Evidence for microevolution in enamel growth rates: preliminary results

Reconstructing the cell mechanisms that generate tooth morphology from histology has been an important approach for gaining insights into the evolution of permanent dentition when compared between hominoid species. However, the microevolution of modern human permanent tooth enamel has received limited research. This study uses dental histological thin sections to examine the daily rate that enamel forming cells deposit new matrix (DSR) in samples of permanent molar crowns from two British populations. One sample dates to the early Roman period in Britain (1-4AD)and is compared to a modern day clinical sample. Thirty-two first and second permanent molars were studied: Roman (n=11) and clinical (n=21). Results display a consistent and significant decrease in the lateral enamel DSRs between the two sample populations. Comparisons of mean inner, middle, and outer region DSRs were all significantly lower (p<0.000) in the clinical sample (inner=3.08µm/day; mid=3.37µm/day; outer=3.69µm/day) compared to the Roman sample (inner=3.67µm/day, mid=4.19µm/day; outer=4.57µm/day). These data provide the first evidence of a change in the daily rate of enamel growth in human permanent molars in ancient Britain, compared to the modern day. Ongoing PhD research will investigate more British populations that date to the 2000 year period seperating the Roman and Clinical samples.