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Jablonski NG. The evolution of human skin pigmentation involved the interactions of genetic, environmental, and cultural variables. Pigment Cell Melanoma Res 2021; 34:707-729. [PMID: 33825328 PMCID: PMC8359960 DOI: 10.1111/pcmr.12976] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/30/2021] [Accepted: 04/03/2021] [Indexed: 12/12/2022]
Abstract
The primary biological role of human skin pigmentation is as a mediator of penetration of ultraviolet radiation (UVR) into the deep layers of skin and the cutaneous circulation. Since the origin of Homo sapiens, dark, protective constitutive pigmentation and strong tanning abilities have been favored under conditions of high UVR and represent the baseline condition for modern humans. The evolution of partly depigmented skin and variable tanning abilities has occurred multiple times in prehistory, as populations have dispersed into environments with lower and more seasonal UVR regimes, with unique complements of genes and cultural practices. The evolution of extremes of dark pigmentation and depigmentation has been rare and occurred only under conditions of extremely high or low environmental UVR, promoted by positive selection on variant pigmentation genes followed by limited gene flow. Over time, the evolution of human skin pigmentation has been influenced by the nature and course of human dispersals and modifications of cultural practices, which have modified the nature and actions of skin pigmentation genes. Throughout most of prehistory and history, the evolution of human skin pigmentation has been a contingent and non-deterministic process.
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Affiliation(s)
- Nina G. Jablonski
- Department of AnthropologyThe Pennsylvania State UniversityUniversity ParkPAUSA
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2
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Lasisi T. The constraints of racialization: How classification and valuation hinder scientific research on human variation. Am J Phys Anthropol 2021; 175:376-386. [PMID: 33675042 DOI: 10.1002/ajpa.24264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 02/15/2021] [Accepted: 02/17/2021] [Indexed: 12/18/2022]
Abstract
Human biological variation has historically been studied through the lens of racialization. Despite a general shift away from the use of overt racial terminologies, the underlying racialized frameworks used to describe and understand human variation still remain. Even in relatively recent anthropological and biomedical work, we can observe clear manifestations of such racial thinking. This paper shows how classification and valuation are two specific processes which facilitate racialization and hinder attempts to move beyond such frameworks. The bias induced by classification distorts descriptions of phenotypic variation in a way that erroneously portrays European populations as more variable than others. Implicit valuation occurs in tandem with classification and produces narratives of superiority/inferiority for certain phenotypic variants without an objective biological basis. The bias of racialization is a persistent impediment stemming from the inheritance of scientific knowledge developed under explicitly racial paradigms. It is also an internalized cognitive distortion cultivated through socialization in a world where racialization is inescapable. Though undeniably challenging, this does not present an insurmountable barrier, and this bias can be mitigated through the critical evaluation of past work, the active inclusion of marginalized perspectives, and the direct confrontation of institutional structures enforcing racialized paradigms.
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Affiliation(s)
- Tina Lasisi
- Department of Anthropology, Pennsylvania State University, State College, Pennsylvania, USA
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3
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Quillen EE, Norton HL, Parra EJ, Lona-Durazo F, Ang KC, Illiescu FM, Pearson LN, Shriver MD, Lasisi T, Gokcumen O, Starr I, Lin YL, Martin AR, Jablonski NG. Shades of complexity: New perspectives on the evolution and genetic architecture of human skin. Am J Phys Anthropol 2018; 168 Suppl 67:4-26. [PMID: 30408154 DOI: 10.1002/ajpa.23737] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 09/17/2018] [Accepted: 09/20/2018] [Indexed: 02/06/2023]
Abstract
Like many highly variable human traits, more than a dozen genes are known to contribute to the full range of skin color. However, the historical bias in favor of genetic studies in European and European-derived populations has blinded us to the magnitude of pigmentation's complexity. As deliberate efforts are being made to better characterize diverse global populations and new sequencing technologies, better measurement tools, functional assessments, predictive modeling, and ancient DNA analyses become more widely accessible, we are beginning to appreciate how limited our understanding of the genetic bases of human skin color have been. Novel variants in genes not previously linked to pigmentation have been identified and evidence is mounting that there are hundreds more variants yet to be found. Even for genes that have been exhaustively characterized in European populations like MC1R, OCA2, and SLC24A5, research in previously understudied groups is leading to a new appreciation of the degree to which genetic diversity, epistatic interactions, pleiotropy, admixture, global and local adaptation, and cultural practices operate in population-specific ways to shape the genetic architecture of skin color. Furthermore, we are coming to terms with how factors like tanning response and barrier function may also have influenced selection on skin throughout human history. By examining how our knowledge of pigmentation genetics has shifted in the last decade, we can better appreciate how far we have come in understanding human diversity and the still long road ahead for understanding many complex human traits.
