Deep population history of North, Central and South America

human-divergence-americas

Open access Reconstructing the Deep Population History of Central and South America, by Posth et al. Cell (2018).

Abstract:

We report genome-wide ancient DNA from 49 individuals forming four parallel time transects in Belize, Brazil, the Central Andes, and the Southern Cone, each dating to at least ∼9,000 years ago. The common ancestral population radiated rapidly from just one of the two early branches that contributed to Native Americans today. We document two previously unappreciated streams of gene flow between North and South America. One affected the Central Andes by ∼4,200 years ago, while the other explains an affinity between the oldest North American genome associated with the Clovis culture and the oldest Central and South Americans from Chile, Brazil, and Belize. However, this was not the primary source for later South Americans, as the other ancient individuals derive from lineages without specific affinity to the Clovis-associated genome, suggesting a population replacement that began at least 9,000 years ago and was followed by substantial population continuity in multiple regions.

Interesting excerpts:

The D4h3a mtDNA haplogroup has been hypothesized to be a marker for an early expansion into the Americas along the Pacific coast (Perego et al., 2009). However, its presence in two Lapa do Santo individuals and Anzick-1 (Rasmussen et al., 2014) makes this hypothesis unlikely.

The patterns we observe on the Y chromosome also force us to revise our understanding of the origins of present-day variation. Our ancient DNA analysis shows that the Q1a2a1b-CTS1780 haplogroup, which is currently rare, was present in a third of the ancient South Americas. In addition, our observation of the currently extremely rare C2b haplogroup at Lapa do Santo disproves the suggestion that it was introduced after 6,000 BP (Roewer et al., 2013).

(…) Our discovery that the Clovis-associated Anzick-1 genome at ∼12,800 BP shares distinctive ancestry with the oldest Chilean, Brazilian, and Belizean individuals supports the hypothesis that an expansion of people who spread the Clovis culture in North America also affected Central and South America, as expected if the spread of the Fishtail Complex in Central and South America and the Clovis Complex in North America were part of the same phenomenon (direct confirmation would require ancient DNA from a Fishtail-context) (Pearson, 2017). However, the fact that the great majority of ancestry of later South Americans lacks specific affinity to Anzick-1 rules out the hypothesis of a homogeneous founding population. Thus, if Clovis-related expansions were responsible for the peopling of South America, it must have been a complex scenario involving arrival in the Americas of sub-structured lineages with and without specific Anzick-1 affinity, with the one with Anzick-1 affinity making a minimal long-term contribution. While we cannot at present determine when the non-Anzick-1 associated lineages first arrived in South America, we can place an upper bound on the date of the spread to South America of all the lineages represented in our sampled ancient genomes as all are ANC-A and thus must have diversified after the ANC-A/ANC-B split estimated to have occurred ∼17,500–14,600 BP (Moreno-Mayar et al., 2018a).

deep-population-history-americas


New paper (behind paywall) Early human dispersals within the Americas, by Moreno-Mayar et al. Science (2018).

Abstract:

Studies of the peopling of the Americas have focused on the timing and number of initial migrations. Less attention has been paid to the subsequent spread of people within the Americas. We sequenced 15 ancient human genomes spanning Alaska to Patagonia; six are ≥10,000 years old (up to ~18× coverage). All are most closely related to Native Americans, including an Ancient Beringian individual, and two morphologically distinct “Paleoamericans.” We find evidence of rapid dispersal and early diversification, including previously unknown groups, as people moved south. This resulted in multiple independent, geographically uneven migrations, including one that provides clues of a Late Pleistocene Australasian genetic signal, and a later Mesoamerican-related expansion. These led to complex and dynamic population histories from North to South America.

Interesting excerpts:

The Australasian signal is not present in USR1 or Spirit Cave, but only appears in Lagoa Santa. None of these individuals has UPopA/Mesoamerican-related admixture, which ap-parently dampened the Australasian signature in South American groups, such as the Karitiana. These findings suggest the Australasian signal, possibly present in a structured ancestral NA population, was absent in NA prior to the Spirit Cave/Lagoa Santa split. Groups carrying this signal were either already present in South America when the ancestors of Lagoa Santa reached the region, or Australasian-related groups arrived later but before 10.4 ka (the Lagoa Santa 14C age). That this signal has not been previously documented in North America implies that an earlier group possessing it had disappeared, or a later-arriving group passed through North America without leaving any genetic trace. If such a signal is ultimately detected in North America it could help determine when groups bear-ing Australasian ancestry arrived, relative to the divergence of SNA groups.

Although we detect the Australasian signal in one of the Lagoa Santa individuals identified as a “Paleoamerican,” it is absent in other “Paleoamericans” (2, 10), including Spirit Cave with its strong genetic affinities to Lagoa Santa. This indicates the “Paleoamerican” cranial form is not associated with the Australasian genetic signal, as previously suggested (6), or any other specific NA clade (2). The cause of this cranial form, if it is representative of broader population pat-terns, evidently did not result from separate ancestry, but likely multiple factors, including isolation and drift and non-stochastic mechanisms.

australasian
f-statistics–based tests show a rapid dispersal into South America, followed by Mesoamerican-related admixture. Schematic representation of a model for SNA formation. This model represents a reasonable fit to most present-day populations.

Open access The genetic prehistory of the Andean highlands 7000 years BP though European contact, by Lindo et al. Science Advances (2018).

