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Race and Global Patterns of Phenotypic Variation

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Abstract

Phenotypic traits have been used for centuries for the purpose of racial classification. Developments in quantitative population genetics have allowed global comparison of patterns of phenotypic variation with patterns of variation in classical genetic markers and DNA markers. Human skin color shows a high degree of variation among geographic regions, typical of traits that show extensive natural selection. Even given this high level of geographic differentiation, skin color variation is clinal and is not well described by discrete racial categories. Craniometric traits show a level of among-region differentiation comparable to genetic markers, with high levels of variation within populations as well as a correlation between phenotypic and geographic distance. Craniometric variation is geographically structured, allowing high levels of classification accuracy when comparing crania from different parts of the world. Nonetheless, the boundaries in global variation are not abrupt and do not fit a strict view of the race concept; the number of races and the cutoffs used to define them are arbitrary. The race concept is at best a crude first-order approximation to the geographically structured phenotypic variation in the human species.

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... Notably, only the 2020 Census held the designation "Hispanic" apart from the self-selected racial categories. pigmentation has been used as a predominant cultural identifier for assortative mating practices (Caspari 2009;Gowland and Thompson 2013;Jablonski 2020;Relethford 2009); however, biological affinity and social race are not necessarily synonymous. The relationship between biological affinity and social race is complex and has been engaged with at length in the literature (Hunley et al. 2009;Jablonski 2020;Klimentidis et al. 2009;Lieberman and Reynolds 1996;Long et al. 2009;Sauer 1992;Wagner et al. 2017). ...
... Thus, in this article we compare reported historical definitions of social race in antemortem documentation to scientific descriptors of human skeletal and genetic variation such as biological affinity or biogeographical origin. Biological affinity, commonly referred to as ancestry within forensic anthropology, highlights the geographical patterning of human morphological variation that is generally attributed to the ancestral origin of an individual (Cuhna and Ubelaker 2020;Konigsberg et al. 2009;Ousley et al. 2009Ousley et al. , 2018Relethford 2009;SWGANTH 2013). Similarly, biogeographic affinity is utilized here to specifically refer to genetics discourse that engages the complex interactions among genetics, environment, and culture to understand human variation and population structure (Elhaik et al. 2014;Harcourt 2012;Phillips 2015;Relethford 2001Relethford , 2002Tishkoff and Kidd 2004). ...
Article
The 1943 Battle of Tarawa resulted in the loss of approximately 1,000 US service members on or around Betio Island, Tarawa Atoll, Republic of Kiribati. Nearly half these casualties were accounted for after the battle. The Defense POW/MIA Accounting Agency (DPAA) has worked to identify the remaining ~510 unaccounted-for service members and has successfully identified ~160 service members to date. Demographic data pulled from historical documentation of the US losses indicate a relatively homogeneous population (99% White, 81% 17–23 years of age, and only two individuals with a documented religious preference other than Protestant or Catholic). Using this demographic data as a framework, three case studies are presented to demonstrate how a holistic biosocial approach to building identity could facilitate forensic identifications. The temporal and sociocultural contextualization of analyses enables anthropologists to navigate inconsistencies between 21st-century and historical (1940s) social identity concepts to overcome challenges to identification. The case studies demonstrate how biological evidence, genetic evidence, and material evidence (material culture) differently contribute to the social identity of an individual and can impact identification efforts when analytical conclusions are incongruent with historical documentation. The first case of US Battle of Tarawa casualties examines how morphometric biological affinity assessments are biased by the fluidity of social identity concepts when complex morphological and metric indicators of biological affinity are not represented in historical race categories. The second case demonstrates how biogeographic genetic affinity predictions, through a discussion of the G2a4 haplogroup, need to be examined holistically in the context of other lines of evidence. The third case highlights how material evidence can further define social identity beyond physicality, genetic structure, and race. The challenges of interpreting identity from human remains, as highlighted through these examples, are commonly encountered by anthropologists working in disaster victim identification and other humanitarian contexts. Thus, it is imperative for anthropologists to be self-aware of implicit biases toward the current prevailing definitions of biological and social identity and to consider historical perceptions of identity when working in these contexts.
... Beginning with the pioneering work of W.W. Howells (1973), there is now near-universal acceptance that human cranial variation is geographically structured, making it highly attractive for reconstructing population history and for assessing ancestry. While phenotypic and morphological variation, including craniometric variation, is subject to nongenetic or environmental influences, numerous studies have demonstrated that phenotypic traits and global patterns of craniometric variation, on average, are consistent with neutral traits (genetic drift and gene flow) thus allowing researchers a way to study the history and evolution of past populations (Betti et al. 2010;Harvati and Weaver 2006;Relethford 2002Relethford , 2004Relethford , 2009Relethford , 2010Roseman 2004;Smith 2009Smith , 2011Smith and von Cramon-Taubadel 2015;von Cramon-Taubadel 2009, 2016von Cramon-Taubadel and Weaver 2009). Groups sharing more metric and nonmetric features in common are considered to be more closely related than groups not sharing these same features (Larsen 2015). ...
... The existence of a significant genetic component for cranial measurements (e.g., Carson 2006;Devor 1987;Hughes and Townsend 2013;Martinez-Abadias et al. 2009;Sjøvold 1984Sjøvold , 1995Sparks and Jantz 2002) has helped increase the use of this category of variation in biological distance studies. Furthermore, because craniometric variation is geographically structured it allows high levels of classification accuracy when crania from different parts of the world are compared (Relethford 2009). ...
Chapter
Biological distance, or biodistance, is a measure of relatedness or divergence among groups separated by time and/or geography based on morphological variation (Buikstra et al. 1990). Biological distance studies, which are undertaken to reconstruct population history and to assess ancestry, dominated bioarchaeological research during the nineteenth and early twentieth centuries. The earliest attempts to comprehend human variation and measure relatedness among human groups, through the construction of typological racial classifications, fell short of their predicted goals. These early attempts were flawed due to limitations of the approach, which included the mistaken belief that humanity could be divided into a finite number of pure races, and the lack of adequate quantitative methods. Advances in evolutionary theory, including quantitative and population genetics, and improvements in computing and statistical procedures in the early twentieth century provided a much...
... Today, I believe most biological anthropologists do not accept the existence of biological races because of evidence that geographic variation is not highly structured; there is widespread gene-flow throughout the species, and there has been at least since the Neolithic. The conclusions of most studies, using various approaches to assess genetic diversity, agree that human subspecies do not exist because of low levels of between-group diversity and the geographic patterning of that diversity (Barbujani & Belle, 2006;Barbujani, Magagni, Minch, & Cavalli-Sforza, 1997;Lewontin, 1972;Long & Healy, 2009;Long & Kittles, 2003;Relethford, 2002Relethford, , 2009Serre & Pääbo, 2004). Since Lewontin (1972), many studies have shown minimal population structure on several levels, undermining the phylogenetic assumption, not only on the level of subspecies, but also on the level of population (Relethford, 2002(Relethford, , 2009Serre & Pääbo, 2004). ...
... The conclusions of most studies, using various approaches to assess genetic diversity, agree that human subspecies do not exist because of low levels of between-group diversity and the geographic patterning of that diversity (Barbujani & Belle, 2006;Barbujani, Magagni, Minch, & Cavalli-Sforza, 1997;Lewontin, 1972;Long & Healy, 2009;Long & Kittles, 2003;Relethford, 2002Relethford, , 2009Serre & Pääbo, 2004). Since Lewontin (1972), many studies have shown minimal population structure on several levels, undermining the phylogenetic assumption, not only on the level of subspecies, but also on the level of population (Relethford, 2002(Relethford, , 2009Serre & Pääbo, 2004). This has been underscored by Templeton (1998Templeton ( , 2013, who has argued that human populations have so little structure that the required "treeness" is not demonstrated within Homo sapiens and phylogenetic tree models are invalid representations of human population relationships. ...
... There is more genetic variation within any specific population than between populations, or groups referred to as a 'race' (which will hereafter appear without quotation marks; see Lewontin 1972;Brown and Armelagos 2001;Relethford 2002). Phenotypes are expressed clinally across geographic locations -there are no strict borders between races or ethnic groups (Keita and Kittles, 1997;Relethford, 2009). Race is a social-cultural construct (Keita and Kittles, 1997); biological human variation does exist, but not very much of it is centred on the socially identified racial groups. ...
... While most anthropologists and about 50% of biological anthropologists (Wagner et al. 2017) do not agree with the concept of race as a strict biological entity now (e.g. Gravlee 2009;Relethford 2002Relethford , 2009, and certainly the racist descriptions and rankings are generally not present in current bioarchaeological and forensic anthropological research, groups of people are often still categorised in the same way as in the earlier research (e.g. Gill and Rhine 1990; Patriquin et al. 2003). ...
... Applying this linguistic and social distinction to physical remains is practically and ethically challenging, and requires an understanding of the colonialist practices in 'Hispanic' regions, which ultimately led to an admixture of Indigenous populations, (enslaved) African and European settlers [104]. It is also important to recognize that the reference populations of Black Americans are the result of racialization that follows centuries of enslavement and discrimination which failed to recognize the substantial phenotypic diversity of individuals with origins or ancestral connections to the African continent [105,106]. This cannot be assumed to be the same perception of 'Black' in Tudor England though its origins can be traced before this period [22]. ...
... As highlighted above, applying forensic ancestry estimation methods to archaeological remains is problematic. We have therefore taken a gestalt approach to the interpretation of the ancestry estimation results, isotope results, artefactual evidence and historical context, with the aim of identifying phenotypic geographic diversity, not culturally defined categories [105,106,137]. These interpretations are made in consideration of available data, but may be revised in future studies with the addition of other forms of evidence used in studies of population affinity, such as ancient DNA (aDNA) analysis, post-cranial metrics and dental morphology [138]. ...
