Immune proteins in tooth enamel shed light on prehistoric humans

A new way of looking at tooth enamel could give scientists a way to a deeper understanding of human health, from ancient times to modern times.

The method, published this week in Journal of Archaeological Scienceexamines two immune proteins found in human tooth enamel: immunoglobulin G, an antibody that fights infection, and C-reactive protein, which is present during inflammation in the body.

These proteins are present in the enamel of the tooth, and it is something we can use to study the health of people’s lives and emotions in the past. Analysis of immune proteins in enamel has never been done before and this opens up the opportunity to study disease and health in the past in a more targeted way than we can today. “

Tammy Buonasera, assistant professor at the University of Alaska Fairbanks and lead author of the paper

The study began when Buonasera was a research fellow at the University of California, Davis. He and colleagues, including representatives of local indigenous tribes, tested the presence and quantity of proteins in tooth enamel from three groups of people:

• Ancestral Ohlone people from the mission center from the late 1700s and early 1800s in the San Francisco Bay Area. Their remains were accidentally discovered during a 2016 construction project at the site. The descendants of the tribe gave permission for their teeth to be used in education.
• European citizens from the late 1800s are buried in San Francisco’s city cemetery.
• Modern warriors who have provided wisdom teeth.

The research team cross-referenced the levels of the two proteins with the known history and experiences of each resident. The native people of the California mission system experienced high mortality rates, severe stress and developed infectious diseases. European immigrants from the 1800s had a shorter life expectancy than today’s population, but, as a group, were thought to have experienced less stress and disease pass the Ohlone group. Modern military cadets were thought to have had better health and nutrition than the two archeological groups.

The researchers found a close correspondence between evidence of high levels of stress and disease in the Indian population and high levels of two proteins in their teeth. The protein levels were significantly higher than those of the other two groups tested.

“We see certain people, especially children, who have very high levels of immunoglobulins, which the body uses to fight disease, and C-reactive protein, which people produce when they are under stress,” said Jelmer Eerkens, a professor of anthropology at the University of In California, Davis is one of the same authors on the paper. “It’s heartbreaking to think about the children who may have lost their parents and families to illness, thrown into a new culture they didn’t understand, and how it affected their well-being. see how.”

Buonasera says this new method of looking at teeth could allow scientists to look more closely at the experiences of historic and prehistoric people, for several reasons.

The first is that teeth appear during different windows in human development, starting in the womb and continuing through adolescence or adulthood. The growth over time in each tooth is like the rings of a tree.

“Therefore, it has the potential to give us a record -; from birth to adulthood -; of the state of human life,” said Buonasera.

Second, the immune proteins in tooth enamel can provide more specific information about health than scientists can get by looking at structural changes in tooth enamel. bones or teeth. Many diseases leave no visible trace on the skeleton, while toothed proteins may record responses to illness or inflammation.

Finally, tooth enamel tends to wear down much more slowly than other tissues in the body. That means there is an opportunity to learn from the proteins in the teeth of ancient people, providing a timeline of human health that begins thousands of years ago.

In addition to gaining new insight into the lives of ancient people, this approach has the potential to enhance discoveries about the effects of stress, disease and lifestyle on modern people.

“Without trying to go too far, looking at stress and immune responses in past populations can provide comparisons to modern lifestyles that can be very valuable. because you have serious time,” Buonasera said.

In addition to being the first to examine serum proteins trapped in enamel, the study also has new approaches because of the precision the new method provides, said Glendon Parker, associate professor of a UC Davis professor and one of the paper’s co-authors.

“We see the approach that Tammy and her team have taken as valuable on many levels, for this and other questions,” Parker said. “These new materials will give us a greater understanding of the lives of people in the past. It is an exciting time for bio-anthropology as these materials become available.”