scholarly journals The Role of Genetic Drift in Shaping Modern Human Cranial Evolution: A Test Using Microevolutionary Modeling

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Heather F. Smith
Keyword(s):  
Temporal Bone ◽  
Genetic Drift ◽  
Geographic Distance ◽  
Modern Human ◽  
Neutral Evolution ◽  
Modern Humans ◽  
Cranial Variation ◽  
History Of ◽  
Mandibular Morphology ◽  
And Migration

The means by which various microevolutionary processes have acted in the past to produce patterns of cranial variation that characterize modern humans is not thoroughly understood. Applying a microevolutionary framework, within- and among-population variance/covariance (V/CV) structure was compared for several functional and developmental modules of the skull across a worldwide sample of modern humans. V/CV patterns in the basicranium, temporal bone, and face are proportional within and among groups, which is consistent with a hypothesis of neutral evolution; however, mandibular morphology deviated from this pattern. Degree of intergroup similarity in facial, temporal bone, and mandibular morphology is significantly correlated with geographic distance; however, much of the variance remains unexplained. These findings provide insight into the evolutionary history of modern human cranial variation by identifying signatures of genetic drift, gene flow, and migration and set the stage for inferences regarding selective pressures that early humans encountered since their initial migrations around the world.

scholarly journals Model-based detection and analysis of introgressed Neanderthal ancestry in modern humans

2017 ◽  
Author(s):  
Matthias Steinrücken ◽  
Jeffrey P. Spence ◽  
John A. Kamm ◽  
Emilia Wieczorek ◽  
Yun S. Song
Keyword(s):  
Genetic Material ◽  
Genetic Load ◽  
Modern Human ◽  
Human Populations ◽  
Effective Population ◽  
Weak Selection ◽  
Modern Humans ◽  
High Coverage ◽  
Model Based ◽  
And Migration

AbstractGenetic evidence has revealed that the ancestors of modern human populations outside of Africa and their hominin sister groups, notably the Neanderthals, exchanged genetic material in the past. The distribution of these introgressed sequence-tracts along modern-day human genomes provides insight into the ancient structure and migration patterns of these archaic populations. Furthermore, it facilitates studying the selective processes that lead to the accumulation or depletion of introgressed genetic variation. Recent studies have developed methods to localize these introgressed regions, reporting long regions that are depleted of Neanderthal introgression and enriched in genes, suggesting negative selection against the Neanderthal variants. On the other hand, enriched Neanderthal ancestry in hair- and skin-related genes suggests that some introgressed variants facilitated adaptation to new environments. Here, we present a model-based method called diCal-admix and apply it to detect tracts of Neanderthal introgression in modern humans. We demonstrate its efficiency and accuracy through extensive simulations. We use our method to detect introgressed regions in modern human individuals from the 1000 Genomes Project, using a high coverage genome from a Neanderthal individual from the Altai mountains as reference. Our introgression detection results and findings concerning their functional implications are largely concordant with previous studies, and are consistent with weak selection against Neanderthal ancestry. We find some evidence that selection against Neanderthal ancestry was due to higher genetic load in Neanderthals, resulting from small effective population size, rather than Dobzhansky-Müller incompatibilities. Finally, we investigate the role of the X-chromosome in the divergence between Neanderthals and modern humans.

scholarly journals The evolutionary history of human spindle genes includes back-and-forth gene flow with Neandertals

2021 ◽  
Author(s):  
Stéphane Peyrégne ◽  
Janet Kelso ◽  
Benjamin Marco Peter ◽  
Svante Pääbo
Keyword(s):  
Gene Flow ◽  
Evolutionary History ◽  
Common Ancestor ◽  
Modern Human ◽  
Modern Humans ◽  
Ancestral Gene ◽  
Cytoskeletal Structure ◽  
Spindle Apparatus ◽  
History Of ◽  
Segregation Of Chromosomes