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Scorrer J, Faillace KE, Hildred A, Nederbragt AJ, Andersen MB, Millet M-A, Lamb AL, Madgwick R. 2021 Diversity aboard a Tudor warship: investigating the origins of the Mary Rose crew using multi-isotope analysis. R. Soc. Open Sci. 8: 202106. https://doi.org/10.1098/rsos.202106 The great Tudor warship, the Mary Rose, which sank tragically in the Solent in 1545 AD, presents a rare archaeological opportunity to research individuals for whom the precise timing and nature of death are known. A long-standing question surrounds the composition of the Tudor navy and whether the crew were largely British or had more diverse origins. This study takes a multi-isotope approach, combining strontium (87Sr/86Sr), oxygen (�18O), sulfur (�34S), carbon (�13C) and nitrogen (�15N) isotope analysis of dental samples to reconstruct the childhood diet and origins of eight of the Mary Rose crew. Forensic ancestry estimation was also employed on a subsample. Provenancing isotope data tentatively suggests as many as three of the crew may have originated from warmer, more southerly climates than Britain. Five have isotope values indicative of childhoods spent in western Britain, one of which had cranial morphology suggestive of African ancestry. The general trend of relatively high �15N and low �13C values suggests a broadly comparable diet to contemporaneous British and European communities. This multi-isotope approach and the nature of the archaeological context has allowed the reconstruction of the biographies of eight Tudor individuals to a higher resolution than is usually possible.
... How Biological Anthropologists View Human Variation." This issue had been based on a multidisciplinary symposium hosted at the Maxwell Museum and Department of Anthropology of the University of New Mexico (Caspari, 2009;Edgar, 2009;Gravlee, 2009;Hunley et al., 2009;Konigsberg et al., 2009;Long et al., 2009;Ousley et al., 2009;Relethford, 2009;Wolpoff, 2009). In this issue, Edgar and Hunley (2009) concluded that inadequate communication and collaboration led to a lack of progress in addressing issues surrounding the race issue and contributed to conflicting communications regarding human variation to our students and the public. ...
... This viewpoint lies at the core of the issue and the rejection by the biological anthropology community of ancestry or race estimation by forensic anthropologists. Global population studies have shown that craniofacial morphology conforms to a neutral evolutionary model as neighboring populations more frequently exchange genes and/or share common ancestry (Relethford, 2009;Ross et al., 2020;von Cramon-Taubadel, 2009). However, tracing population history is more complex than mere geography. ...
Article
In 1992, Norm Sauer called for a language shift in which practitioners would move away from the socially loaded term “race” and replace it with the less provocative term “ancestry.” While many heeded the call and moved towards ancestry in their research and reports, the actual approach to research and analysis did not change. In response to this change, there was a large growth in ancestry estimation method development in the early decade of the 2000s. However, the practice of ancestry estimation did not adequately incorporate evolutionary theory in interpretation or trait selection and continued with little critical reflection. In the past decade, there has been an increase in ancestry validation methods with little critique of the “race” concept or discussion of modern human variation or reference samples. To advance, forensic anthropologists need to reckon with the practice of ancestry estimation as it is currently practiced. We are calling for another reform in the axiom focusing on evolutionary theory, population history, trait selection, and population‐level reference samples. The practice needs to abandon the terms ancestry and race completely and recalibrate to an analysis of population affinity. Population affinity is a statistical approach based on the underlying population structure that would allow the understanding of how microevolutionary forces act in concert with historical events (e.g., colonization, the Transatlantic Slave Trade, etc.) to shape modern human variation. This is not to be confused with geographic ancestry that all too often can be perceived as interchangeable with social race and as an affirmation of the biological concept of race. It is time to critically evaluate the social and scientific implications of the current practice of ancestry estimation, and re‐frame our approach to studying and analyzing modern human variation through a population structure approach.
... The contrary minority view is that race denotes a subspecies, breeding population, genetic cluster, extended family (or some other biologically-based idea along those lines), and that genomic data shows that these exist, and have or might have important relationships to socially valued phenotypic traits among humans (e.g. Andreasen, 2000;Barnes, 2018;Fuerst, 2015;Levin, 1997;Lynn, 2015;Relethford, 2009;Rushton, 2000;Sarich & Miele, 2004;Sesardic, 2010;Spencer, 2015). In line with standard terminology in philosophy (Miller, 2016), the first view will be denoted the social constructivist view (or sometimes, anti-realist), and the second the realist view ("race realism"). ...
Article
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The nature of race differences, and even the mere “existence” of human races, continues to be a major source of controversy and confusion. This brief review summarizes the empirical evidence about race differences and the conceptual issues related to taxonomy, as well as practical implications for medicine and the social sciences. The review shows that human races are distinctive phenotypically and genotypically, the latter with regard to the frequencies of a very large number (millions) of alleles. Distributions of these traits are clinal rather than discrete, and human races are subject to continuous change across evolutionary time.
... The contrary minority view is that race denotes a subspecies, breeding population, genetic cluster, extended family (or some other biologically-based idea along those lines), and that genomic data shows that these exist, and have or might have important relationships to socially valued phenotypic traits among humans (e.g. Lynn, 2015;Rushton, 2000;Sesardic, 2010;Levin, 1997;Sarich & Miele, 2004;Fuerst, 2015;Andreasen, 2000;Spencer, 2015;Relethford, 2009;Barnes, 2018). In line with standard terminology in philosophy (Miller, 2016), the first view will be denoted the social constructivist view (or sometimes, anti-realist), and the second the realist view (i.e. ...
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This document was written with intent to send to the Encyclopedia of Evolutionary Psychological Science, as I was invited to submit an entry for their encyclopedia. However, upon completion, the editor, Todd Shackelford, sent me an email letting me know that “After further discussion, we have decided to eliminate this entry. You are now free to send to a different publication.”. This series of events should probably be interpreted in the light of a recent shaming of Shackelford by a journalist, which happened in between the invitation and the submission of the entry, which has made him more weary of taking on controversial material (Schulson, 2018).
... El desarrollo de este enfoque, el patrón anatómico y morfológico ha sido asignado directamente, en tales taxonomías populares de raza, color de la piel en forma de una capa de identidad. A pesar de la gama continua de coloración en la pigmentación cutánea (Relethford, 2009), estas entidades taxonómicas popular discretos son generalmente vistos en distinciones binarias, y así se simplifican en 'Negro' y 'Blanco' (Shanklin, 1998). Para una discusión concisa de algunos de los problemas relacionados con la piel y la raza, ver Gowland y Thompson (2013). ...
Chapter
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The maqbara located under the Plaza de España in Ecija included many burials dating from the period immediately after the Islamic conquest of Iberia. As only Muslims could be buried there, the individuals buried in the necropolis formed a diverse and yet discrete sample of early medieval people from Andalucía. The palaeopathologies found were very well described and documented in the original excavation reports, and aspects of the skeletal variability of the buried individuals have been the focus of previous bioarchaeological studies. This paper attempts to synthesise these studies and develop the concept of using a series of osteobiographies to form a potentially representative skeletal sample for further study.This enables the multiplicities of identity to be expressed and compared, but maintains the amazing large sample size of the original excavation. The current study places stress on the growth process and understanding the role of activity practices in shaping the individual life course.
... Human skin is diverse in color, since it exhibits a range of white, brown and black tones. This charac- teristic is used to distinguish or classify different ethnicities 1 . Its appearance is due to the blend of pig- ments or chromophores that absorb particular electro- magnetic wavelengths and transmit or reflect them to the visible light spectrum 2-4 . ...
... Esto se debe a que fueron recolectados por expedicionarios de fines del siglo XIX y principios del XX con metodologías propias de la época, que buscaban esqueletos con buen grado de preservación y con rasgos excepcionales, como la modificación cultural del cráneo. Aquellos objetivos estaban relacionados a la clasificación racial y el cráneo se consideraba diagnóstico para esos fines (Stagnaro, 1993;Relethford, 2009). De allí el interés particular por ese elemento anatómico, en detrimento del postcráneo. ...
Article
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Se presenta un estudio multi enfoque basado en entierros humanos provenientes de Laguna del Juncal, depositados en forma de bochones en las colecciones de dos museos regionales del Alto Valle del Río Negro desde la década de 1970. Los restos presentan la característica coloración oscura que ha dado lugar a numerosas menciones a lo largo de la historia de la arqueología del río Negro. El objetivo de este trabajo es estudiar la coloración de los restos (natural vs. antrópica) y evaluar su cronología. Para ello se presenta una caracterización bioarqueológica, cronológica y tafonómica de los individuos y sus matrices sedimentarias, utilizando análisis químicos y microscópicos. Se excavaron dos individuos, un adulto y otro subadulto, ambos con escaso material cultural asociado y fueron datados en 720 ± 24 y 754 ± 24 años AP respectivamente. La preservación del adulto es entre regular y buena, mientras que el subadulto presentó peor preservación. Mediante microanálisis químicos (MEB) se registró alto contenido de manganeso y hierro en los sedimentos, así como en el material óseo, lo cual explicaría su coloración oscura. Se discuten los resultados en el marco de los conocimientos actuales de los entierros del noreste de Patagonia. ABSTRACT We present a multi-focus study based on human burials from Laguna del Juncal, deposited in a plaster wrap in the collections of two regional Museums of the Río Negro Upper Valley since the 1970s. The remains present the characteristic dark coloration that has been frequently mentioned throughout the history of the archaeology of the Negro river, Argentinian Patagonia. The aim of this work is to study the coloration of the remains (natural vs. anthropic) and evaluate their chronology. To achieve this, a bioarchaeological, http://doi.
... There are two retorts. The first is that even if human variation were completely clinal, researchers could still classify it without committing some kind of scientific sin Relethford (2009). Think of age, for example. ...
Article
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Many intellectuals enthusiastically denounce those who argue that genes play some role in cognitive differences between human populations. However, such proposals are perfectly reasonable and are, in fact, consistent with the Darwinian research tradition in which most modern social scientists profess to operate. We argue that population-based cognitive differences are congruent with our best understanding of the world because there are strong reasons to believe that different environments and niches selected for different physical and psychological traits, including general cognitive ability. Like most hereditarians (those who believe it likely that genes contribute to differences in psychological traits among human populations), we do not believe there is decisive evidence about the causes of differences in cognitive ability. But we will argue that a partial genetic hypothesis is most consistent with the Darwinian research tradition.
... Cline distribution. Even at high level of geographic differentiation, the skin colour variation is clinal, varies continuously along clines, not well described by discrete racial categories (Relethford 2009). But the classic pattern of clinal variation is not entirely supportive against species delimitation; rather it is a direct indication of the interaction at least along both the primary and secodary contact zones between two or more taxa. ...
