Excavating past population structures by surname-based sampling: the genetic legacy of the Vikings in northwest England

The genetic structures of past human populations are obscured by recent migrations and expansions and have been observed only indirectly by inference from modern samples. However, the unique link between a heritable cultural marker, the patrilineal surname, and a genetic marker, the Y chromosome, provides a means to target sets of modern individuals that might resemble populations at the time of surname establishment. As a test case, we studied samples from the Wirral Peninsula and West Lancashire, in northwest England. Place-names and archaeology show clear evidence of a past Viking presence, but heavy immigration and population growth since the industrial revolution are likely to have weakened the genetic signal of a 1,000-year-old Scandinavian contribution. Samples ascertained on the basis of 2 generations of residence were compared with independent samples based on known ancestry in the region plus the possession of a surname known from historical records to have been present there in medieval times. The Y-chromosomal haplotypes of these 2 sets of samples are significantly different, and in admixture analyses, the surname-ascertained samples show markedly greater Scandinavian ancestry proportions, supporting the idea that northwest England was once heavily populated by Scandinavian settlers. The method of historical surname-based ascertainment promises to allow investigation of the influence of migration and drift over the last few centuries in changing the population structure of Britain and will have general utility in other regions where surnames are patrilineal and suitable historical records survive.     

mtDNA and Y-chromosome variation in the Talysh of Iran and Azerbaijan

The Northern Talysh from Azerbaijan and the Southern Talysh from Iran self‐identify as one ethnic group and speak a Northwestern Iranian language. However, the Northern and Southern Talysh dialects are so different that they may actually be separate languages. Does this linguistic differentiation reflect internal change due to isolation, or could contact‐induced change have played a role? We analyzed mtDNA HVI sequences, 11 Y‐chromosome bi‐allelic markers, and 9 Y‐STR loci in Northern and Southern Talysh and compared them with their neighboring groups. The mtDNA data show a close relatedness of both groups with each other and with neighboring groups, whereas the Northern Talysh Y‐chromosome variation differs from that of neighboring groups, probably as a result of genetic drift. This genetic drift most likely reflects a founder event in the male gene pool of Northern Talysh: either fewer males than females migrated to Azerbaijan, or there was a higher degree of relatedness among the male migrants. Since we find no evidence of substantial genetic contact between either Northern or Southern Talysh and neighboring groups, we conclude that internal change, rather than contact‐induced change, most likely explains the linguistic differentiation between Northern and Southern Talysh. Am J Phys Anthropol, 2009. © 2008 Wiley‐Liss, Inc.     

Paternal lineages signal distinct genetic contributions from British Loyalists and continental Africans among different Bahamian islands

Over the past 500 years, the Bahamas has been influenced by a wide array of settlers, some of whom have left marked genetic imprints throughout the archipelago. To assess the extent of each group's genetic contributions, high-resolution Y-chromosome analyses were performed, for the first time, to delineate the patriarchal ancestry of six islands in the Northwest (Abaco and Grand Bahama) and Central (Eleuthera, Exuma, Long Island, and New Providence) Bahamas and their genetic relationships with previously published reference populations. Our results reveal genetic signals emanating primarily from African and European sources, with the predominantly sub-Saharan African and Western European haplogroups E1b1a-M2 and R1b1b1-M269, respectively, accounting for greater than 75% of all Bahamian patrilineages. Surprisingly, we observe notable discrepancies among the six Bahamian populations in their distribution of these lineages, with E1b1a-M2 predominating Y-chromosomes in the collections from Abaco, Exuma, Eleuthera, Grand Bahama, and New Providence, whereas R1b1b1-M269 is found at elevated levels in the Long Island population. Substantial Y-STR haplotype variation within sub-haplogroups E1b1a7a-U174 and E1b1ba8-U175 (greater than any continental African collection) is also noted, possibly indicating genetic influences from a variety of West and Central African groups. Furthermore, differential European genetic contributions in each island (with the exception of Exuma) reflect settlement patterns of the British Loyalists subsequent to the American Revolution.     