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Affiliation(s)
- Ellen E Quillen
- Department of Internal Medicine, Section of Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.,Center for Precision Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Heather L Norton
- Department of Anthropology, University of Cincinnati, Cincinnati, Ohio
| | - Esteban J Parra
- Department of Anthropology, University of Toronto - Mississauga, Mississauga, Ontario, Canada
| | - Frida Lona-Durazo
- Department of Anthropology, University of Toronto - Mississauga, Mississauga, Ontario, Canada
| | - Khai C Ang
- Department of Pathology and Jake Gittlen Laboratories for Cancer Research, Penn State College of Medicine, Hershey, Pennsylvania
| | - Florin Mircea Illiescu
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom.,Centro de Estudios Interculturales e Indígenas - CIIR, P. Universidad Católica de Chile, Santiago, Chile
| | - Laurel N Pearson
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
| | - Mark D Shriver
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
| | - Tina Lasisi
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
| | - Omer Gokcumen
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York
| | - Izzy Starr
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York
| | - Yen-Lung Lin
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York
| | - Alicia R Martin
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, Massachusetts.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts.,Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Nina G Jablonski
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
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Iliescu FM, Chaplin G, Rai N, Jacobs GS, Basu Mallick C, Mishra A, Thangaraj K, Jablonski NG. The influences of genes, the environment, and social factors on the evolution of skin color diversity in India. Am J Hum Biol 2018; 30:e23170. [PMID: 30099804 DOI: 10.1002/ajhb.23170] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 06/18/2018] [Accepted: 07/09/2018] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVES Skin color is a highly visible and variable trait across human populations. It is not yet clear how evolutionary forces interact to generate phenotypic diversity. Here, we sought to unravel through an integrative framework the role played by three factors-demography and migration, sexual selection, and natural selection-in driving skin color diversity in India. METHODS Skin reflectance data were collected from 10 diverse socio-cultural populations along the latitudinal expanse of India, including both sexes. We first looked at how skin color varies within and between these populations. Second, we compared patterns of sexual dimorphism in skin color. Third, we studied the influence of ultraviolet radiation on skin color throughout India. Finally, we attempted to disentangle the interactions between these factors in the context of available genetic data. RESULTS We found that the relative importance of these forces varied between populations. Social factors and population structure have played a stronger role than natural selection in shaping skin color diversity across India. Phenotypic overprinting resulted from additional genetic mutations overriding the skin lightening effect of variants such as the SLC24A5 rs1426654-A allele in some populations, in the context of the variable influence of sexual selection. Furthermore, specific genotypes are not associated reliably with specific skin color phenotypes. This result has relevance for DNA forensics and ancient DNA research. CONCLUSIONS India is a crucible of macro- and micro-evolutionary forces, and the complex interactions of physical and social forces are visible in the patterns of skin color seen today in the country.
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Affiliation(s)
- Florin Mircea Iliescu
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom.,Centro de Estudios Interculturales e Indígenas - CIIR, P. Universidad Católica de Chile, Santiago, Chile
| | - George Chaplin
- Department of Anthropology, The Pennsylvania State University, University Park, State Park, Pennsylvania
| | - Niraj Rai
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.,Birbal Sahni Institute of Palaeosciences, Lucknow, India
| | - Guy S Jacobs
- Complexity Institute, Nanyang Technological University, Singapore
| | - Chandana Basu Mallick
- Estonian Biocentre, Tartu, Estonia.,The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Anshuman Mishra
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | | | - Nina G Jablonski
- Department of Anthropology, The Pennsylvania State University, University Park, State Park, Pennsylvania
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5
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Koster J. Family ties: the multilevel effects of households and kinship on the networks of individuals. R Soc Open Sci 2018; 5:172159. [PMID: 29765670 PMCID: PMC5936935 DOI: 10.1098/rsos.172159] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Accepted: 03/13/2018] [Indexed: 06/08/2023]
Abstract
Among social mammals, humans uniquely organize themselves into communities of households that are centred around enduring, predominantly monogamous unions of men and women. As a consequence of this social organization, individuals maintain social relationships both within and across households, and potentially there is conflict among household members about which social ties to prioritize or de-emphasize. Extending the logic of structural balance theory, I predict that there will be considerable overlap in the social networks of individual household members, resulting in a pattern of group-level reciprocity. To test this prediction, I advance the Group-Structured Social Relations Model, a generalized linear mixed model that tests for group-level effects in the inter-household social networks of individuals. The empirical data stem from social support interviews conducted in a community of indigenous Nicaraguan horticulturalists, and model results show high group-level reciprocity among households. Although support networks are organized around kinship, covariates that test predictions of kin selection models do not receive strong support, potentially because most kin-directed altruism occurs within households, not between households. In addition, the models show that households with high genetic relatedness in part from children born to adulterous relationships are less likely to assist each other.
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Abstract
Renewed focus on African populations confirms the complexity of skin pigmentation genetics, and suggests future directions for pigmentation research.
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Affiliation(s)
- Tina Lasisi
- Department of Anthropology, Pennsylvania State University, University Park, PA, 16802, USA.
| | - Mark D Shriver
- Department of Anthropology, Pennsylvania State University, University Park, PA, 16802, USA.
