Generally, humanity’s oral health has solely improved. With increased access to their hygiene tools and doctors who specialize in their health and beauty, our teeth have altogether never looked better. We imagine the crooked or wooden teeth of the past, and tut, enjoying how far technology and science have come. But there are even more differences between ancient and modern teeth that remain unseen. Specifically, changes in the microenvironment of teeth which act as important markers of viral development.
Archaeologists from the University of Edinburgh and the Atlantic Technological University analyzed two 4000-year-old Bronze Age teeth for their remarkably well-preserved microbiomes. In this microbiome, scientists discovered an ancient genome for Streptococcus mutans, the leading cause of oral decay today. Their study focused on the actual tooth, differing from other ancient oral microbiome analyses, whose data was gathered from plaque. Though exceedingly common in modern mouths, there is little ancient record of S. mutans bacteria. Part of this absence stems from the bacteria form. S. mutans is an acid-producing bacteria, which causes the infamous tooth decay, while also destroying the bacteria’s own DNA and preventing fossilization. The other factor in their absence comes from S. mutans’ sweet appetite. Cavities in the archaeological record increased after grain agriculture was adopted but have risen exponentially in the last century with the rapid commercialization of food. In ancient times, the mouth was simply a less favorable habitat for the bacteria to thrive in and less sweet treats to enjoy.
The sampled teeth had no visible decay but produced an “unprecedented amount” of bacteria when tested. This suggests the tooth’s owner was at high risk of developing cavities before they died. Despite the high amounts of S. mutans, other streptococci species were missing, indicating that mutans had resolutely outcompeted them. The overwhelming power of S. mutans mirrors the modern bacterial record, as it has undergone significant development and evolution since the advent of humanity’s commercial sugar consumption. It has maintained a strong diversity, but this new data shines a light on how new human behaviors shift communal and personal health.
Alongside their insights into the ancient propensity for cavities and bacterial diversity, researchers also found further support for the disappearing microbiome hypothesis. This hypothesis posits that the modern human microbiome is less diverse than the ancient ones, sparking concerns over general human health, immunity and well-being. These ancient teeth held two widely variable strains of Tannerella forsythia, a gum disease-causing bacteria. These two strains from a singular skeleton are more varied than any two modern strains across the whole world. Not only does it tell of the general decrease in microbiome diversity, but it also speaks to the dominance of T. forsythia’s oral colonization. It again reveals the minute but notable biological differences that begin in human bodies as lifestyles change. Actions affect life, even in ways visible and invisible.
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Works Cited
Trinity College Dublin. “Scientists extract genetic secrets from 4,000-year-old teeth to illuminate the impact of changing human diets over the centuries.” ScienceDaily. ScienceDaily, 27 March 2024.
Trinity College Dublin.