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Recent Humans (recent + human)

Distribution by Scientific Domains
Life Sciences71%

Terms modified by Recent Humans

  • recent human evolution
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    Selected Abstracts

    Phosphorus and phosphate metabolism in veterinary patients

    JOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 2 2007
    Diana M. Schropp DVM
    Abstract Objective: To review phosphorus and phosphate metabolism and the importance of phosphate abnormalities in veterinary patients. Data sources: A review of recent human and veterinary medical literature. Human data synthesis: There is a significant amount of original research on human patients with phosphate abnormalities. Hypophosphatemia has been studied in patients with diabetic ketoacidosis (DKA), head trauma, refeeding syndrome, hypothermia and in ventilator patients that fail to wean. Hyperphosphatemia has been studied in patients with renal failure and malignancy. Phosphate levels have also been evaluated for prognostic value in sepsis and acute liver failure. Veterinary data synthesis: Although animal models were used in early experimental research, fewer studies have been published on the effects of phosphate abnormalities in veterinary patients. Hypophosphatemia has been studied in animals with DKA, with refeeding syndrome and with hyperparathyroidism. Hyperphosphatemia has been studied in animals with renal failure and with secondary hypoparathyroidism. Conclusion: Phosphorus and phosphate are important in many biological functions. This paper is a review of their role in normal metabolism and the clinical importance of phosphate imbalances for our emergency and critical care patients. [source]

    Hybridization among cryptic species of the cellar fungus Coniophora puteana (Basidiomycota)

    MOLECULAR ECOLOGY, Issue 2 2007
    HĹVARD KAUSERUD
    Abstract In this study we have analysed the genetic variation and phylogeography in a global sample of the cellar fungus Coniophora puteana, which is an important destroyer of wooden materials indoor. Multilocus genealogies of three DNA regions (beta tubulin, nrDNA ITS and translation elongation factor 1,) revealed the occurrence of three cryptic species (PS1,3) in the morphotaxon C. puteana. One of the lineages (PS3) is apparently restricted to North America while the other two (PS1,2) have wider distributions on multiple continents. Interspecific hybridization has happened between two of the lineages (PS1 and PS3) in North America. In three dikaryotic isolates, two highly divergent beta tubulin alleles coexisted, one derived from PS1 and one from PS3. Furthermore, one isolate included a recombinant ITS sequence, where ITS1 resembled the ITS1 version of PS3 while ITS2 was identical to a frequent PS1 ITS2 version. This pattern must be due to hybridization succeeded by intralocus recombination in ITS. The results further indicated that introgression has happened between subgroups appearing in PS1. We hypothesize that the observed reticulate evolution is due to previous allopatric separation followed by more recent reoccurrence in sympatry, where barriers to gene flow have not yet evolved. A complex phylogeographical structure is observed in the morphotaxon C. puteana caused by (i) cryptic speciation; (ii) the interplay between natural migration and distribution patterns and probably more recent human mediated dispersal events; and (iii) hybridization and introgression. [source]

    Comparing methods for analysing mortality profiles in zooarchaeological and palaeontological samples

    INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 6 2005
    T. E. Steele
    Abstract In this study, I examine three methods that are currently used for comparing mortality profiles from zooarchaeological and palaeontological samples: (1) histograms with 10% of life-span age classes; (2) boxplots showing tooth crown height medians; and (3) triangular plots of the proportions of young, prime and old animals. I assess the advantages and disadvantages of each method using data collected on two samples of Northern Yellowstone elk (Cervus elaphus nelsoni) with known, or cementum annuli-determined, ages at death. One sample was hunted by wolves (n,=,96), and the other was hunted by recent humans using rifles (n,=,226). I tested each method with the known or cementum annuli age distributions and with age estimation techniques appropriate for archaeological assemblages. Histograms are best used when the relationship between dental eruption/attrition and age is well established so that individuals can be confidently assigned into 10% of life-span groups, and when more than 30 or 40 individuals are present in the assemblage. Boxplots employ raw crown heights, thus removing the error introduced by assigning specimens to age classes, and therefore they allow the analysis of species where the relationship between dental eruption/attrition and age is unknown. Confidence intervals around the medians allow samples to be statistically compared. Triangular plots are easy to use and allow multiple samples and species to be considered simultaneously, but samples cannot be statistically compared. Modified triangular plots bootstrap samples to provide 95% confidence ellipses, allowing for statistical comparisons between samples. When possible, samples should be examined using multiple methods to increase confidence in the results. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    The influence of masticatory loading on craniofacial morphology: A test case across technological transitions in the Ohio valley

    AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010
    Carolina Paschetta
    Abstract Masticatory loading is one of the main environmental stimuli that generate craniofacial variation among recent humans. Experimental studies on a wide variety of mammals, including those with retrognathic postcanine teeth, predict that responses to masticatory loading will be greater in the occlusal plane, the inferior rostrum, and regions associated with the attachments of the temporalis and masseter muscles. Here we test these experimentally-derived predictions on an extinct human population from the middle and upper Ohio valley that underwent a marked shift from hunting-gathering to extensive farming during the last 3,000 years and for which we have good archaeological evidence about diet and food processing technology. Geometric morphometric methods were used to detect and measure the putative effect of diet changes on cranial shape independent of size. Our results partially confirm only some of the experimental predictions. The effect of softer and/or less tough diets on craniofacial shape seem to be concentrated in the relative reduction of the temporal fossa and in a displacement of the attachment of the temporal muscle. However, there were few differences in craniofacial shape in regions closer to the occlusal plane. These results highlight the utility of exploring specific localized morphological shifts using a hierarchical model of craniofacial integration. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source]

