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Sökning: WFRF:(Comas David)

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  • Lazaridis, Iosif, et al. (författare)
  • Ancient human genomes suggest three ancestral populations for present-day Europeans
  • 2014
  • Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 513:7518, s. 409-
  • Tidskriftsartikel (refereegranskat)abstract
    • We sequenced the genomes of a similar to 7,000-year-old farmer from Germany and eight similar to 8,000-year-old hunter-gatherers from Luxembourg and Sweden. We analysed these and other ancient genomes(1-4) with 2,345 contemporary humans to show that most present-day Europeans derive from at least three highly differentiated populations: west European hunter-gatherers, who contributed ancestry to all Europeans but not to Near Easterners; ancient north Eurasians related to Upper Palaeolithic Siberians(3), who contributed to both Europeans and Near Easterners; and early European farmers, who were mainly of Near Eastern origin but also harboured west European hunter-gatherer related ancestry. We model these populations' deep relationships and show that early European farmers had similar to 44% ancestry from a 'basal Eurasian' population that split before the diversification of other non-African lineages.
  • Atsawawaranunt, Kamolphat, et al. (författare)
  • The SISAL database : a global resource to document oxygen and carbon isotope records from speleothems
  • 2018
  • Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 10:3, s. 1687-1713
  • Tidskriftsartikel (refereegranskat)abstract
    • Stable isotope records from speleothems provide information on past climate changes, most particularly information that can be used to reconstruct past changes in precipitation and atmospheric circulation. These records are increasingly being used to provide "out-of-sample" evaluations of isotope-enabled climate models. SISAL (Speleothem Isotope Synthesis and Analysis) is an international working group of the Past Global Changes (PAGES) project. The working group aims to provide a comprehensive compilation of speleothem isotope records for climate reconstruction and model evaluation. The SISAL database contains data for individual speleothems, grouped by cave system. Stable isotopes of oxygen and carbon (delta O-18, delta C-13) measurements are referenced by distance from the top or bottom of the speleothem. Additional tables provide information on dating, including information on the dates used to construct the original age model and sufficient information to assess the quality of each data set and to erect a standardized chronology across different speleothems. The metadata table provides location information, information on the full range of measurements carried out on each speleothem and information on the cave system that is relevant to the interpretation of the records, as well as citations for both publications and archived data.
  • Ballantyne, Kaye N., et al. (författare)
  • Toward Male Individualization with Rapidly Mutating Y-Chromosomal Short Tandem Repeats
  • 2014
  • Ingår i: Human Mutation. - : John Wiley & Sons. - 1059-7794 .- 1098-1004. ; 35:8, s. 1021-1032
  • Tidskriftsartikel (refereegranskat)abstract
    • Relevant for various areas of human genetics, Y-chromosomal short tandem repeats (Y-STRs) are commonly used for testing close paternal relationships among individuals and populations, and for male lineage identification. However, even the widely used 17-loci Yfiler set cannot resolve individuals and populations completely. Here, 52 centers generated quality-controlled data of 13 rapidly mutating (RM) Y-STRs in 14,644 related and unrelated males from 111 worldwide populations. Strikingly, greater than99% of the 12,272 unrelated males were completely individualized. Haplotype diversity was extremely high (global: 0.9999985, regional: 0.99836-0.9999988). Haplotype sharing between populations was almost absent except for six (0.05%) of the 12,156 haplotypes. Haplotype sharing within populations was generally rare (0.8% nonunique haplotypes), significantly lower in urban (0.9%) than rural (2.1%) and highest in endogamous groups (14.3%). Analysis of molecular variance revealed 99.98% of variation within populations, 0.018% among populations within groups, and 0.002% among groups. Of the 2,372 newly and 156 previously typed male relative pairs, 29% were differentiated including 27% of the 2,378 father-son pairs. Relative to Yfiler, haplotype diversity was increased in 86% of the populations tested and overall male relative differentiation was raised by 23.5%. Our study demonstrates the value of RMY-STRs in identifying and separating unrelated and related males and provides a reference database.
