Dental developmental anomalies in primates and the evolution of human third molar agenesis

Third molar (M3) agenesis, the developmental absence of wisdom teeth, is observed in approximately 20% of present-day humans. Also, other third molar anomalies are observed at high frequencies in modern humans, including impacted and extremely reduced M3s. The extreme M3 reduction observed in present day humans is associated with an overall process of dental reduction initiated with the evolution of the genus Homo. Beyond humans, other primate species show dental developmental anomalies, for example a high incidence of supernumerary fourth molars in orangutan dentitions.

Through this project, we will find commonalities linking dental developmental anomalies in molar numbers across humans and other primates. Large skeletal collections of humans and nonhuman primates will be assessed to identify individuals with molar agenesis or with supernumerary molars. Using virtual anthropology techniques and geometric morphometric methods, the size and shape of molars and jaws will be measured and compared between individuals with and without dental anomalies for each species, accounting for differences in diet and rearing history. These comparisons will help us find regularities linking dental anomalies to the variation of teeth and jaws.  

Based on these primate-wide regularities and on the comparison between humans with and without M3 agenesis, we will be able to identify causal factors underlying M3 agenesis and to link them to evolutionary changes observed in the hominin fossil record. The results of the project will shed light on the mechanisms underlying dental developmental anomalies in humans and other primates, with implications for oral health in humans and beyond.