Mitochondrial DNA patterns in the Macaronesia islands: Variation within and among archipelagos

Macaronesia covers four Atlantic archipelagos: the Azores, Madeira, the Canary Islands, and the Cape Verde islands. When discovered by Europeans in the 15th century, only the Canaries were inhabited. Historical reports highlight the impact of Iberians on settlement in Macaronesia. Although important differences in their settlement are documented, its influence on their genetic structures and relationships has yet to be ascertained. In this study, the hypervariable region I (HVRI) sequence and coding region polymorphisms of mitochondrial DNA (mtDNA) in 623 individuals from the Azores (120) and Canary Islands (503) were analyzed. Combined with published data, these give a total of 1,542 haplotypes from Macaronesia and 1,067 from the Iberian Peninsula. The results obtained indicate that Cape Verde is the most distinctive archipelago, with an mtDNA pool composed almost exclusively of African lineages. However, the other archipelagos present an mtDNA profile dominated by the presence of West‐Eurasian mtDNA haplogroups with African lineages present in varying proportions. Moreover, no signs of integration of typical Canarian U6 lineages in the other archipelagos were detected. The four Macaronesia archipelagos currently have differentiated genetic profiles, and the Azores present the highest intra‐archipelago differentiation and the lowest values of diversity. The analyses performed show that the present‐day genetic profile of the Macaronesian archipelagos was mainly determined by the initial process of settlement and further microdifferentiation probably as a consequence of the small population size of some islands. Moreover, contacts between archipelagos seem to have had a low impact on the mtDNA genetic pool of each archipelago. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

Tracing the Genetic Legacy of the Tibetan Empire in the Balti

The rise and expansion of Tibetan Empire in the 7th to 9th centuries AD affected the course of history across East Eurasia, but the genetic impact of Tibetans on surrounding populations remains undefined. We sequenced 60 genomes for four populations from Pakistan and Tajikistan to explore their demographic history. We showed that the genomes of Balti people from Baltistan comprised 22.6–26% Tibetan ancestry. We inferred a single admixture event and dated it to about 39–21 generations ago, a period that postdated the conquest of Baltistan by the ancient Tibetan Empire. The analyses of mitochondrial DNA, Y, and X chromosome data indicated that both ancient Tibetan males and females were involved in the male-biased dispersal. Given the fact that the Balti people adopted Tibetan language and culture in history, our study suggested the impact of Tibetan Empire on Baltistan involved dominant cultural and minor demic diffusion.     

Unequal contributions of male and female gene pools from parental populations in the African descendants of the city of Melo, Uruguay

In admixed populations, genetic contributions from males and females of specific parental populations can be of different proportions due to past directional mating during the process of genetic admixture. In this research paper, we provide evidence of such male- and female-specific differential admixture components of African, European, and American Indian origin in an admixed population from the city of Melo, in the northeastern region of Uruguay. From data on 11 autosomal markers from a sample of 41 individuals of mixed African descent, we estimated 47% African, 38% European, and 15% Amerindian contributions. In contrast, 6 mtDNA site-specific polymorphic markers showed that the mtDNA genome of these individuals was 52% African, 19% European, and 29% Amerindian, while from 3 Y-specific polymorphic sites, we estimated 30% African, 64% European, and 6% Amerindian contributions. We argue that this heterogeneity of admixture estimates results from disproportionate unions of European males with African and American Indian females from which this mixed African population was formed. Also, we argue that the asymmetry of the admixture estimates from the three sets of markers (autosomal, mtDNA, and Y-linked) is a result of the changes in the direction of mating during the history of the population. Implications of such evidence of directional mating are discussed, indicating the need of further demographic data for a quantitative assessment of the impact of directional mating on genetic structure of admixed populations.     

Variation of female and male lineages in sub-Saharan populations: the importance of sociocultural factors

In this paper, we present a study of genetic variation in sub-Saharan Africa, which is based on published and unpublished data on fast-evolving (hypervariable region 1 of mitochondrial DNA and six microsatellites of Y chromosome) and slow-evolving (haplogroup frequencies) polymorphisms of mtDNA and Y chromosome. Our study reveals a striking difference in the genetic structure of food-producer (Bantu and Sudanic speakers) and hunter-gatherer populations (Pygmies, Kung, and Hadza). In fact, the ratio of mtDNA to Y-chromosome Nupsilon is substantially higher in food producers than in hunter-gatherers as determined by fast-evolving polymorphisms (1.76 versus 0.11). This finding indicates that the two population groups differ substantially in female and male migration rate and/or effective size. The difference also persists when linguistically homogeneous populations are used and outlier populations are eliminated (1.78 vs 0.19) or when the jacknife procedure is applied to a paired population data set (1.32 to 7.84 versus 0.14 to 0.66). The higher ratio of mtDNA to Y-chromosome Nnu in food producers than in hunter-gatherers is further confirmed by the use of slow-evolving polymorphisms (1.59 to 7.91 versus 0.12 to 0.35). To explain these results, we propose a model that integrates demographic and genetic aspects and incorporates ethnographic knowledge. In such a model, the asymmetric gene flow, polyginy, and patrilocality play an important role in differentiating the genetic structure of sub-Saharan populations. The existence of an asymmetric gene flow is supported by the phylogeographic features of mtDNA and Y-chromosome haplogroups found in the two population groups. The role of polyginy and patrilocality is sustained by the evidence of a differential pressure of genetic drift and gene flow on maternal and paternal lineages of food producers and hunter-gatherers that is revealed through the analysis of mitochondrial and Y-chromosomal intrapopulational variation.     