Article
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Abstract. The subspecies of the biological species concept with incomplete reproductive isolation versus the incipient sibling species of the phylogenetic species concept with permeable reproductive barrier are still applied side by side in the everyday practice of taxonomy. Both terms refer to the same organisms diverged mostly in allopatry with various stages of reproductive isolation. Question remained: how human ranks these entities organised by nature? The reliable ranking of living hierarchies is retarded and even obscured by the suppressed state of taxonomy. Disappointing scenario: the science of biodiversity is stuck in century old macromorphologies without innovation of fine phenomics and without exploring its hightech and high-throughput potential. The empirical science of taxonomy is “modernised” by the neutral DNA marker industry diverting the epistemological focus from empirical to virtual. Virtuality of noumenon is used to camouflage the phenomenon of the adverse environmental processes, the wasteful byproducts of the profit oriented liberalized economy. The sensual reality of species and the accelerated species extinction is effectively masked by the virtual sciences of the abstract: numbers, data, statistics, algorithms, equations, models and ideas. To understand the birth of a young incipient species we have briefly reviewed the postmodern development of the unified phylogenetic species concept. (1) The reality of species and higher phylogenetic taxa. (2) The biological and phylogenetic species. (3) How to delineate phylogenetic species? (4) The infinite versus finite division of phylogenetic species. (5) The construct of the unified species concept. (6) Taking subspecies and race out of science. Without recognition of incipient siblings of the phylogenetic species the biodiversity remains underestimated and the pharisaic anti-science ranking of humans remains with us. The discovery of speciation trait that is the sexual adaptive structures in reproductive barrier building, which are detectable by fine phenomics, gives perspective to find the finite division, the dynamic initial split in the continuous process of diversification. The speciation traits produced by integrative organisation, as opposed to competitive selection, help to unify the operational criteria of the biological species concept that is the speciation by reproductive isolation with the general concept of phylogenetic species that is the causal process of the separately evolving metapopulation lineages. The subspecies and racial ranking is untenable anymore, we suggest taking subspecies and race out of science: the finite division of the initial split detected by speciation traits is the birth of the phylogenetic incipient sibling species. There is no “subspecies”and “races”, as there is no “subindividual” in the biological organisation. In the present caddisfly taxonomy the subspecies remained as a valid status in the Potamophylax cingulatus caddisfly species group. With a clear distinction between the neutral and adaptive traits in the P. cingulatus species group and applying the subtle and stable shape divergences in phallic fine structures we have proposed to change the taxonomic status of subspecies to incipient sibling phylogenetic species rank: Potamophylax alpinus stat. nov., P. depilis stat nov., P. ibericus stat. nov., P. inermis stat. nov., reinstated the species status of P. cingulatus stat. restit. and we have described three new species: P. fesus Oláh, P. portugalicus Oláh et Szczesny, and P. transalpinus Oláh & Coppa, spp. nov.
... Cline distribution. Even at high level of geographic differentiation, the skin colour variation is clinal, varies continuously along clines, not well described by discrete racial categories (Relethford 2009). But the classic pattern of clinal variation is not entirely supportive against species delimitation; rather it is a direct indication of the interaction at least along both the primary and secodary contact zones between two or more taxa. ...
Article
Full-text available
Abstract. The subspecies of the biological species concept with incomplete reproductive isolation versus the incipient sibling species of the phylogenetic species concept with permeable reproductive barrier are still applied side by side in the everyday practice of taxonomy. Both terms refer to the same organisms diverged mostly in allopatry with various stages of reproductive isolation. Question remained: how human ranks these entities organised by nature? The reliable ranking of living hierarchies is retarded and even obscured by the suppressed state of taxonomy. Disappointing scenario: the science of biodiversity is stuck in century old macromorphologies without innovation of fine phenomics and without exploring its hightech and high-throughput potential. The empirical science of taxonomy is “modernised” by the neutral DNA marker industry diverting the epistemological focus from empirical to virtual. Virtuality of noumenon is used to camouflage the phenomenon of the adverse environmental processes, the wasteful byproducts of the profit oriented liberalized economy. The sensual reality of species and the accelerated species extinction is effectively masked by the virtual sciences of the abstract: numbers, data, statistics, algorithms, equations, models and ideas. To understand the birth of a young incipient species we have briefly reviewed the postmodern development of the unified phylogenetic species concept. (1) The reality of species and higher phylogenetic taxa. (2) The biological and phylogenetic species. (3) How to delineate phylogenetic species? (4) The infinite versus finite division of phylogenetic species. (5) The construct of the unified species concept. (6) Taking subspecies and race out of science. Without recognition of incipient siblings of the phylogenetic species the biodiversity remains underestimated and the pharisaic anti-science ranking of humans remains with us. The discovery of speciation trait that is the sexual adaptive structures in reproductive barrier building, which are detectable by fine phenomics, gives perspective to find the finite division, the dynamic initial split in the continuous process of diversification. The speciation traits produced by integrative organisation, as opposed to competitive selection, help to unify the operational criteria of the biological species concept that is the speciation by reproductive isolation with the general concept of phylogenetic species that is the causal process of the separately evolving metapopulation lineages. The subspecies and racial ranking is untenable anymore, we suggest taking subspecies and race out of science: the finite division of the initial split detected by speciation traits is the birth of the phylogenetic incipient sibling species. There is no “subspecies”and “races”, as there is no “subindividual” in the biological organisation. In the present caddisfly taxonomy the subspecies remained as a valid status in the Potamophylax cingulatus caddisfly species group. With a clear distinction between the neutral and adaptive traits in the P. cingulatus species group and applying the subtle and stable shape divergences in phallic fine structures we have proposed to change the taxonomic status of subspecies to incipient sibling phylogenetic species rank: Potamophylax alpinus stat. nov., P. depilis stat nov., P. ibericus stat. nov., P. inermis stat. nov., reinstated the species status of P. cingulatus stat. restit. and we have described three new species: P. fesus Oláh, P. portugalicus Oláh et Szczesny, and P. transalpinus Oláh & Coppa, spp. nov.
... The results suggest that postcrania are better at identifying sex than ancestry. Osteometric variation has been shown to demonstrate correlations with population history and structure [20,31]. The results of the current study are consistent with previously published postcraniometric data [12,14]. ...
Article
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With the acceptance of the Daubert criteria as the standards for best practice in forensic anthropological research, more emphasis is being placed on the validation of published methods. Methods, both traditional and novel, need to be validated, adjusted, and refined for optimal performance within forensic anthropological analyses. Recently, a custom postcranial database of modern South Africans was created for use in Fordisc 3.1. Classification accuracies of up to 85% for ancestry estimation and 98% for sex estimation were achieved using a multivariate approach. To measure the external validity and report more realistic performance statistics, an independent sample was tested. The postcrania from 180 black, white, and colored South Africans were measured and classified using the custom postcranial database. A decrease in accuracy was observed for both ancestry estimation (79%) and sex estimation (95%) of the validation sample. When incorporating both sex and ancestry simultaneously, the method achieved 70% accuracy, and 79% accuracy when sex-specific ancestry analyses were run. Classification matrices revealed that postcrania were more likely to misclassify as a result of ancestry rather than sex. While both sex and ancestry influence the size of an individual, sex differences are more marked in the postcranial skeleton and are therefore easier to identify. The external validity of the postcranial database was verified and therefore shown to be a useful tool for forensic casework in South Africa. While the classification rates were slightly lower than the original method, this is expected when a method is generalized.
... Several non-pathogenic phenotypes, particularly physical appearance traits, have been widely used in physical anthropology for racial classification, as they show high heritability and consistent differentiation between continental populations (Griffiths 2012;Relethford 2002;Relethford 2009). Furthermore, variation in continental ancestry proportions in Latin Americans (and other admixed populations) is significantly associated with physical appearance traits, being pigmentation the most studied one (Beleza et al. 2013;Hernandez-Pacheco et al. 2017;Parra et al. 2003;Ruiz-Linares et al. 2014;Shriver et al. 2003;Wilson et al. 2011). ...
Conference Paper
The history of Latin America involved extensive genetic admixture, particularly between Native Americans, Europeans and Africans. Although these conti-nental contributions to the genetic make-up of the region have been explored previously with genetic data, more precise information about sub-continental contributions has proven elusive. Applying new haplotype-based approaches to ~600,000 SNPs in ~7,000 Latin Americans from Brazil, Chile, Colombia, Mexico and Peru, this PhD thesis provides a comprehensive analysis of the sub-continental ancestry and demographic history of Latin America at a resolu-tion not previously achieved. Furthermore, using measurements on sampled individuals' physical appearances, I explore the impact of this fine-scale genet-ic structure on phenotypic variation across Latin America. To achieve these aims, I use a novel haplotype-based statistical technique that I compare to previously published haplotype-based and allele-frequency-based methods, using real data and simulations mimicking Latin American admixture. I show that this new approach provides a substantial increase in accuracy, al-lowing more precise inference about ancestral components at both regional and individual levels. Strikingly, Native American ancestry across Latin Ameri-ca mirrors the geographic locations of present-day Native groups. Furthermore, non-Native ancestries match to precise areas within the Iberian Peninsula and elsewhere, consistent with historical records detailing migrations and highlight-ing previously unseen ancestry sources. For the first time in single-sampled individuals, I date the timings of these non-Native Post-Columbian genetic contributions, including newly identified recent contributions related to East Asia. Finally, I show how this sub-continental ancestral reconstruction corre-lates with variation in pigmentation and facial features in Latin Americans, un-earthing new associations that could not be found with available techniques. Overall, I demonstrate how increasing the robustness and accuracy of fine-scale genetic structure analysis allows a comprehensive picture of the histori-cal and biological diversity of Latin America, highlighting the impact of regional genetic variation on human phenotypic diversity.
... A more realistic view of human variation involves a multivariate perspective, reducing the overlap between groups (Edwards, 2003). Both genetic (Allocco, Song, Gibbons, Ramoni, & Kohane, 2007;Bamshad et al., 2003;Jorde & Wooding, 2004;Pritchard, Stephens, & Donnelly, 2000;Rosenberg et al., 2002) and cranial morphological studies (Howells, 1973(Howells, , 1989(Howells, , 1995Ousley, Jantz, & Freid, 2009;Relethford, 2009;Roseman & Weaver, 2004) employing multiple variables have revealed geographic patterning in worldwide samples, which allows classification rates greater than those expected by random chance. However, overlap will always exist, therefore rejecting an extremist, typological view of classification. ...
