Dental caries in human evolution: frequency of carious lesions in South African fossil hominins

Abstract

AbstractCaries frequencies in South African fossil hominins were observed and compared with other hominin samples. Species studied includeParanthropus robustus,Homo naledi,Australopithecus africanus,early HomoandA. sediba. Teeth were viewed macroscopically with Micro-CT scans used to confirm lesions. Position and severity of each lesion were also noted and described. For all South African fossil hominin specimens studied, 16 have carious lesions, six of which are described for the first time in this study. These are from a minimum of six individuals, and include fourP. robustus,oneH. naledi,and oneearly Homoindividual. No carious lesions were found on deciduous teeth, or any teeth assigned toA. africanus. Most are located interproximal, and only posterior teeth are affected. Caries frequency typically ranges between 1-5% of teeth in non-agricultural human samples, and this pattern seemingly holds true for at least the past two million years in the hominin lineage. Non-agricultural populations significantly above or below this threshold generally have a specialized diet, supporting other dietary evidence thatA. africanuslikely consumed large amounts of tough, non-cariogenic vegetation. Given the common occurrence of caries in the other hominin species, cariogenic bacteria and foods were evidently common in their collective oral environment. Along with recent research highlighting additional examples of caries inH. neanderthalensis, earlyHomoand PleistoceneH. sapiens, caries is clearly an ancient disease that was much more common than once maintained throughout the course of human evolution.