Exploring the legacy of African and Indigenous Caribbean admixture in Puerto Rico

Objectives

From an anthropological genetic perspective, little is known about the ethnogenesis of African descendants in Puerto Rico. Furthermore, historical interactions between Indigenous Caribbean and African descendant peoples that may be reflected in the ancestry of contemporary populations are understudied. Given this dearth of genetic research and the precedence for Afro-Indigenous interactions documented by historical, archeological, and other lines of evidence, we sought to assess the biogeographic origins of African descendant Puerto Ricans and to query the potential for Indigenous ancestry within this community.

Materials and Methods

Saliva samples were collected from 58 self-identified African descendant Puerto Ricans residing in Puerto Rico. We sequenced whole mitochondrial genomes and genotyped Y chromosome haplogroups for each male individual (n = 25). Summary statistics, comparative analyses, and network analysis were used to assess diversity and variation in haplogroup distribution between the sample and comparative populations.

Results

As indicated by mitochondrial haplogroups, 66% had African, 5% had European, and 29% had Indigenous American matrilines. Along the Y chromosome, 52% had African, 28% had Western European, 16% had Eurasian, and, notably, 4% had Indigenous American patrilines. Both mitochondrial and Y chromosome haplogroup frequencies were significantly different from several comparative populations.

Discussion

Biogeographic origins are consistent with historical accounts of African, Indigenous American, and European ancestry. However, this first report of Indigenous American paternal ancestry in Puerto Rico suggests distinctive features within African descendant communities on the island. Future studies expanding sampling and incorporating higher resolution genetic markers are necessary to more fully understand African descendant history in Puerto Rico.     

Peopling of three Mediterranean islands (Corsica,Sardinia, and Sicily) inferred by Y-chromosome biallelic variability

An informative set of biallelic polymorphisms was used to study the structure of Y-chromosome variability in a sample from the Mediterranean islands of Corsica and Sicily, and compared with data on Sardinia to gain insights into the ethnogenesis of these island populations. The results were interpreted in a broader Mediterranean context by including in the analysis neighboring populations previously studied with the same methodology. All samples studied were enclosed in the comparable spectrum of European Y-chromosome variability. Pronounced differences were observed between the islands as well as in the percentages of haplotypes previously shown to have distinctive patterns of continental phylogeography. Approximately 60% of the Sicilian haplotypes are also prevalent in Southern Italy and Greece. Conversely, the Corsican sample had elevated levels of alternative haplotypes common in Northern Italy. Sardinia showed a haplotype ratio similar to that observed in Corsica, but with a remarkable difference in the presence of a lineage defined by marker M26, which approaches 35% in Sardinia but seems absent in Corsica. Although geographically adjacent, the data suggest different colonization histories and a minimal amount of recent gene flow between them. Our results identify possible ancestral continental sources of the various island populations and underscore the influence of founder effect and genetic drift. The Y-chromosome data are consistent with comparable mtDNA data at the RFLP haplogroup level of resolution, as well as linguistic and historic knowledge.     

The genetic legacy of Mother Goose– phylogeographic patterns of lesser snow goose Chen caerulescens caerulescens maternal lineages

By using the polymerase chain reaction to amplify and sequence 178 bp of a rapidly evolving region of the mtDNA genome (segment I of the control region) from 81 individuals, approximately 11% of the variation present in the lesser snow goose Chen caerulescens caerulescens L. mitochondrial genome was surveyed. The 26 types of mtDNA detected formed two distinct mitochondrial clades that differ by an average of 6.7% and are distributed across the species range. Restriction analysis of amplified fragments was then used to assign the mtDNA of an additional 29 individuals to either of these clades. Within one major clade, sequence among mtDNAs was concordant with geographic location. Within the other major clade the degree of sequence divergence among haplotypes was lower and no consistent geographic structuring was evident. The two major clades presumably result from vicariant separation of lesser snow geese during the Pleistocene.     

