Bioarchaeological Diet Reconstruction: Reading History in Ancient Bones and Pots

An individual's life story is written in their bones, and for bioarchaeologists, the most compelling chapters often revolve around what they ate. The old adage, "you are what you eat," is the cornerstone of a fascinating scientific field that deciphers the diets of ancient peoples, providing profound insights into their lives, cultures, and the environments they inhabited. By meticulously examining the chemical and physical clues left behind in skeletal remains and the pottery they used, researchers can reconstruct ancient menus with astonishing detail. This journey back in time not only reveals what was on the dinner table hundreds or thousands of years ago but also uncovers stories of migration, social status, and human adaptation.

The Chemical Echo: Stable Isotope Analysis

Imagine being able to tell what a person ate not from their fossilized stomach contents, but from the very atoms that make up their bones and teeth. This is the power of stable isotope analysis, a revolutionary technique that has transformed our understanding of past diets. The principle is simple: the isotopic signatures of the foods consumed are incorporated into an individual's tissues.

Carbon and nitrogen are two of the most informative elements. The ratio of different carbon isotopes (¹³C and ¹²C) in bone collagen can distinguish between the consumption of different types of plants. For instance, it can reveal a diet rich in C4 plants like maize and sorghum versus one based on C3 plants like wheat, rice, and most vegetables. Nitrogen isotopes (¹⁵N and ¹⁴N), on the other hand, can indicate an individual's position in the food chain. A person who regularly consumed animal protein would have higher nitrogen isotope values than someone with a plant-based diet.

Case Study: The Pictish Monastery of Portmahomack

A compelling example of this technique comes from the excavation of a Pictish monastery in Portmahomack, Scotland, dating from the 6th to 17th centuries AD. Analysis of 178 skeletons revealed a dramatic dietary shift over time. The earlier Pictish communities had a diet heavily reliant on terrestrial plants and animals. However, the later parish community, following the monastic period, showed a significant increase in marine and freshwater fish consumption. This not only painted a picture of their changing menu but also hinted at evolving economic and social structures, possibly influenced by the monastery's development and its trade connections. By analyzing different tissues, such as bones which reflect the diet of the last several years of life, and teeth which preserve a record from childhood, scientists can even reconstruct an individual's dietary history.

A Microscopic Menu: Dental Microwear Analysis

If isotopes provide the broad strokes of an ancient diet, dental microwear analysis adds the fine details. This method involves studying the microscopic pits and scratches that form on teeth as a result of chewing. The nature of these marks is directly related to the physical properties of the food consumed. Harder foods, like nuts and seeds, tend to leave behind complex patterns of pits, while tougher foods, like meat and leaves, create more linear scratches.

The texture of the food, including the presence of abrasive particles like grit from grinding stones or dust from the environment, also leaves its signature on the enamel. By comparing the microwear patterns on ancient teeth to those of modern individuals with known diets, researchers can make remarkably precise inferences about what ancient people were eating in the days and weeks before their death.

Case Study: The Varied Diets of Medieval Pontevedra

A 2023 study on skeletons from two medieval cemeteries in Pontevedra, Spain, beautifully illustrates the power of combining dental microwear with stable isotope analysis. The individuals, belonging to a guild of fishers and artisans, had a diet rich in marine protein, as confirmed by isotope data. Their teeth, however, told a more nuanced story. They exhibited severe dental wear from a young age, a characteristic often associated with a diet high in abrasive marine resources. This combined approach not only confirmed their reliance on the sea but also cautioned against using dental wear alone to estimate age in coastal populations, as their unique diet accelerated the wear process.

Echoes from the Embers: Pottery Residue Analysis

The pots and pans of the past also hold tantalizing clues to ancient cuisines. Organic residue analysis focuses on the micro-remains of foods that have been absorbed into the porous surfaces of ceramic vessels during cooking and storage. These residues can include lipids (fats and oils), proteins, and even starches.

By extracting and analyzing these molecules, archaeologists can identify the specific types of plants and animals that were processed in these pots. This technique has been instrumental in understanding the adoption of agriculture, the domestication of animals, and the development of culinary traditions across the globe.

Case Study: A Neolithic Feast at the Ness of Brodgar

At the remarkable Neolithic site of the Ness of Brodgar in Orkney, Scotland, a recent analysis of over 300 pottery samples is rewriting our understanding of ceremonial feasting. The research, which won the Royal Archaeological Institute prize for science in April 2024, revealed that the inhabitants were processing a variety of foods in their distinctive Grooved Ware pottery. The analysis of lipid residues showed evidence of the consumption of dairy products and ruminant carcass fats, suggesting large-scale feasting events. The study also hinted at a seasonal use of the pottery, with dairy processing likely occurring in the spring and summer, and the rendering of animal fats in the autumn and winter. These findings provide a vivid picture of the social and ceremonial life of this ancient community.

The Power of a Combined Approach

The most powerful insights into ancient diets come from combining these different lines of evidence. A multi-proxy approach, integrating stable isotope analysis, dental microwear, and residue analysis, allows for a more holistic and robust reconstruction of past foodways. For example, a study on the Neolithic site of Çatalhöyük in Turkey used protein analysis from pottery residues to identify a mix of cereals, legumes, and animal products, including the milk of sheep and goats. This provided a much more detailed picture than could be gleaned from any single method alone.

The Future is Now: New Frontiers in Dietary Reconstruction

The field of bioarchaeological diet reconstruction is constantly evolving, with new technologies offering even more detailed glimpses into the past.

Proteomics: The Protein Puzzle

The analysis of ancient proteins, or paleoproteomics, is a rapidly growing area. Proteins can provide more specific taxonomic information than lipids, helping to distinguish between different animal species, for example. Recent studies have successfully recovered milk proteins from dental calculus, the hardened plaque on teeth, providing direct evidence of dairy consumption. While challenges in extracting and identifying ancient proteins from pottery remain, recent advancements are showing great promise. A 2024 study on pottery from a prehistoric Maltese site, for instance, highlighted the potential of proteomics to identify key dietary staples like wheat.

Artificial Intelligence: The Digital Detective

Artificial intelligence (AI) and machine learning are also beginning to revolutionize the field. AI algorithms can be trained to analyze vast datasets of skeletal features, dental microwear patterns, and isotopic signatures, identifying subtle patterns that might be missed by the human eye. This can help to classify artifacts, reconstruct 3D models of skeletal remains, and even predict the location of undiscovered archaeological sites. A 2023 study demonstrated how AI could identify animal species from their remains with over 90% accuracy, a significant improvement over human experts. While still an emerging application, AI has the potential to automate and enhance the analysis of ancient dietary data, leading to more robust conclusions about past populations.

The Unwritten Cookbook of Humanity

The study of ancient diets is more than just an academic exercise. It connects us to our ancestors on a deeply human level, revealing the challenges they faced, the innovations they developed, and the diverse ways they sustained themselves. From the surprisingly early adoption of settled life by Scandinavian fishing communities to the intricate feasting rituals of Neolithic Britons, the stories written in ancient bones and pots continue to enrich our understanding of the human story. As technology advances, we can expect even more detailed and captivating narratives to emerge from the unwritten cookbook of humanity.