A new way to look at tooth enamel could give scientists a path to better understand human health, from ancient to modern times.
The technique, published this week in the Journal of Archaeological Science, tests for two immune proteins embedded in human tooth enamel: immunoglobulin G, an infection-fighting antibody, and C-reactive protein, which appears when there is inflammation in the body.
“These proteins are present in tooth enamel and can be used to study the biological, and possibly emotional, health of past humans. Analysis of immune proteins in enamel has never been done before, which opens the door to studying disease and health in the past in a more targeted way than is currently possible.”
Tammy Buonasera, assistant professor at the University of Alaska Fairbanks and lead author of the paper
The study began when Buonasera was a research associate at the University of California, Davis, when she and her collaborators, including representatives of local indigenous groups, tested for the presence and amount of proteins in the tooth enamel of three groups of people.
The ancestral Ohloni people of missions built in the San Francisco Bay Area in the late 1700s and early 1800s. Their remains were discovered by chance during construction work in the area in 2016. Descendants of the tribe allowed their teeth to be used for research. A European settler from the late 1800s buried in a San Francisco city cemetery. A modern-day military cadet who donated his wisdom teeth.
The research team then cross-referenced the levels of the two proteins with the known history and experiences of each population. Native people in the California mission system experienced high mortality rates, extreme stress, and introduced infectious diseases. European settlers in the 1800s had shorter life spans than modern-day people, but as a group, they are estimated to have experienced lower levels of stress and disease than the Ohlone. Modern-day cadets are estimated to be healthier and better nourished than both archaeological groups.
The researchers found a close correlation between higher levels of stress and disease among Indigenous people and higher levels of two proteins in their teeth, the levels of which were much higher than in the other two groups tested.
“We know that certain individuals, particularly children, have very high levels of immunoglobulins, which the body uses to fight disease, and C-reactive protein, which is produced when people are stressed,” said Jelmar Arkens, a professor of anthropology at the University of California, Davis and one of the study’s corresponding authors. “It’s heartbreaking to think about these children who have lost parents and family members to illness and then been thrown into a new cultural environment that they don’t understand, and how that has affected their health.”
Buonasera said this new way of looking at teeth may allow scientists to get a closer look at historical and prehistoric human experiences for several reasons.
First, teeth form at different times during human development, starting in the womb and continuing through late adolescence or early adulthood. The way teeth grow over time is similar to the growth rings of a tree.
“Thus, this technology has the potential to provide a record of a person’s health from birth to early adulthood,” Buonasera said.
Second, immune proteins in tooth enamel could provide more specific information about health than scientists can get by observing structural changes in bones or teeth: Many diseases don’t leave visible traces in the skeleton, but dental proteins could record responses to disease and inflammation.
Finally, tooth enamel tends to deteriorate much slower than other tissues in the body, meaning we could potentially learn from ancient dental proteins and provide a timeline of human health going back thousands of years.
As well as providing new insights into ancient people’s lives, the method could also accelerate discoveries about how stress, disease and lifestyle influences modern people, she said.
“Without trying to go overboard, studying stress and immune responses in people from the past could provide comparisons with modern lifestyles, which is particularly valuable given the depth of time,” Buonasera said.
The study is revolutionary not only for the first time looking at serum proteins trapped in enamel, but also for the precision the new method offers, said Glendan Parker, an adjunct associate professor at UC Davis and one of the paper’s co-authors.
“We think the approach that Tammy and her team have taken will have implications for this and other questions in many contexts,” Parker said. “These new tools will give us even greater insight into the lives of people in the past. It’s an exciting time for biological anthropology, with these tools available.”
sauce:
University of Alaska Fairbanks
Journal References:
Buonasera, T., et al. (2024) Immune proteins recovered from tooth enamel are a biochemical record of past population health: A paleoproteomic analysis of Mission Period Native Californians. Journal of Archaeological Science. doi.org/10.1016/j.jas.2024.106069.