Between Andes and Amazon: The genetic profile of the Arawak‐speaking Yanesha

The Yanesha are a Peruvian population who inhabit an environment transitional between the Andes and Amazonia. They present cultural traits characteristic of both regions, including in the language they speak: Yanesha belongs to the Arawak language family (which very likely originated in the Amazon/Orinoco lowlands), but has been strongly influenced by Quechua, the most widespread language family of the Andes. Given their location and cultural make‐up, the Yanesha make for an ideal case study for investigating language and population dynamics across the Andes‐Amazonia divide. In this study, we analyze data from high and mid‐altitude Yanesha villages, both Y chromosome (17 STRs and 16 SNPs diagnostic for assigning haplogroups) and mtDNA data (control region sequences and 3 SNPs and one INDEL diagnostic for assigning haplogroups). We uncover sex‐biased genetic trends that probably arose in different stages: first, a male‐biased gene flow from Andean regions, genetically consistent with highland Quechua‐speakers and probably dating back to Inca expansion; and second, traces of European contact consistent with Y chromosome lineages from Italy and Tyrol, in line with historically documented migrations. Most research in the history, archaeology and linguistics of South America has long been characterized by perceptions of a sharp divide between the Andes and Amazonia; our results serve as a clear case‐study confirming demographic flows across that ‘divide’. Am J Phys Anthropol 155:600–609, 2014. © 2014 The Authors. American journal of physical Anthropology published by Wiley Periodocals, Inc.     

Taurine and zebu admixture in Near Eastern cattle: a comparison of mitochondrial, autosomal and Y-chromosomal data

Eight Bos taurus cattle breeds from the Near East region were screened with a Bos indicus (zebu)-diagnostic Y-specific microsatellite (INRA124) to estimate the proportion of zebu Y chromosomes in each population. This value was compared with previously published values for zebu introgression for both the mitochondrial and autosomal gene pools of the same breeds. All breeds revealed considerable levels of introgression from B. indicus cattle when the autosomal data were taken into consideration; this was particularly apparent in cattle populations from Iraq in the east, and declined in the populations further west towards Anatolia. This non-random pattern of introgression and admixture is suggestive of the introduction of zebu cattle from the region corresponding to present-day Iran and northern Pakistan. In addition, the maternal and paternal markers demonstrate that the movement of cattle into and within the Near East was complex.     

Sex: differences in mutation, recombination, selection, gene flow, and genetic drift

In many instances, there are large sex differences in mutation rates, recombination rates, selection, rates of gene flow, and genetic drift. Mutation rates are often higher in males, a difference that has been estimated both directly and indirectly. The higher male mutation rate appears related to the larger number of cell divisions in male lineages but mutation rates also appear gene- and organism-specific. When there is recombination in only one sex, it is always the homogametic sex. When there is recombination in both sexes, females often have higher recombination but there are many exceptions. There are a number of hypotheses to explain the sex differences in recombination. Sex-specific differences in selection may result in stable polymorphisms or for sex chromosomes, faster evolutionary change. In addition, sex-dependent selection may result in antagonistic pleiotropy or sexually antagonistic genes. There are many examples of sex-specific differences in gene flow (dispersal) and a number of adaptive explanations for these differences. The overall effective population size (genetic drift) is dominated by the lower sex-specific effective population size. The mean of the mutation, recombination, and gene flow rates over the two sexes can be used in a population genetics context unless there are sex-specific differences in selection or genetic drift. Sex-specific differences in these evolutionary factors appear to be unrelated to each other. The evolutionary explanations for sex-specific differences for each factor are multifaceted and, in addition, explanations may include chance, nonadaptive differences, or mechanistic, nonevolutionary factors.     

