The Neandertal nature of the Atapuerca Sima de los Huesos mandibles

The recovery of additional mandibular fossils from the Atapuerca Sima de los Huesos (SH) site provides new insights into the evolutionary significance of this sample. In particular, morphological descriptions of the new adult specimens are provided, along with standardized metric data and phylogenetically relevant morphological features for the expanded adult sample. The new and more complete specimens extend the known range of variation in the Atapuerca (SH) mandibles in some metric and morphological details. In other aspects, the addition of new specimens has made it possible to confirm previous observations based on more limited evidence. Pairwise comparisons of individual metric variables revealed the only significant difference between the Atapuerca (SH) hominins and Neandertals was a more vertical symphysis in the latter. Similarly, principal components analysis of size-adjusted variables showed a strong similarity between the Atapuerca (SH) hominins and Neandertals. Morphologically, the Atapuerca (SH) mandibles show nearly the full complement of Neandertal-derived features. Nevertheless, the Neandertals differ from the Atapuerca (SH) mandibles in showing a high frequency of the H/O mandibular foramen, a truncated, thinned and inverted gonial margin, a high placement of the mylohyoid line at the level of the M3, a more vertical symphysis and somewhat more pronounced expression of the chin structures. Size-related morphological variation in the SH hominins includes larger retromolar spaces, more posterior placement of the lateral corpus structures, and stronger markings associated with the muscles of mastication in larger specimens. However, phylogenetically relevant features in the SH sample are fairly stable and do not vary with the overall size of the mandible. Direct comparison of the enlarged mandibular sample from Atapuerca (SH) with the Mauer mandible, the type specimen of H. heidelbergensis, reveals important differences from the SH hominins, and there is no morphological counterpart of Mauer within the SH sample, suggesting the SH fossils should not be assigned to this taxon. The Atapuerca (SH) mandibles show a greater number of derived Neandertal features, particularly those related to midfacial prognathism and in the configuration of the superior ramus, than other European middle Pleistocene specimens. This suggests that more than one evolutionary lineage co-existed in the middle Pleistocene, and, broadly speaking, it appears possible to separate the European middle Pleistocene mandibular remains into two distinct groupings. One group shows a suite of derived Neandertal features and includes specimens from the sites of Atapuerca (SH), Payre, l'Aubesier and Ehringsdorf. The other group includes specimens that generally lack derived Neandertal features and includes the mandibles from the sites of Mauer, Mala Balanica, Montmaurin and (probably) Visogliano. The two published Arago mandibles differ strongly from one another, with Arago 2 probably belonging to this former group, and Neandertal affinities being more difficult to identify in Arago 13. Outside of the SH sample, derived Neandertal features in the mandible only become more common during the second half of the middle Pleistocene. Acceptance of a cladogenetic pattern of evolution during the European middle Pleistocene has the potential to reconcile the predictions of the accretion model and the two phases model for the appearance of Neandertal morphology. The precise taxonomic classification of the SH hominins must contemplate features from the dentition, cranium, mandible and postcranial skeleton, all of which are preserved at the SH site. Nevertheless, the origin of the Neandertal clade may be tied to a speciation event reflected in the appearance of a suite of derived Neandertal features in the face, dentition and mandible, all of which are present in the Atapuerca (SH) hominins. This same suite of features also provides a useful anatomical basis to include other European middle Pleistocene mandibles and crania within the Neandertal clade.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEBinghamton UniversityMinisterio de Ciencia e Innovación y UniversidadesJunta de Castilla y Leónpu

Postcranial morphology of the middle Pleistocene humans from Sima de los Huesos, Spain