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7
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Abstract
BACKGROUND Skin color is a well-recognized adaptive trait and has been studied extensively in humans. Understanding the genetic basis of adaptation of skin color in various populations has many implications in human evolution and medicine. DISCUSSION Impressive progress has been made recently to identify genes associated with skin color variation in a wide range of geographical and temporal populations. In this review, we discuss what is currently known about the genetics of skin color variation. We enumerated several cases of skin color adaptation in global modern humans and archaic hominins, and illustrated why, when, and how skin color adaptation occurred in different populations. Finally, we provided a summary of the candidate loci associated with pigmentation, which could be a valuable reference for further evolutionary and medical studies. CONCLUSION Previous studies generally indicated a complex genetic mechanism underlying the skin color variation, expanding our understanding of the role of population demographic history and natural selection in shaping genetic and phenotypic diversity in humans. Future work is needed to dissect the genetic architecture of skin color adaptation in numerous ethnic minority groups around the world, which remains relatively obscure compared with that of major continental groups, and to unravel the exact genetic basis of skin color adaptation.
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Affiliation(s)
- Lian Deng
- Chinese Academy of Sciences (CAS) Key Laboratory of Computational Biology, Max Planck Independent Research Group on Population Genomics, CAS-MPG Partner Institute for Computational Biology (PICB), Shanghai Institutes for Biological Sciences, CAS, Shanghai, 200031 China.,University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Shuhua Xu
- Chinese Academy of Sciences (CAS) Key Laboratory of Computational Biology, Max Planck Independent Research Group on Population Genomics, CAS-MPG Partner Institute for Computational Biology (PICB), Shanghai Institutes for Biological Sciences, CAS, Shanghai, 200031 China.,University of Chinese Academy of Sciences, Beijing, 100049 China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210 China.,Collaborative Innovation Center of Genetics and Development, Shanghai, 200438 China
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8
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Elias PM, Williams ML. Basis for the gain and subsequent dilution of epidermal pigmentation during human evolution: The barrier and metabolic conservation hypotheses revisited. Am J Phys Anthropol 2016; 161:189-207. [PMID: 27324932 DOI: 10.1002/ajpa.23030] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 05/27/2016] [Accepted: 05/29/2016] [Indexed: 12/25/2022]
Abstract
The evolution of human skin pigmentation must address both the initial evolution of intense epidermal pigmentation in hominins, and its subsequent dilution in modern humans. While many authorities believe that epidermal pigmentation evolved to protect against either ultraviolet B (UV-B) irradiation-induced mutagenesis or folic acid photolysis, we hypothesize that pigmentation augmented the epidermal barriers by shifting the UV-B dose-response curve from toxic to beneficial. Whereas erythemogenic UV-B doses produce apoptosis and cell death, suberythemogenic doses benefit permeability and antimicrobial function. Heavily melanized melanocytes acidify the outer epidermis and emit paracrine signals that augment barrier competence. Modern humans, residing in the cooler, wetter climes of south-central Europe and Asia, initially retained substantial pigmentation. While their outdoor lifestyles still permitted sufficient cutaneous vitamin D3 (VD3) synthesis, their marginal nutritional status, coupled with cold-induced caloric needs, selected for moderate pigment reductions that diverted limited nutritional resources towards more urgent priorities (=metabolic conservation). The further pigment-dilution that evolved as humans reached north-central Europe (i.e., northern France, Germany), likely facilitated cutaneous VD3 synthesis, while also supporting ongoing, nutritional requirements. But at still higher European latitudes where little UV-B breaches the atmosphere (i.e., present-day UK, Scandinavia, Baltic States), pigment dilution alone could not suffice. There, other nonpigment-related mutations evolved to facilitate VD3 production; for example, in the epidermal protein, filaggrin, resulting in reduced levels of its distal metabolite, trans-urocanic acid, a potent UV-B chromophore. Thus, changes in human pigmentation reflect a complex interplay between latitude, climate, diet, lifestyle, and shifting metabolic priorities.
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Affiliation(s)
- Peter M Elias
- Department of Veterans Affairs Medical Center, Dermatology Service, University of California San Francisco, California. .,Department of Dermatology, Dermatology Service, University of California San Francisco, California.