Origins and genetic diversity of New World Creole cattle: inferences from mitochondrial and Y chromosome polymorphisms

The ancestry of New World cattle was investigated through the analysis of mitochondrial and Y chromosome variation in Creoles from Argentina, Brazil, Mexico, Paraguay and the United States of America. Breeds that influenced the Creoles, such as Iberian native, British and Zebu, were also studied. Creoles showed high mtDNA diversity (H = 0.984 ± 0.003) with a total of 78 haplotypes, and the European T3 matriline was the most common (72.1%). The African T1a haplogroup was detected (14.6%), as well as the ancestral African‐derived AA matriline (11.9%), which was absent in the Iberian breeds. Genetic proximity among Creoles, Iberian and Atlantic Islands breeds was inferred through their sharing of mtDNA haplotypes. Y‐haplotype diversity in Creoles was high (H = 0.779 ± 0.019), with several Y1, Y2 and Y3 haplotypes represented. Iberian patrilines in Creoles were more difficult to infer and were reflected by the presence of H3Y1 and H6Y2. Y‐haplotypes confirmed crossbreeding with British cattle, mainly of Hereford with Pampa Chaqueño and Texas Longhorn. Male‐mediated Bos indicus introgression into Creoles was found in all populations, except Argentino1 (herd book registered) and Pampa Chaqueño. The detection of the distinct H22Y3 patriline with the INRA189‐90 allele in Caracú suggests introduction of bulls directly from West Africa. Further studies of Spanish and African breeds are necessary to elucidate the origins of Creole cattle, and determine the exact source of their African lineages.     

A multi‐perspective view of genetic variation in Cameroon

In this study, we report the genetic variation of autosomal and Y‐chromosomal microsatellites in a large Cameroon population dataset (a total of 11 populations) and jointly analyze novel and previous genetic data (mitochondrial DNA and protein coding loci) taking geographic and cultural factors into consideration. The complex pattern of genetic variation of Cameroon can in part be described by contrasting two geographic areas (corresponding to the northern and southern part of the country), which differ substantially in environmental, biological, and cultural aspects. Northern Cameroon populations show a greater within‐ and among‐group diversity, a finding that reflects the complex migratory patterns and the linguistic heterogeneity of this area. A striking reduction of Y‐chromosomal genetic diversity was observed in some populations of the northern part of the country (Podokwo and Uldeme), a result that seems to be related to their demographic history rather than to sampling issues. By exploring patterns of genetic, geographic, and linguistic variation, we detect a preferential correlation between genetics and geography for mtDNA. This finding could reflect a female matrimonial mobility that is less constrained by linguistic factors than in males. Finally, we apply the island model to mitochondrial and Y‐chromosomal data and obtain a female‐to‐male migration Nν ratio that was more than double in the northern part of the country. The combined effect of the propensity to inter‐populational admixture of females, favored by cultural contacts, and of genetic drift acting on Y‐chromosomal diversity could account for the peculiar genetic pattern observed in northern Cameroon. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

Incidence,mortality and receptor status of breast cancer in African Caribbean women: Data from the cancer registry of Guadeloupe

BackgroundGeographical disparities in breast cancer incidence and outcomes are reported worldwide. Women of African descent show lower incidence, higher mortality rates and earlier age of onset. We analyzed data from the cancer registry of Guadeloupe for the period 2008–2013.MethodsWe describe breast cancer characteristics by molecular subtype, as well as estimated observed and net survival. We used Cox proportional hazard models to determine associations between cancer subtypes and death rate, adjusted for variables of interest.ResultsOverall, 1275 cases were recorded with a mean age at diagnosis of 57(±14) years. World standardized incidence and mortality were respectively 71.9/100,000 and 14.1/100,000 person-years. Age-specific incidence rates were comparable to European and US populations below the age of 45, and higher in Guadeloupean women aged between 45 and 55 years. Overall, 65.1% of patients were hormone receptor (HR)+ and 20.1% were HR-. Triple negative breast cancers (TNBC) accounted for 14% of all cases, and were more frequent in patients under 40 (21.6% vs. 13.4%, p = 0.02). Five-year net survival was 84.9% [81.4-88.6]. It was higher for HR+/Her2+ and HR+/Her2- subtypes, and lower for HR-/Her2+ and TNBC patients.ConclusionWe found high age-specific incidence rates of breast cancer in women aged 45 to 55 years, which warrants further investigation in our population. However, this population of mainly African descent had good overall survival rates, and data according to subtypes are consistent with those reported internationally. These results may suggest that poorer survival in other African descent populations may not be an inherent feature of the disease but may be amenable to improvement.     

