Disease: Palaeopathology and Pathogen aDNA
Palaeopathology is the study of diseases and injuries in people who lived in the past. In this project, we studied skeletons to determine the kinds of diseases that affected those who were buried at the various sites. This enables us to find out the kinds of infectious diseases, cancers and injuries and other conditions that were most common at that time.
We look at the bones to detect changes to their shape and surface appearance that result from diseases damaging those bones. We can use imaging such as X-rays and CT scans to look inside the bones for signs of disease that are not visible on the outer surface. In recent years, ancient DNA (aDNA) has become increasingly important to the study of paleopathology: many of the previously invisible diseases that affected past human societies can now be detected through the DNA of the pathogens causing them. Research using aDNA can help to answer important questions regarding the incidence, affect and severity of disease in the past.
Many diseases only affect the soft tissues and not the bones or teeth, so they are normally invisible in skeletal remains. However, working with the ancient DNA specialists on the team may allow us to pick up some of those diseases.
Image: Jenna Dittmar
Skeletons from medieval Cambridge reveal a wide range of health problems. Many people died as children, without reaching adulthood; this is most visible in the parish cemetery All Saints by the Castle, as the Hospital of St. John and the Augustinian Friary served mostly adult populations. At all sites, a lot of adults show skeletal signs of childhood stresses such as poor nutrition and episodes of disease; these are evident in linear enamel hypoplasias in their teeth, in cribra orbitalia, and in reduced adult stature.
Once people reached adulthood, they suffered many health problems. Some – such as poor mental health or most infectious diseases – would not have left traces on their bones, but we have found evidence of bubonic plague (Yersinia pestis) DNA in skeletons from several sites. Anglo Saxon skeletons from Edix Hill with plague DNA attest the First Pandemic or so-called Plague of Justinian, a Europe-wide epidemic in the sixth century. For the fourteenth to fifteenth centuries, plague victims have been found at the cemetery of All Saints by the Castle, a small plague pit in Bene't St., and at the Augustinian Friary.
Skeletons have provided evidence for a wide range of other health conditions.
infectious disease was common. While we often are unable to tell which infection it was, signs such as new bone formation in reaction to infection are very widely found.
some cases of vitamin D deficiency were found, mostly in the Hospital of St. John.
tuberculosis was a common disease; for some reason, it was more common in women than men. It was a long-term, chronic disease which would have incapacitated many sufferers with advanced cases. Along with other bacterial and viral infections we are unable to see archaeologically, it was probably one of the major killers of medieval people.
leprosy was found in four individuals, evidenced through skeletal changes from the disease and/or DNA from the disease bacterium. Interestingly, although Cambridge had a leprosy hospital for much of the later Middle Ages, all of the cases we found lived in their communities. It is possible that people with the infection were not always diagnosed as such, or that many or most lepers did not actually live in leper hospitals, contrary to popular images of the Middle Ages.
we investigated cancers by systematically scanning bones radiographically, which reveals their internal structure. This revealed a higher rate of cancers than simply looking at the surfaces of bones does, and showed that cancer may have been an important health problem in the Middle Ages.
among minor conditions related to affluence, there were some cases of gout, and DISH (a mostly asymptomatic metabolic condition perhaps related to rich diet) was moderately common. Hallux valgus, a skeletal condition related to bunions, was common, particularly in males and particularly in the later fourteenth to fifteenth centuries. Hallux valgus has been related to tight, constricting footwear, and this seems likely to evidence the increasing popularity of pointy-toed footwear in fashion-conscious later medieval males.
Traumatic injuries were very common; overall, about a third of people in all groups had some healed fractures or other injuries visible in their skeleton. Most of these were common fractures such as a broken forearm or hand bone, but a few were very severe (such a friar with complete fractures of both his right and left femurs, perhaps from a dramatic accident; as both were unhealed, he probably died of his injuries). There were some injuries probably due to violence, including some unhealed ones which may reflect warfare injuries in a small group of thirteenth century people.
Interestingly, skeletons of ordinary townspeople, religious professionals and the Hospital people display interesting differences in health and growth – see the section on Social Osteology and Osteobiography for more detail.