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Objectives: Probit has not been applied to ancestry estimation in forensic anthropology. The goals of this study were to: (1) evaluate the performance of probit analysis as a classification tool for ancestry estimation using ordinal data and (2) expand our current understanding of human cranial variation for an understudied population. Methods: Multivariate probit models were used to classify the ancestral affiliation of Filipino crania using morphoscopic traits. Ancestral reference populations represented Africa, Asia, and Europe in a three-group model, with the addition of Hispanics in a four-group model. Posterior probabilities across these groups were interpreted as admixture proportions of an individual. Model performance was also evaluated for individuals with missing data. Results: The overall correct classification rates for the three-group and four-group models were 72.1% and 68.6%, respectively. Filipinos classified as Asian 52.9% of the time using three ancestral reference groups and 48.6% using four groups. A large portion of Filipinos also classified as African. There were no significant differences in classification trends or accuracy rates between complete crania and crania with at least one missing variable. Conclusions: Multivariate probit models using morphoscopic traits perform well when populations are represented in both training and test samples. Probit can also accommodate individuals with missing data. Classifying Filipinos showed only moderate success. Filipinos are more phenotypically similar to Africans than the other Asian samples used here, but still affiliate most closely as Asian. Ancestry methods would benefit from including Filipinos as a reference sample given the additional variation they provide to the continental category of Asian.
... This perspective complements Livingstone's famous "there are no races, only clines" (1962) statement, which refers to the spectrum of continuous human phenotypic variation we see globally. Two examples of continuous geographic variation in the human species include human cranial shape and size (Relethford 2009) and skin color, a trait strongly influenced by natural selection, showing clinal variation in epidermal melanin moving north and south away from the most intensive UV radiation around the Equator (Gibbons 2014;Fig. 3). ...
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Abstract In 1956, evolutionary biologist J.B.S. Haldane posed a question to anthropologists: “Are the biological differences between human groups comparable with those between groups of domestic animals such as greyhounds and bulldogs…?” It reads as if it were posted on social media today. The analogy comparing human races to dog breeds is not only widespread in history and pop culture, but also sounds like scientific justification for eschewing the social construction of race, or for holding racist beliefs about human nature. Here we answer Haldane’s question in an effort to improve the public understanding of human biological variation and “race”—two phenomena that are not synonymous. Speaking to everyone without expert levels of familiarity with this material, we investigate whether the dog breed analogy for human race stands up to biology. It does not. Groups of humans that are culturally labeled as “races” differ in population structure, genotype–phenotype relationships, and phenotypic diversity from breeds of dogs in unsurprising ways, given how artificial selection has shaped the evolution of dogs, not humans. Our demonstration complements the vast body of existing knowledge about how human “races” differ in fundamental sociocultural, historical, and political ways from categories of nonhuman animals. By the end of this paper, readers will understand how the assumption that human races are the same as dog breeds is a racist strategy for justifying social, political, and economic inequality.
... The deconstruction of race has been mostly successful in science circles, to the extent that the biological basis of race is without foundation and most basic biological and social scientists have rejected the concept (Eberhardt, 2005;Eberhardt & Randall, 1997;Relethford, 2009). The deconstruction of race by scientists has not been accepted widely outside of specific academic circles, however. ...
... Genetic variation (although there is not much) between populations tends to be geographically structured, as expected from the partial isolation of human populations during much of their history (Jorde & Wooding 2004). In this regard, race may be considered first-order approximation to the geographically structured phenotypic variation in the human species (Relethford 2009). The influence of environmental exposure, resulting from geographic variation, on the development of endometriosis has been suggested (Soave et al. 2015). ...
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Endometriosis is a chronic, multisystemic disease often presenting with significant phenotypic variation amongst patients. The impact of race/ethnicity on the prevalence of endometriosis, as well as disease presentation, is a question of interest which has been explored for the last century. This narrative review explores the historical perspective of endometriosis and race/ethnicity as well as the evidence available to date. Furthermore, we discuss the potential implication of the bias perpetuated on this topic, specifically in the areas of medical education, research, and clinical care. In consideration of these intersecting realms, we suggest priorities for future consideration of race/ethnicity as it pertains to the delivery of care for endometriosis patients. Lay summary: The relationship between race/ethnicity and endometriosis has been explored for over a century. Historical bias and poorly conducted research have led to the idea that this condition is less likely to be diagnosed in certain racial groups, such as Black women. We review the current state of evidence and highlight important limitations within medical education and research on this topic. Finally, we advocate for a shifting viewpoint as we strive to deliver equitable and outstanding care for all endometriosis patients.
... 33 There is an established relationship between the variation in cranial phenotypes and geographical distances. 34 The individuals chosen for study were from different parts of Nepal. However, due to a relatively small sample size it cannot be generalized. ...
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Background: The description of the human face has been a major concern since long time. Indi­vidual identification is one such field where anthropometric parameters, especially cephalo-facial measurements, are an important tool in determining the various shapes of head and face. Hence the objective of the study was to determine the shapes of head and face. Methods: The present study was a cross-sectional and observational type which consisted of 222 individuals (115 female and 107 male). It was conducted from January to June, 2019 after receiving ethical approval. The cephalic and facial indices were derived after measuring length and breadth of head and face. The collected data was entered in excel and analyzed with SPSS (22.0). Results: The present study observed that the most common type of face was hyperleptoprosopic 168 (75.68%) followed by leptoprosopic 43 (19.37%), mesoprosopic 10 (4.50% female only) and euryprosopic 1 (0.93% male only). Similarly, the most common type of head was dolicocephalic 165 (74.33%), followed by mesocephalic 51 (22.97%), and brachycephalic 6 (2.70%). Conclusions: This study concluded that the hyperleptoprosopic face was most common type and the least common type was euryprosopic face. The most common type of head was found to be dolicocephalic and the least common type was found to be brachycephalic.
... wide or roundheaded) is viewed as more great under cool pressure, while a long head, i.e., dolichocephalic, is relied upon to be more helpful during hot climatic conditions. [13][14]. Nonetheless, in chilly environment Upper East Asian examples, these ends are invalidated, with wide and extended crania that don't actually squeeze into assumed cranial shape alterations for cold-environment gatherings. ...
Article
Cephalic record is otherwise called cranial list or broadness file. It's processed as the length separated by the width of the skull times by 100. Assessing varieties in cephalic records across guardians, children, and family members can uncover if hereditary qualities are passed down hereditarily. The exploration included 480 clinical understudies (296 male and 184 female understudies). Hardlika's methodology was utilized to decide the cranial record. Most of the people were Mesocephalic (cephalic record 7579.9). 43.58 percent of guys and 42.93 percent of young ladies had a mesocephalic head. Men’s had an average cephalic record of 81.24 3.66, while ladies had a regular cephalic file of 80.31 4.28. Somatometric estimations, for example, the face and cephalic records, are used in human criminological sciences. These lists utilized a human's sex and racial populace to compute their singular character. This exploration aims to give benchmark data to cephalic records and face files in the Central Indian populace, contrasting these outcomes with past research. This material will be helpful to legal specialists, anatomists, and others in related disciplines. The cephalic record (CI), in some cases called the cranial list, is the proportion of the head's maximal expansiveness to length. The motivation behind the review was to research the anthropometry of cranial qualities. The review's objective was to check out the anthropometry of cranial qualities utilizing google structures circled in the school gatherings. Experts in scientific science will see the data as advantageous, just as in clinical, medico-lawful, anthropological, and excavator settings.
... Bethard and DiGangi argue against the evolutionary and ecogeographic grounding of cranial morphoscopic traits central to forensic anthropological application, but assume a notion of heredity that is unreasonable in this context. Some, if not most, cranial morphoscopic traits are latent traits (i.e., interorbital breadth and nasal width are visual assessments of cranial measurements) and as such, heritability estimates can be extrapolated from studies exploring the continuous and genetic data [51][52][53][54][55][56][57][58]. Hefner and Linde [52] provide succinct descriptions of each morphoscopic trait and include such topics as heritability, historical development, gross anatomy, and functional morphology in their discussion. ...
... They investigate a variety of traits, recognizing that not all of these characteristics are distributed in the same way through the different populations under study, and that the reliability of their results may vary drastically depending on the relations between those populations and available comparative samples. These different identifications are not made because these groups are fundamental biological types of humans (Relethford 2009). They are made because human populations are physically variable in all kinds of detectable ways, because the remains that are found often reflect the makeup of local populations, and because both law enforcement agencies and communities at large need to know the identities of the dead. ...
... The relationship between phenotypic traits and genetic biogeographic ancestry can be predicted, to some extent, due to intrinsic distinctions presented by ancestor populations around the globe [60]. Furthermore, pigmentation traits prediction can be considerably improved by the inclusion of phenotypic categories in the underlying classification models [61]. ...
Article
Background The advent of massively parallel sequencing (MPS) applications focused on the generation of forensic-quality full mitochondrial genome sequences led to a popularization of the technique on a global scale. However, the lack of forensic-graded population databases has refrained a wider adoption of full genome sequences as the industry standard, despite its better discrimination capacity of individual maternal lineages. Purpose This work describes a forensic-oriented full mtDNA genome database comprised of 480 samples from a Southern Brazilian population. Methods A collection of mitochondrial sequences were obtained from low-pass, full genome DNA sequencing results. The complete sample set was evaluated regarding haplotype composition and distribution. Summary statistics and forensic parameters were calculated and are presented for the database, with detailed information concerning the impact of removing genetic information in the form of specific variants or increasingly larger genomic regions. Interpopulational analysis comparing haplotypical diversity in Brazilian and 26 worldwide populations was also performed. The association between mitochondrial genetic variability and phenotypic diversity was also evaluated in populations, with self-declared ancestry and three distinct phenotypic pigmentation traits (eyes, skin and hair colors) as parameters. Results The presented database can be used to evaluate mitochondrial-related genetic evidence, providing LR values of up to 20,465 for unobserved haplotypes. Haplotype distribution in Southern Brazil seems to be different than the remaining of the country, with a larger contribution of maternal lines with European origin. Despite association can be found between lighter and darker phenotypes or self-declared ancestry and haplotype distribution, prediction models cannot be reliably proposed due to the admixed nature of the Brazilian population. Conclusions The proposed database provides a basis for statistical calculation and frequency estimation of full mitochondrial genomes, and can be part of an integrated, representative, national database comprising most of the genetic diversity of maternal lineages in the country.
