The oldest dental cavities on a mammal date back 54 million years. As a matter of fact, experts have stated that cavities were actually quite common in early primates, specifically Microsyops latidens which were alive during the Early Eocene Period. Dental cavities have been found in more than 7% of the fossils belonging to that species.
While there isn’t much information regarding the Microsyops latidens species since they have no living descendants, experts believe that they lived in trees and ate fruits as well as insects.
There were a total of 1,030 dental fossils (jaws and teeth) that were found in Wyoming’s Southern Bighorn Basin that span a time frame of approximately 544,000 years during the Early Eocene Period. Of those samples, 77 of them (or 7.48%) contained cavities. The researchers stated that this is the “largest sample to date of fossil caries in a single extinct mammal species,” and the “earliest known sample of dental caries in an extinct mammal.” Another extinct primate that lived about 12.5 million years ago previously held the record for the oldest dental cavity until now.
As for what caused the cavities, scientists think that they were probably due to the consumption of sweet fruits and other sugary foods. Cavities form when mouth bacteria eats away sugar that is on the teeth and delivers a very acidic by-product that then eats the dental tissue; therefore creating a hole (cavity).
Additionally, the changes in the cavities throughout that time period suggested that the primates varied their food habits with some containing more sugar than others (the oldest and youngest fossils had the fewest number of cavities). This may have been caused by the climate fluctuating during the Early Eocene Period that could have affected vegetation and food.
Keegan Selig from the University of Toronto Scarborough explained this further, “We cannot be 100% certain that it was fruit that caused these cavities in M. Latidens. Other factors such as the pH and biochemistry of the mouth might also produce cavities,” adding, “But fruit, and specifically sugar, are major culprits in producing cavities, just like in our own mouths today.”
Some of the cavities found in the Microsyops latidens teeth were quite minor while others were severe. Experts are unsure whether or not the cavities had an effect on the primates’ health, but as Selig explained, “...having cavities, especially large ones, can lead to many health problems” like having an infection, soreness while chewing, and even losing the tooth. (A picture of an upper jaw with two cavities can be seen here.)
The study was published in Scientific Reports where it can be read in full.