, dating back 42,000 and 50,000 years ago, respectively.
“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”, says lead author Dr Laura Weyrich from the University of Adelaide. “Genetic analysis of this DNA 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 behaviour.”
The analyses show clear differences in diet between the two Neanderthal groups, based on the surroundings in which they lived. The Neanderthals from the Spy cave, living in steppes, consumed mainly meat, such as woolly rhinoceros and wild sheep, supplemented with wild mushrooms. The ones from El Sidrón had a largely vegetarian diet. Researchers did not find evidence of meat consumption, but there was evidence of pine nuts, moss, mushrooms and tree bark, all typical of forest surroundings.
One of the most surprising finds, however, was in a Neanderthal from El Sidrón, who suffered from a dental abscess visible on the jawbone. The plaque showed that he also had an intestinal parasite that causes acute diarrhoea, so clearly he was quite sick. He was eating poplar, which contains the pain killer salicylic acid (the active ingredient of aspirin), and we could also detect a natural antibiotic mould (Penicillium).
These results reaffirm the results from a study published in 2012 and led by Karen Hardy. She was the one to demonstrate for the first time the use of medicinal plants among our prehistoric ancestors with chemical analyses of the dental plaque of the same individual found in El Sidrón. She also verified his mainly vegetarian diet.
“Identifying now the bacteria which caused his dental abscess and stomach pains confirm the results we obtained in our study. There is no doubt that the Neanderthals used plants to treat illnesses, and it also demonstrates once again that they had detailed knowledge of their surroundings and the ability to use plants in a variety of ways”, Hardy points out.
“Apparently, Neanderthals possessed a good knowledge of medicinal plants and their various anti-inflammatory and pain-relieving properties, and seem to be self-medicating. 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.”, says Professor Alan Cooper, Director of the Australian Centre for Ancient DNA (ACAD).
Sharing microbes with humans
The reconstruction of the Neanderthal's oral microbes and their comparison to other modern and ancient humans has allowed researchers to confirm that the groups shared pathogens, including the bacteria which cause dental caries and gum disease. With the Neanderthal dental plaque, it was able to almost fully reconstruct the genome of one of the bacteria - Methanobrevibacter oralis - dating back some 48,000 years, the oldest genome obtained to date. 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 comparison also shows how bacterial population in Neanderthals and both ancient and modern humans correlated closely with the amount of meat in the diet and how rapidly the oral microbial community has altered in recent history. The Neanderthals from El Sidrón are similar to chimpanzees and our forager ancestors in Africa. In contrast, the Belgian Neanderthal bacteria were similar to early hunter gatherers, and quite close to modern humans and early farmers.
“The DNA preserved in the dental plaque once more not only shows to be an important source of information on the habits and health of ancient hominins, but is also a unique way in which to study long-term microbial evolution”, Karen Hardy indicates.
The study included the participation of researchers from the Institute of Evolutionary Biology (UPF-CSIC), the Spanish National Museum of Natural Sciences and the University of Oviedo.
Original article: Neanderthal behaviour, diet and disease inferred from ancient DNA in dental calculus. Nature. http://dx.doi.org/10.1038/nature21674