A fresh perspective on tooth enamel could pave the way for researchers to gain a deeper insight into the health of various human populations, ranging from ancient civilizations to today’s society. This innovative method focuses on two immune proteins located in human tooth enamel: immunoglobulin G, an antibody that helps combat infections, and C-reactive protein, which is elevated during times of inflammation in the body.
A fresh perspective on tooth enamel could pave the way for researchers to gain a deeper insight into the health of various human populations, ranging from ancient civilizations to today’s society.
This approach, featured in this week’s Journal of Archaeological Science, investigates two immune proteins found within human tooth enamel: immunoglobulin G, known for fighting infections, and C-reactive protein, which indicates inflammation in the body.
“These proteins found in tooth enamel are instrumental in examining both the biological and potentially emotional health of historic human populations,” explained Tammy Buonasera, an assistant professor at the University of Alaska Fairbanks and lead author of the study. “Previous analyses of immune proteins in enamel have not occurred, and this opens new avenues for investigating health and disease in historical contexts more precisely than we currently can.”
The research commenced while Buonasera was a research associate at the University of California, Davis. Together with collaborators, including members from local Indigenous tribes, they examined the presence and concentration of these proteins in the tooth enamel of three different groups:
- Ancestral Ohlone individuals from a mission site dating back to the late 1700s and early 1800s in the San Francisco Bay Area. Their skeletal remains were unintentionally uncovered during a construction project in 2016. Tribal descendants granted permission for the use of their teeth in the research.
- European settlers from the late 1800s who were buried in a cemetery in San Francisco.
- Modern military cadets who contributed their wisdom teeth for the study.
The researchers then compared the levels of the two proteins with the known histories and experiences of each population. Native people in the California mission system faced high mortality rates, significant stress, and exposure to new infectious diseases. In contrast, European settlers from the 1800s had shorter lifespans compared to current populations but were generally believed to experience less stress and disease than the Ohlone group. It was presumed that the modern military cadets enjoyed better health and nutrition than both historical groups.
The findings revealed a strong correlation between indications of high stress and disease in Indigenous people and elevated levels of the two proteins in their tooth enamel. The protein levels in this group were significantly higher than those observed in the other two groups studied.
“We observed certain individuals, particularly children, exhibiting very elevated levels of immunoglobulins, which the body produces to fend off diseases, and C-reactive protein, which signifies stress,” stated Jelmer Eerkens, an anthropology professor at UC Davis and co-author of the study. “It’s truly heart-wrenching to consider the plight of children who may have lost their family members to illness, who were placed in an unfamiliar cultural setting, and the impact this had on their well-being.”
Buonasera mentioned that this novel perspective on teeth could enable researchers to conduct a more comprehensive examination of historical and prehistoric human experiences for several reasons.
Firstly, teeth develop during specific stages of a person’s growth, commencing in utero and continuing into late adolescence or early adulthood. The incremental growth over time in each tooth is comparable to the rings of a tree.
“Thus, it provides us with a potential record—from birth to early adulthood—of an individual’s health status,” Buonasera added.
Secondly, the immune proteins found within tooth enamel could yield more precise health-related information than what can be inferred from structural alterations in bones or teeth. Many health issues leave no visible evidence on bones, while the proteins in teeth may demonstrate responses to diseases or inflammation.
Finally, tooth enamel decomposes much more slowly than other body tissues. This durability presents an opportunity to learn from the proteins in ancient human teeth, establishing a timeline of human well-being that spans thousands of years.
Apart from enhancing our understanding of ancient human life, this method could also lead to valuable discoveries regarding the impacts of stress, illness, and lifestyle on contemporary humans.
“While I don’t want to exaggerate, studying the stresses and immune reactions of historical populations could draw comparisons with modern lifestyles that can be particularly insightful due to the extended timeframe we have,” Buonasera explained.
Not only is this study the first to investigate serum proteins trapped in enamel, but it also stands out for the accuracy this new method offers, according to Glendon Parker, an adjunct associate professor at UC Davis and co-author of the paper.
“We view the approach taken by Tammy and her team as applicable in numerous contexts, addressing various questions,” Parker said. “These new tools will deepen our understanding of past populations’ lives. It’s an exciting time for bio-anthropology as these methodologies become available.”
