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Gopalan S, Atkinson EG, Buck LT, Weaver TD, Henn BM. Inferring archaic introgression from hominin genetic data. Evol Anthropol 2021; 30:199-220. [PMID: 33951239 PMCID: PMC8360192 DOI: 10.1002/evan.21895] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 08/03/2020] [Accepted: 03/29/2021] [Indexed: 01/05/2023]
Abstract
Questions surrounding the timing, extent, and evolutionary consequences of archaic admixture into human populations have a long history in evolutionary anthropology. More recently, advances in human genetics, particularly in the field of ancient DNA, have shed new light on the question of whether or not Homo sapiens interbred with other hominin groups. By the late 1990s, published genetic work had largely concluded that archaic groups made no lasting genetic contribution to modern humans; less than a decade later, this conclusion was reversed following the successful DNA sequencing of an ancient Neanderthal. This reversal of consensus is noteworthy, but the reasoning behind it is not widely understood across all academic communities. There remains a communication gap between population geneticists and paleoanthropologists. In this review, we endeavor to bridge this gap by outlining how technological advancements, new statistical methods, and notable controversies ultimately led to the current consensus.
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Affiliation(s)
- Shyamalika Gopalan
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York, USA.,Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA
| | - Elizabeth G Atkinson
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York, USA.,Analytic and Translational Genetics Unit, Massachusetts General Hospital and Stanley Center for Psychiatric Research, Broad Institute, Boston, Massachusetts, USA
| | - Laura T Buck
- Research Centre in Evolutionary Anthropology and Palaeoecology, Liverpool John Moores University, Liverpool, UK
| | - Timothy D Weaver
- Department of Anthropology, University of California, Davis, California, USA
| | - Brenna M Henn
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York, USA.,Department of Anthropology, University of California, Davis, California, USA.,UC Davis Genome Center, University of California, Davis, California, USA
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What have the revelations about Neanderthal DNA revealed about Homo sapiens? ANTHROPOLOGICAL REVIEW 2020. [DOI: 10.2478/anre-2020-0008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genetic studies have presented increasing indications about the complexity of the interactions between Homo sapiens, Neanderthals and Denisovans, during Pleistocene. The results indicate potential replacement or admixture of the groups of hominins that lived in the same region at different times. Recently, the time of separation among these hominins in relation to the Last Common Ancestor – LCA has been reasonably well established. Events of mixing with emphasis on the Neanderthal gene flow into H. sapiens outside Africa, Denisovans into H. sapiens ancestors in Oceania and continental Asia, Neanderthals into Denisovans, as well as the origin of some phenotypic features in specific populations such as the color of the skin, eyes, hair and predisposition to develop certain kinds of diseases have also been found. The current information supports the existence of both replacement and interbreeding events, and indicates the need to revise the two main explanatory models, the Multiregional and the Out-of-Africa hypotheses, about the origin and evolution of H. sapiens and its co-relatives. There is definitely no longer the possibility of justifying only one model over the other. This paper aims to provide a brief review and update on the debate around this issue, considering the advances brought about by the recent genetic as well as morphological traits analyses.
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Affiliation(s)
- John Hawks
- Department of Anthropology, University of Wisconsin, Madison, Wisconsin 53706;
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Hawks J, Cochran G, Harpending HC, Lahn BT. A genetic legacy from archaic Homo. Trends Genet 2008; 24:19-23. [DOI: 10.1016/j.tig.2007.10.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 10/25/2007] [Accepted: 10/26/2007] [Indexed: 11/28/2022]
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Eswaran V, Harpending H, Rogers AR. Genomics refutes an exclusively African origin of humans. J Hum Evol 2006; 49:1-18. [PMID: 15878780 DOI: 10.1016/j.jhevol.2005.02.006] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2004] [Revised: 12/14/2004] [Accepted: 02/08/2005] [Indexed: 11/16/2022]
Abstract
Ten years ago, evidence from genetics gave strong support to the "recent African origin" view of the evolution of modern humans, which posits that Homo sapiens arose as a new species in Africa and subsequently spread, leading to the extinction of other archaic human species. Subsequent data from the nuclear genome not only fail to support this model, they do not support any simple model of human demographic history. In this paper, we study a process in which the modern human phenotype originates in Africa and then advances across the world by local demic diffusion, hybridization, and natural selection. While the multiregional model of human origins posits a number of independent single locus selective sweeps, and the "out of Africa" model posits a sweep of a new species, we study the intermediate case of a phenotypic sweep. Numerical simulations of this process replicate many of the seemingly contradictory features of the genetic data, and suggest that as much as 80% of nuclear loci have assimilated genetic material from non-African archaic humans.
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Affiliation(s)
- Vinayak Eswaran
- Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, India 208016.
