Study of Dental Calculus Informs Historical Cause of Death, Examines Impact of Systemic Racism in Historically Marginalized Communities

A multi-institution interdisciplinary research team investigated the conditions surrounding the death of a 23-year-old Black male who died in the 1930s with the goal of better understanding the social systems that influenced his health and well-being during his life in early 20^th century St. Louis, Missouri. The researchers refer to him as St. Louis Individual, or St. LI, to protect his identity. Their study, “Remembering St. Louis Individual—structural violence and acute bacterial infections in a historical anatomical collection,” was recently published in Communications Biology.

“It’s extremely rare that researchers can identify exactly what killed people in the past, or their cause of death, but the bacterial DNA in St. LI’s calculus precisely matches their recorded cause of death of pneumonia,” said Molly Zuckerman, study coauthor and professor in the Department of Anthropology and Middle Eastern Cultures at Mississippi State University. “This means that dental calculus, or calcified human dental plaque, which dentists scrape off the teeth of the living, can give us an otherwise impossible window into what killed many people in the past and shed light into the end of their lives. This is especially true for many who were historically marginalized, such as those shuttered in institutions, like asylums and public hospitals, and whose end-of-life experiences have largely been lost to history.”

When examining his dental calculus, researchers found bacteria that commonly caused pneumonia and hospital infections before antibiotics became widespread in the 1940s. Pneumonia was one of the most common causes of death amongst humans in the past, especially for the poor, older adults and other marginalized communities living in crowded and cramped cities from the medieval period into the Industrial Revolution. However, pneumonia does not leave marks on the skeleton and was often not well diagnosed by doctors and other medical professionals into the early 1900s.

Rita Austin, the first author of the study and currently a postdoctoral researcher at the University of Oslo in Norway, said, “Combining information from DNA preserved within dental calculus on St. LI’s teeth with historical documents that contextualize their life, and information about their overall health and well-being gleaned from their skeleton, has given us an extraordinary look into how racism, poverty and violence in 1930s St. Louis shaped this person’s life.”

Even in the 1930s, pneumonia was not typically fatal for young adults. But St. LI’s skeleton shows that he was in extremely poor health, especially for his age, and may have been immunosuppressed, leaving him vulnerable to the infection. Specifically, his skeleton shows traces of having experienced trauma, including a poorly healed jaw fracture, which study author Geoff Ward says is “indicative of an exposure to violence and other harm, and inadequate health care, throughout his short lifetime,” noting the “widespread political violence, occupational hazards, and interpersonal conflicts in the period and places where his life unfolded.” 

The research team said that St. LI was also probably infected with tuberculosis. Study coauthor Hedwig Lee said TB “was common in the crowded, poor-quality housing Black and African Americans experienced in St. Louis and other cities in the late 19^th and early 20^th century, such as Philadelphia, as evidenced in research conducted by W.E.B. DuBois during this time period.”

St. LI also didn’t have access to life-saving antibiotics, which weren’t widely available until after WWII. However, DNA from the pneumonia-causing bacteria in his calculus has antibiotic resistance markers, meaning that the pneumonia may have resisted treatment even if antibiotics would have been available.

Courtney Hofman, President’s Associates Presidential Professor of Anthropology in the Dodge Family College of Arts and Sciences at the University of Oklahoma and the team lead for the study, said, “Finding these markers before widespread antibiotic use shows that antibiotic resistance, which is an urgent, rising public health problem in present-day populations, is a long-standing phenomenon.

“This research gives us insights into the otherwise invisible and forgotten experiences of St. LI, revealing how his life, death and final resting place within a historical documented collection were shaped by poverty and racism, and enables researchers to identify one of the most common killers of humans in the past, especially in marginalized communities,” Hofman added. 

St. LI's skeleton is held in the Robert J. Terry Anatomical Collection at the Smithsonian Institution’s National Museum of Natural History. The Terry Collection includes about 1,700 human skeletons, which represent individuals who lived and died around St. Louis between 1898 and 1967. Most of these individuals were poor and recent European immigrants and/or from communities of color who died in public institutions like prisons and mental asylums. Prior to “willed body programs” that ensured donor consent, these bodies were collected for medical training and included in the collection without their consent.

“These historical documented collections and the individuals within them have often been thought of as objects for scientific study, without consideration of their unique experiences, circumstances, and places within history or the violent processes which led to their collection,” Zuckerman said. “Many were dissected without their permission when family members could not claim their bodies for burial. St. LI’s death certificate shows he died from pneumonia in St. Louis Hospital Number 2, an infamously underfunded, segregated hospital, and was then dissected.”

The researchers say poor, marginalized communities and communities of color have persistently been harmed by scientific practices, including many genetic analyses. The researchers involved in this study are working with the Smithsonian Institution and researchers at other museums and universities to develop new guidelines for teaching, research and care of individuals in these collections. They hope this work will produce scholarship that pays attention to the origins of these individuals, the social and historical factors that led to their inclusion in collections, and recognizes and respects skeletal individuals and their living, descendant communities.

“This research represents a call to scientific communities to not only be more attentive to the historic and continuing harm research practices can have on present-day communities, such as destructive genetic testing without the permission of descendent communities or allowing public access to human genetic information in online databases,” said Austin. “The highly personalized narrative of St. LI’s life that researchers were able to reconstruct highlights that scientists working with historical documented collections, as well as skeletons in other similar collections around the world, have to be conscious of the potential harm caused by their research.”