Parasites from medieval latrines unlock secrets of human history

A radical new approach combining archaeology, genetics and microscopy can reveal long-forgotten secrets of human diet, sanitation and movement from studying parasites in ancient poo. Researchers at the University of Oxford's Department of Zoology and School of Archaeology have applied genetic analysis to 700-year-old parasites found in archaeological stool samples to understand a variety of characteristics of a human population. It is the first time this combined parasitological and ancient DNA (aDNA) approach has been applied to understand the epidemiology of historical parasites. The findings have just been published in  Proceedings of The Royal Society B. Gathered from medieval latrines in Lübeck, Germany, these armoured relics that passed through human faeces - nematode (roundworm) and cestode (tapeworms) eggs - have tough shells that withstand time and decay, perfectly preserving their DNA. Lead researcher Adrian Smith said: 'This new approach could be critical as an artefact independent tool for the study of people in the past. Human faeces were not typically traded but the parasites which can live in humans for 10 years or more are deposited wherever the people went.' Analysis shows that high numbers of cestodes (tapeworms) were found in latrines from medieval Lübeck, one of the world's leading ports during the Middle Ages. As freshwater fish was a known source of these cestodes the researchers could deduce that in Lübeck they had a diet high in freshwater fish which wasn't effectively cooked, a practice distinct from other regions.