| | - Mary L Williams
- Department of Dermatology, University of California, San Francisco, California.,Department of Pediatrics, University of California, San Francisco, California
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9
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Norton HL, Hanna M, Werren E, Friedlaender J. The rs387907171 SNP in TYRP1is not associated with blond hair color on the Island of Bougainville. Am J Hum Biol 2016; 28:431-5. [DOI: 10.1002/ajhb.22795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 08/13/2015] [Accepted: 09/13/2015] [Indexed: 11/06/2022] Open
Affiliation(s)
- Heather L. Norton
- Department of Anthropology; University of Cincinnati; Cincinnati Ohio
| | - Megan Hanna
- Department of Anthropology; University of Cincinnati; Cincinnati Ohio
| | - Elizabeth Werren
- Department of Anthropology; University of Cincinnati; Cincinnati Ohio
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10
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Lasisi T, Ito S, Wakamatsu K, Shaw CN. Quantifying variation in human scalp hair fiber shape and pigmentation. Am J Phys Anthropol 2016; 160:341-52. [DOI: 10.1002/ajpa.22971] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 02/10/2016] [Accepted: 02/12/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Tina Lasisi
- Department of Archaeology and Anthropology, PAVE Research Group; University of Cambridge; UK
- Department of Anthropology; Pennsylvania State University, University Park; PA 16802
| | - Shosuke Ito
- Department of Chemistry; Fujita Health University School of Health Sciences; Toyoake Aichi Japan
| | - Kazumasa Wakamatsu
- Department of Chemistry; Fujita Health University School of Health Sciences; Toyoake Aichi Japan
| | - Colin N. Shaw
- Department of Archaeology and Anthropology, PAVE Research Group; University of Cambridge; UK
- Department of Archaeology and Anthropology; McDonald Institute for Archaeological Research, University of Cambridge; UK
- Department of Zoology, Cambridge BioTomography Centre; University of Cambridge; UK
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Norton HL, Werren E, Friedlaender J. MC1R diversity in Northern Island Melanesia has not been constrained by strong purifying selection and cannot explain pigmentation phenotype variation in the region. BMC Genet 2015; 16:122. [PMID: 26482799 PMCID: PMC4615358 DOI: 10.1186/s12863-015-0277-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 10/06/2015] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Variation in human skin pigmentation evolved in response to the selective pressure of ultra-violet radiation (UVR). Selection to maintain darker skin in high UVR environments is expected to constrain pigmentation phenotype and variation in pigmentation loci. Consistent with this hypothesis, the gene MC1R exhibits reduced diversity in African populations from high UVR regions compared to low-UVR non-African populations. However, MC1R diversity in non-African populations that have evolved under high-UVR conditions is not well characterized. METHODS In order to test the hypothesis that MC1R variation has been constrained in Melanesians the coding region of the MC1R gene was sequenced in 188 individuals from Northern Island Melanesia. The role of purifying selection was assessed using a modified McDonald Kreitman's test. Pairwise FST was calculated between Melanesian populations and populations from the 1000 Genomes Project. The SNP rs2228479 was genotyped in a larger sample (n = 635) of Melanesians and tested for associations with skin and hair pigmentation. RESULTS We observe three nonsynonymous and two synonymous mutations. A modified McDonald Kreitman's test failed to detect a significant signal of purifying selection. Pairwise FST values calculated between the four islands sampled here indicate little regional substructure in MC1R. When compared to African, European, East and South Asian populations, Melanesians do not exhibit reduced population divergence (measured as FST) or a high proportion of haplotype sharing with Africans, as one might expect if ancestral haplotypes were conserved across high UVR populations in and out of Africa. The only common nonsynonymous polymorphism observed, rs2228479, is not significantly associated with skin or hair pigmentation in a larger sample of Melanesians. CONCLUSIONS The pattern of sequence diversity here does not support a model of strong selective constraint on MC1R in Northern Island Melanesia This absence of strong constraint, as well as the recent population history of the region, may explain the observed frequencies of the derived rs2228479 allele. These results emphasize the complex genetic architecture of pigmentation phenotypes, which are controlled by multiple, possibly interacting loci. They also highlight the role that population history can play in influencing phenotypic diversity in the absence of strong natural selection.
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Affiliation(s)
- Heather L Norton
- Department of Anthropology, University of Cincinnati, 481 Braunstein Hall, PO Box 210380, Cincinnati, OH, 45221, USA.
| | - Elizabeth Werren
- Department of Anthropology, 101 West Hall, University of Michigan, 1085 South University Ave, Ann Arbor, MI, 48109, USA.
| | - Jonathan Friedlaender
- Department of Anthropology, Temple University, Gladfelter Hall, 1115 West Berks Street, Philadelphia, PA, 19122, USA.