Proteins associated with the spindle apparatus, a cytoskeletal structure that ensures the proper segregation of chromosomes during cell division, experienced an unusual number of amino acid substitutions in modern humans after the split from the ancestors of Neandertals and Denisovans. Here, we analyze the history of these substitutions and show that some of the genes in which they occur may have been targets of positive selection. We also find that the two changes in the kinetochore scaffold 1 (KNL1) protein, previously believed to be specific to modern humans, were present in some Neandertals. We show that the KNL1 gene of these Neandertals shared a common ancestor with present-day Africans about 200,000 years ago due to gene flow from the ancestors (or relatives) of modern humans into Neandertals. Subsequently, some non-Africans inherited this modern human-like gene variant from Neandertals, but none inherited the ancestral gene variants. These results add to the growing evidence of early contacts between modern humans and archaic groups in Eurasia and illustrate the intricate relationships among these groups.

scholarly journals Unconstrained cranial evolution in Neandertals and modern humans compared to common chimpanzees

2015 ◽  
Vol 282 (1817) ◽  
pp. 20151519 ◽  
Author(s):  
Timothy D. Weaver ◽  
Chris B. Stringer
Keyword(s):  
Genetic Drift ◽  
Dna Sequences ◽  
Modern Human ◽  
Effective Population ◽  
Evolutionary Processes ◽  
Modern Humans ◽  
Developmental Constraints ◽  
Time Estimates ◽  
Cranial Measurements ◽  
Common Chimpanzee

A variety of lines of evidence support the idea that neutral evolutionary processes (genetic drift, mutation) have been important in generating cranial differences between Neandertals and modern humans. But how do Neandertals and modern humans compare with other species? And how do these comparisons illuminate the evolutionary processes underlying cranial diversification? To address these questions, we used 27 standard cranial measurements collected on 2524 recent modern humans, 20 Neandertals and 237 common chimpanzees to estimate split times between Neandertals and modern humans, and between Pan troglodytes verus and two other subspecies of common chimpanzee. Consistent with a neutral divergence, the Neandertal versus modern human split-time estimates based on cranial measurements are similar to those based on DNA sequences. By contrast, the common chimpanzee cranial estimates are much lower than DNA-sequence estimates. Apparently, cranial evolution has been unconstrained in Neandertals and modern humans compared with common chimpanzees. Based on these and additional analyses, it appears that cranial differentiation in common chimpanzees has been restricted by stabilizing natural selection. Alternatively, this restriction could be due to genetic and/or developmental constraints on the amount of within-group variance (relative to effective population size) available for genetic drift to act on.

scholarly journals The human genome reveals the evolution of Homo sapiens

2021 ◽  
Vol 134 (1) ◽  
pp. 38-45
Author(s):  
K. Schwartz ◽  
◽  
M. Sorokin ◽  
Keyword(s):  
Human Genome ◽  
Homo Sapiens ◽  
Genetic Research ◽  
Modern Human ◽  
Homo Erectus ◽  
Max Planck ◽  
Modern Humans ◽  
Language Communication ◽  
History Of ◽  
Development Of Language

The evolution of modern humans began two and a half million years ago as Homo erectus. Several hundred thousand years ago, Neanderthals, Denisovans, and modern men Homo sapiens have been separated from the Homo erectus branch. Nevertheless, Homo sapiens is the only one that has survived to our days. The complex history of Homo is revealed by genetic research and comparison of the modern human genome with genes of Neanderthals and Denisovans. Svante Pääbo, a professor at the Max Planck Institute for Evolutionary Anthropology, made a significant contribution to these studies and decoded the genome of Neanderthals and Denisovans. Comparison of the genome of modern humans with the genes of Neanderthals and Denisovans made it possible to reveal the size of the population, the paths and times of migrations, interactions of various groups of ancient humans and their biological crossing. It was found that in Eurasia, modern man carries traces of Neanderthal genes, whereas in Asia and Oceania – Denisovan genes. According to anthropological research, the survival of Homo sapiens was driven by the cognitive revolution, which took place about seventy thousand years ago and included the development of language, communication and association in large groups.

