A human jawbone housed in a small Bristol museum has contributed ancient DNA to ground-breaking research into bacteria.

The jawbone was found in Fishmonger’s Swallet, a cave in South Gloucestershire, and is now in the University of Bristol Spelaeological Society’s museum.

This was one of four samples from across the UK, ranging from 2,300 to 600 years ago, that helped researchers at the Francis Crick Institute and UCL in London use ancient DNA to pinpoint the evolution and spread of Borrelia recurrentis, a type of bacteria that causes relapsing fever.

Fishmonger’s Swallet, which featured on a Time Team dig in 2000, has yielded an astonishing amount of material from the Iron Age, including people and dogs radiocarbon dated to the late pre-Roman Iron Age between 200BC to 35BC.

The research is published this week in the academic journal Science. Until now it was not known when B. recurrentis made the jump from ticks to lice and what impact this had on disease transmission and severity in humans.

Researchers concluded that the evolution of B. recurrentis highlights that a combination of genetic and environmental changes can help pathogens spread and infect populations more easily. This transition may have coincided with changes in human lifestyles, like living closer together and the beginning of the wool trade.

Museum curator Linda Wilson said: “Our museum is an amazing treasure trove of ancient material that punches well above its weight in its contribution to research. Our collection supports cutting-edge scientific studies like this one, and by preserving and making this material available we enable scientists to deepen our understanding the past. Fishmonger’s Swallet is a fascinating site that has by no means given up all its secrets. Only two weeks ago, we were working there with members of the Hades Caving Club and archaeologists affiliated with Amgueddfa Cymru/Museum Wales, recovering more material for future research.”

The Francis Crick Institute provides further information here.