No abstract

Archaeological evidence shows that humans began living in the high altitude Andes approximately 12,000 years ago. Andean highlanders are known to have developed the most complex societies of pre-Columbian South America despite challenges to their health and reproductive success resulting from chronic exposure to hypoxia. While the physiological adaptations to this environmental stressor are well studied in contemporary Andean highlanders, the molecular evolutionary processes associated with such adaptations remain unclear. We aim to better understand how humans managed to demographically establish in this harsh environment by addressing a central question: did exposure to hypoxia drive adaptation via natural selection within Andean populations or did an existing phenotype –characterized by reduced susceptibility to hypoxic stress–enable human settlement of the Andes? We genotyped three variable loci within the NOS3 and EGLN1 genes previously associated with adaptation to high altitude in 150 ancient human DNA samples from Peruvian high altitude and coastal low altitude sites in a time frame between ~8500–560 BP. We compare the data of 109 successful samples to forward simulations of genetic drift with natural selection and find that selection, rather than drift, explains the gradual frequency changes observed in the highland populations for two of the three SNPs.

The majority of Native Americans nearly exclusively belong to group O of the ABO blood group system. Several hypotheses have been formulated to explain this observation, primarily differing by the presumption that the observed patterns of ABO diversity are due to the processes of the initial peopling of the Americas or due to subsequent events, especially the demographic consequences in the wake of European contact. A promising strategy to reveal possible diachronic ABO frequency changes is the molecular genetic analysis of relevant genetic markers in precontact populations. A previous study by Halverson and Bolnick [Am J Phys Anthropol 137 (2008) 342‐347] already accomplished this for indigenous North American populations. Here we present the first study to analyze ABO blood types from pre‐Columbian individuals from South America using molecular genetic methods and comparing them to several extant South American, North American, and Siberian populations. We tried to determine ABO blood types for 59 individuals from the southern Peruvian highlands dating to ∼650 to 1250 AD using a newly developed multiplex PCR/SBE assay coamplifying the fragments relevant for blood type determination and three highly discriminating autosomal STRs. Analysis was successful for 31 individuals and revealed that all are exclusively in the O group, predominantly carrying the O02 (01v) allele. No significant difference could be observed between the ancient and modern Native American populations, while all significantly differed from the extant Siberian populations, supporting the suggestion that low ABO diversity results from founder effects during the initial peopling of the Americas. Am J Phys Anthropol 149:242–249, 2012. © 2012 Wiley Periodicals, Inc.

Certain Polymorphisms in the DRD4 gene have been associated with behavioral traits such as novelty seeking (NS), impulsivity, and ADHD. Research has suggested that these personality traits may affect individual fitness differently depending on social structure, subsistence patterns, and mobility. To test this hypothesis this study examines the diachronic change in the frequency of the C allele of the −521 C/T SNP in the DRD4 promoter region, thought to contribute to the NS phenotype, analyzing ancient DNA from pre-Columbian South America. We used a SBE PCR based approach to analyze the DRD4 SNP in 125 prehistoric samples dating from 8000 BP to the end of the pre-Columbian period and deriving from a diversity of socioeconomic environments. We performed forward simulations of genetic drift with selection to test if difference in allele frequencies over time can solely be explained by random evolutionary processes or if selection has to be considered. Further, we performed statistical tests to explore possible association of observed differences with socioeconomic or environmental factors. DRD4 genotypes for 79 individuals were obtained. We find signals of slight selection acting on the DRD4-521 T allele. While the postulated association between the −521 C/T DRD4 SNP with modes of subsistence was not confirmed the results suggest a possible impact of socioeconomic complexity Adaptive Human Behavior and Physiology (2016) 2:77-91 DOI 10.1007/s40750-015-0033-5 Electronic