Book
Disseminating what is currently known about the skeletal biology of the ancient Rapanui and placing it within the wider context of Polynesian skeletal variation, this volume is the culmination of over thirty years of research into the remotely inhabited Easter Island. Compiling osteological data deriving from Rapanui skeletal remains into one succinct analysis, this book demonstrates how the application of modern skeletal biology research techniques can effectively be employed to address questions of human population origins and microevolution. Craniometrics and DNA analysis are used to provide indications as to Rapanui ancestral lineage. Evidence is presented in a user-friendly manner to allow researchers and graduates to critically analyse the current knowledge of prehistoric Rapanui skeletal variation. An important resource providing valuable evidence from human biology that modifies earlier archaeological and cultural anthropological views, this book will stimulate further research into the Rapanui. Provides a comprehensive analysis of Rapanui prehistory, useful for archaeologists, bioarchaeologists and researchers interested in the history of Easter Island Biological evidence is presented in a succinct and easy to read manner, allowing researchers to further evaluate preconceptions originating from cultural anthropology and folklore Cranial differences are combined with DNA evidence to examine the genetic relationships between different Rapanui tribes.
Chapter
It is not easy to accurately describe one's cultural identity. There are many factors to consider – from diversity narratives constructed over a single lifetime to those that have been accrued by greater populations. One way to engage this discussion is to provide an overview of diversity key terms that are most closely associated with culture. Important historical events should also be emphasized, as they provide context to many of the challenges faced in modern times. Such topics often cause friction among European Americans – many of whom are loath to judge the actions of those who share their skin color. To start this conversation, the chapter introduces the author, Kimberly, and the five interviewees, Lina, Darnell, Alice, Sheila, and Talia, who discuss their understanding of cultural identity as it applies to their lives.
Chapter
This chapter draws on bioarchaeological research of activity to explore how daily life was transformed for urban colonial inhabitants of Mexico City. It examines a portion of the skeletal remains that were found in association with the architectural remains of the hospital during rescue excavations in the early 1990s when a new metro line was being built through the historic downtown of Mexico City. Europeans mostly male, arrived at positions of power in the colonial government or as missionaries of various different Christian orders. The kind of work a person performed was one of the many ways that social reputation was understood in colonial Mexico. Bioarchaeologists analyze variations in the skeleton that result from biomechanical stress to reconstruct what kind of daily activities a person performed throughout their life. Social identities, in all their intersecting forms, constrained the kinds of labor opportunities available to individuals in urban New Spain.
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This chapter discusses patterns that are often observed from the study of human differences that can be organized by racial groupings. Debates over the validity of the concept of race are divided into two camps called “race deniers” and “race acknowledgers.” This chapter reviews how concepts about race, racial differences, and racism are discussed within the social sciences, generally, and cultural competence advocacy, specifically. © Springer International Publishing AG, part of Springer Nature 2018.
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Grasping the various aspects of Islamophobia in Muslim societies requires much finer methods in order to decipher the intentions of the actors in distinctive life situations varying from the media to education. This article engages in a debate as to whether Islamophobia is a new type of racism, i.e., cultural, geographical, phenotypical, or Xeno-racism, and the relatively recent type that has emerged in neo-liberal states: anti-Muslim racism. In a Muslim-majority society, the ‘culture’ of members is fairly homogenous, so Islamophobia takes another cue, focusing on external markers, like the headscarf or beard. While anti-Muslim racism is sometimes exercised along more subtle lines of cultural difference in Muslim societies, it prevails through old-fashioned, phenotypical racism. The representation or rather misrepresentation of Islam and/or Muslims in the media can be understood as the prevailing source of antagonism between the secular and the traditionalist segments of Turkish society; indeed, Turkish media representation produces and reproduces a racialization of the majority, predominately by rendering Islam invisible, or by depicting Muslims in ways that denigrate their clothing, manners, style, and way of living across various mass media forms.
Article
Assigning correct population affinity to a skeleton can contribute important information to an investigation-yet recent work highlights high error rates when classifying Latinos with a traditional tool, Fordisc 3.1 (FD3). Our study examines whether misclassification trends exist, and whether these can be used to infer population affinity. We examine the relationships among ancestry, geography, and FD3 misclassifications of Latinos using canonical variate analysis and unsupervised model-based clustering of craniometrics. Northern Mexicans appear more strongly associated with FD3 references samples with elevated amounts of European ancestry (e.g., American Blacks and Whites), while Southern Mexicans are more strongly associated with FD3 reference samples with reduced amounts of European ancestry (e.g., Guatemalans and Native Americans). FD3 classifications revealed that Latinos exhibited lower posterior probabilities when compared to other common case demographics (Whites and African Americas), even when the classification was "correct." We make recommendations for practitioner interpretation of FD3 reports for casework.
Article
Regional variation in pelvic morphology and childbirth has long occurred alongside traditional labour support and an understanding of possible normal courses of childbirth for each population. The process of migration and globalization has broken down these links, while a European model of ‘normal’ labour has become widespread. The description of ‘normal’ childbirth provided within obstetrics and midwifery textbooks, in fact, is modelled on a specific pelvic morphology that is common in European women. There is mounting evidence, however, that this model is not representative of women's diversity, especially for women of non-white ethnicities. The human birth canal is very variable in shape, both within and among human populations, and differences in pelvic shapes have been associated with differences in the mechanism of labour. Normalizing a white-centred model of female anatomy and of childbirth can disadvantage women of non-European ancestry. Because they are less likely to fit within this model, pelvic shape and labour pattern in non-white women are more likely to be considered ‘abnormal’, potentially leading to increased rates of labour intervention. To ensure that maternal care is inclusive and as safe as possible for all women, obstetric and midwifery training need to incorporate women's diversity. This article is part of the theme issue ‘Multidisciplinary perspectives on social support and maternal–child health’.
Chapter
Social media is awash with the latest discoveries about the human past. Headlines read: “DNA of ancient skeleton linked to modern indigenous peoples,” “Ancient DNA suggests the first Americans sidestepped the glaciers,” and “Ancient DNA reveals secrets of human history.” These headlines all come from respected outlets with a connection to the academic community (Smithsonian, Science, and Nature, respectively). However, news media outlets with a more popular audience have also become interested in the stories and histories being revealed about our ancestors through modern and ancient DNA, and new toolkits include a heavy bioinformatics component. As expected, these headlines are a bit more sensational: “Are you tall? Then thank your ancient cousins: Neanderthal DNA still helps dictate your HEIGHT and whether you suffer from lupus and schizophrenia” reads a Daily Mail headline about Neanderthal admixture. Another reads: “The ‘founding father’ of Europe: DNA reveals all Europeans are related to a group that lived around 35,000 years ago.” Yet another, seemingly contradictory, headline reads: “Europeans drawn from three ancient ‘tribes.’” Communications technology has evolved in lockstep with advances in DNA recovery and analysis over the last two decades, perhaps giving the impression that studies of past population movements are a recent development. However, interest in “ancient migrations” has a deep history in western science, beginning with analyses of the skull using what are now referred to as biological distance methods.
Article
As of 2015, 204 cases of missing and murdered Indigenous women and girls (MMIWG) remained unsolved in Canada, making it a major concern for Canadian Indigenous communities, who are still pressing for the resolution of these cases. In forensic anthropology, the assessment of population affinity can be useful to help identify victims. Population affinity, previously referred to as ancestry, is evaluated based on morphological analyses, which examine the size and shape of skeletal features, and metric analyses, which utilise skeletal measurements. However, morphological analyses strongly depend on an anthropologist’s experience with human variation, which makes the analyses particularly challenging to reproduce and standardise. The purpose of this study is to improve the rigour of morphological analyses by using 3D technology to quantify relevant cranial nonmetric population affinity traits. As there is currently little morphological data available for the Canadian Indigenous population, this research aims to develop a new technique that could aid in the identification of MMIWG. The study comprised a total of 87 adult female crania, including 24 of Canadian Inuit origin, 50 of European descent and 13 of African descent. The samples were imaged using photogrammetry, then analysed using a 3D shape analysis in 3DS Max. Results show that this method is satisfactory in correctly evaluating population affinity with an accuracy of 87.36% (jackknifed: 80.46%) and an average repeatability of 97%. Unfortunately, the small Canadian Indigenous sample size impacted the applicability of the results and further research will be required before the technique can be used to aid in the identification of MMIWG in Canada.
Article
Objectives: Thousands of migrants have died along the United States/Mexico border and many remain unidentified. The purpose of this research is to test whether estimations of population affinity, derived from craniometric data, can facilitate identification of migrant remains and provide a geographic region of origin rather than the broad label Hispanic. The appropriateness of current forensic reference data will also be assessed. Methods: A case study combined with craniometric data from positively identified and unidentified migrants from the Pima County Office of the Medical Examiner (n = 489) in Arizona and operation identification (n = 201) in Texas were compared to skeletal data representing Guatemalan (n = 87) and Mexican (n = 65) Mayans. Biological distance and discriminant function analyses were used to assess overall population relationships and classificatory models for forensic anthropological application. Results: The majority of evidence indicates that estimations of population affinity can assist in the facilitation identification of migrant remains, even when a broad classification is used. Biological distances among the groups suggest that positively identified Guatemalan and Mexican migrants are similar to one another but differ from Guatemalan and Mexican Mayans. Conclusions: Population affinity estimations can aid migrant identification, and current reference data used in forensic anthropological practice should be replaced with data from positive identifications. Estimates of geographic origin may be more useful than the broad generic term Hispanic for narrowing down the search for a missing person, but more data and research is needed to achieve this goal. Although, the utility of geographic origin estimates relies on transnational data centralization and sharing, which is not always the case.