Current knowledge of the evolution of the postcranial skeleton in the genus Homo is hampered by a geographically and chronologically scattered fossil record. Here we present a complete characterization of the postcranium of the middle Pleistocene paleodeme from the Sima de los Huesos (SH) and its paleobiological implications. The SH hominins show the following: (i) wide bodies, a plesiomorphic char- acter in the genus Homo inherited from their early hominin ancestors; (ii) statures that can be found in modern human middle-latitude pop- ulations that first appeared 1.6–1.5 Mya; and (iii) large femoral heads in some individuals, a trait that first appeared during the middle Pleistocene in Africa and Europe. The intrapopulational size variation in SH shows that the level of dimorphism was similar to modern humans (MH), but the SH hominins were less encephalized than Ne- andertals. SH shares many postcranial anatomical features with Ne- andertals. Although most of these features appear to be either plesiomorphic retentions or are of uncertain phylogenetic polarity, a few represent Neandertal apomorphies. Nevertheless, the full suite of Neandertal-derived features is not yet present in the SH popula- tion. The postcranial evidence is consistent with the hypothesis based on the cranial morphology that the SH hominins are a sister group to the later Neandertals. Comparison of the SH postcranial skeleton to other hominins suggests that the evolution of the postcranium oc- curred in a mosaic mode, both at a general and at a detailed level

Zika virus pathogenesis in rhesus macaques is unaffected by pre-existing immunity to dengue virus

Zika virus (ZIKV) is a re-emerging virus that has recently spread into dengue virus (DENV) endemic regions and cross-reactive antibodies (Abs) could potentially affect ZIKV pathogenesis. Using DENV-immune serum, it has been shown in vitro that antibody-dependent enhancement (ADE) of ZIKV infection can occur. Here we study the effects of pre-existing DENV immunity on ZIKV infection in vivo. We infect two cohorts of rhesus macaques with ZIKV; one cohort has been exposed to DENV 2.8 years earlier and a second control cohort is naïve to flaviviral infection. Our results, while confirming ADE in vitro, suggest that pre-existing DENV immunity does not result in more severe ZIKV disease. Rather our results show a reduction in the number of days of ZIKV viremia compared to naïve macaques and that the previous exposure to DENV may result in modulation of the immune response without resulting in enhancement of ZIKV pathogenesis

Sources and distribution of organic matter in northern Patagonia fjords, Chile (~44–47° S) : a multi–tracer approach for carbon cycling assessment

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Continental Shelf Research 31 (2011): 315-329, doi:10.1016/j.csr.2010.05.013.We investigated the provenance of organic matter in the inner fjord area of northern Patagonia, Chile (~44–47° S), by studying the elemental (organic carbon, total nitrogen), isotopic (δ13C, δ15N), and biomarker (n–alkanoic acids from vascular plant waxes) composition of surface sediments as well as local marine and terrestrial organic matter. Average end–member values of N/C, δ13C, and δ15N from organic matter were 0.127 ± 0.010, –19.8 ± 0.3‰, and 9.9 ± 0.5‰ for autochthonous (marine) sources and 0.040 ± 0.018, –29.3 ± 2.1‰, 0.2 ± 3.0‰ for allochthonous (terrestrial) sources. Using a mixing equation based on these two end–members, we calculated the relative contribution of marine and terrestrial organic carbon from the open ocean to the heads of fjords close to river outlets. The input of marine–derived organic carbon varied widely and accounted for 13 to 96% (average 61%) of the organic carbon pool of surface sediments. Integrated regional calculations for the inner fjord system of northern Patagonia, which encompasses an area of ~ 4,280 km2, suggest that carbon accumulation may account for between 2.3 and 7.8 x 104 ton C yr–1. This represents a storage capacity of marine–derived carbon between 1.8 and 6.2 x 104 tons yr–1, which corresponds to an assimilation rate of CO2 by marine photosynthesis between 0.06 and 0.23 x 106 tons yr–1. This rate suggests that the entire fjord system of Patagonia, which covers an area of ~ 240,000 km2, may represent a potentially important region for the global burial of marine organic matter and the sequestration of atmospheric CO2.J. Sepúlveda was funded by a M.S. scholarship from the Graduate School at UDEC and by Fundación Andes through the Woods Hole Oceanographic Institution (WHOI)/UDEC agreement during a research visit at WHOI. This research was funded by the Ministerio de Hacienda de Chile and the Comité Oceanográfico Nacional (CONA) through the CIMAR–7 FIORDO Program (Grant C7F 01–10 to SP), CONICYT/NSF Grant 2001–120, Fundación Andes–Chile, and the Center for Oceanographic Research in the eastern South Pacific (COPAS) and COPAS Sur– Austral (PFB–31/2007)