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Weaver T, Roseman C. Ancient DNA, Late Neandertal Survival, and Modern‐Human–Neandertal Genetic Admixture. CURRENT ANTHROPOLOGY 2005. [DOI: 10.1086/432776] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Pearson OM. Has the combination of genetic and fossil evidence solved the riddle of modern human origins? Evol Anthropol 2004. [DOI: 10.1002/evan.20017] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Lahr MM, Foley RA. Towards a theory of modern human origins: geography, demography, and diversity in recent human evolution. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 1999; Suppl 27:137-76. [PMID: 9881525 DOI: 10.1002/(sici)1096-8644(1998)107:27+<137::aid-ajpa6>3.0.co;2-q] [Citation(s) in RCA: 288] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The origins of modern humans have been the central debate in palaeoanthropology during the last decade. We examine the problem in the context of the history of anthropology, the accumulating evidence for a recent African origin, and evolutionary mechanisms. Using a historical perspective, we show that the current controversy is a continuation of older conflicts and as such relates to questions of both origins and diversity. However, a better fossil sample, improved dates, and genetic data have introduced new perspectives, and we argue that evolutionary geography, which uses spatial distributions of populations as the basis for integrating contingent, adaptive, and demographic aspects of microevolutionary change, provides an appropriate theoretical framework. Evolutionary geography is used to explore two events: the evolution of the Neanderthal lineage and the relationship between an ancestral bottleneck with the evolution of anatomically modern humans and their diversity. We argue that the Neanderthal and modern lineages share a common ancestor in an African population between 350,000 and 250,000 years ago rather than in the earlier Middle Pleistocene; this ancestral population, which developed mode 3 technology (Levallois/Middle Stone Age), dispersed across Africa and western Eurasia in a warmer period prior to independent evolution towards Neanderthals and modern humans in stage 6. Both lineages would thus share a common large-brained ancestry, a technology, and a history of dispersal. They differ in the conditions under which they subsequently evolved and their ultimate evolutionary fate. Both lineages illustrate the repeated interactions of the glacial cycles, the role of cold-arid periods in producing fragmentation of populations, bottlenecks, and isolation, and the role of warmer periods in producing trans-African dispersals.
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Affiliation(s)
- M M Lahr
- Departamento de Biologia, Instituto de Biociências, Universidade de São Paulo, Brasil
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Ambrose SH. Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans. J Hum Evol 1998; 34:623-51. [PMID: 9650103 DOI: 10.1006/jhev.1998.0219] [Citation(s) in RCA: 494] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The "Weak Garden of Eden" model for the origin and dispersal of modern humans (Harpending et al., 1993) posits that modern humans spread into separate regions from a restricted source, around 100 ka (thousand years ago), then passed through population bottlenecks. Around 50 ka, dramatic growth occurred within dispersed populations that were genetically isolated from each other. Population growth began earliest in Africa and later in Eurasia and is hypothesized to have been caused by the invention and spread of a more efficient Later Stone Age/Upper Paleolithic technology, which developed in equatorial Africa. Climatic and geological evidence suggest an alternative hypothesis for Late Pleistocene population bottlenecks and releases. The last glacial period was preceded by one thousand years of the coldest temperatures of the Later Pleistocene (approximately 71-70 ka), apparently caused by the eruption of Toba, Sumatra. Toba was the largest known explosive eruption of the Quaternary. Toba's volcanic winter could have decimated most modern human populations, especially outside of isolated tropical refugia. Release from the bottleneck could have occurred either at the end of this hypercold phase, or 10,000 years later, at the transition from cold oxygen isotope stage 4 to warmer stage 3. The largest populations surviving through the bottleneck should have been found in the largest tropical refugia, and thus in equatorial Africa. High genetic diversity in modern Africans may thus reflect a less severe bottleneck rather than earlier population growth. Volcanic winter may have reduced populations to levels low enough for founder effects, genetic drift and local adaptations to produce rapid population differentiation. If Toba caused the bottlenecks, then modern human races may have differentiated abruptly, only 70 thousand years ago.
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Affiliation(s)
- S H Ambrose
- Department of Anthropology, University of Illinois, Urbana 61801, USA.
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Abstract
Genetic diversity patterns in nuclear versus mitochondrial systems and in low versus high mutation rate systems do not support the hypothesis of a recent African origin for all of humanity following a split between Africans and non-Africans 100,000 years ago, nor do genetic distance data. Geographical analyses of nuclear and mitochondrial gene trees do not support the hypothesis of a recent global replacement of humans coming out of Africa, although a local replacement event in Europe is indicated by these analyses and recent studies on Neandertal DNA. The gene tree analyses instead indicate that genetic interchanges have ensured that all of humanity has evolved as a single evolutionary lineage with no major splits.
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Affiliation(s)
- A R Templeton
- Department of Biology, Washington University, St. Louis, Missouri 63130-4899, USA.
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Abstract
Palaentology and archaeology are disciplines that traditionally deal with the reconstruction of human origins and history. Recently, however, molecular genetics has come to make increasing contributions to this area. In particular, several data sets indicate that variation of the human gene pool originated in Africa within the last 200,000 years. Furthermore, the study of DNA sequences allows the detection of expansions in population size. Here we briefly summarize and exemplify how DNA sequences can be used to reconstruct the history of populations.
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