Scientific studies show that prehistoric humans generally exhibited lower rates of dental cavities compared with modern populations even without the use of toothbrush, floss and mouthwashes. Archaeological and genetic analyses suggest that changes in diet, oral microbiome, and food processing over thousands of years have strongly influenced dental health patterns.
Early human diets, particularly during Paleolithic (hunter-gatherer) periods were dominated by meat, vegetables, nuts, and fibrous foods, with very limited amounts of processed carbohydrates and refined sugars. These foods required extensive chewing and naturally reduced plaque buildup, limiting the fuel available for cavity-causing bacteria. 3
Acid-producing bacteria such as Streptococcus mutans, which are strongly associated with tooth decay, thrive on fermentable carbohydrates and sugars. Early humans lacked access to refined sugar and abundant starches, decreasing the habitat and energy source for these bacteria. Archaeological research indicates S. mutans was rare in most ancient oral microbiomes before widespread farming and sugar consumption.
A 4,000-year-old dental DNA study found that ancient mouths during bronze age harboured diverse oral microbiomes including Streptococcus mutans and Tannerella forsythia compared with modern humans. This higher microbial diversity in ancient oral environments may have helped maintain a balance that protected tooth enamel.
The Agricultural Revolution (~10,000 years ago) marked a significant shift in human diets toward grains and starchy foods. This dietary change provided more fermentable carbohydrates that S. mutans and similar bacteria could metabolize, producing acids that erode tooth enamel and initiate cavities. 1
Later, during the Industrial Revolution, refined sugar became widely available, further increasing the incidence of cavities. Refined sucrose allows bacteria to adhere more strongly to tooth surfaces and produce acids that demineralize enamel.
These dietary shifts are linked to the dramatic rise in dental caries in skeletal remains and modern populations, contrasting with lower cavity rates among hunter-gatherers and early agriculturalists.
Modern diets are characterised by large amounts of added sugars, refined carbohydrates, and processed foods, all of which provide abundant food sources for acid-producing oral bacteria. These bacteria metabolize sugars and produce acids that decalcify (weaken) tooth enamel, leading to cavities (dental caries).
Research using ancient and modern dental calculus suggests that modern oral microbiomes are less diverse than those of our ancestors. This reduction in beneficial bacterial diversity can make it easier for harmful bacteria like S. mutans to dominate, increasing susceptibility to cavities. 1
While modern dental hygiene products such as toothbrushes, mouthwash, and floss improve plaque control, they do not fully counteract the effects of frequent sugar intake and acidic foods. Additionally, dental erosion from acidic beverages and inadequate oral hygiene contributes to enamel breakdown, predisposing teeth to cavities and other dental diseases.
Dental caries develop when acid produced by bacterial metabolism of sugars and carbohydrates demineralizes tooth enamel over time, creating pits and holes (cavities). This process is influenced by diet, oral hygiene, bacteria composition, saliva pH, and enamel strength.
Modern preventive dentistry focuses on balancing oral bacteria, reducing sugar intake, and using fluoride to strengthen enamel and inhibit demineralization.
Scientific evidence strongly indicates that prehistoric humans generally experienced fewer cavities than modern humans, largely due to dietary patterns low in sugars and processed carbohydrates and differences in oral microbiome composition. In contrast, modern diets rich in refined sugars, soft foods, and processed carbohydrates contribute significantly to the higher prevalence of dental caries seen today, despite advances in oral hygiene practices.
Why did cavemen not get cavities?
Cavemen had fewer cavities because their diets were low in sugar and processed carbohydrates, which limited the growth of cavity-causing bacteria. They ate fibrous, unprocessed foods that helped naturally clean teeth and supported a healthier oral microbiome, reducing tooth decay.
References
Burke, Elizabeth, Ph.D. “Digging Into the Past to Uncover the Cause of Our Cavities.” Genome.gov, National Human Genome Research Institute, December 5, 2013. Accessed January 2026. https://www.genome.gov/digging-into-the-past-to-uncover-the-cause-of-our-cavities.
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, March 27, 2024. Accessed January 2026. https://www.sciencedaily.com/releases/2024/03/240327124735.htm. ScienceDaily
The Environmental Literacy Council. “Why Did Cavemen Have No Cavities? Unpacking the Dental Secrets of Our Ancestors.” Environmental Literacy Council, published 2025. Accessed January 2026. https://enviroliteracy.org/why-did-cavemen-have-no-cavities/.