Ancient Genomics of Modern Humans: The First Decade

2018 ◽  
Vol 19 (1) ◽  
pp. 381-404 ◽  
Author(s):  
Pontus Skoglund ◽  
Iain Mathieson
Keyword(s):  
Genetic Diversity ◽  
Natural Selection ◽  
Phenotypic Diversity ◽  
Modern Human ◽  
Modern Humans ◽  
Human Genomes ◽  
African Populations ◽  
History Of ◽  
Out Of Africa ◽  
Genomic Basis

The first decade of ancient genomics has revolutionized the study of human prehistory and evolution. We review new insights based on prehistoric modern human genomes, including greatly increased resolution of the timing and structure of the out-of-Africa expansion, the diversification of present-day non-African populations, and the earliest expansions of those populations into Eurasia and America. Prehistoric genomes now document population transformations on every inhabited continent—in particular the effect of agricultural expansions in Africa, Europe, and Oceania—and record a history of natural selection that shapes present-day phenotypic diversity. Despite these advances, much remains unknown, in particular about the genomic histories of Asia (the most populous continent) and Africa (the continent that contains the most genetic diversity). Ancient genomes from these and other regions, integrated with a growing understanding of the genomic basis of human phenotypic diversity, will be in focus during the next decade of research in the field.

2. Finding our place

2019 ◽  
pp. 7-23
Author(s):  
Bernard Wood
Keyword(s):  
Molecular Biology ◽  
Human Evolution ◽  
Scientific Method ◽  
Common Ancestor ◽  
Natural World ◽  
Modern Human ◽  
Human Origins ◽  
Modern Humans ◽  
History Of ◽  
The Common

When did the process of using reason to try and understand human origins begin, and how did it develop? When was the scientific method first applied to the study of human evolution? ‘Finding our place’ begins by reviewing the history of how first philosophers and then scientists came to realize that modern humans are part of the natural world. It then explains why, using advances in molecular biology, scientists think chimpanzees and bonobos are more closely related to modern humans than they are to gorillas, and why they think the common ancestor of the chimpanzee/bonobo and modern human clades lived between six and eight million years ago.

scholarly journals The evolutionary history of Neandertal and Denisovan Y chromosomes

2020 ◽  
Author(s):  
Martin Petr ◽  
Mateja Hajdinjak ◽  
Qiaomei Fu ◽  
Elena Essel ◽  
Hélène Rougier ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Evolutionary History ◽  
Genetic Load ◽  
Modern Human ◽  
Gene Pools ◽  
Human History ◽  
Effective Population ◽  
Modern Humans ◽  
Y Chromosomes ◽  
History Of

AbstractAncient DNA has allowed the study of various aspects of human history in unprecedented detail. However, because the majority of archaic human specimens preserved well enough for genome sequencing have been female, comprehensive studies of Y chromosomes of Denisovans and Neandertals have not yet been possible. Here we present sequences of the first Denisovan Y chromosomes (Denisova 4 and Denisova 8), as well as the Y chromosomes of three late Neandertals (Spy 94a, Mezmaiskaya 2 and El Sidrón 1253). We find that the Denisovan Y chromosomes split around 700 thousand years ago (kya) from a lineage shared by Neandertal and modern human Y chromosomes, which diverged from each other around 370 kya. The phylogenetic relationships of archaic and modern human Y chromosomes therefore differ from population relationships inferred from their autosomal genomes, and mirror the relationships observed on the level of mitochondrial DNA. This provides strong evidence that gene flow from an early lineage related to modern humans resulted in the replacement of both the mitochondrial and Y chromosomal gene pools in late Neandertals. Although unlikely under neutrality, we show that this replacement is plausible if the low effective population size of Neandertals resulted in an increased genetic load in their Y chromosomes and mitochondrial DNA relative to modern humans.

