Quantitative and population genetic approaches for testing modern human out-of-Africa models

Molekulare und morphologische Daten sind wesentlich für die phylogenetische Rekonstruktion der Taxa und Populationsgeschichte innerhalb einer Spezies. Während beide Beweislinien parallel verwendet werden, um die menschliche Evolutionsgeschichte zu rekonstruieren, können sie manchmal zu widersprüchlichen Ergebnissen führen. Diese kumulative Dissertation zielt darauf hin, konkurrierende Hypothesen zur Verbreitung moderner Menschen aus Afrika zu testen. Hierzu werden parallel molekulare und morphologische Daten verwendet. Populations- und quantitativ-genetische Methoden werden mit genomischen und Schädelformdaten von Populationen aus Afrika, Asien und Australien verwendet. Die erste Studie untersucht den Zusammenhang von neutraler genomischer Variation und Schädelform. Hierzu werdenjeweils Einzel-Nukleotid-Polymorphismen (SNPs) und anatomische 3D Landmarks quantifiziert. Das Ergebnis dieser ersten Studie ist, dass insbesonders die Form des Schläfenbeins ein starkes Signal der Populationsgeschichte der neutralen Differenzierung des modernen Menschen wiederspiegelt. In der zweiten Studie, werden SNPs und Schläfenbeinform als unabhängige Beweislinien verwendet, um konkurrierende Out-of-Africa Hypothesen zu testen. Beide Datensätze bekräftigen die ‘multiple dispersal’ Hypothese, nach der anatomisch modernen Menschen sich während des Mittelpleistozäns entlang einer südlichen Route nach Asien ausbreiteten und erst im Spätpleistozän entlang einer nördlichen Route nach Eurasien auswanderten.In der dritten Studie werden Schädelformdaten von Fossilien aus dem Mittel- und Spätpleistozän Afrikas und der Levante genutzt, um die ‘multiple dispersal’ Hypothese zu bekräftigen. In der vierten Studie werden diese Ergebnisse in einer Rezension diskutiert. Um widersprüchliche Beweislinien und laufende Debatten in Einklang zu bringen, wird ein nuanciertes Out-of-Africa Szenario, das eine frühe Ausbreitung in Südwestasien und eine verzögerte Expansion in Eurasien vorsieht, vorgeschlagen. Schließlich wird in der fünften Studie der Zusammenhang zwischen Schädelformvariation und linguistischer Variation diskutiert, wobei das Potential linguistischer Daten zur Rekonstruktion der menschlichen Evolutionsgeschichte hervorgehoben wird. Die in dieser Dissertation erfolgte Synthese aus morphologischen, genotypischen, und linguistischen Daten vermag wichtige biologische und kulturelle Aspekte der menschlichen Evolutionsgeschichte zu beleuchten

Frontal bone virtual reconstruction and geometric morphometric analysis of the mid-Pleistocene hominin KNM-OG 45500 (Olorgesailie, Kenya)

KNM-OG 45500 is a hominin fossil composed of parts of a frontal bone, left temporal bone, and cranial vault pieces. Since its discovery along the Olorgesailie Formation (Kenya) in 2003, it has been associated with the Homo erectus hypodigm. The specimen, derived from a geological context dated to ca. 900 Ka BP, has been described as a very small individual of probable female sex. However, despite its status as an important hominin specimen, it has not been used in a quantitative comparative framework because of its fragmentary condition. Here, we undertake a virtual reconstruction of the better-preserved fragment, the frontal bone. We additionally apply geometric morphometric analyses, using a geographically diverse fossil and modern human sample, in order to investigate the morphological affinities of KNM-OG 45500. Our results show that the frontal shape of KNM-OG 45500 exhibits similarities with Early Pleistocene fossils from Eurasia and Africa that are assigned to H. erectus sensu lato (s.l.). Its size, on the other hand, is notably smaller than most other Homo erectus fossils and modern humans and similar to the specimens from Dmanisi (Georgia) and to Homo naledi. Taken together, our analyses of the frontal bone suggest a taxonomic attribution of KNM-OG 45500 to H. erectus s.l. and extend even further the range of size variability associated with this taxon around 900 Ka BP

Patterns of Recent Natural Selection on Genetic Loci Associated with Sexually Differentiated Human Body Size and Shape Phenotypes

