부산대학교 도서관

An important amount of data about "chimpanzees" (Pan troglodytes) have improved the earlier scheme of ape dental development. These data include age estimates at which calcification of tooth crowns and roots may be observed. However, P. paniscus is always absent from "chimpanzees" cross-sectional samples. This situation possibly biases the interpretation of early hominid dental maturation when one aims to see whether patterns documented for fossil hominids demonstrate features in common with humans, with apes, or are unique using possible discriminating criteria. Indeed, Kinzey, in his study on dental eruption in P. paniscus, noticed its tendency for the eruption of lateral permanent incisors to be delayed, compared to the common chimpanzee. Importantly, this distinction within chimpanzees does not exist between extant humans and P. troglodytes. Using computed tomography, we undertook the first study on permanent tooth crows and roots calcification in the numerous P. paniscus specimens housed at the "Music Royal de l'Afrique Centrale." We found that some currently-used discriminating criteria between P. troglodytes (supposed to represent "chimpanzees") and extant humans may not be useful at all as long as P. paniscus dental maturation is not documented. For example, we found that overlapping crown formation between permanent molars (M1/M2 for example) is not demonstrated by all pygmy chimpanzees, as it frequently occurs in extant humans (individuals or populations). This is an important point to emphasize because molars delay has often been cited to mark the prolonged developmental period of extant humans. These results mean that further investigations are needed before interpreting early hominid developmental patterns and putative differential life histories (i.e., "more human" or "more chimpanzee").