Evolutionary significance of the mandibular foramen area in Neandertals.

An unusual morphology of the mandibular foramen area is described, and its incidence determined for several fossil and modern hominid skeletal samples. This morphology, designated the horizontal-oval type mandibular foramen, is found in 46.2% of the 26 Neandertal foramina examined and in 23.1% of a European Upper Paleolithic sample of 13 foramina. In a total of 747 foramina from five modern skeletal samples, the highest incidence is 3.72%. Possible explanations for the presence of the H-0 trait and its unusually high incidence in Neandertals are examined. It is concluded that this feature is probably a genetic trait which either (1) might be selected for in Neandertals as a part of a massive masticatory apparatus, or (2) represents a discrete cranial trait without functional significance that simply reflects the high incidence of certain genes in Neandertal gene pools.