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12
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Norton HL, Edwards M, Krithika S, Johnson M, Werren EA, Parra EJ. Quantitative assessment of skin, hair, and iris variation in a diverse sample of individuals and associated genetic variation. Am J Phys Anthropol 2015; 160:570-81. [PMID: 27435525 DOI: 10.1002/ajpa.22861] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 07/27/2015] [Accepted: 08/25/2015] [Indexed: 11/06/2022]
Abstract
OBJECTIVES The main goals of this study are to 1) quantitatively measure skin, hair, and iris pigmentation in a diverse sample of individuals, 2) describe variation within and between these samples, and 3) demonstrate how quantitative measures can facilitate genotype-phenotype association tests. MATERIALS AND METHODS We quantitatively characterize skin, hair, and iris pigmentation using the Melanin (M) Index (skin) and CIELab values (hair) in 1,450 individuals who self-identify as African American, East Asian, European, Hispanic, or South Asian. We also quantify iris pigmentation in a subset of these individuals using CIELab values from high-resolution iris photographs. We compare mean skin M index and hair and iris CIELab values among populations using ANOVA and MANOVA respectively and test for genotype-phenotype associations in the European sample. RESULTS All five populations are significantly different for skin (P <2 × 10(-16) ) and hair color (P <2 × 10(-16) ). Our quantitative analysis of iris and hair pigmentation reinforces the continuous, rather than discrete, nature of these traits. We confirm the association of three loci (rs16891982, rs12203592, and rs12913832) with skin pigmentation and four loci (rs12913832, rs12203592, rs12896399, and rs16891982) with hair pigmentation. Interestingly, the derived rs12203592 T allele located within the IRF4 gene is associated with lighter skin but darker hair color. DISCUSSION The quantitative methods used here provide a fine-scale assessment of pigmentation phenotype and facilitate genotype-phenotype associations, even with relatively small sample sizes. This represents an important expansion of current investigations into pigmentation phenotype and associated genetic variation by including non-European and admixed populations. Am J Phys Anthropol 160:570-581, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Heather L Norton
- Department of Anthropology, University of Cincinnati, Cincinnati, OH, 45238
| | - Melissa Edwards
- Department of Anthropology, University of Toronto Mississauga, Toronto, ON, Canada
| | - S Krithika
- Department of Anthropology, University of Toronto Mississauga, Toronto, ON, Canada
| | - Monique Johnson
- Department of Anthropology, University of Toronto Mississauga, Toronto, ON, Canada
| | - Elizabeth A Werren
- Department of Anthropology, University of Cincinnati, Cincinnati, OH, 45238
| | - Esteban J Parra
- Department of Anthropology, University of Toronto Mississauga, Toronto, ON, Canada
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13
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Jonnalagadda M, Ozarkar S, Ashma R, Kulkarni S. Skin pigmentation variation among populations of West Maharashtra, India. Am J Hum Biol 2015; 28:36-43. [PMID: 26126512 DOI: 10.1002/ajhb.22738] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Revised: 04/22/2015] [Accepted: 05/02/2015] [Indexed: 12/11/2022] Open
Abstract
OBJECTIVES Global patterns of skin pigmentation have evolved as an adaptation to local ultraviolet radiation (UVR). Indian populations exposed to intense UVR show great variation in skin pigmentation. The UVR-based selection model cannot satisfactorily address the high prevalence of light skin among these populations. Thus, the present study examines pigmentation variation among populations of West Maharashtra and the Indian subcontinent within the context of population structure and social hierarchy. METHODS Melanin index (MI) was measured from 555 individuals representing six endogamous populations of West Maharashtra. Skin pigmentation was assessed in terms of variation between populations and differences between and among castes and tribes. A linear regression analysis was run to assess the relationship among MI, UVR, and social hierarchy using published MI data from 13 Indian endogamous populations. RESULTS Skin pigmentation differed significantly among populations of West Maharashtra. Significant pigmentation variation exists between castes and tribes of West Maharashtra as well as across the Indian subcontinent. We observe a significant negative relationship between social hierarchy and skin pigmentation, whereas the relationship between UVR and MI is weak. CONCLUSIONS Our results suggest that various factors may have contributed to pigmentation diversity across the Indian subcontinent. The lack of correlation between UVR and MI suggests that natural selection may not have played a significant role in shaping pigmentation variation across the subcontinent. We discuss other possible explanations, including metabolic conservation and cultural factors such as traditional social hierarchies and strict endogamy that have led to the development of population structure.
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Affiliation(s)
- Manjari Jonnalagadda
- Department of Anthropology, Savitribai Phule Pune University, Pune, 411007, Maharashtra, India
| | - Shantanu Ozarkar
- Department of Anthropology, Savitribai Phule Pune University, Pune, 411007, Maharashtra, India
| | - Richa Ashma
- Department of Zoology, Savitribai Phule Pune University, Pune, 411007, Maharashtra, India
| | - Shaunak Kulkarni
- Department of Anthropology, Savitribai Phule Pune University, Pune, 411007, Maharashtra, India
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14
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Eaton K, Edwards M, Krithika S, Cook G, Norton H, Parra EJ. Association study confirms the role of twoOCA2polymorphisms in normal skin pigmentation variation in East Asian populations. Am J Hum Biol 2015; 27:520-5. [DOI: 10.1002/ajhb.22678] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 12/11/2014] [Accepted: 12/21/2014] [Indexed: 01/08/2023] Open
Affiliation(s)
- Katherine Eaton
- Department of Anthropology; University of Toronto at Mississauga; Mississauga Ontario Canada
| | - Melissa Edwards
- Department of Anthropology; University of Toronto at Mississauga; Mississauga Ontario Canada
| | - S. Krithika
- Department of Anthropology; University of Toronto at Mississauga; Mississauga Ontario Canada
| | - Gillian Cook
- Department of Anthropology; University of Toronto at Mississauga; Mississauga Ontario Canada
| | - Heather Norton
- Department of Anthropology; University of Cincinnati; Cincinnati Ohio
| | - Esteban J. Parra
- Department of Anthropology; University of Toronto at Mississauga; Mississauga Ontario Canada
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15
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Norton HL, Correa EA, Koki G, Friedlaender JS. Distribution of an allele associated with blond hair color across Northern Island Melanesia. Am J Phys Anthropol 2014; 153:653-62. [PMID: 24449225 DOI: 10.1002/ajpa.22466] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 12/20/2013] [Indexed: 11/07/2022]
Abstract
Pigmentation of the skin, hair, and eyes is a complex trait controlled by multiple genetic loci. Recently a non-synonymous mutation in the pigmentation candidate gene TYRP1 was shown to be significantly associated with a blond-hair phenotype in populations from the Solomon Islands. The distribution of this mutation in the islands of Northern Island Melanesia, where the blondism phenotype is also prevalent, was unknown. Here, we present data describing the distribution of this allele in 550 individuals sampled from across this region, and test for associations between genotype at this locus and quantitatively measured skin and hair pigmentation phenotype. We report that the frequency of the 93C allele is notably lower than observed in the Solomons (0.12 vs. 0.26). The allele exhibits significant geographic heterogeneity across the islands sampled (χ(2) = 108.4, P < 0.0001). It is observed at its highest frequencies on the islands of New Ireland and New Hanover, while being almost completely absent from the large island of New Britain. Using linear regression with age, sex, and island as covariates we report that, as in the Solomons, the 93C allele is significantly associated with a decrease in hair pigmentation but not skin pigmentation. We discuss the distribution of the 93C allele across the Southwest Pacific in light of its possible place of origin and dispersal.
