What Ancient Teeth Reveal About Diet

Teeth are among the most resilient biological structures in the human body, frequently surviving intact in archaeological contexts where fragile skeletal bones have long since dissolved into acidic soil. For bioarchaeologists, this durability transforms human dentition into an extraordinary archive of ancient life. While the visible surfaces of teeth—composed of highly mineralised enamel—can document physical stress, developmental trauma, and dietary abrasion, it is the substance adhering to them that has recently revolutionised historical research. Dental calculus, commonly known as tartar, is a form of mineralised plaque that calcifies during an individual's lifetime. As it hardens, it traps micro-particles of food, environmental debris, and entire communities of oral bacteria within a protective matrix of calcium phosphate, effectively sealing an undisturbed biological time capsule for thousands of years.

By comparing dental remains from different archaeological eras, researchers have traced the profound consequences of major economic and subsistence shifts on human oral ecology. During the Upper Palaeolithic period, when hominins relied on foraging, hunting, and fishing, oral health was surprisingly robust. Although teeth from this era often show extensive mechanical wear caused by the mastication of fibrous plants and tough game, evidence of infectious decay is remarkably scarce. The fundamental turning point occurred during the Neolithic transition, when communities abandoned mobile lifestyles in favour of sedentary farming. The regular consumption of cultivated cereals, such as emmer wheat and barley, flooded the oral cavity with fermentable carbohydrates. Bacteria adapted rapidly to this constant influx of simple sugars, generating acidic by-products that dissolved tooth enamel and triggered a dramatic rise in dental caries.

Alongside changes in bacterial infection, the physical texture of ancient food left distinctive signatures on dental morphology. In many early agrarian societies, grain processing relied heavily on grinding implements made of volcanic rock or sandstone. As grains were crushed between rough rotary querns or saddle stones, minute mineral particles detached from the rock and became mixed with the flour. The resulting coarse bread acted like an abrasive paste, wearing down the biting surfaces of molars over successive decades. While this rapid attrition flattened the deep fissures where bacteria typically accumulated—ironically keeping some forms of decay at bay—it frequently wore the crowns down to the sensitive internal pulp, resulting in excruciating nerve exposure, chronic abscesses, and widespread alveolar bone loss.

In recent decades, analytical techniques have shifted from macro-structural observations of tooth wear to microscopic and chemical evaluations of dental calculus. Within this mineralised matrix, researchers have recovered intact phytoliths—rigid microscopic structures made of silica that form inside plant tissues. Because phytoliths vary in shape depending on the plant family, their presence within ancient tartar provides indisputable evidence of specific consumed botanicals, from wild grasses to cultivated tubers. Furthermore, advanced mass spectrometry has succeeded in identifying trace dairy proteins, notably beta-lactoglobulin, within the calculus of Bronze Age pastoralists. This discovery confirmed that early farming populations consumed liquid animal milk well before the widespread genetic adaptation for adult lactose tolerance had evolved.

The history of dental health also mirrors social stratification and international trade. During the late medieval and early modern periods, the importation of cane sugar from overseas plantations transformed dietary habits across western Europe. Because sugar was initially an expensive luxury, severe dental caries became a curious marker of high social standing. Historical records indicate that some individuals in sixteenth-century England deliberately blackened their teeth with charcoal or soot to mimic the rot caused by sugar consumption among the wealthy elite. By the eighteenth century, however, industrial refining techniques drastically lowered the cost of sugar, causing dental deterioration to spread rapidly through all social classes and transforming tooth decay into a universal affliction.

The biological consequence of this modern dietary shift was not merely an increase in cavities, but a permanent disruption of the human oral microbiome. High-throughput genetic sequencing of bacterial DNA extracted from calculus spanning the past several millennia indicates that the microbial diversity inside the human mouth has collapsed. Where ancient hunter-gatherers hosted rich, balanced ecosystems containing hundreds of mutually regulating bacterial strains, modern mouths are dominated by a narrow set of acid-producing specialists. This monoculture-like state appears to foster persistent oral inflammation, leaving contemporary populations uniquely vulnerable to periodontal disease.

Today, dental bioarchaeology extends beyond nutritional studies to shed light on ancient occupational hazards and systemic illnesses. Particles of charcoal, textile fibres, and metal dust embedded in dental calculus have revealed the working environments of craftspeople, whilst genomic analyses of preserved pathogens have uncovered strains responsible for historic plagues. Ultimately, the human mouth preserves an intimate, enduring record of the dietary and technological revolutions that have shaped our species.