A research project led jointly by researchers from the University of Oxford, the University of Copenhagen and University of Cambridge shows that large-scale mapping of prehistoric teeth and bones provides new knowledge of present-day infectious diseases. This may, among other things, have an impact on the development of vaccines.
Using a specialised method to analyse prehistoric disease DNA, researchers have, for the first time, successfully mapped an entire catalogue of infectious diseases, spanning 214 known human pathogens in total, that afflicted prehistoric populations and still circulate today.
The analyses, published in Nature . also provide crucial new insights into the emergence of zoonoses - diseases transmitted from animals to humans, such as plague, leprosy, and yersinosis. The researchers show that many of these diseases first began to appear around 6,500 years ago, which closely coincides with the period when our ancestors started living in close proximity to domesticated animals.
Approximately 70 percent of all new infectious diseases discovered in recent years are zoonotic - that is diseases that can be transmitted from animals to humans. Known zoonoses include diseases such as salmonella, listeriosis, Yersinia enterocolitica (which causes gastrointestinal infection), Borrelia recurrentis (which causes louse-borne relapsing fever), rabies and MRSA.
Astrid Iversen, Professor of Virology and Immunology at University of Oxford's Nuffield Department of Clinical Neurosciences , and one of the co-authors of the Nature article, said: 'Before 6,500 years ago, we only found DNA from one pathogenic microorganism in the samples from Eurasia, which we could classify as a zoonosis. After that time, zoonoses, to some extent, start causing people to die, and about 5,000 years ago, zoonoses really took off, according to our analyses of ancient human remains.'
The significant increase in the incidence of zoonoses around 5,000 years ago coincides with a migration to north-western Europe from the Pontic Steppe - that is from parts of present-day Ukraine, south-western Russia and western Kazakhstan.
Professor Iversen added: 'Zoonoses first became a major problem for humans when we started keeping animals together in large herds and living close to these animals - eating their meat and drinking their milk. This meant that the animals could more easily infect each other, and that the risk of them infecting humans increased.'
The rise of zoonoses 5,000 years ago also shows that the way we live has a major impact on which pathogenic microorganisms we are exposed to. It is also a reminder that zoonoses are not a static phenomenon.
The study is based on DNA analyses of bones and teeth from 1,313 individuals who lived across Europe and Asia (Eurasia) from the Early Stone Age, around 12,500 years ago, up to about 200 years ago. Remarkably, seven of the samples are even older than the Early Stone Age - the oldest dating back 37,000 years.
The discovery was made by an international team of researchers headed by Eske Willerslev, Professor of Evolutionary Biology at the University of Copenhagen's Lundbeck Foundation GeoGenetics Centre and at the University of Cambridge.
According to Eske Willerslev, who led the project together with Associate Professor Martin Sikora (University of Copenhagen) and Professor Astrid Iversen (University of Oxford), the mapping of prehistoric infectious diseases offers a range of exciting perspectives - many of which are highly relevant today.
'In addition to providing information on historical conditions related to infectious diseases, the mapping also provides a deeper understanding of a number of these diseases that can still affect humans today. For example, you can see how some of the pathogenic microorganisms have genetically changed over time,' said Eske Willerslev.
