The largest and earliest known sample of dental caries in an extinct mammal (Mammalia, Euarchonta, Microsyops latidens) and its ecological implications

Keegan R Selig,Mary T Silcox

doi:10.1038/s41598-021-95330-x

Keegan R Selig, Mary T Silcox

Open Access

https://doi.org/10.1038/s41598-021-95330-x

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Abstract

Dental cavities or caries is a common disease among modern humans, affecting almost every adult. Caries frequency has been used to study dietary change in humans over time, based on an inferred tie between the incidence of caries and a carbohydrate-rich diet. However, the disease is not unique to our species. Among non-human primates, there is also variation in caries frequency associated with diet, suggesting that this metric may provide a mechanism for studying diet in broader contexts, and across geological time. To date, very few studies have examined caries among fossil mammals, and none have done so among Eocene mammals. Here, we present our analysis of the largest sample to date of fossil caries in a single extinct mammal species, Microsyops latidens, a stem primate from the early Eocene, which is known from over a thousand specimens from the Southern Bighorn Basin of Wyoming (n = 1030). Our results show that Microsyops latidens is characterized by a high prevalence of dental caries (7.48% of individuals), with notable variation through time, reaching 17.24% of individuals from a particular interval. This interval is also associated with a change in overall dental form, as quantified by dental topographic analysis, which measures functional aspects of the chewing surface of teeth. These observations suggest that this species experienced a shift in their diet to include more fruit or other sugar rich-foods for a short period. Our analysis, therefore, suggests that the diet of M. latidens fluctuated over time, as well as providing a framework for assessing caries in other fossil taxa.

Highlights

Dental caries is a prevalent disease among humans, affecting nearly every adult during their lifetime[1]
When specimens are binned at 20-m intervals (Fig. 3), caries frequencies peak as high as 17.24% of the minimum number of individuals (MNI)
Our results are most consistent with the frequencies observed in wild tamarins (Saguinus sp.) (Table S1), which are known to consume high levels of sugar-rich foods like fruit and sap[65]

Summary

Introduction

Dental caries is a prevalent disease among humans, affecting nearly every adult during their lifetime[1]. Among the potential factors influencing caries occurrence are salivary and oral biochemistry, dietary abrasiveness, and fissure depth. Perhaps the most common cause of caries occurs when dental tissues are demineralized by oral bacteria releasing acids as they digest carbohydrates in the mouth. Provides insight into important facets of the life of an individual such as diet and health, so patterns of caries frequencies in the past have the potential to shed light on the ecology of extinct animals. Whereas dental caries can potentially provide useful information for reconstructing the diet of extinct animals e.g.,9,10, palaeontologists tend to study dental morphology and dental wear as proxies for diet e.g.,11–14. Very little is known about caries in older fossil mammals, or about how caries frequency may vary over time within a single species

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