1Anthropology, Texas A&M University, 2Hominid Paleoneurology, Centro Nacional de Investigación sobre la Evolución Humana
Friday All day, Park Concourse
Most studies of frontal bone morphology have focused on the browridge or have analyzed the entire bone, thus mixing information from the neurocranium and facial skeleton. Yet, the frontal squama is considered to be diagnostic for modern H. sapiens who are described as having vertical or bulging frontals. The morphology of the frontal squama is influenced by its position and orientation relative to other cranial components. Hence, in this study we analyzed the shape of the frontal squama alone, independent of its orientation relative to other cranial components, and quantified its variation in Pleistocene and recent humans. We examined 37 Middle and Late Pleistocene fossils from throughout Eurasia and Africa as well as 83 recent humans from 10 different populations. We analyzed frontal squama outlines taken from the supratoral sulcus to bregma using coordinates superimpositions and multivariate statistics. Our results demonstrate that modern and archaic humans are clearly separated on the basis of frontal curvature and bulging. However, there is some overlap among modern and non-modern groups, making it difficult to use this trait when diagnosing the taxonomic affinity of individual specimens. There is no separation of fossil and recent modern humans. Among modern humans, the majority of populations are distributed along a continuum characterized by frontal flattening at one end and frontal bulging at the other. However, according to this preliminary survey the Khoisan display a different morphology from the rest of the modern sample because of their marked frontal curvature.
The National Science Foundation (BCS 0004139) the Wenner-Gren Foundation, Washington University in St. Louis, and Texas A&M University provided funding for data collection to SA. EB and JMC are funded by the Ministerio de Ciencia e Innovación, Spain (CGL2009-12703-C03-01/02/03), and by the Junta de Castilla y León (Grupo de Excelencia GR-249).