Scientific analysis under way during road works has uncovered a church and a 1,000-year-old burial ground in Co Donegal, writes Dr Claire O'Connell
It has got the bones of a good story. Scientists are preparing to analyse a large collection of human skeletons discovered at a medieval burial site in the south of Co Donegal. Their study, at Queen's University Belfast (QUB) and IT Sligo, will help us better understand how our Irish ancestors lived and died.
In late 2003, archaeologists discovered ancient human bones along the route of a proposed bypass at Ballyhanna near Ballyshannon, says Mr Michael MacDonagh, the National Roads Authority (NRA) project archaeologist in the Donegal National Road Design Office. The team dug further and was surprised to unearth the foundations of a small church and skeletal assemblages from about 1,200 humans. "It was a wonderful discovery," he says. "We weren't expecting it."
Many of these "Ballyhanna bodies" were laid out flat and positioned on an east to west axis, indicating Christian burial, says MacDonagh. He estimates the site was in use from 1100 to 1300 AD, adding that there are also signs of earlier, Bronze Age burial and two much more recent mass graves dating from around the 17th century, possibly the result of an epidemic.
The initial excavation in Donegal also threw up some other grisly clues about how the medieval population lived and died.
Some of the skeletons bore sword nicks and one man had an iron arrowhead embedded in his spine.
The NRA has now funded research studentships to find out more about these ancient skeletons. Studies scheduled to begin over the coming months will involve morphology, radiocarbon dating, genetic analysis and trace element profiles, and are to be carried out under licence from the National Museum of Ireland.
Looking at the bones in detail will provide baseline information about the health of the medieval population, according to QUB lecturer Dr Eileen Murphy, who is an expert in the osteoarchaeology of human bones.
She and medieval specialist Dr Colm Donnelly will work with a PhD student to examine the skeletal assemblages. "We will be looking at each individual and identifying the sex, age at death, height and indicators of disease," she explains.
Amazingly, the naked eye can pick out tell-tale signs of illness even in 900-year old bones - if you know what to look for. "Each different disease leaves its own characteristic signature on the bone," explains Dr Murphy.
"In tuberculosis, bacteria attack specific parts of the body and you can see the abscesses and the little plaques of new bone formation," she says. "In leprosy the bones of the hands and feet start to resorb away - it's very nasty and you can end up losing entire toes and fingers, your nose collapses and your front teeth fall out."
The human remains will also be carbon-dated at a new accelerated-mass-spectrometry laboratory in Queens to identify phases of activity at the burial site, says Dr Murphy.
Meanwhile, collaborating scientists at IT Sligo will look for clues that lie deeper in the bones. For example, with child skeletons it can be difficult to determine the gender based on shape alone. So the researchers will extract ancient DNA from half-gram samples of tooth or compact bone and look at a marker gene called amelogenin on the sex chromosomes to confirm sex, explains Dr Jerry Bird, a lecturer at IT Sligo. He notes that working with ancient DNA presents certain challenges, as it may be degraded or become contaminated by modern sequences.
With Dr Ted McGowan, the Sligo team will also test bone samples for a wide range of trace elements, including iron, magnesium and lead. "That will provide baseline information to look at the evaluation of diet, social, environmental and toxicological factors from that population," says Dr Bird.
"These people would have been involved in a lot of different activities such as metalworking - communities had to provide things for themselves back then."
The researchers hope their collaborative, bio-cultural approach to this snapshot of history will enrich our understanding of life and death in an Irish medieval town. In the meantime, the ancient church site is being preserved as a small heritage park.