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Affiliation(s)
- Heather L Norton
- Department of Anthropology, University of Cincinnati, Cincinnati, OH
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Basu Mallick C, Iliescu FM, Möls M, Hill S, Tamang R, Chaubey G, Goto R, Ho SYW, Gallego Romero I, Crivellaro F, Hudjashov G, Rai N, Metspalu M, Mascie-Taylor CGN, Pitchappan R, Singh L, Mirazon-Lahr M, Thangaraj K, Villems R, Kivisild T. The light skin allele of SLC24A5 in South Asians and Europeans shares identity by descent. PLoS Genet 2013; 9:e1003912. [PMID: 24244186 PMCID: PMC3820762 DOI: 10.1371/journal.pgen.1003912] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 09/07/2013] [Indexed: 11/18/2022] Open
Abstract
Skin pigmentation is one of the most variable phenotypic traits in humans. A non-synonymous substitution (rs1426654) in the third exon of SLC24A5 accounts for lighter skin in Europeans but not in East Asians. A previous genome-wide association study carried out in a heterogeneous sample of UK immigrants of South Asian descent suggested that this gene also contributes significantly to skin pigmentation variation among South Asians. In the present study, we have quantitatively assessed skin pigmentation for a largely homogeneous cohort of 1228 individuals from the Southern region of the Indian subcontinent. Our data confirm significant association of rs1426654 SNP with skin pigmentation, explaining about 27% of total phenotypic variation in the cohort studied. Our extensive survey of the polymorphism in 1573 individuals from 54 ethnic populations across the Indian subcontinent reveals wide presence of the derived-A allele, although the frequencies vary substantially among populations. We also show that the geospatial pattern of this allele is complex, but most importantly, reflects strong influence of language, geography and demographic history of the populations. Sequencing 11.74 kb of SLC24A5 in 95 individuals worldwide reveals that the rs1426654-A alleles in South Asian and West Eurasian populations are monophyletic and occur on the background of a common haplotype that is characterized by low genetic diversity. We date the coalescence of the light skin associated allele at 22–28 KYA. Both our sequence and genome-wide genotype data confirm that this gene has been a target for positive selection among Europeans. However, the latter also shows additional evidence of selection in populations of the Middle East, Central Asia, Pakistan and North India but not in South India. Human skin color is one of the most visible aspects of human diversity. The genetic basis of pigmentation in Europeans has been understood to some extent, but our knowledge about South Asians has been restricted to a handful of studies. It has been suggested that a single nucleotide difference in SLC24A5 accounts for 25–38% European-African pigmentation differences and correlates with lighter skin. This genetic variant has also been associated with skin color variation among South Asians living in the UK. Here, we report a study based on a homogenous cohort of South India. Our results confirm that SLC24A5 plays a key role in pigmentation diversity of South Asians. Country-wide screening of the variant reveals that the light skin associated allele is widespread in the Indian subcontinent and its complex patterning is shaped by a combination of processes involving selection and demographic history of the populations. By studying the variation of SLC24A5 sequences among a diverse set of individuals, we show that the light skin associated allele in South Asians is identical by descent to that found in Europeans. Our study also provides new insights into positive selection acting on the gene and the evolutionary history of light skin in humans.
