Ancient DNA found in the dental plaque of Neanderthals – our nearest extinct relatives – has provided remarkable new insights into their behaviour, diet and evolutionary history, including their use of plant-based medicines to treat pain and illness.
An international team of researchers from the University of Liverpool in the United Kingdom and the University of Adelaide in Australia has uncovered the complexity of Neanderthal behaviour, including dietary differences between Neanderthal groups and their knowledge of medication.
Results of the research were published on 8 March in Nature.
“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 bacteria that lived in the mouths of both Neanderthals and modern humans,” says Professor 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.”
The researchers analysed and compared dental plaque samples from four Neanderthals found at the cave sites of Spy in Belgium and El Sidrón in Spain. The four samples ranged from 50,000-42,000 years-old and are the oldest dental plaque ever to be genetically analysed.
“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 of the Nature paper, Dr Laura Weyrich, a research fellow with the University of Adelaide’s Australian Centre for Ancient DNA.
“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 behaviour.”
Centre Director Professor Alan Cooper says the researchers found that the Neanderthals from Spy Cave consumed woolly rhinoceros and European wild sheep, supplemented with wild mushrooms. Those from El Sidrón Cave, however, showed no evidence for meat consumption, but appeared instead to have a largely vegetarian diet, comprising pine nuts, moss, mushrooms and tree bark: in other words, quite different lifestyles between the two groups.
One of the most surprising finds 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.
“But he was also eating poplar, 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,” Cooper says.
“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 as well as ancient and modern 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 bacteria 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 discovered how rapidly the oral microbial community has altered in recent history. The composition of oral bacterial populations in Neanderthals, and both ancient and modern humans, correlated closely with the amount of meat in their diet. The Spanish Neanderthals were similar to chimpanzees and humans’ forager ancestors in Africa, whereas the Belgian Neanderthal bacteria were similar to early hunter gatherers, and quite close to modern humans and early farmers.
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