  • Behar, Doron M., et al. (författare)
  • The genome-wide structure of the Jewish people
  • 2010
  • Ingår i: Nature. - : Macmilan. - 0028-0836 .- 1476-4687. ; 466:7303, s. 238-242
  • Tidskriftsartikel (refereegranskat)abstract
    • A comparison of genomic data from 14 Jewish communities across the world with data from 69 non-Jewish populations reveals a close relationship between most of today's Jews and non-Jewish populations from the Levant. This fits in with the idea that most contemporary Jews are descended from ancient Hebrew and Israelite residents of the Levant. By contrast, the Ethiopian and Indian Jewish communities cluster with neighbouring non-Jewish populations in Ethiopia and western India, respectively. This may be partly because a greater degree of genetic, religious and cultural crossover took place when the Jewish communities in these areas became established.
  • Schael, S, et al. (författare)
  • Precision electroweak measurements on the Z resonance
  • 2006
  • Ingår i: Physics Reports. - : Elsevier. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
  • Forskningsöversikt (refereegranskat)abstract
    • We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
  • Breton, Gwenna (författare)
  • Human demographic history : Insights on the human past based on genomes from Southern through Central Africa
  • 2020
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Evidence from paleontology, archaeology and population genetics support that modern humans originated in Africa. While the out-of-Africa event and subsequent colonization of all continents are well documented, human history in Africa at that time and before is less studied. Some current-day hunter-gatherer populations trace most of their genetic lineages to populations who inhabited Sub-Saharan Africa until the arrival of farming. They are informative about human history before and after the arrival of farming.I studied high-coverage genomes from two such groups, the Khoe-San from Southern Africa and the rainforest hunter-gatherers from Central Africa. I generated a total of 74 genomes, significantly increasing the number of genomes from Sub-Saharan African hunter-gatherers. I compared several versions of a commonly used pipeline for high-coverage genomes and showed that using standard ascertained reference datasets has no significant impact on variant calling in populations from Sub-Saharan Africa. Using the full genome information, I described the genetic diversity in the Khoe-San and in the rainforest hunter-gatherers and showed that gene flow from agropastoralist groups increased the Khoe-San genetic diversity. I also detected a signal of population size decline in the Khoe-San around the time of the out-of-Africa event, and I evaluated the power of the method to detect bottlenecks by applying it to simulated data. I investigated the history of modern humans in Africa by estimating divergence times between populations and applying an Approximate Bayesian Computation analysis. We confirmed that the earliest divergence event was between the Khoe-San ancestral lineage and the rest of modern humans, ~250-350 kya. I also showed that the possibility of high gene flow should be incorporated in models of human evolution.I furthermore examined SNP array data for two BaTwa populations from Zambia and showed that 20-30% of their autosomal diversity is hunter-gatherer-like. The estimated times for the admixture between a presumably local hunter-gatherer population and incoming agropastoralist groups are consistent with archaeological records.In this thesis, I investigated questions related to human history in Sub-Saharan Africa, from the emergence of modern humans ~300 kya to recent events related to the expansion of farming.
  • Comas-Bru, Laia, et al. (författare)
  • Evaluating model outputs using integrated global speleothem records of climate change since the last glacial
  • 2019
  • Ingår i: Climate of the Past. - : COPERNICUS GESELLSCHAFT MBH. - 1814-9324 .- 1814-9332. ; 15:4, s. 1557-1579
  • Tidskriftsartikel (refereegranskat)abstract
    • Although quantitative isotope data from speleothems has been used to evaluate isotope-enabled model simulations, currently no consensus exists regarding the most appropriate methodology through which to achieve this. A number of modelling groups will be running isotope-enabled palaeoclimate simulations in the framework of the Coupled Model Intercomparison Project Phase 6, so it is timely to evaluate different approaches to using the speleothem data for data-model comparisons. Here, we illustrate this using 456 globally distributed speleothem delta O-18 records from an updated version of the Speleothem Isotopes Synthesis and Analysis (SISAL) database and palaeoclimate simulations generated using the ECHAM5-wiso isotope-enabled atmospheric circulation model. We show that the SISAL records reproduce the first-order spatial patterns of isotopic variability in the modern day, strongly supporting the application of this dataset for evaluating model-derived isotope variability into the past. However, the discontinuous nature of many speleothem records complicates the process of procuring large numbers of records if data-model comparisons are made using the traditional approach of comparing anomalies between a control period and a given palaeoclimate experiment. To circumvent this issue, we illustrate techniques through which the absolute isotope values during any time period could be used for model evaluation. Specifically, we show that speleothem isotope records allow an assessment of a model's ability to simulate spatial isotopic trends. Our analyses provide a protocol for using speleothem isotope data for model evaluation, including screening the observations to take into account the impact of speleothem mineralogy on delta O-18 values, the optimum period for the modern observational baseline and the selection of an appropriate time window for creating means of the isotope data for palaeo-time-slices.
