Research challenges human evolution and the origins of disease

Tuesday, 12 April 2016

Simon Underdown

A study by researchers at Oxford Brookes University and Cambridge University challenges the dominant theories surrounding the decline of the Neanderthals, suggesting it was infectious diseases which modern humans brought with them that may have caused their demise.

The paper, which has received significant attention in the press, was published this week (11 April) in the American Journal of Physical Anthropology. It explores how Neanderthals across Europe may well have been infected with diseases carried out of Africa by waves of anatomically modern humans, or Homo sapiens. 

As both were species of hominin, it would have been easier for pathogens to jump populations, say researchers. This might have contributed to the demise of Neanderthals.

Far from being the only ‘human’ species it’s now clear that the Neanderthals, traditionally thought of as stupid and brutal, were in fact our equal in terms of language, symbolic thought and ultimately were just as ‘human’ as us.

Dr Simon Underdown, Principal Lecturer in Biological Anthropology, Oxford Brookes University

Dr Simon Underdown, Principal Lecturer in Biological Anthropology at Oxford Brookes and Dr Charlotte Houldcroft from Cambridge’s Division of Biological Anthropology, reviewed the latest evidence gleaned from pathogen genomes and DNA from ancient bones, and concluded that some infectious diseases are likely to be many thousands of years older than previously believed.

The longstanding view of infectious disease is that it exploded with the dawning of agriculture some 8,000 years ago, as increasingly dense and sedentary human populations coexisted with livestock, creating a perfect storm for disease to spread. The researchers say the latest evidence suggests disease had a much longer “burn in period” that pre-dates agriculture.

Dr Simon Underdown said: “In combination with archaeological and fossil data we can now build a much more sophisticated model of our evolutionary journey. Far from being the only ‘human’ species it’s now clear that the Neanderthals, traditionally thought of as stupid and brutal, were in fact our equal in terms of language, symbolic thought and ultimately were just as ‘human’ as us. We now know that not only did we interbreed with the Neanderthals multiple times in Asia and Europe but that all non-African humans have up to four per cent Neanderthal DNA.”

There is as yet no hard evidence of infectious disease transmission between humans and Neanderthals; however, considering the overlap in time and geography, and not least the evidence of interbreeding, both Dr Underdown and Dr Huldcroft believe that it must have occurred.

Two diseases that they believe humans passed to Neanderthals are Helicobacter pylori, a bacterium that causes stomach ulcers, and herpes simplex 2, the virus which causes genital herpes. There is evidence preserved in the genome of this disease that suggests it was transmitted to humans in Africa 1.6 million years ago from another, currently unknown hominin species that in turn acquired it from chimpanzees.

He continues: “Our research demonstrates that very close contact between hominin species in the past was common and that exchange of disease, genes and even ideas have played a key role in shaping our evolution and how we live in the world today.”

Dr Simon Underdown is part of the Human Origins and Palaeo-Environments Research Group in the Department of Social Science at Oxford Brookes. More information about research in the Department can be found on their website at www.brookes.ac.uk/social-sciences/research/