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Unformatted text preview: New immature hominin fossil from European Lower Pleistocene shows the earliest evidence of a modern human dental development pattern Jos Mara Bermdez de Castro a,1 , Mara Martinn-Torres a , Leyre Prado a , Aida Gmez-Robles a , Jordi Rosell b , Luca Lpez-Poln b , Juan Lus Arsuaga c , and Eudald Carbonell b a Centro Nacional de Investigacin sobre Evolucin Humana, 09002 Burgos, Spain; b Institut Catal de Paleoecologia Humana i Evoluci Social, 43005 Tarragona, Spain; and c Universidad Complutense de Madrid-Instituto de Salud Carlos III (UCM-ISCIII), Centro de Investigacin de Evolucin y Comportamiento Humanos, 28029 Madrid, Spain Contributed by Juan Lus Arsuaga, May 17, 2010 (sent for review December 15, 2009) Here we present data concerning the pattern of dental develop- ment derived from the microcomputed tomography (microCT) study of a recently discovered immature hominin mandible with a mixed dentition recovered from the TD6 level of the Gran Dolina Lower Pleistocene cave site in Sierra de Atapuerca, northern Spain. These data con fi rm our previous results that nearly 1 million years ago at least one European hominin species had a fully modern pattern of dental development with a clear slowdown in the de- velopment of the molar fi eld regarding the anterior dental fi eld. Furthermore, using available information about enamel formation times and root extension rates in chimpanzees, early hominins, and modern humans, we have estimated that the formation time of the upper and lower fi rst molars of individual 5 (H5) from TD6, which had just erupted at the time of the death of this individual, ranges between 5.3 and 6.6 y. Therefore, the eruption time of the fi rst permanent molars (M1) in the TD6 hominins was within the range of variation of modern human populations. Because the time of M1 eruption in primates is a robust marker of life history, we sug- gest, as a working hypothesis, that these hominins had a prolonged childhood in the range of the variation of modern humans. If this hypothesis is true, it implies that the appearance in Homo of this important developmental biological feature and an associated in- crease in brain size preceded the development of the neocortical areas leading to the cognitive capabilities that are thought to be exclusive to Homo sapiens . Atapuerca | childhood | human evolution | life-history pattern F ossils of infant and juvenile hominins are extremely rare, and most hominin fossil assemblages are dominated by adult spec- imens. Nonetheless, only subadult individuals, in whom teeth were still developing and erupting, provide the opportunity to study precisely the evolution of growth and development in the human lineage, and subadults are therefore important for recon- structing the life history of fossil species. Modern humans are characterized by a unique developmental trajectory, in which a prolonged childhood is associated with the growth of our rela- tively large brains (1 3). Although brain size has been estimated3)....
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This note was uploaded on 07/08/2010 for the course ANTH 3 taught by Professor Apple during the Spring '10 term at Acadia.
- Spring '10