title: Possible Further Evidence of Low Genetic Diversity in the El Sidrón (Asturias, Spain) Neandertal Group: Congenital Clefts of the Atlas.
abstract: We present here the first cases in Neandertals of congenital clefts of the arch of the atlas. Two atlases from El Sidrón, northern Spain, present respectively a defect of the posterior (frequency in extant modern human populations ranging from 0.73% to 3.84%), and anterior (frequency in extant modern human populations ranging from 0.087% to 0.1%) arch, a condition in most cases not associated with any clinical manifestation. The fact that two out of three observable atlases present a low frequency congenital condition, together with previously reported evidence of retained deciduous mandibular canine in two out of ten dentitions from El Sidrón, supports the previous observation based on genetic evidence that these Neandertals constituted a group with close genetic relations. Some have proposed for humans and other species that the presence of skeletal congenital conditions, although without clinical significance, could be used as a signal of endogamy or inbreeding. In the present case this interpretation would fit the general scenario of high incidence of rare conditions among Pleistocene humans and the specific scenariothat emerges from Neandertal paleogenetics, which points to long-term small and decreasing population size with reduced and isolated groups. Adverse environmental factors affecting early pregnancies would constitute an alternative, non-exclusive, explanation for a high incidence of congenital conditions. Further support or rejection of these interpretations will come from new genetic and skeletal evidence from Neandertal remains.
authors.affiliation: Group of Paleoanthropology, Department of Paleobiology, Museo Nacional de Ciencias Naturales, Madrid, Spain; Department of Physical Anthropology, Aranzadi Society of Sciences, Donostia, Basque Country, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Ríos
authors.affiliation: Group of Paleoanthropology, Department of Paleobiology, Museo Nacional de Ciencias Naturales, Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Rosas
authors.affiliation: Group of Paleoanthropology, Department of Paleobiology, Museo Nacional de Ciencias Naturales, Madrid, Spain.
authors.forename: Almudena
authors.initials: A
authors.lastname: Estalrrich
authors.affiliation: Group of Paleoanthropology, Department of Paleobiology, Museo Nacional de Ciencias Naturales, Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: García-Tabernero
authors.affiliation: Group of Paleoanthropology, Department of Paleobiology, Museo Nacional de Ciencias Naturales, Madrid, Spain.
authors.forename: Markus
authors.initials: M
authors.lastname: Bastir
authors.affiliation: Institut Catalá de Palecologia Humana i Evolució Social IPHES, Area de Prehistoria, Universidad Rovira i Virgili, Unidad Asociada al CSIC, Tarragona, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Huguet
authors.affiliation: Museo Anatómico, Department of Anatomy and Radiology, Faculty of Medicine, Universidad de Valladolid, Valladolid, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Pastor
authors.affiliation: Department of Anatomy and Human Embriology, Faculty of Medicine, Universidad de Valencia, Valencia, Spain.
authors.forename: Juan Alberto
authors.initials: JA
authors.lastname: Sanchís-Gimeno
authors.affiliation: Área de Prehistoria, Department of History, Universidad de Oviedo, Oviedo, Spain.
authors.forename: Marco
authors.initials: M
authors.lastname: de la Rasilla
mesh_terms: D000818:Animals; D001270:Cervical Atlas / Q000002:abnormalities* / Q000473:pathology; D005580:Fossils; D014644:Genetic Variation; D005828:Genetics, Population; D059125:Neanderthals / Q000235:genetics*; D013030:Spain