scholarly journals Skeletal remains of a Pleistocene modern human (Homo sapiens) from Sulawesi

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257273
Author(s):  
Adam Brumm ◽  
David Bulbeck ◽  
Budianto Hakim ◽  
Basran Burhan ◽  
Adhi Agus Oktaviana ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Homo Sapiens ◽  
Modern Human ◽  
Skeletal Remains ◽  
Modern Humans ◽  
Human Right ◽  
Southeastern Part ◽  
Occlusal Wear ◽  
Frontal Process ◽  
History Of

Major gaps remain in our knowledge of the early history of Homo sapiens in Wallacea. By 70–60 thousand years ago (ka), modern humans appear to have entered this distinct biogeographical zone between continental Asia and Australia. Despite this, there are relatively few Late Pleistocene sites attributed to our species in Wallacea. H. sapiens fossil remains are also rare. Previously, only one island in Wallacea (Alor in the southeastern part of the archipelago) had yielded skeletal evidence for pre-Holocene modern humans. Here we report on the first Pleistocene human skeletal remains from the largest Wallacean island, Sulawesi. The recovered elements consist of a nearly complete palate and frontal process of a modern human right maxilla excavated from Leang Bulu Bettue in the southwestern peninsula of the island. Dated by several different methods to between 25 and 16 ka, the maxilla belongs to an elderly individual of unknown age and sex, with small teeth (only M1 to M3 are extant) that exhibit severe occlusal wear and related dental pathologies. The dental wear pattern is unusual. This fragmentary specimen, though largely undiagnostic with regards to morphological affinity, provides the only direct insight we currently have from the fossil record into the identity of the Late Pleistocene people of Sulawesi.

Intraocular tuberculosis, a challenge in diagnosis and treatment

2020 ◽  
Vol 3 ◽  
pp. 4
Author(s):  
Martina Larroude ◽  
Gustavo Ariel Budmann
Keyword(s):  
Developing Countries ◽  
Clinical Signs ◽  
Steady Increase ◽  
Ocular Tuberculosis ◽  
Industrial Countries ◽  
Choroidal Granuloma ◽  
History Of ◽  
And Migration ◽  
Ocular Tb

Ocular tuberculosis (TB) is an extrapulmonary tuberculous condition and has variable manifestations. The incidence of TB is still high in developing countries, and a steady increase in new cases has been observed in industrial countries as a result of the growing number of immunodeficient patients and migration from developing countries. Choroidal granuloma is a rare and atypical location of TB. We present a case of a presumptive choroidal granuloma. This case exposes that diagnosis can be remarkably challenging when there is no history of pulmonary TB. The recognition of clinical signs of ocular TB is extremely important since it provides a clinical pathway toward tailored investigations and decision making for initiating anti-TB therapy and to ensure a close follow-up to detect the development of any complication.

Magistri Legis. Eine Studie zur dogmatischen Funktion im industriellen System

2011 ◽  
Vol 2 (2) ◽  
pp. 69-112
Author(s):  
Pierre Legendre
Keyword(s):  
Social Function ◽  
Modern Human ◽  
Human Behaviour ◽  
Cultural Reproduction ◽  
Industrial System ◽  
The West ◽  
History Of ◽  
History Of Law ◽  
New Look

"Der Beitrag reevaluiert die «dogmatische Funktion», eine soziale Funktion, die mit biologischer und kultureller Reproduktion und folglich der Reproduktion des industriellen Systems zusammenhängt. Indem sie sich auf der Grenze zwischen Anthropologie und Rechtsgeschichte des Westens situiert, nimmt die Studie die psychoanalytische Frage nach der Rolle des Rechts im Verhalten des modernen Menschen erneut in den Blick. </br></br>This article reappraises the dogmatic function, a social function related to biological and cultural reproduction and consequently to the reproduction of the industrial system itself. On the borderline of anthropology and of the history of law – applied to the West – this study takes a new look at the question raised by psychoanalysis concerning the role of law in modern human behaviour. "

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