2011 Dahlberg Award Winner Evaluation of the utility of deciduous molar morphological variation in great ape phylogenetic analysis

The teeth of the great apes bear an uncanny resemblance to those of humans in terms of their overall morphology. While the permanent teeth of humans and great apes have been studied in depth for several decades, deciduous teeth are often overlooked. Unlike permanent teeth, which are often used in both metric and non-metric studies to trace genetic drift and population variation, deciduous teeth are rarely studied in detail or in large numbers in either humans or primates. Since non-metric traits in adult primates have been used in many important studies they can serve as an example for work that can be done with deciduous primate teeth. Several studies offer trait frequency data for non-metric traits in great ape adult dentitions (e.g., Bailey 2008, Swindler 2005, Swarts 1988) and Swindler (2005) provides some description of the morphology of great ape deciduous teeth. Human deciduous dental morphology has been described by Jorgensen (1956) and Scott and Turner (1997). The present study addresses the dearth of information on great ape deciduous dentitions by looking at the variation in tooth crown morphology of subadult chimpanzees and gorillas. Previous research on non-metric traits among humans has revealed that they are useful in assessing population relatedness as well as population movements through time (e.g. Scott and Turner, 1997; Irish, 2006; Hanihara, 2008), and analysis of the deciduous dentition of the great apes may allow for similar assessments. In this study, variations in frequencies and patterns of occurrence for 28 dental traits are examined in five great ape subspecies. The utility of the deciduous dentition is assessed in addressing questions of population affinity and contributing to a set of standards and traits that can be used in further studies.