  • Enattah, Nabil Sabri, et al. (författare)
  • Evidence of still-ongoing convergence evolution of the lactase persistence T-13910 alleles in humans
  • 2007
  • Ingår i: American Journal of Human Genetics. - : Cell Press. - 0002-9297. ; 81:3, s. 615-625
  • Tidskriftsartikel (refereegranskat)abstract
    • A single-nucleotide variant, C/T-13910, located 14 kb upstream of the lactase gene (LCT), has been shown to be completely correlated with lactase persistence (LP) in northern Europeans. Here, we analyzed the background of the alleles carrying the critical variant in 1,611 DNA samples from 37 populations. Our data show that the T-13910 variant is found on two different, highly divergent haplotype backgrounds in the global populations. The first is the most common LP haplotype (LP H98) present in all populations analyzed, whereas the others (LP H8-H12), which originate from the same ancestral allelic haplotype, are found in geographically restricted populations living west of the Urals and north of the Caucasus. The global distribution pattern of LP T-13910 H98 supports the Caucasian origin of this allele. Age estimates based on different mathematical models show that the common LP T-13910 H98 allele (similar to 5,000-12,000 years old) is relatively older than the other geographically restricted LP alleles (similar to 1,400-3,000 years old). Our data about global allelic haplotypes of the lactose-tolerance variant imply that the T-13910 allele has been independently introduced more than once and that there is a still-ongoing process of convergent evolution of the LP alleles in humans.
  • Enattah, Nabil Sabri, et al. (författare)
  • Independent introduction of two lactase-persistence alleles into human populations reflects different history of adaptation to milk culture
  • 2008
  • Ingår i: American Journal of Human Genetics. - : Cell Press. - 0002-9297. ; 82:1, s. 57-72
  • Tidskriftsartikel (refereegranskat)abstract
    • The T-13910 variant located in the enhancer element of the lactase (LCT) gene correlates perfectly with lactase persistence (LP) in Eurasian populations whereas the variant is almost nonexistent among Sub-Saharan African populations, showing high prevalence of LP. Here, we report identification of two new mutations among Saudis, also known for the high prevalence of LP. We confirmed the absence of the European T-13910 and established two new mutations found as a compound allete: T/G(-13915) within the -13910 enhancer region and a synonymous SNP in the exon 17 of the MCM6 gene T/C-3712, -3712 bp from the LCT gene. The compound allele is driven to a high prevalence among Middle East population(s). Our functional analyses in vitro showed that both SNPs of the compound allele, located 10 kb apart, are required for the enhancer effect, most probably mediated through the binding of the hepatic nuclear factor 1 alpha (HNF1 alpha). High selection coefficient (s) similar to 0.04 for LP phenotype was found for both T-13910 and the compound allele. The European T-13910 and the earlier identified East African G(-13907) LP allele share the same ancestral background and most likely the same history, probably related to the same cattle domestication event. In contrast, the compound Arab allele shows a different, highly divergent ancestral haplotype, suggesting that these two major global LP alleles have arisen independently, the latter perhaps in response to camel milk consumption. These results support the convergent evolution of the LP in diverse populations, most probably reflecting different histories of adaptation to milk culture.
  • Schael, S., et al. (författare)
  • Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP
  • 2013
  • Ingår i: Physics Reports. - : Elsevier. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244
  • Forskningsöversikt (refereegranskat)abstract
    • Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma - 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019. (C) 2013 Elsevier B.V. All rights reserved.
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