Researchers have conducted a large-scale study mapping the spread of infectious diseases in humans over thousands of years. The study, led by Professor Eske Willerslev from the Universities of Cambridge and Copenhagen, highlights how human interactions with domesticated animals and large migrations influenced the prevalence of diseases.
The team analyzed ancient DNA from 214 known human pathogens found in prehistoric humans across Eurasia. Their findings reveal that zoonotic diseases—those transmitted from animals to humans—date back approximately 6,500 years, becoming more common around 5,000 years ago.
Among their discoveries is the world's oldest genetic trace of Yersinia pestis, the plague bacterium, in a sample dated to 5,500 years ago. Other detected diseases include malaria (4,200 years ago), leprosy (1,400 years ago), hepatitis B virus (9,800 years ago), and diphtheria (11,100 years ago).
Published in Nature, this research involved DNA analysis from over 1,300 prehistoric humans dating back as far as 37,000 years. The study provides insights into disease development caused by bacteria, viruses, and parasites.
Professor Willerslev stated: “We’ve long suspected that the transition to farming and animal husbandry opened the door to a new era of disease – now DNA shows us that it happened at least 6,500 years ago.” He further noted that these infections might have contributed to population collapse and migration.
The rise in zoonoses around 5,000 years ago aligns with migrations to north-western Europe from regions such as present-day Ukraine and Kazakhstan by Yamnaya herders. This migration significantly impacted the genetic profile of modern north-western Europeans.
Associate Professor Martin Sikora emphasized the importance of understanding historical disease patterns for future vaccine development: “If we understand what happened in the past it can help us prepare for the future.”
Samples for this research were primarily sourced from European and Asian museums. They were extracted mainly from teeth enamel and petrosa bones due to their protective properties against DNA degradation.
The Lundbeck Foundation funded this research project.
Reference: Sikora M. et al., ‘The spatiotemporal distribution of human pathogens in ancient Eurasia.’ Nature July 2025 DOI:10.1038/s41586-025-09192-8
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