Asymmetric male and female genetic histories among Native Americans from Eastern North America

Previous studies have investigated the human population history of eastern North America by examining mitochondrial DNA (mtDNA) variation among Native Americans, but these studies could only reconstruct maternal population history. To evaluate similarities and differences in the maternal and paternal population histories of this region, we obtained DNA samples from 605 individuals, representing 16 indigenous populations. After amplifying the amelogenin locus to identify males, we genotyped 8 binary polymorphisms and 10 microsatellites in the male-specific region of the Y chromosome. This analysis identified 6 haplogroups and 175 haplotypes. We found that sociocultural factors have played a more important role than language or geography in shaping the patterns of Y chromosome variation in eastern North America. Comparisons with previous mtDNA studies of the same samples demonstrate that male and female demographic histories differ substantially in this region. Postmarital residence patterns have strongly influenced genetic structure, with patrilocal and matrilocal populations showing different patterns of male and female gene flow. European contact also had a significant but sex-specific impact due to a high level of male-mediated European admixture. Finally, this study addresses long-standing questions about the history of Iroquoian populations by suggesting that the ancestral Iroquoian population lived in southeastern North America.     

Y-chromosome diversity in Native Mexicans reveals continental transition of genetic structure in the Americas

The genetic characterization of Native Mexicans is important to understand multiethnic based features influencing the medical genetics of present Mexican populations, as well as to the reconstruct the peopling of the Americas. We describe the Y-chromosome genetic diversity of 197 Native Mexicans from 11 populations and 1,044 individuals from 44 Native American populations after combining with publicly available data. We found extensive heterogeneity among Native Mexican populations and ample segregation of Q-M242* (46%) and Q-M3 (54%) haplogroups within Mexico. The northernmost sampled populations falling outside Mesoamerica (Pima and Tarahumara) showed a clear differentiation with respect to the other populations, which is in agreement with previous results from mtDNA lineages. However, our results point toward a complex genetic makeup of Native Mexicans whose maternal and paternal lineages reveal different narratives of their population history, with sex-biased continental contributions and different admixture proportions. At a continental scale, we found that Arctic populations and the northernmost groups from North America cluster together, but we did not find a clear differentiation within Mesoamerica and the rest of the continent, which coupled with the fact that the majority of individuals from Central and South American samples are restricted to the Q-M3 branch, supports the notion that most Native Americans from Mesoamerica southwards are descendants from a single wave of migration. This observation is compatible with the idea that present day Mexico might have constituted an area of transition in the diversification of paternal lineages during the colonization of the Americas.     

Phylogeography of the common pandora Pagellus erythrinus in the central Mediterranean Sea: sympatric mitochondrial lineages and genetic homogeneity

The distribution of the genetic diversity and the population structure of Pagellus erythrinus were analysed using mitochondrial control region sequences and cytochrome b restriction profiles in a total of 128 and 508 individuals, respectively, that were collected from 15 sampling sites in the central Mediterranean Sea and from one site in the Atlantic Ocean. No population genetic structure was detected within the central Mediterranean and thus, the commonly recognized transition zones in the area do not seem to affect population connectivity. The comparison between the Mediterranean samples and the single Atlantic sample suggests weak differentiation between the two basins. Three mitochondrial lineages were identified, each including individuals from almost every sampling site. The haplotype and nucleotide diversity values, mismatch distribution and demographic parameters indicate that the sympatry of these lineages can be ascribed to a period of isolation followed by genetic divergence, population expansion and secondary contact, all of which are likely to be associated with climatic oscillations that occurred during the middle and late Pleistocene.     

Early population differentiation in extinct aborigines from Tierra del Fuego-Patagonia: ancient mtDNA sequences and Y-chromosome STR characterization

Ancient mtDNA was successfully recovered from 24 skeletal samples of a total of 60 ancient individuals from Patagonia-Tierra del Fuego, dated to 100-400 years BP, for which consistent amplifications and two-strand sequences were obtained. Y-chromosome STRs (DYS434, DYS437, DYS439, DYS393, DYS391, DYS390, DYS19, DYS389I, DYS389II, and DYS388) and the biallelic system DYS199 were also amplified, Y-STR alleles could be characterized in nine cases, with an average of 4.1 loci per sample correctly typed. In two samples of the same ethnic group (Aonikenk), an identical and complete eight-loci haplotype was recovered. The DYS199 biallelic system was used as a control of contamination by modern DNA and, along with DYS19, as a marker of American origin. The analysis of both mtDNA and Y-STRs revealed DNA from Amerindian ancestry. The observed polymorphisms are consistent with the hypothesis that the ancient Fuegians are close to populations from south-central Chile and Argentina, but their high nucleotide diversity and the frequency of single lineages strongly support early genetic differentiation of the Fuegians through combined processes of population bottleneck, isolation, and/or migration, followed by strong genetic drift. This suggests an early genetic diversification of the Fuegians right after their arrival at the southernmost extreme of South America.