DNA tests on bones show that neanderthals swapped diseases and bodily fluids with homo sapiens before going extinct 40,000 years ago
Neanderthals and modern humans could have caught genital herpes and stomach ulcer-causing bacteria from each other, say anthropologists who believe the infectious diseases were carried out of Africa around 52,000 years ago.
© Dr Charlotte Houldcroft
Genomes and DNA from incredibly ancient bones, studied by experts from Cambridge and Oxford Brookes universities, show that viruses spread from early homo sapiens to Neanderthals and were “probably” passed back during mating.
Researchers unravelled DNA strands to find a much longer “burn in period” for diseases than previously thought, long before the dawning of agriculture 8,000 years ago, when an explosion in infections had been attributed to the close co-existence of dense populations and livestock.
Dr Charlotte Houldcroft, from Cambridge’s Division of Biological Anthropology, says tapeworm, tuberculosis, stomach ulcers and types of herpes would have weakened hunter-gatherers and catalysed Neanderthal extinction.
“The ‘intermediate’ hominin that bridged the virus between chimps and humans shows that diseases could leap between hominin species,” she says. “The herpesvirus is transmitted sexually and through saliva.
“As we now know that humans bred with Neanderthals, and we all carry two-to-five percent of Neanderthal DNA as a result, it makes sense to assume that, along with bodily fluids, humans and Neanderthals transferred diseases.
“Hunter-gatherers lived in small foraging groups. Neanderthals lived in groups of between 15-30 members, for example. So disease would have broken out sporadically, but have been unable to spread very far.”
An expert in modern infections at Great Ormond Street Hospital, Houldcroft says that infections have evolved and afflicted people for “tens of thousands to millions of years”.
Diseases such as tuberculosis were passed to livestock by humans, although Neanderthals would have adapted to European diseases, and genetic interbreeding saved humans from illnesses including blood poisoning from infected wounds and encephalitis.
Helicobacter pylori, a culprit for stomach ulcers, is a “prime candidate” for infecting humans in Africa between 88,000 and 116,000 years ago. The genome of herpes simplex 2 suggests it was transmitted to humans by chimpanzees via an unknown hominin species 1.6 million years ago.
Theories on the demise of Neanderthals, around 40,000 years ago, range from climate change to an early human alliance with wolves, potentially resulting in domination of the food change. Dr Houldcroft thinks a combination of factors caused their extinction.
“The evidence is building that spread of disease was an important one,” she says. “Humans migrating out of Africa would have been a significant reservoir of tropical diseases.
“For the Neanderthal population of Eurasia, adapted to that geographical infectious disease environment, exposure to new pathogens carried out of Africa may have been catastrophic.
“It is unlikely to have been similar to Columbus bringing disease into America and decimating native populations. It’s more likely that small bands of Neanderthals each had their own infection disasters, weakening the group and tipping the balance against survival.”
- The paper has been published in the American Journal of Physical Anthropology.
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Three museums to meet Neanderthals in
National Museum Cardiff
Discover the secrets of our ancestors from the Neanderthals a quarter of a million years ago in the Archaeology gallery, Origins: in search of early Wales. Everyday objects and beautiful artefacts tell the stories of people in Wales and explore our links with the past.
Planet Earth and Dinosaur Museum, Newhaven
Includes an extraordinary portrayal of Neanderthal man, with a large collection of tools illustrating the complex society that existed.
Harris Museum and Art Gallery, Preston
Nothing Happens, Twice is inspired by the work of Samuel Beckett and The Theatre of the Absurd and includes the première of a major new film by Nathaniel Mellors, Ourhouse, Ep.-1: Time, winner of the Contemporary Art Society Annual Award, in partnership with the Harris Museum. Shot in Preston's iconic and brutalist bus station and other extraordinary locations throughout the city, the film features an eccentric family who find themselves unexpectedly visited by Neanderthals. Until June 4 2016.