Deciduous teeth enamel as a biological archive of life's earliest chapters

It is often said that our teeth record the story of what we eat, but new research reveals they also tell the biological story of who we are. A recent landmark review published in Neuroscience and Biobehavioral Reviews in 2024 by Alessia Nava and colleagues synthesises cutting-edge research from anthropology, neuroscience, chemistry, and evolutionary biology. It shows how baby teeth can be read like tree rings, capturing everything from breastfeeding patterns to episodes of illness and maternal health during pregnancy [1].

For centuries, dentists have been fascinated by the resilience of enamel. Now, scientists are discovering that beneath its smooth surface lies an exquisite biological diary. Each microscopic line in enamel, along with subtle chemical traces, records the rhythm of growth, stress, and diet during the earliest and most formative years of life. Dental enamel begins forming in the womb and continues into adolescence, preserving with atomic precision the imprint of our developmental journey. Skeletal remains provide one way to access this information for humans recovered before historical periods. Teeth, in particular, are retrospective archives of information that can be accessed through morphological, micromorphological, and biogeochemical methods [1, 2].

Nava and her team describe enamel as a kind of biological time capsule, preserving an exceptionally detailed record of early life that bone cannot. Using laser-based biogeochemical analysis and high-resolution microscopy, researchers can now read enamel much like dendrochronologists read tree rings. The spacing of microscopic growth lines, known as Retzius lines, reveals daily and weekly biological rhythms that reflect longer underlying physiological processes. Accentuated lines, or Wilson bands, mark episodes of physiological stress such as illness, malnutrition, weaning, or other disruptions to metabolic stability. One of the most striking features is the neonatal line, a distinct boundary that separates life before birth from life after birth [1,2,3].

This ability to map early-life stress and nutrition has transformed bioarchaeology. By studying teeth from archaeological sites, scientists can reconstruct patterns of breastfeeding and weaning, provide clues about maternal stress and health, and trace population mobility. Teeth also shed light on the evolution of human cooperative caregiving. Humans wean far earlier than other primates, long before brain growth is complete. This early weaning was likely possible because infants evolved within supportive communities where multiple caregivers shared responsibilities beyond the mother. More caregivers enabled more social interaction, which helped tune the developing social brain. Teeth preserve the chemical and structural markers that allow researchers to track this evolutionary shift [1,3].

Using laser ablation ICP-MS, researchers analyse trace elements locked inside enamel. Ratios of elements such as strontium and barium shift predictably during weaning, distinguishing prenatal nutrition from breast milk and solid food. Multi-elemental analyses can also reveal exposure to toxic trace metals such as cadmium, mercury, and lead during in-utero development, infancy, and childhood, helping identify exposure events during critical life stages such as brain development. Isotopic fingerprints can reveal where a child was born, whether their family migrated, and the environmental conditions that shaped growth [1,2].

Accentuated lines in teeth record physiological stress events such as fever, nutritional shortages, or maternal illness. In one example, Roman-era children’s teeth from Isola Sacra in Italy revealed peaks of stress around one year of age, likely corresponding to the transition from breastfeeding to solid food. Researchers can identify stress events within weeks of a child’s life, nearly two thousand years ago [1,3].

The concept originated in anthropology, where researchers used teeth to study ancient populations and reveal diets, stress events, mobility patterns, and health. These same techniques are now being adapted to modern clinical research. By combining tooth-based chemical signatures with detailed records from contemporary birth cohort studies, scientists hope to understand how early-life exposures shape lifelong health trajectories [3,4].

Conclusion

Baby teeth naturally exfoliate and are painless to collect, offering an opportunity for large-scale screening. Researchers anticipate a future in which analysing a child’s first shed tooth becomes part of routine pediatric care, helping identify children at risk for developmental delays or environmental exposures before symptoms appear. Potential benefits include earlier public health interventions, improved monitoring of environmental toxins, personalised pediatric care, and a better understanding of vulnerable developmental windows.

For dental professionals, this research reframes the tooth as both a clinical and scientific marvel. Every child’s smile carries a deep biological record, etched line by line and element by element, reflecting life’s earliest struggles and triumphs. From ancient graves to modern clinics, the study of enamel connects past, present, and future in ways few other tissues can [1,5].

References

1. Nava A, Lugli F, Lemmers S, Cerrito P, Mahoney P, Bondioli L, Müller W. Reading children’s teeth to reconstruct life history and the evolution of human cooperation and cognition: The role of dental enamel microstructure and chemistry. Neuroscience and Biobehavioral Reviews. 2024;163:105745. doi:10.1016/j.neubiorev.2024.1057
2. Sipovac M, Petrovic B, Amzirkov M, Stefanovic S. Enamel incremental markings in the deciduous teeth of children from the Early Bronze and modern ages. Archives of Oral Biology. 2023;148:105635. doi:10.1016/j.archoralbio.2023.105635
3. Nava A, Bondioli L, Coppa A, Dreossi D, Fattore L, Mancini L, Zanolli C. Virtual histological reconstruction of prenatal dental enamel in human deciduous teeth. Proceedings of the International Conference on Tomography of Materials and Structures. 2017; Padova, Italy.
4. Humphrey LT, Dean MC, Jeffries TE, Penn M. Unlocking evidence of early diet from tooth enamel. Proceedings of the National Academy of Sciences of the USA. 2008;105:6834–6839. doi:10.1073/pnas.0711513105
5. Davis KA, Mountain RV, Pickett OR, Den Besten PK, Bidlack FB, Dunn EC. Teeth as potential new tools to measure early-life adversity and subsequent mental health risk: an interdisciplinary review and conceptual model. Biological Psychiatry. 2020;87:502–513.

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