New views on American colonization: critical tests from South America

The traditional view of colonization of the Americas as a migration across Beringia and subsequent dispersal southward following the last glacial maximum is being increasingly questioned. In North America, archaeological links to Siberia are tenuous and genetic data are more consistent with an earlier entry of people into the Americas, from Central rather than Northeast Siberia. An entry of populations into the Americas prior to the last glacial maximum forces a reconsideration not only of timing, but also geographic points of entry and speed of dispersal, based on ecological theory. A number of emerging alternative hypotheses on the colonization of the Americas predict early entry and dispersal of people into South America - earlier than, or coeval with, initial dispersal in North America. The study of genetic, morphological, and archaeological variation across South America is critical to testing these new, alternative hypotheses of Native American origins. I will review the evidence for emerging, alternative views of American Colonization, and suggest ways in which data from South American populations and prehistory will be crucial in testing them.Asociación de Antropología Biológica de la República Argentina (AABRA

Contradictions and Concordances in American Colonization Models

The traditional view of American colonization during the late Pleistocene has largely been conditioned on early conceptions of the timing and extent of continental glaciations and the age and distribution of archeological sites. A review of newer, high resolution genetic data, both from modern populations and ancient DNA samples, along with the emergence of several early archeological sites in both North and South America, and reconsiderations of the glacial dynamics in North America indicate that some aspects of the traditional view need reconsideration. It seems obvious from archeological data that a preglacial occupation of the Americas needs to be closely examined. Accumulating molecular genetic data raises new questions about the timing and population size of the initial colonization(s), while a closer examination of glacial models suggests that a number of routes into the Americas may have been available until fairly late in the last glacial cycle

Introduction: origins and settlement of the indigenous populations of the Aleutian Archipelago

Journal ArticleThe series of papers in this special issue of Human Biology use an interdisciplinary approach to address regional questions and to integrate disparate Aleutian data into a broad, synthetic effort. The contributors leverage decades of data on Aleut origins, biogeography, and behavior through integration of molecular analyses, linguistics, archaeology, and ethnography. This research explores the origin and colonization of the Aleutian archipelago, communication and the extent of prehistoric cultural exchange among Aleut subgroups, ethnographic information as applied to human biological variation, metric and genetic variation among Aleut groups, and prehistoric dietary reconstruction. The Aleutian archipelago, composed of eastern, central, and western islands, extends 1,800 km between the North American and Asian continents and divides the northern Pacific Ocean from the Bering Sea. Volcanic in origin and formed during the early Tertiary, the archipelago is composed of more than 200 islands divided into six groups, separated by ocean passes. The climate is maritime and is characterized by foggy and cloudy weather, frequent rain and winds, and often cold but not severe annual temperatures. The Aleutians form the southern boundary for the most biologically and commercially important region of the Pacific-the Bering Sea. Until recently, this area was a rich ecotone that supported abundant populations of large marine mammals, ocean fisheries, thick kelp forests, complex near-shore ecosystems and intertidal zones, spawning streams, and a highly diverse avian fauna pivotal to the adaptations and survival of the human groups who, in the past, peopled the islands of the archipelago. However, the Aleutians, once considered one of the richest island ecosystems in the world, have been undergoing considerable biotic turnover (Estes and Duggins 1995). Population densities of marine mammals and some economical fish have dramatically declined, and the once thick kelp forests have decreased (Committee on the Alaska Groundfish Fishery and Steller Sea Lions 2003; Trites et al. 1999). In contrast, Aleutian waters have witnessed increases in sea urchin, pollack, and shark populations, species that were historically uncommon in this ecosystem (Estes et al. 1998; Springer 1999). This biotic restructuring has occurred over a short time period and carries socioeconomic consequences and lessons for local inhabitants-and the world community, especially if rapid global warming is the cause (Estes et al. 1998)

Patterns of genetic variation in native America

Journal ArticleAllele frequencies from seven polymorphic red cell antigen loci (ABO, Rh, MN, S, P, Duffy, and Diego) were examined in 144 Native American populations. Mean genetic distances (Nei's D) and the fixation index FST are approximately equal for the North and South American samples but are reduced in the Central American geographic area

Biochemical heterozygosity and morphologic variation in a colony of papio hamadryas hamadryas baboons

