I feel ill, pass the poplar ddp images

What a difference 1000 kilometres make. Neanderthals living in prehistoric Belgium enjoyed their meat – but the Neanderthals who lived in what is now northern Spain seem to have survived on an almost exclusively vegetarian diet.

This is according to new DNA analysis that also suggests sick Neanderthals could self-medicate with naturally occurring painkillers and antibiotics, and that they shared mouth microbiomes with humans – perhaps exchanged by kissing.

Neanderthals didn’t clean their teeth particularly well – which is lucky for scientific investigators. Over time, plaque built up into a hard substance called dental calculus, which still clings to the ancient teeth even after tens of thousands of years.


Researchers have already identified tiny food fragments in ancient dental calculus to get an insight into the diets of prehistoric hominins. Now Laura Weyrich at the University of Adelaide, Australia, and her colleagues have shown that dental calculus also carries ancient DNA that can reveal both what Neanderthals ate and which bacteria lived in their mouths.

The team focused on three Neanderthals – two 48,000-year-old specimens from a site called El Sidrón in Spain and a 39,000-year-old specimen from a site called Spy in Belgium. The results suggested that the Spy Neanderthal often dined on woolly rhinoceros, sheep and mushrooms – but no plants. The El Sidrón Neanderthals ate more meagre fare: moss, bark and mushrooms – and, apparently, no meat.

Vegetarian cannibals?

“That was really a surprise to us,” says Weyrich. “I think the assumption has always been that Neanderthals had diets based around heavy meat consumption. For us not to find any meat in the El Sidrón individuals was quite strange.”

There is a certain irony to that finding, says Paola Villa at the University of Colorado Museum, Boulder, given that cut marks on Neanderthal bones from El Sidrón are often interpreted as evidence of cannibalism. “They may have had a diet of mostly plants but paradoxically they provided meat to the Neanderthals that killed them,” she says.

Other researchers say it makes sense that Neanderthals would have adapted to eat a plant-rich diet if there was less opportunity to hunt animals in their local environment. “To imagine otherwise would be a bit simplistic,” says Amanda Henry at Leiden University in the Netherlands.

But Henry cautions against taking the new DNA findings too literally. “The overwhelming component of the DNA is from the oral bacteria,” she says – only about 0.3 per cent of it comes from the animals, plants and fungi that the Neanderthals ate. “To suggest they are recovering the entirety of the diet here is a bit premature.”

Henry’s earlier work has, in fact, suggested that the Spy Neanderthals ate roots and tubers as well as meat. The new DNA work didn’t recover evidence of those plants, hinting that it provides an incomplete picture.

It’s likely that the Spy diet did contain substantial quantities of plants or mushrooms, says Luca Fiorenza at Monash University in Clayton, Australia, because humans – and probably Neanderthals – can’t cope with a diet exclusively based on animal protein (with little or no animal fat). “You begin to show signs of what is called rabbit starvation,” he says. “It leads to diarrhoea, fever, and even death.”

The study also adds to emerging evidence that mushrooms and other fungi were an important component of ancient human diets – they were eaten both at Spy and El Sidrón.

“Mushrooms have often been forgotten by archaeologists,” says Hannah O’Regan at the University of Nottingham, UK – they are unlikely to be preserved intact at ancient sites.

Neanderthal “doctors”

One of the two El Sidrón individuals – a teenage boy – is known to have had a large dental abscess. The new DNA analysis shows he had a diarrhoea-causing gut parasite in his system, too. “It’s likely he wasn’t a very happy individual,” says Weyrich.

Previous studies have suggested the teenager was eating plants with anti-inflammatory properties. The new study also finds DNA sequences of poplar plants, which are known to contain the natural pain killer salicylic acid (closely related to the active ingredient in aspirin).

That may not have been the only medication or self-medication he did: there was DNA from Penicillium fungus – the source of penicillin – in his dental calculus.

However, it is difficult to say for sure whether Neanderthals actively consumed the fungus for its medicinal properties. Penicillium grows naturally on plant material as it moulds, so they could have eaten it by coincidence. “It’s difficult to tell these specific moulds apart unless you have a hand lens,” says O’Regan.

But Weyrich points out that the Penicillium was only in the dental calculus of the sick teenager – none was found in the calculus of the second El Sidrón individual, who is thought to have led a healthy life. “They might have had some knowledge that mouldy grains could help them when they were sick – we just don’t really know,” she says.

Evidence of foreplay?

There was one more surprise in the dental calculus of the sick teenager. Weyrich and her colleagues extracted enough DNA to reconstruct the genome of a species of oral bacteria called Methanobrevibacter oralis. At 48,000-years-old it is the oldest microbial genome ever sequenced, according to Weyrich and her colleagues.

Comparing the ancient genome with the M. oralis genome found in the mouths of living people, the researchers discovered that the Neanderthal and modern human versions both descended from a common ancestor that lived about 110,000 to 140,000 years ago.

This date roughly coincides with when we think humans and Neanderthals first interbred.

“It’s really well understood that bacteria are swapped between people when they kiss,” says Weyrich. It’s possible that humans and Neanderthals kissed during sex 110,000 years ago, which could explain why the descendants of those interbreeding events – including both the El Sidrón Neanderthals and modern humans – ended up with similar forms of M. oralis bacteria in their mouths.

It’s an interesting idea, says Adam Siepel at the Cold Spring Harbor Laboratory in New York, although he thinks there may be more mundane ways for oral bacteria to be shared. “Once humans and Neanderthals began to occupy the same geographical ranges, it is likely that they drank from the same streams, perhaps salvaged food from one another,” he says. This may be how oral bacteria were swapped.

Weyrich agrees that there are several ways oral bacteria can be exchanged, but the possibility of kissing is still a thought-provoking one, particularly since it is unclear whether the ancient interbreeding events were forced or consensual. “It’s a very different interaction from brash interbreeding,” she says. “It’s very intimate.”

Journal reference: Nature, DOI: 10.1038/nature21674

Read more: Neanderthal chefs may have spiced up menus with wild herbs; Eats bark, fruit and leaves: diet of ancient human; Ancient leftovers show the real Paleo diet was a veggie feast