Perikymata numbers and enamel lateral formation times in the incisors of three modern human populations from Maltravieso Cave (Cáceres) and Mirador Cave (Burgos)

Abstract

Crown formation times can be assessed by adding the imbricational and the appositional enamel formation times, so it can be estimated based entirely on the enamel. Previous research in the last decades have focused in the imbricational enamel because it is relatively easier to count long-period lines (perikymata) on its surface and establish formation times. Some authors have studied the variability of the total number of perikymata in different modern human populations, as well as the rate of enamel extension by dividing the crown height in ten deciles and counting the perikymata in each of the deciles. These authors have found that some modern human populations show a significantly lower number of perikymata, but little is known about the variability of these traits in modern humans. Our aim is to add new data on this topic and discuss imbricational enamel formation time variability in modern humans. The sample analysed consists in 23 incisors from three different populations: a Calcolithic and a Bronze Age populations from the Atapuerca-Mirador Cave, and a presumably Bronze Age population from Maltravieso Cave. Perikymata were count by obtaining several images using an environmental scanning electron microscope (ESEM). The perikymata number and imbricational enamel formation times of the incisors from these three archaeological populations are closer to the European and Inuit values rather than to South African values. The results obtained in our study support the intrapopulational homogeneity of the European and Inuit populations for the perikymata number. However, more information from other African samples is needed to test whether the low number of perikymata is exclusive to the South African group or can be generalized to the whole African continent.