Evidence of dental agenesis in late pleistocene Homo.

OBJECTIVE: Differential diagnosis and tabulation of cases of dental agenesis in Middle and Upper Paleolithic Western Eurasian humans to synthesize this data and to test previous hypotheses about when recent human patterns of third molar agenesis were established.

MATERIALS: 139 Late Pleistocene human remains and 149 individuals from three Epi-Paleolithic/ Holocene non-agricultural comparative collections.

METHODS: All remains were visually and radiographically recorded by the author.

RESULTS: In addition to establishing that third molar agenesis was common during the Late Upper Paleolithic (22,500-10,000 years BP), this study suggests a pattern of increasing prevalence through time.

CONCLUSIONS: An increase in the prevalence of third molar agenesis in the Late Upper Paleolithic could indicate selection for dental size reduction and orthognathy, but also bio-cultural changes from more intensive food preparation techniques.

SIGNIFICANCE: Third molar agenesis, a well-known developmental defect, is often reported for recent human skeletal collections, but the prevalence of the condition for Pleistocene hominins had not been previously quantified in order to consider patterns through time. Hypotheses posited for the high prevalence of third molar agenesis, or hypodontia in general, in some recent human groups require an understanding of the prevalence of these traits in the past.

LIMITATIONS: Paleolithic skeletal remains are incomplete, so these values are under-estimations. Individuals are also separated diachronically and geographically and should not be assumed to represent a single population sample.

SUGGESTIONS FOR FURTHER RESEARCH: Hypotheses on some of the potential selective forces acting on dental size reduction and subsequent agenesis could be tested in recent humans.