Chapter
The urgent need for disaster behavioral health services commonly brings together service providers from locations around the world to care for disaster-affected populations. Additionally, providers working in the United States are encountering more ethnically and culturally diverse clients. Now and in the future, relief workers should anticipate the need to provide culturally sensitive services to people from diverse backgrounds. Disaster survivors’ interpretation of and response to disasters are highly influenced by their culture. It is evident that cultural competence is crucial in providing effective disaster behavioral health services. In this chapter, we describe guiding principles and resources needed to optimally support providers in effectively planning and delivering trauma-informed and culturally competent mental health services. Behavioral health providers can utilize and adapt these guidelines as needed to address the unique needs of culturally diverse communities. Cultural competence is complex and contextual. Perhaps it is not a goal to be achieved, but rather an ongoing, evolving process. We invite the reader to think beyond the frameworks provided in this chapter and continue to remain open and curious toward the various intersections of social identities.
Article
Racial designations have evolved over the years to accommodate the changes in our population demographics. The Federal Office of Management and Budget (OMB) has developed Federal Standards to assist with the uniform documentation and reporting of race and ethnicity. A minimum of five defined categories currently exist for race (American Indian or Alaska Native, Asian, Black or African American, Native Hawaiian or Other Pacific Islander and White). Ethnicity is separated into either Hispanic origin or Non-Hispanic origin. Current death certificates allow for the selection of one or more races; however, only one ethnicity may be chosen. Race of unknown decedents is either based subjectively on the observer's opinion or, in severely decomposed or skeletal remains, by anthropological analysis utilizing sound statistical methodology. If the data and statistical analysis suggest a good classification, the race determination will be correct more often than not. Information obtained from the National Missing and Unidentified Persons System (NamUs) indicates that absence of race determination does not hinder the identification potential. Mortality rates, life expectancy, disease risk and causes of death are often disaggregated by race and/or ethnicity. Differences in the presentation, etiology and outcomes of many diseases have been based on race and ethnicity data. Uniform collection of this data is the key to its importance. Medical examiners, coroners and others tasked with examination of decedents should utilize the defined categories set forth in the OMB Revised Standards for race and ethnicity documentation.
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We argue that because of a long history of intergroup conflict and competition, humans evolved to be tribal creatures. Tribalism is not inherently bad, but it can lead to ideological thinking and sacred values that distort cognitive processing of putatively objective information in ways that affirm and strengthen the views and well-being of one’s ingroup (and that increase one’s own standing within one’s ingroup). Because of this shared evolutionary history of intergroup conflict, liberals and conservatives likely share the same underlying tribal psychology, which creates the potential for ideologically distorted information processing. Over the past several decades, social scientists have sedulously documented various tribal and ideological psychological tendencies on the political right, and more recent work has documented similar tendencies on the political left. We contend that these tribal tendencies and propensities can lead to ideologically distorted information processing in any group. And this ideological epistemology can become especially problematic for the pursuit of the truth when groups are ideologically homogenous and hold sacred values that might be contradicted by empirical inquiry. Evidence suggests that these conditions might hold for modern social science; therefore, we conclude by exploring potential ideologically driven distortions in the social sciences.
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Biological racial realists face a range of problems. These problems depend on whether they claim races are natural objective classificatory groups (i.e., that races are monistic) or that races are pragmatic or investigation dependent classifications (i.e., that races are pluralistic). Realists who say races are objective face selection problems in which they must choose between equally valid but non-concordant classifications that cannot be decided objectively, and realists who claim that racial classifications can be decided by practical considerations face the problem of pragmatics in which they construct what races are according to investigation dependent criteria decided by the interests of the investigator. I conclude that monistic theorists cannot prove that races are objective and pluralist theories risk not being able to distinguish themselves from constructionism. In review of the literature, I argue that there are no viable biologically realist racial theories left and that the best explanations we have to account for racial phenomena are socially constructionist theories.
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It is often taken for granted that the human species is divided in rather homogeneous groups or races, among which biological differences are large. Studies of allele frequencies do not support this view, but they have not been sufficient to rule it out either. We analyzed human molecular diversity at 109 DNA markers, namely 30 microsatellite loci and 79 polymorphic restriction sites (restriction fragment length polymorphism loci) in 16 populations of the world. By partitioning genetic variances at three hierarchical levels of population subdivision, we found that differences between members of the same population account for 84.4% of the total, which is in excellent agreement with estimates based on allele frequencies of classic, protein polymorphisms. Genetic variation remains high even within small population groups. On the average, microsatellite and restriction fragment length polymorphism loci yield identical estimates. Differences among continents represent roughly 1/10 of human molecular diversity, which does not suggest that the racial subdivision of our species reflects any major discontinuity in our genome.
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We analyzed admixture in samples of six different African-American populations from South Carolina: Gullah-speaking Sea Islanders in coastal South Carolina, residents of four counties in the "Low Country" (Berkeley, Charleston, Colleton, and Dorchester), and persons living in the city of Columbia, located in central South Carolina. We used a battery of highly informative autosomal, mtDNA, and Y-chromosome markers. Two of the autosomal markers (FY and AT3) are linked and lie 22 cM apart on chromosome 1. The results of this study indicate, in accordance with previous historical, cultural, and anthropological evidence, a very low level of European admixture in the Gullah Sea Islanders (m = 3.5 +/- 0.9%). The proportion of European admixture is higher in the Low Country (m ranging between 9. 9 +/- 1.8% and 14.0 +/- 1.9%), and is highest in Columbia (m = 17.7 +/- 3.1%). A sex-biased European gene flow and a small Native American contribution to the African-American gene pool are also evident in these data. We studied the pattern of pairwise allelic associations between the FY locus and the nine other autosomal markers in our samples. In the combined sample from the Low Country (N = 548), a high level of linkage disequilibrium was observed between the linked markers, FY and AT3. Additionally, significant associations were also detected between FY and 4 of the 8 unlinked markers, suggesting the existence of significant genetic structure in this population. A continuous gene flow model of admixture could explain the observed pattern of genetic structure. A test conditioning on the overall admixture of each individual showed association of ancestry between the two linked markers (FY and AT3), but not between any of the unlinked markers, as theory predicts. Thus, even in the presence of genetic structure due to continuous gene flow or some other factor, it is possible to differentiate associations due to linkage from spurious associations due to genetic structure.
Article
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We studied human population structure using genotypes at 377 autosomal microsatellite loci in 1056 individuals from 52 populations. Within-population differences among individuals account for 93 to 95% of genetic variation; differences among major groups constitute only 3 to 5%. Nevertheless, without using prior information about the origins of individuals, we identified six main genetic clusters, five of which correspond to major geographic regions, and subclusters that often correspond to individual populations. General agreement of genetic and predefined populations suggests that self-reported ancestry can facilitate assessments of epidemiological risks but does not obviate the need to use genetic information in genetic association studies.
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The success of many strategies for finding genetic variants that underlie complex traits depends on how genetic variation is distributed among human populations. This realization has intensified the investigation of genetic differences among groups, which are often defined by commonly used racial labels. Some scientists argue that race is an adequate proxy of ancestry, whereas others claim that race belies how genetic variation is apportioned. Resolving this controversy depends on understanding the complicated relationship between race, ancestry and the demographic history of humans. Recent discoveries are helping us to deconstruct this relationship, and provide better guidance to scientists and policy makers.
Article
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Extensive research in human genetics on presumably neutral loci has shown that the overwhelming majority of human diversity is found among individuals within local populations. Previous apportionments of craniometric diversity are similar to these genetic apportionments, implying that interregionally differing selection pressures have played a limited role in producing contemporary human cranial diversity. Here we show that when cranial variation is independently partitioned using principal components analysis of Mosimann shape variables, some estimates of interregional craniometric differentiation are larger than those for most genetic loci. These estimates are similar to estimates for genetic loci where interregionally differing selection pressures are implicated in producing the observed patterns of variation within and among regions. These results suggest that differences among regions in at least some cranial features, particularly in the nasal region, are in part the product of interregionally differing selection pressures. Moreover, these results have implications for assessing the biological affinities of prehistoric samples that are temporally separated from contemporary human reference populations.
Article
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New genetic data has enabled scientists to re-examine the relationship between human genetic variation and 'race'. We review the results of genetic analyses that show that human genetic variation is geographically structured, in accord with historical patterns of gene flow and genetic drift. Analysis of many loci now yields reasonably accurate estimates of genetic similarity among individuals, rather than populations. Clustering of individuals is correlated with geographic origin or ancestry. These clusters are also correlated with some traditional concepts of race, but the correlations are imperfect because genetic variation tends to be distributed in a continuous, overlapping fashion among populations. Therefore, ancestry, or even race, may in some cases prove useful in the biomedical setting, but direct assessment of disease-related genetic variation will ultimately yield more accurate and beneficial information.
Article
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Equilibrium models of isolation by distance predict an increase in genetic differentiation with geographic distance. Here we find a linear relationship between genetic and geographic distance in a worldwide sample of human populations, with major deviations from the fitted line explicable by admixture or extreme isolation. A close relationship is shown to exist between the correlation of geographic distance and genetic differentiation (as measured by F ST) and the geographic pattern of heterozygosity across populations. Considering a worldwide set of geographic locations as possible sources of the human expansion, we find that heterozygosities in the globally distributed populations of the data set are best explained by an expansion originating in Africa and that no geographic origin outside of Africa accounts as well for the observed patterns of genetic diversity. Although the relationship between F ST and geographic distance has been interpreted in the past as the result of an equilibrium model of drift and dispersal, simulation shows that the geographic pattern of heterozygosities in this data set is consistent with a model of a serial founder effect starting at a single origin. Given this serial-founder scenario, the relationship between genetic and geographic distance allows us to derive bounds for the effects of drift and natural selection on human genetic variation. • genetic distance • genetic drift • HGDP-CEPH • human origins • microsatellites
Chapter
It has always been obvious that organisms vary, even to those pre-Darwinian idealists who saw most individual variation as distorted shadows of an ideal. It has been equally apparent, even to those post-Darwinians for whom variation between individuals is the central fact of evolutionary dynamics, that variation is nodal, that individuals fall in clusters in the space of phenotypic description, and that those clusters, which we call demes, or races, or species, are the outcome of an evolutionary process acting on the individual variation. What has changed during the evolution of scientific thought, and is still changing, is our perception of the relative importance and extent of intragroup as opposed to intergroup variation. These changes have been in part a reflection of the uncovering of new biological facts, but only in part. They have also reflected general sociopolitical biases derived from human social experience and carried over into “scientific” realms. I have discussed elsewhere (Lewontin, 1968) long-term trends in evolutionary doctrine as a reflection of long-term changes in socioeconomic relations, but even in the present era of Darwinism there is considerable diversity of opinion about the amount or importance of intragroup variation as opposed to the variation between races and species. Muller, for example (1950), maintained that for sexually reproducing species, man in particular, there was very little genetic variation within populations and that most men were homozygous for wild-type genes at virtually all their loci.
