Artist impression of Eosimias primate. It lived between 45-40 million years ago. CLAUS LUNAU/SCIENCEPHOTO LIBRARY
Sugars in our carbohydrate-rich diet are known to encourage oral bacteria that releases demineralising acid. This makes it more likely we will develop dental cavities. Evidence suggests that this problem dates back to the early days primate evolution. Microsyops, a prehistoric primate, lived in the Early Eocene 54 million years ago and had to deal with cavities.
Keegan Selig, a Canadian University of Toronto Scarborough student, said that while going through the fossil sample, I noticed these holes in the teeth of the animals and wondered what they were. It was quite surprising to find cavities in these animals, and even more surprising to discover how common they were. They were not expected to be as common as living primates.
Mary Silcox, a colleague at the University of Toronto Scarborough also examined fossilized teeth from 1030 individuals taken from the southern Bighorn Basin in Wyoming. They discovered that 7.48 percent of individuals had cavities. This is a much higher rate than in any living primate, with the exception of some capuchins or tamarins.
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According to Selig and Silcox, the M. latidens teeth represent the oldest evidence of dental cavities in any mammal.
M. latidens likely had a preference for high-sugar foods like fruit. This could have contributed to cavities.
The critters didn't have toothbrushes or dental floss, so you would expect cavities to form all over the tooth. However, the cavities formed only on the main chewing surface, which is quite surprising. Selig says that we don't know why.
These fossils are evidence that M. latidens was a large population for a long period of time, possibly over thousands of years. They come from different levels of the ancient rock sequence. Cavities were more common at certain levels of the sequence. At one level, 17% of people were affected. Researchers believe that diet changes could explain this fluctuation.
The results are fascinating, but Ian Towle from London South Bank University in UK suggests that the damage to teeth could be due to a diet high in acidic foods and not sugary. He says that the methodology used can't distinguish between these types tissue losses, as both are caused by acids desineralising dental tissue.
Journal reference: Scientific Reports, DOI: 10.1038/s41598-021-95330-x
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