    Size variation in early human mandibles and molars from Klasies River, South Africa: Comparison with other middle and late Pleistocene assemblages and with modern humans,

    AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009
    Danielle F. Royer
    Abstract Previous studies of the Middle Stone Age human remains from Klasies River have concluded that they exhibited more sexual dimorphism than extant populations, but these claims have not been assessed statistically. We evaluate these claims by comparing size variation in the best-represented elements at the site, namely the mandibular corpora and M2s, to that in samples from three recent human populations using resampling methods. We also examine size variation in these same elements from seven additional middle and late Pleistocene sites: Skh,l, Dolní V,stonice, Sima de los Huesos, Arago, Krapina, Shanidar, and Vindija. Our results demonstrate that size variation in the Klasies assemblage was greater than in recent humans, consistent with arguments that the Klasies people were more dimorphic than living humans. Variation in the Skh,l, Dolní V,stonice, and Sima de los Huesos mandibular samples is also higher than in the recent human samples, indicating that the Klasies sample was not unusual among middle and late Pleistocene hominins. In contrast, the Neandertal samples (Krapina, Shanidar, and Vindija) do not evince relatively high mandibular and molar variation, which may indicate that the level of dimorphism in Neandertals was similar to that observed in extant humans. These results suggest that the reduced levels of dimorphism in Neandertals and living humans may have developed independently, though larger fossil samples are needed to test this hypothesis. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source]

    Modern human cranial diversity in the Late Pleistocene of Africa and Eurasia: Evidence from Nazlet Khater, Pe,tera cu Oase, and Hofmeyr

    AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009
    Isabelle Crevecoeur
    Abstract The origin and evolutionary history of modern humans is of considerable interest to paleoanthropologists and geneticists alike. Paleontological evidence suggests that recent humans originated and expanded from an African lineage that may have undergone demographic crises in the Late Pleistocene according to archaeological and genetic data. This would suggest that extant human populations derive from, and perhaps sample a restricted part of the genetic and morphological variation that was present in the Late Pleistocene. Crania that date to Marine Isotope Stage 3 should yield information pertaining to the level of Late Pleistocene human phenotypic diversity and its evolution in modern humans. The Nazlet Khater (NK) and Hofmeyr (HOF) crania from Egypt and South Africa, together with penecontemporaneous specimens from the Pe,tera cu Oase in Romania, permit preliminary assessment of variation among modern humans from geographically disparate regions at this time. Morphometric and morphological comparisons with other Late Pleistocene modern human specimens, and with 23 recent human population samples, reveal that elevated levels of variation are present throughout the Late Pleistocene. Comparison of Holocene and Late Pleistocene craniometric variation through resampling analyses supports hypotheses derived from genetic data suggesting that present phenotypic variation may represent only a restricted part of Late Pleistocene human diversity. The Nazlet Khater, Hofmeyr, and Oase specimens provide a unique glimpse of that diversity. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source]

    The shape of the early hominin proximal femur

    AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009
    Elizabeth H. Harmon
    Abstract Postcranial skeletal variation among Plio-Pleistocene hominins has implications for taxonomy and locomotor adaptation. Although sample size constraints make interspecific comparisons difficult, postcranial differences between Australopithecus afarensis and Australopithecus africanus have been reported (McHenry and Berger: J Hum Evol 35 1998 1,22; Richmond et al.: J Hum Evol 43 [2002] 529,548; Green et al.: J Hum Evol 52 2007 187,200). Additional evidence indicates that the early members of the genus Homo show morphology like recent humans (e.g., Walker and Leakey: The Nariokotome Homo erectus skeleton. Cambridge: Harvard, 1993). Using a larger fossil sample than previous studies and novel methods, the early hominin proximal femur is newly examined to determine whether new data alter the current view of femoral evolution and inform the issue of interspecific morphological variation among australopiths. Two- and three-dimensional data are collected from large samples of recent humans, Pan, Gorilla, and Pongo and original fossil femora of Australopithecus, Paranthropus, and femora of African fossil Homo. The size-adjusted shape data are analyzed using principal components, thin plate spline analysis, and canonical variate analysis to assess shape variation. The results indicate that femora of fossil Homo are most similar to modern humans but share a low neck-shaft angle (NSA) with australopiths. Australopiths as a group have ape-like greater trochanter morphology. A. afarensis differs from P. robustus and A. africanus in attributes of the neck and NSA. However, interspecific femoral variation is low and australopiths are generally morphologically similar. Although the differences are not dramatic, when considered in combination with other postcranial evidence, the adaptive differences among australopiths in craniodental morphology may have parallels in the postcranium. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source]