Conference Paper
Sewall Wright's population structure statistic, F-ST, measured among samples of world populations is often 15% or less. This would indicate that 85% of genetic variation occurs within groups while only 15% can be attributed to allele frequency differences among groups. In this paper, we show that this low value reflects strong biases that result from violating hidden assumptions that define FST. These limitations on FST are demonstrated algebraically and in the context of analyzing dinucleotide repeat allele frequencies for a set of eight loci genotyped in eight human groups and in chimpanzees. In our analyses, estimates of FST fail to identify important variation. For example, when the analysis includes only humans, F-ST = 0.119, but adding the chimpanzees increases it only a little, F-ST = 0.183. By relaxing the underlying statistical assumptions, the results for chimpanzees become consistent with common knowledge, and we see a richer pattern of human genetic diversity. Some human groups are far more diverged than would be implied by standard computations of F-ST, while other groups are much less diverged. We discuss the relevance of these findings to the application of biological race concepts to humans. Four different race concepts are considered: typological, population, taxonomic, and lineage. Surprisingly, a great deal of genetic variation within groups is consistent with each of these concepts. However, none of the race concepts is compatible with the patterns of variation revealed by our analyses.
Article
Race is generally used as a synonym for subspecies, which traditionally is a geographically circumscribed, genetically differentiated population. Sometimes traits show independent patterns of geographical variation such that some combination will distinguish most populations from all others. To avoid making "race" the equivalent of a local population, minimal thresholds of differentiation are imposed. Human "races" are below the thresholds used in other species, so valid traditional subspecies do not exist in humans. A "subspecies" can also be defined as a distinct evolutionary lineage within a species. Genetic surveys and the analyses of DNA haplotype trees show that human "races" are not distinct lineages, and that this is not due to recent admixture; human "races" are not and never were "pure." Instead, human evolution has been and is characterized by many locally differentiated populations coexisting at any given time, but with sufficient genetic contact to make all of humanity a single lineage sharing a common evolutionary fate.
Article
Leonard Lieberman, Rod Kirk, and Alice Littlefield report a significant decrease over the past 20 years in the percentage of physical anthropologists who support the race concept, while Matt Cartmill concludes that use of this concept did not decline during that period among anthropologists who study modern human variation. Neither study contradicts the other, since the two used different definitions and sampled different populations. More extensive sampling of the literature and more reliable survey techniques are needed to resolve the issue, [Keywords: race, history of ideas, biological anthropology]
Article
Recent controversies surrounding models of modern human origins have focused on among-group variation, particularly the reconstruction of phylogenetic trees from mitochondrial DNA (mtDNA) and, the dating of population divergence. Problems in tree estimation have been seen as weakening the case for a replacement model and favoring a multiregional evolution model. There has been less discussion of patterns of within-group variation, although the mtDNA evidence has consistently shown the greatest diversity within African populations. Problems of interpretation abound given the numerous factors that can influence within-group variation, including the possibility of earlier divergence, differences in population size, patterns of population expansion, and variation in migration rates. We present a model of within-group phenotypic variation and apply it to a large set of craniometric data representing major Old World geographic regions (57 measurements for 1,159 cases in four regions: Europe, Sub-Saharan Africa, Australasia, and the Far East). The model predicts a linear relationship between variation within populations (the average within-group variance) and variation between populations (the genetic distance of populations to pooled phenotypic means). On a global level this relationship should hold if the long-term effective population sizes of each region are correctly specified. Other potential effects on withingroup variation are accounted for by the model. Comparison of observed and expected variances under the assumption of equal effective sizes for four regions indicates significantly greater within-group variation in Africa and significantly less within-group variation in Europe. These results suggest that the long-term effective population size was greatest in Africa. Closer examination of the model suggests that the long-term African effective size was roughly three times that of any other geographic region. Using these estimates of relative population size, we present a method for analyzing ancient population structure, which provides estimates of ancient migration. This method allows us to reconstruct migration history between geographic regions after adjustment for the effect of genetic drift on interpopulational distances. Our results show a clear isolation of Africa from other regions. We then present a method that allows direct estimation of the ancient migration matrix, thus providing us with information on the actual extent of interregional migration. These methods also provide estimates of time frames necessary to reach genetic equilibrium. The ultimate goal is extracting as much information from present-day patterns of human variation relevannt to issues of human origins. Our results are in agreement with mismatch distribution analysis of mtDNA, and they support a “weak Garden o Eden” model. In this model, modern-day variation can be explained by divergence from an initial source (perhaps Africa) into a number o small isolated populations, followed by later population expansion throughout our species. The major populationn expansions of Homo sapiens during and after the late Pleistocene have had the effect of “freezing” ancient patterns of population structure. While this is not the only possible scenario, we do note the close agreement with ecent analyses of mtDNA mismatch distibutions. © 1994 Wiley-Liss, Inc.
Article
Authors of three studies (Leonard Lieberman, Blaine W. Stevenson, Larry T. Reynolds, and Matt Cartmill) agree that the concept of race has approached its lowest level of acceptance in a century. However, one of the studies (that of Cartmill) seems to show no significant change from 1965 to 1996. We analyze this paradox in terms of possible differences in the populations studied. [Keywords: race, physical anthropology, variation]
Article
Skin colour data obtained by reflectance spectrophotometry on indigenous populations are compared with environmental variables--latitude, temperature, humidity and altitude. Association with latitude predominates at all wavelengths. Temperatures show a small but appreciable association at the shorter wavelengths, humidity at wavelengths above 595 nm. Over 80 per cent of the total interpopulation variance at each wave length is accounted for by these variables, more at the shorter wavelengths. It is suggested that skin colour should be regarded as a complex of entities of differing selective values rather than a single entity.
Article
Skin color is a polygenically determined quantitative trait. Although it has been used extensively in studies of between-population variation, there have been relatively few studies of the inheritance of skin color. In this article we use measurements on 359 members of the Jirel population of eastern Nepal to assess the heritabilities and additive genetic correlations of three skin reflectance measures. Skin color was measured at the upper inner arm site at three wavelengths. A maximum likelihood approach was used to estimate sex and age effects on skin reflectance, heritabilities, and phenotypic variances at each wavelength and both additive genetic and environmental correlations between wavelengths. This technique incorporated information from 36 pedigrees with 2-25 members and 173 independent individuals. Likelihood ratio tests were used to assess the significance of specific variance/covariance components. The results indicate that skin reflectances are moderately heritable at all three wavelengths. The pairwise phenotypic correlations ranged from 0.76 to 0.88. The observed additive genetic correlations were not significantly different from 1.00, suggesting that the same loci influence variation at each wavelength. This evidence for relatively complete pleiotropy implies that measurements at multiple wavelengths yield little additional genetic information, although they may be useful for reducing measurement error. Based on estimates of the genetic and phenotypic covariance matrices, we determined that skin reflectance measurements are expected to provide only as much information for assessing local between-population genetic variation as a single two-allele polymorphic marker. Therefore microevolutionary studies based on skin color variation should be viewed with caution.
Article
Most anthropologists have abandoned the concept of race as a research tool and as a valid representation of human biological diversity. Yet, race identification continues to be one of the central foci of forensic anthropological casework and research. It is maintained in this paper that the successful assignment of race to a skeletal specimen is not a vindication of the race concept, but rather a prediction that an individual, while alive was assigned to a particular socially constructed 'racial' category. A specimen may display features that point to African ancestry. In this country that person is likely to have been labeled Black regardless of whether or not such a race actually exists in nature.
Article
A major goal in anthropological genetics is the assessment of the effects of different microevolutionary forces. Harpending and Ward (1982) developed a model that aids in this effort by comparing observed and expected heterozygosity within populations in a local region. The expected heterozygosity within a population is a function of the total heterozygosity of the entire region and the distance of the population from the regional mean centroid of allele frequencies. Greater than average gene flow from an external source will result in a population having greater heterozygosity than expected. Less than average gene flow from an external source will result in a population having less heterozygosity than expected. We extend the Harpending-Ward model to quantitative traits using an equal and additive effects model of inheritance. Here the additive genetic variance within a population is directly proportional to heterozygosity, and its expectation is directly proportional to the genetic distance from the centroid. Under certain assumptions the expectations for phenotypic variances are similar. Observed and expected genetic or phenotypic variance can then be compared to assess the effects of differential external gene flow. When the additive genetic covariance matrix or heritabilities are not known, the phenotypic covariance matrix can be used to provide a conservative application of the model. In addition, we develop new methods for estimation of the genetic relationship matrix (R) from quantitative traits. We apply these models to two data sets: (1) six principal components derived from twenty dermatoglyphic ridge count measures for nine villages in Nepal and (2) ten anthropometric measurements for seven isolated populations in western Ireland. In both cases both the univariate and multivariate analyses provide results that can be directly interpreted in terms of historically known patterns of gene flow.
Article
Anthropometric measurements (head length, head breadth, bizygomatic diameter, minimum frontal diameter, head circumference, and stature) for 526 adult Jirels are utilized to establish the pattern of phenotypic relationships between seven villages in eastern Nepal. An analytical framework is provided that justifies the interpretation of biological distances as minimum genetic distances. Using this approach, estimates of the minimum pairwise genetic distances between villages and the minimum FST for the population are derived from the purely phenotypic data. The FST obtained in this way is consistent with results obtained from other data available for this population, confirming the utility of phenetic analysis of quantitative traits for elucidating genetic structure.
