King’s CRA finds Neanderthals may have contracted diseases from humans

Photo of Dr Charlotte Houldcroft

King’s alumna and College Research Associate (CRA), Dr Charlotte Houldcroft, along with Dr Simon Underdown of Oxford Brookes, have discovered that some infectious diseases are tens of thousands of years older than previously thought. This much earlier timeline for infections like tapeworm, tuberculosis, stomach ulcers and types of herpes challenges longstanding views about the origins of infectious diseases and suggests that Neanderthals may have contracted human diseases.

In their recent article for the American Journal of Physical Anthropology, Houldcroft and Underdown dispute the prevailing view that infectious diseases exploded with the advent of agriculture, some 8,000 years ago. Studying pathogen genomes and ancient DNA, they find much earlier timestamps for certain diseases, like the appearance of the bacterium Helicobacter plori (causing stomach ulcers) 88 to 116 thousand years ago and the herpes simplex 2 virus (causing genital herpes) 1.6 million years ago. They also suggest that some diseases, including tuberculosis, traditionally labeled as ‘zoonoses’, transferred from herd animals to humans, were actually transmitted the other way around.

Although there is no direct evidence of disease transmission between humans and Neanderthals, there is evidence that viruses moved from other hominins into humans. There is also evidence of interbreeding between Neanderthals and humans. Given these findings and the overlap in time and geography for Neanderthals and humans, Houldcroft and Underdown suggest that humans transferred infectious diseases to Neanderthals.

Photo of Dr Charlotte Houldcroft

“Humans migrating out of Africa would have been a significant reservoir of tropical diseases,” says Houldcroft. “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.”

“However, 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,” says Houldcroft.

A range of explanations for the Neanderthal extinction has been proposed, from climate change to an early human alliance with wolves. Houldcroft explains, “It is probable that a combination of factors caused the demise of Neanderthals, and the evidence is building that spread of disease was an important one.”

Further coverage of the findings is provided by The Guardian and The Independent.

In 2014, Dr Charlotte Houldcroft was one of the first CRAs to be appointed at King’s. The new findings are the result of her CRA research. Further information is available about the College Research Associates.

Dr Houldcroft has an MA in Human Sciences from Oxford and a PhD in Molecular Biology from Cambridge. She is now an affiliate lecturer in the Division of Biological Anthropology.

12 April 2016