Levels of sex differences for human body size and shape phenotypes are hypothesized to have adaptively reduced following the agricultural transition as part of an evolutionary response to relatively more equal divisions of labor and new technology adoption. In this study, we tested this hypothesis by studying genetic variants associated with five sexually differentiated human phenotypes: height, body mass, hip circumference, body fat percentage, and waist circumference. We first analyzed genome-wide association (GWAS) results for UK Biobank individuals (~194,000 females and ~167,000 males) to identify a total of 114,199 single nucleotide polymorphisms (SNPs) significantly associated with at least one of the studied phenotypes in females, males, or both sexes (P \u3c 5x10-8). From these loci we then identified 3,016 SNPs (2.6%) with significant differences in the strength of association between the female- and male-specific GWAS results at a low false-discovery rate (FDR \u3c 0.001). Genes with known roles in sexual differentiation are significantly enriched for co-localization with one or more of these SNPs versus SNPs associated with the phenotypes generally but not with sex differences (2.73-fold enrichment; permutation test; P = 0.0041). We also confirmed that the identified variants are disproportionately associated with greater phenotype effect sizes in the sex with the stronger association value. We then used the singleton density score statistic, which quantifies recent (within the last ~3,000 years; post-agriculture adoption in Britain) changes in the frequencies of alleles underlying polygenic traits, to identify a signature of recent positive selection on alleles associated with greater body fat percentage in females (permutation test; P = 0.0038; FDR = 0.0380), directionally opposite to that predicted by the sex differences reduction hypothesis. Otherwise, we found no evidence of positive selection for sex difference-associated alleles for any other trait. Overall, our results challenge the longstanding hypothesis that sex differences adaptively decreased following subsistence transitions from hunting and gathering to agriculture

Biocultural Evidence of Precise Manual Activities in an Early Holocene Individual of the High-Altitude Peruvian Andes

OBJECTIVES: Cuncaicha, a rockshelter site in the southern Peruvian Andes, has yielded archaeological evidence for human occupation at high elevation (4,480 masl) during the Terminal Pleistocene (12,500–11,200 cal BP), Early Holocene (9,500–9,000 cal BP), and later periods. One of the excavated human burials (Feature 15‐06), corresponding to a middle‐aged female dated to ~8,500 cal BP, exhibits skeletal osteoarthritic lesions previously proposed to reflect habitual loading and specialized crafting labor. Three small tools found in association with this burial are hypothesized to be associated with precise manual dexterity. MATERIALS AND METHODS: Here, we tested this functional hypothesis through the application of a novel multivariate methodology for the three‐dimensional analysis of muscle attachment surfaces (entheses). This original approach has been recently validated on both lifelong‐documented anthropological samples as well as experimental studies in nonhuman laboratory samples. Additionally, we analyzed the three‐dimensional entheseal shape and resulting moment arms for muscle opponens pollicis. RESULTS: Results show that Cuncaicha individual 15‐06 shows a distinctive entheseal pattern associated with habitual precision grasping via thumb‐index finger coordination, which is shared exclusively with documented long‐term precision workers from recent historical collections. The separate geometric morphometric analysis revealed that the individual\u27s opponens pollicis enthesis presents a highly projecting morphology, which was found to strongly correlate with long joint moment arms (a fundamental component of force‐producing capacity), closely resembling the form of Paleolithic hunter‐gatherers from diverse geo‐chronological contexts of Eurasia and North Africa. DISCUSSION: Overall, our findings provide the first biocultural evidence to confirm that the lifestyle of some of the earliest Andean inhabitants relied on habitual and forceful precision grasping tasks

Reconstructing the Deep Population History of Central and South America

We report genome-wide ancient DNA from 49 individuals forming four parallel time transects in Belize, Brazil, the Central Andes, and the Southern Cone, each dating to at least 9,000 years ago. The common ancestral population radiated rapidly from just one of the two early branches that contributed to Native Americans today. We document two previously unappreciated streams of gene flow between North and South America. One affected the Central Andes by 4,200 years ago, while the other explains an affinity between the oldest North American genome associated with the Clovis culture and the oldest Central and South Americans from Chile, Brazil, and Belize. However, this was not the primary source for later South Americans, as the other ancient individuals derive from lineages without specific affinity to the Clovis-associated genome, suggesting a population replacement that began at least 9,000 years ago and was followed by substantial population continuity in multiple regions

Mis casos clínicos de especialidades odontológicas

Libro que muestra la atención de casos clínicos particulares referente a las diferentes especialidades odontológicasLibro que muestra la atención de casos clínicos particulares referente a las diferentes especialidades odontológicasUniversidad Autónoma de Campeche Universidad Autónoma del Estado de Hidalgo Universidad Autónoma del Estado de Méxic