Article
Previous studies of genetic markers and mitochondrial DNA have found that the amount of variation among major geographic groupings of Homo sapiens is relatively low, accounting for roughly 10% of total variation. This conclusion has had implications for the study of human variation and consideration of alternative models for the origin of modern humans. By contrast, it has often been assumed that the level of among-group variation for morphological traits is much higher. This study examines the level of among-group variation based on Craniometric data from a large sample of modern humans originally collected by W. W. Howells. A multivariate method based on quantitative genetics theory was used to provide an estimate of FST — a measure of among-group variation that can be compared with results from studies of genetic markers. Data for 57 Craniometric variables on 1,734 crania were analyzed. These data represent six core areas: Europe, Sub-Saharan Africa, Australasia, Polynesia, the Americas, and the Far East. An additional set of analyses was performed using a three-region subset (Europe, Sub-Saharan Africa, and the Far East) to provide comparability with several genetic studies. The minimum FST (assuming complete heritability) for the three-region analysis is 0.065, and the minimum FST for the six-region analysis is 0.085. Both of these are less than the average FST from genetic studies (average estimates of 0.10–0.11). The smaller value of the minimum FST estimates is expected since it provides an estimate of FST expected under complete heritability. Using an estimate of average craniometric heritability from the literature provides an estimate of FST of 0.112 for the three-region analysis and 0.144 for the six-region analysis. These results show that genetic and craniometric data are in agreement, qualitatively and quantitatively, and that there is limited variation in modern humans among major geographic regions.
Article
This study examines the genetic impact of the Great Famine (1846-1851) on the regional genetic structure of Ireland. The Great Famine resulted in a rapid decrease in population size throughout Ireland in a short period of time, increasing the possibility of genetic drift. Our study is based on migration and anthropometric data collected originally in the 1930s from 7211 adult Irish males. These data were subdivided into three time periods defined by year of birth: 1861-1880, 1881-1900, and 1901-1920. Within each time period the data were further subdivided into six geographic regions of Ireland. Estimates of Wright's FST were calculated from parent-offspring migration data and from 17 anthropometric variables (10 head measures, 7 body measures). Over time, the average population size decreased, but average rates of migration increased. The estimates of FST at equilibrium from migration matrix analysis suggest that the net effect of these opposite effects is a reduction in among-group variation. Closer examination shows that within each time period the rate of convergence to equilibrium is slow, meaning that the expected levels of genetic homogeneity revealed from migration matrix analysis are not likely to be seen over short intervals of time. Estimates of FST from anthropometric data show either relatively little change in microdifferentiation or some increase, depending on which variables are analyzed. Investigation of a simple model of demographic and genetic change shows that, given the demographic changes in post-Famine Ireland, FST could in theory increase, decrease, or remain the same over short intervals of time. Overall, the Great Famine appears to have had minimal impact on the genetic structure of Ireland on a regional level. Comparison with studies focusing on local genetic structure shows the opposite. It appears that the level of genetic impact depends strongly on the level of analysis; local populations are affected to a greater extent by demographic shifts than regional populations. We also provide formulas for the standard errors of FST from metric traits and related statistics.
Article
Previous studies of human skin color have shown a strong relationship between skin color and distance from the equator, which has been interpreted as a link between skin color, latitude, and the intensity of ultraviolet radiation. The underlying assumptions are that UV radiation is greatest at the equator and that it diminishes with increasing latitude to the same extent in both the Northern and Southern Hemispheres. The standard analysis of human skin color is based on these assumptions, such that skin color is assumed to be darkest at the equator, and the decrease of skin color with latitude is assumed to be the same in both hemispheres. A nonlinear piecewise regression model was developed to test these assumptions and applied to mean skin reflectance data from 102 male samples and 65 female samples from across the Old World. For both males and females, skin reflectance (%) is lowest at the equator (darkest skin). Among males, skin reflectance increases roughly 8.2% for every 10 degrees of latitude in the Northern Hemisphere but only 3.3% for every 10 degrees of latitude in the Southern Hemisphere. Among females, the corresponding numbers are 8.1% in the Northern Hemisphere and 4.7% in the Southern Hemisphere. These results indicate that human skin color is darker in the Southern Hemisphere than in the Northern Hemisphere at equivalent latitude. Recent research shows that UV radiation is higher in the Southern Hemisphere than in the Northern Hemisphere at similar latitude. This difference, relating to astronomical and climatic conditions, may have existed in the past at different times and perhaps influenced the evolution of human skin color.
Article
Skin color is one of the most conspicuous ways in which humans vary and has been widely used to define human races. Here we present new evidence indicating that variations in skin color are adaptive, and are related to the regulation of ultraviolet (UV) radiation penetration in the integument and its direct and indirect effects on fitness. Using remotely sensed data on UV radiation levels, hypotheses concerning the distribution of the skin colors of indigenous peoples relative to UV levels were tested quantitatively in this study for the first time.
Article
Previous studies of genetic and craniometric traits have found higher levels of within-population diversity in sub-Saharan Africa compared to other geographic regions. This study examines regional differences in within-population diversity of human skin color. Published data on skin reflectance were collected for 98 male samples from eight geographic regions: sub-Saharan Africa, North Africa, Europe, West Asia, Southwest Asia, South Asia, Australasia, and the New World. Regional differences in local within-population diversity were examined using two measures of variability: the sample variance and the sample coefficient of variation. For both measures, the average level of within-population diversity is higher in sub-Saharan Africa than in other geographic regions. This difference persists even after adjusting for a correlation between within-population diversity and distance from the equator. Though affected by natural selection, skin color variation shows the same pattern of higher African diversity as found with other traits.
Article
Sewall Wright's population structure statistic, F(ST), measured among samples of world populations is often 15% or less. This would indicate that 85% of genetic variation occurs within groups while only 15% can be attributed to allele frequency differences among groups. In this paper, we show that this low value reflects strong biases that result from violating hidden assumptions that define F(ST). These limitations on F(ST) are demonstrated algebraically and in the context of analyzing dinucleotide repeat allele frequencies for a set of eight loci genotyped in eight human groups and in chimpanzees. In our analyses, estimates of F(ST) fail to identify important variation. For example, when the analysis includes only humans, F(ST) = 0.119, but adding the chimpanzees increases it only a little, F(ST) = 0.183. By relaxing the underlying statistical assumptions, the results for chimpanzees become consistent with common knowledge, and we see a richer pattern of human genetic diversity. Some human groups are far more diverged than would be implied by standard computations of F(ST), while other groups are much less diverged. We discuss the relevance of these findings to the application of biological race concepts to humans. Four different race concepts are considered: typological, population, taxonomic, and lineage. Surprisingly, a great deal of genetic variation within groups is consistent with each of these concepts. However, none of the race concepts is compatible with the patterns of variation revealed by our analyses.
Article
Migration is expected to affect craniometric variation in three ways: 1) movement into a different environment leading to developmental plasticity; 2) movement into a different environment followed by in situ adaptation through natural selection; and 3) changes in among-group differentiation and genetic distance through the action of gene flow. The relative influence of these three factors has been argued in the literature, most recently in a series of articles debating the statistical and biological significance of Boas's immigration studies as they relate to cranial plasticity. The Boas debate is discussed within the broader context of debate over genetic and environmental influences on craniometric variation. Additional examples are provided from an ongoing study of global craniometric variation. Although developmental plasticity and climatic adaptation have had an impact on craniometric variation, these factors tend not to erase, or even obscure greatly, underlying patterns of population structure and history that fit a neutral model of quantitative variation. Thus, craniometric data can be used to explore questions of gene flow and genetic affinity.
Article
This comparison of morphological and neutral genetic variation in 10 human populations was designed to test a neutral hypothesis of cranial evolution in living and recent humans and to explain deviations from neutrality where detected. Overall, among-population differences in extant Homo sapiens cranial morphology are proportional to among-population differences in neutral molecular characteristics. For most of the populations studied, cranial morphology varies among regions in a manner consistent with neutral expectations. Removal of the effects of shared population history and structure by using the partial Mantel's test, however, does not remove the correlation between some aspects of cranial morphology and a measure of coldness of climate. The excess differentiation is most apparent in those population comparisons that involve a Siberian population living in an extremely cold environment. This finding suggests the action of natural selection, associated with regional variation in temperature, leading to among-population differentiation in excess of neutral expectations for some cranial dimensions. Those dimensions reflect the breadth of the skull, cranial vault size and shape, and aspects of nasal morphology. Although morphology for most of the world appears to vary among populations in accordance with neutral expectations in the context of population structure and history, morphology of the Siberian population appears to have undergone adaptation by natural selection.
Article
The isolation-by-distance model predicts that genetic similarity between populations will decrease exponentially as the geographic distance between them increases, because of the limiting effect of geographic distance on rates of gene flow. Many studies of human populations have applied the isolation-by-distance model to genetic variation between local populations in a limited geographic area, but few have done so on a global level, and these few used different models and analytical methods. I assess genetic variation between human populations across the world using data on red blood cell polymorphisms, microsatellite DNA markers, and craniometric traits. The isolation-by-distance model provides an excellent fit to average levels of genetic similarity within geographic distance classes for all three data sets, and the rate of distance decay is the same in all three. These results suggest that a common pattern of global gene flow mediated by geographic distance is detectable in diverse genetic and morphological data. An alternative explanation is that the correspondence between genetic similarity and geographic distance reflects the history of dispersal of the human species out of Africa.
Article
Starting with "mitochondrial Eve" in 1987, genetics has played an increasingly important role in studies of the last two million years of human evolution. It initially appeared that genetic data resolved the basic models of recent human evolution in favor of the "out-of-Africa replacement" hypothesis in which anatomically modern humans evolved in Africa about 150,000 years ago, started to spread throughout the world about 100,000 years ago, and subsequently drove to complete genetic extinction (replacement) all other human populations in Eurasia. Unfortunately, many of the genetic studies on recent human evolution have suffered from scientific flaws, including misrepresenting the models of recent human evolution, focusing upon hypothesis compatibility rather than hypothesis testing, committing the ecological fallacy, and failing to consider a broader array of alternative hypotheses. Once these flaws are corrected, there is actually little genetic support for the out-of-Africa replacement hypothesis. Indeed, when genetic data are used in a hypothesis-testing framework, the out-of-Africa replacement hypothesis is strongly rejected. The model of recent human evolution that emerges from a statistical hypothesis-testing framework does not correspond to any of the traditional models of human evolution, but it is compatible with fossil and archaeological data. These studies also reveal that any one gene or DNA region captures only a small part of human evolutionary history, so multilocus studies are essential. As more and more loci became available, genetics will undoubtedly offer additional insights and resolutions of human evolution.
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