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Affiliation(s)
- Chandana Basu Mallick
- Department of Evolutionary Biology, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- Estonian Biocentre, Tartu, Estonia
- * E-mail: (CBM); (TK)
| | - Florin Mircea Iliescu
- Division of Biological Anthropology, University of Cambridge, Cambridge, United Kingdom
| | - Märt Möls
- Estonian Biocentre, Tartu, Estonia
- Institute of Mathematical Statistics, University of Tartu, Tartu, Estonia
| | - Sarah Hill
- Division of Biological Anthropology, University of Cambridge, Cambridge, United Kingdom
| | - Rakesh Tamang
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | | | - Rie Goto
- Division of Biological Anthropology, University of Cambridge, Cambridge, United Kingdom
| | - Simon Y. W. Ho
- School of Biological Sciences, University of Sydney, Sydney, Australia
| | - Irene Gallego Romero
- Division of Biological Anthropology, University of Cambridge, Cambridge, United Kingdom
| | - Federica Crivellaro
- Leverhulme Centre for Human Evolutionary Studies, University of Cambridge, Cambridge, United Kingdom
| | - Georgi Hudjashov
- Department of Evolutionary Biology, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- Estonian Biocentre, Tartu, Estonia
| | - Niraj Rai
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Mait Metspalu
- Department of Evolutionary Biology, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- Estonian Biocentre, Tartu, Estonia
| | | | - Ramasamy Pitchappan
- Chettinad Academy of Research and Education, Chettinad Health City, Chennai, India
| | - Lalji Singh
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
- Banaras Hindu University, Varanasi, India
| | - Marta Mirazon-Lahr
- Leverhulme Centre for Human Evolutionary Studies, University of Cambridge, Cambridge, United Kingdom
| | | | - Richard Villems
- Department of Evolutionary Biology, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- Estonian Biocentre, Tartu, Estonia
- Estonian Academy of Sciences, Tallinn, Estonia
| | - Toomas Kivisild
- Department of Evolutionary Biology, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- Estonian Biocentre, Tartu, Estonia
- Division of Biological Anthropology, University of Cambridge, Cambridge, United Kingdom
- * E-mail: (CBM); (TK)
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Jablonski NG, Chaplin G. Epidermal pigmentation in the human lineage is an adaptation to ultraviolet radiation. J Hum Evol 2013; 65:671-5. [DOI: 10.1016/j.jhevol.2013.06.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 05/13/2013] [Accepted: 06/01/2013] [Indexed: 11/29/2022]
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Swiatoniowski AK, Quillen EE, Shriver MD, Jablonski NG. Technical Note: Comparing von Luschan skin color tiles and modern spectrophotometry for measuring human skin pigmentation. Am J Phys Anthropol 2013; 151:325-30. [DOI: 10.1002/ajpa.22274] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 03/18/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Anna K. Swiatoniowski
- Department of Anthropology; The Pennsylvania State University; State College; PA; 16802
| | - Ellen E. Quillen
- Department of Anthropology; The Pennsylvania State University; State College; PA; 16802
| | - Mark D. Shriver
- Department of Anthropology; The Pennsylvania State University; State College; PA; 16802
| | - Nina G. Jablonski
- Department of Anthropology; The Pennsylvania State University; State College; PA; 16802
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Candille SI, Absher DM, Beleza S, Bauchet M, McEvoy B, Garrison NA, Li JZ, Myers RM, Barsh GS, Tang H, Shriver MD. Genome-wide association studies of quantitatively measured skin, hair, and eye pigmentation in four European populations. PLoS One 2012; 7:e48294. [PMID: 23118974 DOI: 10.1371/journal.pone.0048294] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 09/25/2012] [Indexed: 12/21/2022] Open
Abstract
Pigmentation of the skin, hair, and eyes varies both within and between human populations. Identifying the genes and alleles underlying this variation has been the goal of many candidate gene and several genome-wide association studies (GWAS). Most GWAS for pigmentary traits to date have been based on subjective phenotypes using categorical scales. But skin, hair, and eye pigmentation vary continuously. Here, we seek to characterize quantitative variation in these traits objectively and accurately and to determine their genetic basis. Objective and quantitative measures of skin, hair, and eye color were made using reflectance or digital spectroscopy in Europeans from Ireland, Poland, Italy, and Portugal. A GWAS was conducted for the three quantitative pigmentation phenotypes in 176 women across 313,763 SNP loci, and replication of the most significant associations was attempted in a sample of 294 European men and women from the same countries. We find that the pigmentation phenotypes are highly stratified along axes of European genetic differentiation. The country of sampling explains approximately 35% of the variation in skin pigmentation, 31% of the variation in hair pigmentation, and 40% of the variation in eye pigmentation. All three quantitative phenotypes are correlated with each other. In our two-stage association study, we reproduce the association of rs1667394 at the OCA2/HERC2 locus with eye color but we do not identify new genetic determinants of skin and hair pigmentation supporting the lack of major genes affecting skin and hair color variation within Europe and suggesting that not only careful phenotyping but also larger cohorts are required to understand the genetic architecture of these complex quantitative traits. Interestingly, we also see that in each of these four populations, men are more lightly pigmented in the unexposed skin of the inner arm than women, a fact that is underappreciated and may vary across the world.
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Kenny EE, Timpson NJ, Sikora M, Yee MC, Moreno-Estrada A, Eng C, Huntsman S, Burchard EG, Stoneking M, Bustamante CD, Myles S. Melanesian blond hair is caused by an amino acid change in TYRP1. Science 2012; 336:554. [PMID: 22556244 DOI: 10.1126/science.1217849] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Naturally blond hair is rare in humans and found almost exclusively in Europe and Oceania. Here, we identify an arginine-to-cysteine change at a highly conserved residue in tyrosinase-related protein 1 (TYRP1) as a major determinant of blond hair in Solomon Islanders. This missense mutation is predicted to affect catalytic activity of TYRP1 and causes blond hair through a recessive mode of inheritance. The mutation is at a frequency of 26% in the Solomon Islands, is absent outside of Oceania, represents a strong common genetic effect on a complex human phenotype, and highlights the importance of examining genetic associations worldwide.