Journal ArticleThis analysis examines the association between genetic heterozygosity and individual morphologic variation in a captive population of Papio hamadryas hamadryas consisting of 403 juveniles and adults. The population structure of the colony was artificially generated and maintained and is thus rigorously defined. Subpopulations delimited by age, sex, and degree of inbreeding are also explored. Heterozygosity, as enumerated from six simple Mendelian biochemical loci, is compared with the residual morphologic variation of each individual for each of 20 quantitative traits. Use of a sequential Bonferroni technique nullifies all significant correlations. Principalcomponents analysis reduces the morphometries to a single or few significant axes in each population. The first axis of the total population contains 86.07% of the variation in the sample and the absolute values of the factor scores exhibit a significant positive correlation with heterozygosity at P < 0.05. Correcting for age- and sex-related variation in the total population with a linear model subsequently demonstrates that no significant correlation between heterozygosity and morphologic variation exists

Ascertainment bias for non-twin relatives in twin proband studies

Journal ArticleWhen families are ascertained through affected twins, as for example when twin probands are selected from a registry and their non-twin relatives studied, a correction for ascertainment bias is needed. It is shown that probandwise counting (where relatives of doubly ascertained twin pairs are counted twice) is the appropriate method. The bias resulting from pairwise counting is given and depends on the genetic model and on the probability of selecting an affected twin as a proband. For the multifactorial and generalized single major locus models the bias is small, and the problems associated with nonindependent ascertainment are negligible in practice

South from Alaska: a pilot aDNA study of genetic history on the Alaska Peninsula and the Eastern Aleutians

Journal ArticleAbstract The Aleutian Islands were colonized, perhaps several times, from the Alaskan mainland. Earlier work documented transitions in the relative frequencies of mtDNA haplogroups over time, but little is known about potential source populations for prehistoric Aleut migrants. As part of a pilot investigation, we sequenced the mtDNA first hypervariable region (HVRI) in samples from two archaeological sites on the Alaska Peninsula (the Hot Springs site near Port Moller, Alaska; and samples from a cluster of sites in the Brooks River area near Katmai National Park and Preserve) and one site from Prince William Sound (Mink Island). The sequences revealed not only the mtDNA haplogroups typically found in both ancient and modern Aleut populations (A2 and D2) but also haplogroups B2 and D1 in the Brooks River samples and haplogroup D3 in one Mink Islander. These preliminary results suggest greater mtDNA diversity in prehistoric populations than previously observed and facilitate reconstruction of migration scenarios from the peninsula into the Aleutian archipelago in the past

Refutation of the general single locus model for the etiology of schizophrenia

Journal ArticleAll published studies on the familial incidence of schizophrenia appropriate for testing the applicability of the general single-locus two-allele model are examined under the assumption of a unitary etiology for all schizophrenia. We show that the single major locus model is inadequate to predict the incidence in four classes of relatives of schizophrenic probands (parents, siblings, monozygotic, and dizygotic cotwins). In addition, the observed proportion of affected offspring from dual matings differ significantly from the model's prediction. The lack of an overall fit between the published familial distributions and the monogenic model suggests that a single major locus is insufficient for the etiology of schizophrenia. Further efforts in examining multifactorial models, mixed models, and other transmission models may be fruitful

Unangan past and present: the contrasts between observed and inferred histories

Journal ArticleAbstract Academic research focusing on the population and culture history of the Aleut (Unangan) people began in the late 19th century and continues to the present. The papers in this special issue of Human Biology summarize the latest results from archaeological, linguistic, genetic, and morphometric research approaches that bear on our current understanding of Unangan history and prehistory. Although these new analyses have provided a level of description and resolution previously unattainable, explanatory models and mechanisms for the patterned variation observed over time in the biological and cultural record of the Aleutian region remains elusive. Bringing the diverse data sets into concordance to represent an integrated synthesis of Aleut population and culture history and of Unangan origins and their relationships with other groups in the region remains a goal for future investigators

Spatial and temporal stability of mtDNA haplogroup frequencies in native North America

Journal ArticleMitochondrial DNA lineage frequencies in prehistoric Aleut, eastern Utah Fremont, Southwestern Anasazi, Pyramid Lake, and Stillwater Marsh skeletal samples from northwest Nevada and the Oneota of western Illinois are compared with those in 41 contemporary aboriginal populations of North America. The ancient samples range in age from 300 years to over 6,000 years