1School of Humanities and Social Sciences, Nazarbayev University, 2Evolutionary Studies Institute and Centre of Excellence in PalaeoSciences, University of the Witwatersrand, 3School of Anthropology and Conservation, University of Kent, 4Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, 5College of Veterinary Medicine, North Carolina State University, College of Veterinary Medicine
April 16, 2016 4:45, A 706/707
Dental maturation, comprising tooth formation and emergence, is closely linked to life history and social behavior. To shed light on these ecological adaptations in Homo naledi, we analyze dental maturation in this extinct species, based on visual appraisal and CT scans of the well associated, largely in situ dentitions of both an infant and an adolescent mandible. In the infant, occlusal wear and root development of the deciduous teeth indicate a human-like eruption sequence, with dc preceding dm2 in contrast to the chimpanzee sequence. Both deciduous and permanent tooth formation of this infant cannot be distinguished from a human pattern. The adolescent shows delayed M2 eruption and formation relative to the premolars, but slightly delayed canine eruption and advanced M3 formation compared to most living humans. The overall picture of infant and adolescent dental development in H. naledi is derived compared to apes and australopiths, comparable to Early and Middle Pleistocene Homo. In the context of the hominin fossil record, the combination of largely derived dental development and primitive brain and body size in H. naledi conflicts with current theories linking dental development and life history. Primitive brain size and canine eruption imply a rapid life history on par with australopiths, whereas delayed M2 emergence is associated with a slowed life history according to “Schultz’s Rule.” H. naledi suggests that a derived pattern of dental development evolved early in the genus Homo before increased in brain size.
This work was funded by the National Geographic Society and the National Research Foundation of South Africa.