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Affiliation(s)
- Eimear E Kenny
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
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Friedlaender JS, Friedlaender FR, Reed FA, Kidd KK, Kidd JR, Chambers GK, Lea RA, Loo JH, Koki G, Hodgson JA, Merriwether DA, Weber JL. The genetic structure of Pacific Islanders. PLoS Genet 2008; 4:e19. [PMID: 18208337 DOI: 10.1371/journal.pgen.0040019] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 12/13/2007] [Indexed: 11/29/2022] Open
Abstract
Human genetic diversity in the Pacific has not been adequately sampled, particularly in Melanesia. As a result, population relationships there have been open to debate. A genome scan of autosomal markers (687 microsatellites and 203 insertions/deletions) on 952 individuals from 41 Pacific populations now provides the basis for understanding the remarkable nature of Melanesian variation, and for a more accurate comparison of these Pacific populations with previously studied groups from other regions. It also shows how textured human population variation can be in particular circumstances. Genetic diversity within individual Pacific populations is shown to be very low, while differentiation among Melanesian groups is high. Melanesian differentiation varies not only between islands, but also by island size and topographical complexity. The greatest distinctions are among the isolated groups in large island interiors, which are also the most internally homogeneous. The pattern loosely tracks language distinctions. Papuan-speaking groups are the most differentiated, and Austronesian or Oceanic-speaking groups, which tend to live along the coastlines, are more intermixed. A small “Austronesian” genetic signature (always <20%) was detected in less than half the Melanesian groups that speak Austronesian languages, and is entirely lacking in Papuan-speaking groups. Although the Polynesians are also distinctive, they tend to cluster with Micronesians, Taiwan Aborigines, and East Asians, and not Melanesians. These findings contribute to a resolution to the debates over Polynesian origins and their past interactions with Melanesians. With regard to genetics, the earlier studies had heavily relied on the evidence from single locus mitochondrial DNA or Y chromosome variation. Neither of these provided an unequivocal signal of phylogenetic relations or population intermixture proportions in the Pacific. Our analysis indicates the ancestors of Polynesians moved through Melanesia relatively rapidly and only intermixed to a very modest degree with the indigenous populations there. The origins and current genetic relationships of Pacific Islanders have been the subjects of interest and controversy for many decades. By analyzing the variation of a large number (687) of genetic markers in almost 1,000 individuals from 41 Pacific populations, and comparing these with East Asians and others, we contribute to the clarification and resolution of many of these issues. To judge by the populations in our survey, we find that Polynesians and Micronesians have almost no genetic relation to Melanesians, but instead are strongly related to East Asians, and particularly Taiwan Aborigines. A minority of Island Melanesian populations have indications of a small shared genetic ancestry with Polynesians and Micronesians (the ones that have this tie all speak related Austronesian languages). Inland groups who speak Papuan languages are particularly divergent and internally homogeneous. The genetic divergence among Island Melanesian populations, which is neatly organized by island, island size/topography, as well as their coastal or inland locations, is remarkable for such a small region, and enlarges our understanding of the texture of contemporary human variation.
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Lao O, de Gruijter JM, van Duijn K, Navarro A, Kayser M. Signatures of positive selection in genes associated with human skin pigmentation as revealed from analyses of single nucleotide polymorphisms. Ann Hum Genet 2007; 71:354-69. [PMID: 17233754 DOI: 10.1111/j.1469-1809.2006.00341.x] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Phenotypic variation between human populations in skin pigmentation correlates with latitude at the continental level. A large number of hypotheses involving genetic adaptation have been proposed to explain human variation in skin colour, but only limited genetic evidence for positive selection has been presented. To shed light on the evolutionary genetic history of human variation in skin colour we inspected 118 genes associated with skin pigmentation in the Perlegen dataset, studying single nucleotide polymorphisms (SNPs), and analyzed 55 genes in detail. We identified eight genes that are associated with the melanin pathway (SLC45A2, OCA2, TYRP1, DCT, KITLG, EGFR, DRD2 and PPARD) and presented significant differences in genetic variation between Europeans, Africans and Asians. In six of these genes we detected, by means of the EHH test, variability patterns that are compatible with the hypothesis of local positive selection in Europeans (OCA2, TYRP1 and KITLG) and in Asians (OCA2, DCT, KITLG, EGFR and DRD2), whereas signals were scarce in Africans (DCT, EGFR and DRD2). Furthermore, a statistically significant correlation between genotypic variation in four pigmentation candidate genes and phenotypic variation of skin colour in 51 worldwide human populations was revealed. Overall, our data also suggest that light skin colour is the derived state and is of independent origin in Europeans and Asians, whereas dark skin color seems of unique origin, reflecting the ancestral state in humans.
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Affiliation(s)
- O Lao
- Department of Forensic Molecular Biology, Erasmus University Medical Centre Rotterdam, The Netherlands
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