Dental Records: Teeth hold clues to shifting diets in victims of the Great Irish Famine

Dental Records: Teeth hold clues to shifting diets in victims of the Great Irish Famine

In the mid-19th century, a devastating famine hit Ireland. The country’s inhabitants saw their primary food staple destroyed by blight, a bacterial disease that makes potatoes uneatable. Blight continued to cause potato crop failure for several years, leading to one of the worst famines in history – an estimated 1.5 million people died, and over 1 million emigrated from Ireland to escape disease and starvation.

During the famine, many of the county’s poor avoided starvation by migrating to the Kilkenny Union workhouse, where they received food and shelter in return for hard labor. But infectious disease spread quickly in the overcrowded workhouse, and many died, forcing authorities to dig mass graves.

Over 160 years later, researchers began excavating the remains of the 970 people buried in the Kilkenny Union workhouse famine cemetery. Julia Beaumont, lecturer in biological anthropology at the School of Archaeological Sciences, University of Bradford, U.K., and colleagues saw this site as a unique opportunity to examine how a historical famine affected people’s diets.

Her team analyzed 20 teeth, each collected from a different person excavated from the Kilkenny Union site, to investigate dietary and physiological changes the individuals went through during the Great Irish Famine. The team found isotopic signatures in the teeth that reflected the expected dietary change from potatoes to maize, which was imported from America to provide relief during the famine. The study, published in PLOS ONE, also revealed prolonged nutritional and other physiological stress resulting from insufficient sustenance during childhood.

To learn more about Beaumont’s research, I interviewed her via email.

Julia Beaumont teachingYou worked as a dentist for many years before you decided to jump into research. What prompted the switch, and why did you decide to study dental development in past populations?

JB: [As a child] I attended an all-girl senior school and admired the science teachers I saw there, great role models who made science interesting and exciting. I have always been easily bored, and when my daughter was visiting the University of Bradford to study there, I spoke to the academics in Archaeological Sciences about getting involved with research. They sat me down for a chat with Janet Montgomery whose ground breaking research using dental enamel was establishing the methods for investigating migration. I was hooked, applied to study a Master’s and then a PhD part- time, and realized that my “past life” gave me the perfect grounding to work out how and at what period of life the chemical signals are incorporated into developing teeth. Research, I find, can never be boring!

Why are teeth good indicators of a person’s diet?

JB: Teeth grow at a really regular rate, and in every population and even in times of hardship. As teeth use the proteins from your food and drink to grow dentine, “you are what you ate,” and by recovering the carbon and nitrogen isotope ratios from the teeth, we can estimate your diet at that age.

“The unique benefit of working with individuals from such a well-recorded historical period is the fascinating combination of scientific research and contemporaneous documentary evidence.”

How did you become interested in studying the people of the Great Irish Famine in particular?

JB: My PhD work started with a cemetery in London where migrants from the Great Irish Famine were buried, with hints at the changes in diet in their bones and teeth we later found in the Kilkenny workhouse. The unique benefit of working with individuals from such a well-recorded historical period is the fascinating combination of scientific research and contemporaneous documentary evidence.

In your new study you used a technique called “incremental dentine collagen analysis,” which evaluates stable isotope ratios of carbon and nitrogen in tooth dentine. You also analyzed rib bones from the Kilkenny Union workhouse inmates. What does comparing teeth and rib bones tell us about changes in diet?

JB: This technique for sampling tooth dentine allows us to estimate how old an individual was when the tooth was growing, and gives us a profile of the diet during that time: with the right tooth we can go from pre-birth (with a milk tooth) right through to the early 20’s (with a wisdom tooth). The rib bones are re-modelling throughout your life, and therefore, only represent an average of the last 2–5 years. This means that in adults we can compare childhood diet (from teeth) with the diet in recent years (in the rib). The measurements showed that adults in this group were mainly eating potatoes as children and in the period before death, had eaten maize as their main source of calories: with one notable exception, a woman who had also eaten maize at the time of an earlier famine in her childhood.

You mentioned in your press release that you could identify the marker for starvation in the teeth you studied prior to the workhouse residents being given maize as famine-relief food. What was the marker and why is this finding significant?

JB: The marker we have found is a pattern of “opposing co-variance” with nitrogen isotope ratios rising while the carbon isotope ratios reduce. This is the first time that these changes have been
identified in dentine. We know that in times of stress, you can recycle parts of your protein and fat which produces these changes: these have been seen in other tissues such as hair, but are too short-term to appear in bones like the rib, and the historical records of the foods consumed in this famine have allowed us to be sure that what we see is real, and not caused by an unusual diet.

What are some possible applications for this study, and what’s next for your research? 

JB: Being able to identify short-term markers for nutritional stress opens possibilities for identifying mass famines in the past of which previously we have been unaware. It may also help in forensic cases where a modern child has suffered neglect – either nutritional or physiological stress. My current research is using donated milk teeth from modern children in order to identify markers for stress in childhood where we know the medical histories: the Tooth Fairy project in Bradford.

Research Article: Beaumont J, Montgomery J (2016) The Great Irish Famine: Identifying Starvation in the Tissues of Victims Using Stable Isotope Analysis of Bone and Incremental Dentine Collagen. PLoS ONE 11(8): e0160065. doi:10.1371/journal.pone.0160065

Image Credit: Famine Memorial by Eddie Wong via Flickr


Jen is the Editorial Media Manager at PLOS. Before her time at PLOS, she's worked in broadcast news, radio and online media.

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