Neural network analysis by using the Self-Organizing Maps (SOMs) applied to human fossil dental morphology: A new methodology
ABSTRACT Recent studies focusing on dental morphology of extinct and extant human populations have shown, on a global scale, the considerable
potential of dental traits as a tool to understand the phenetic relations existing between populations. The aim of this paper
is to analyze the dental morphologic relationships between archaic Homo and anatomically modern Homo sapiens by means of a new methodology derived from artificial neural networks called Self Organizing Maps (SOMs). The graph obtained
by SOMs to some extent recalls a classical Multidimensional Scaling (MDS) or a Principal Component Analysis (PCA) plot. The
most important advantages of SOMs is that they can handle vectors with missing components without interpolating missing data.
The analyzed database consisted of 1055 Lower-Middle and (Early) Late Pleistocene specimens, which were scored by using dental
morphological traits of the Arizona State University Dental Anthropology System (ASUDAS). The principal result indicates a
close relationship between the Homo erectus s.l. and Middle Pleistocene specimens and the later Neandertal groups. Furthermore, the dental models of anatomically modern
Homo sapiens are particularly different compared to the more archaic populations. Thus, SOMs can be considered a valuable tool in the
field of dental morphological studies since they enable the analysis of samples at an individual level without any need i) to interpolate missing data or ii) place individuals in predetermined groups.
Keywordsneural network analysis-Self-Organizing Maps (SOMs)-multidimensional scaling-dental morphology-Arizona State University Dental Anthropology System (ASUDAS)-Lower Pleistocene specimen-Middle Pleistocene specimen-Late Pleistocene specimen
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ABSTRACT: Fieldwork performed during the last 15 years in various Early Pleistocene East African sites has significantly enlarged the fossil record of Homo erectus sensu lato (s.l.). Additional evidence comes from the Danakil Depression of Eritrea, where over 200 late Early to early Middle Pleistocene sites have been identified within a ∼1000 m-thick sedimentary succession outcropping in the Dandiero Rift Basin, near Buia. Along with an adult cranium (UA 31), which displays a blend of H. erectus-like and derived morpho-architectural features and three pelvic remains, two isolated permanent incisors (UA 222 and UA 369) have also been recovered from the 1 Ma (millions of years ago) Homo-bearing outcrop of Uadi Aalad. Since 2010, our surveys have expanded to the nearby (4.7 km) site of Mulhuli-Amo (MA). This is a fossiliferous area that has been preliminarily surveyed because of its exceptional concentration of Acheulean stone tools. So far, the site has yielded 10 human remains, including the unworn crown of a lower permanent molar (MA 93). Using diverse analytical tools (including high resolution μCT and μMRI), we analysed the external and internal macromorphology and microstructure of the three specimens, and whenever possible compared the results with similar evidence from early Homo, H. erectus s.l., H. antecessor, H. heidelbergensis (from North Africa), Neanderthals and modern humans. We also assessed the UA 369 lower incisor from Uadi Aalad for root completion timing and showed that it compares well with data for root apex closure in modern human populations.Journal of Human Evolution 05/2014; 74. DOI:10.1016/j.jhevol.2014.04.005 · 3.87 Impact Factor