OPRM1 and EGFR contribute to skin pigmentation differences between Indigenous Americans and Europeans.

Contemporary variation in skin pigmentation is the result of hundreds of thousands years of human evolution in new and changing environments. Previous studies have identified several genes involved in skin pigmentation differences among African, Asian, and European populations. However, none have examined skin pigmentation variation among Indigenous American populations, creating a critical gap in our understanding of skin pigmentation variation. This study investigates signatures of selection at 76 pigmentation candidate genes that may contribute to skin pigmentation differences between Indigenous Americans and Europeans. Analysis was performed on two samples of Indigenous Americans genotyped on genome-wide SNP arrays. Using four tests for natural selection--locus-specific branch length (LSBL), ratio of heterozygosities (lnRH), Tajima's D difference, and extended haplotype homozygosity (EHH)--we identified 14 selection-nominated candidate genes (SNCGs). SNPs in each of the SNCGs were tested for association with skin pigmentation in 515 admixed Indigenous American and European individuals from regions of the Americas with high ground-level ultraviolet radiation. In addition to SLC24A5 and SLC45A2, genes previously associated with European/non-European differences in skin pigmentation, OPRM1 and EGFR were associated with variation in skin pigmentation in New World populations for the first time.

The Uto-Aztecan premolar among North and South Amerindians: Geographic variation and genetics.

The Uto-Aztecan premolar (UAP) is a dental polymorphism characterized by an exaggerated distobuccal rotation of the paracone in combination with the presence of a fossa at the intersection of the distal occlusal ridge and distal marginal ridge of upper first premolars. This trait is important because, unlike other dental variants, it has been found exclusively in Native American populations. However, the trait's temporal and geographic variation has never been fully documented. The discovery of a Uto-Aztecan premolar in a prehistoric skeletal series from northern South America calls into question the presumed linguistic and geographic limits of this trait. We examined published and unpublished data for this rare but highly distinctive trait in samples representing over 5,000 Native Americans from North and South America. Our findings in living Southwest Amerindian populations corroborate the notion that the variable goes beyond the bounds of the Uto-Aztecan language family. It is found in prehistoric Native Americans from South America, eastern North America, Northern and Central Mexico, and in living and prehistoric populations in the American Southwest that are not members of the Uto-Aztecan language stock. The chronology of samples, its geographic distribution, and trait frequencies suggests a North American origin (Southwest) for UAP perhaps between 15,000 BP and 4,000 BP and a rapid and widespread dispersal into South America during the late Holocene. Family data indicate that it may represent an autosomal recessive mutation that occurred after the peopling of the Americas as its geographic range appears to be limited to North and South Amerindian populations.

El impacto de la colonización española: evidencias paleopatológicas e isotópicas de cambios en la saludoral y reducción de la diversidad en la dieta en sociedades coloniales nativas del sur occidente de Colombia / The impact of the Spanish colonization: paleopathological and isotopic evidences of changes in oral health and dietary diversity in native colonial societies from the Colombian Southwest

Las sociedades amerindias sufrieron un profundo deterioro de la salud durante el contacto Europeo y la posterior colonización de las Américas. Igualmente la diversidad en la dieta y la calidad nutricional decrecieron mientras que la violencia y las labores de trabajo se incrementaron considerablemente. Las consecuencias socioculturales de dicho contacto han sido suficientemente documentadas por la arqueología, la historia y la etnohistoria. Sin embargo las secuelas biológicas son menos claras. Este artículo evalúa el impacto biológico de la llegada de los colonizadores Europeos al norte de Sur América a través del estudio de los restos óseos de dos comunidades coloniales Nativas del Sur-occidente de Colombia. La primera proviene del yacimiento arqueológico “El Alto del Rey” (ca 1200-1600 d.C) en el Departamento del Cauca y la segunda proviene del cementerio posthispánico de “Maridías” (1615-1720 a.C) en el Departamento de Nariño. Se obtuvieron datos de diferentes tipos de enfermedades dentales, así como de estrés fisiológico y de radios de isótopos estables de carbono (12C y 13C) y nitrógeno (15N) para conocer mejor el tipo de alimentación, la diversidad dietaría y nutrición y el estado de salud oral de las comunidades nativas colombianas bajo eldominio Español. Los análisis paleopatológico-dentales muestran un notable incremento en los índices de caries, cálculo, enfermedad periodontal, perdida dental antemortem (PDA) e hipoplasias del esmalte. En concordancia el estudio isotópico reveló un abrupto incremento en el consumo de plantas ricas en carbohidratos y alta dependencia de plantas como el maíz y otros granos. Este análisis muestra que el impacto europeo fue más notable en la población de Maridías dado que estuvo expuesta a un periodo de contacto más duradero y directo que el Alto del Rey. Al mismo tiempo esta investigación sugiere un notorio y profundo cambio en la nutrición, salud y forma de vida de estas comunidades.

Native American societies suffered a profund deterioration of health under European colonization. In addition, diet diversity and nutritional quality decreased whereas workloads and violence increased considerably. Social and cultural consequences of such contact have been well documented by archaeology, history and ethno-history. However, the true biological impact is poorly understood. This paper assess the biological impact of the European arrival to northern South America through the study of human skeletal remains of two native Colonial societies from the post-contact period in the Colombian South West. The first sample came from “El Alto del Rey” (ca 1200-1600 a.C), at Cauca Department, and the second from “Maridías” (1615-1720 a.C), at Nariño Department. Data from several types of dental diseases were obtained as well as physiological stress indicators and stable isotopes ratios of carbon (12C y 13C) and nitrogen (15N). These data were used to try to determine food intake, dietary diversity, nutrition, and the state of oral health of the Colombian native communities under Spanish control. Dental paleopathological analyses showed a high increase in the rates of caries, dental calculus, periodontal disease, antemortem tooth loose (AMTL) and enamel hypoplasias In agreement with these results, the isotope analysis reveals an abrupt increase in the plants rich in carbohydrates consumption and high dependency on plants such as corn and other grains. Changes were more considerable in Maridías than in El Alto del Rey, since the former was exposed to a longer and more direct colonial contact. In addition, this study suggests deep changes in diet, health and way of life of these communities. The bioarchaeological analysis of human skeletal remains represents an important source for a better understanding of the dynamics of the biocultural change resulting from colonization in Colombia.