Abstract
Once considered rare in fossil hominins, caries has recently been reported in several hominin species, requiring a new assessment of this condition during human evolution. Caries prevalence and location on the teeth of South African fossil hominins were observed and compared with published data from other hominin samples. Teeth were viewed macroscopically, with lesion position and severity noted and described. For all South African fossil hominin specimens studied to date, a total of 10 carious teeth (14 lesions), including 4 described for the first time here, have been observed. These carious teeth were found in a minimum of seven individuals, including five Paranthropus robustus, one early Homo, and one Homo naledi. All 14 lesions affected posterior teeth. The results suggest cariogenic biofilms and foods may have been present in the oral environment of a wide variety of hominins. Caries prevalence in studied fossil hominins is similar to those in pre-agricultural human groups, in which 1–5% of teeth are typically affected.Significance:
 
 This study adds to the growing evidence that dental caries was present throughout the course of human evolution. Caries prevalence in the fossil species studied is similar to those in non-agricultural human groups, with 1–5% of teeth displaying cavities.
 Differences in prevalence and position of dental caries can provide insight into dietary aspects of past populations. South African fossil hominins display lesions on their posterior teeth, suggesting sugary foods were consumed.
Highlights
A range of different intraoral bacteria may have been involved in caries formation in the past, including one of the most common forms today, Streptococcus mutans
The South African material that was analysed included specimens assigned to early Homo, Homo naledi, Australopithecus sediba, Australopithecus africanus and Paranthropus robustus, all of which are curated at the University of the Witwatersrand and Ditsong National Museum of Natural History
We added four new cases to the six carious teeth already described in the literature for South African hominins (Table 1)
Summary
A range of different intraoral bacteria may have been involved in caries formation in the past, including one of the most common forms today, Streptococcus mutans. Postindustrial populations, in particular, evidence a marked increase in cariogenic bacteria, as well as less diverse microbiotic ecosystems.[1,2] Recent studies suggest the entire microbiota has to be considered in caries research, with a variety of species acting collectively in creating carious lesions.[3] Types and proportions of bacteria today differ substantially between active lesions in different locations (e.g. white spot enamel caries vs deep dentine lesions), as well as between individuals.[4] When acids from these bacterial consortiums cannot be neutralised by saliva, lesions form.[5] Some foods are especially cariogenic, such as those with high levels of refined carbohydrates and sugars[6,7,8], as well as fruits, honey, and some nuts and seeds.[9,10] Tough and fibrous foods are linked with low caries prevalence, as they create a more alkaline oral environment related to substantial saliva production.[7,8,11] Diets rich in meat and certain plants have been associated with low caries prevalence.[10,11]
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