Abstract:

The peopling of the Andean highlands above 2500 m in elevation was a complex process that included cultural, biological, and genetic adaptations. Here, we present a time series of ancient whole genomes from the Andes of Peru, dating back to 7000 calendar years before the present (BP), and compare them to 42 new genome-wide genetic variation datasets from both highland and lowland populations. We infer three significant features: a split between low- and high-elevation populations that occurred between 9200 and 8200 BP; a population collapse after European contact that is significantly more severe in South American lowlanders than in highland populations; and evidence for positive selection at genetic loci related to starch digestion and plausibly pathogen resistance after European contact. We do not find selective sweep signals related to known components of the human hypoxia response, which may suggest more complex modes of genetic adaptation to high altitude.

Related

Native American genetic continuity and oldest mtDNA hg A2ah in the Andean region

Native American gene continuity to the modern admixed population from the Colombian Andes: Implication for biomedical, population and forensic studies by Criollo-Rayo et al., Forensic Sci Int Genet (2018), in press, corrected proof.

Abstract (emphasis mine):

Andean populations have variable degrees of Native American and European ancestry, representing an opportunity to study admixture dynamics in the populations from Latin America (also known as Hispanics). We characterized the genetic structure of two indigenous (Nasa and Pijao) and three admixed (Ibagué, Ortega and Planadas) groups from Tolima, in the Colombian Andes. DNA samples from 348 individuals were genotyped for six mitochondrial DNA (mtDNA), seven non-recombining Y-chromosome (NRY) region and 100 autosomal ancestry informative markers. Nasa and Pijao had a predominant Native American ancestry at the autosomal (92%), maternal (97%) and paternal (70%) level. The admixed groups had a predominant Native American mtDNA ancestry (90%), a substantial frequency of European NRY haplotypes (72%) and similar autosomal contributions from Europeans (51%) and Amerindians (45%). Pijao and nearby Ortega were indistinguishable at the mtDNA and autosomal level, suggesting a genetic continuity between them. Comparisons with multiple Native American populations throughout the Americas revealed that Pijao, had close similarities with Carib-speakers from distant parts of the continent, suggesting an ancient correlation between language and genes. In summary, our study aimed to understand Hispanic patterns of migration, settlement and admixture, supporting an extensive contribution of local Amerindian women to the gene pool of admixed groups and consistent with previous reports of European-male driven admixture in Colombia.

andean-y-dna-mtdna
Ancestral uniparental haplogroups and diversity in Tolima. Geography of sampling locations. The
top and middle sections show the frequency of Native American mtDNA haplogroups and NRY lineages for all
populations. Gene diversity is shown below their respective pie chart. The lower part depicts the geography of the
region where the sampling sites of Ortega and Pijao are closely located in Tolima’s Magdalena river valley and
Ibague, Planadas and Nasa located in the Andes cordilleras (additional geographic details are shown in SF1).

Highlights from the paper:

  • MtDNA suggest a pre/post Columbian genetic continuity in the Colombian Andes.
  • Y-chromosome diversity follows a clinal gradient in the studied region.
  • Sex-biased/male-driven admixture process, involving Pijao women with European men.
  • Admixed closer to Indigenous resguardos have a higher Native American ancestry.

Also interesting is the recent paper Mitochondrial lineage A2ah found in a pre‐Hispanic individual from the Andean region, by Russo et al., in American Journal of Human Biology (2018), with an interesting sample from the Regional Developments II period (540 ± 60 BP).

phylogeny-a2ah-mtdna
Phylogeny of the A2ah mitochondrial lineage based on HVR I sequences. Both MaximumParsimony andMaximumLikelihood reconstructions led to the same typology. The tree was rooted with the RSRS. Sample ID: Cueva: Pukara de La Cueva, STACRUZ: Santa Cruz, BNI: Beni, BR: South-eastern Brazil, TobaChA: TobaGranChaco

Related:

Male-biased expansions and migrations also observed in Northwestern Amazonia

Open access preprint Cultural Innovations influence patterns of genetic diversity in Northwestern Amazonia, by Arias et al., bioRxiv (2018).

Abstract (emphasis mine):

Human populations often exhibit contrasting patterns of genetic diversity in the mtDNA and the non-recombining portion of the Y-chromosome (NRY), which reflect sex-specific cultural behaviors and population histories. Here, we sequenced 2.3 Mb of the NRY from 284 individuals representing more than 30 Native-American groups from Northwestern Amazonia (NWA) and compared these data to previously generated mtDNA genomes from the same groups, to investigate the impact of cultural practices on genetic diversity and gain new insights about NWA population history. Relevant cultural practices in NWA include postmarital residential rules and linguistic-exogamy, a marital practice in which men are required to marry women speaking a different language. We identified 2,969 SNPs in the NRY sequences; only 925 SNPs were previously described. The NRY and mtDNA data showed that males and females experienced different demographic histories: the female effective population size has been larger than that of males through time, and both markers show an increase in lineage diversification beginning ~5,000 years ago, with a male-specific expansion occurring ~3,500 years ago. These dates are too recent to be associated with agriculture, therefore we propose that they reflect technological innovations and the expansion of regional trade networks documented in the archaeological evidence. Furthermore, our study provides evidence of the impact of postmarital residence rules and linguistic exogamy on genetic diversity patterns. Finally, we highlight the importance of analyzing high-resolution mtDNA and NRY sequences to reconstruct demographic history, since this can differ considerably between males and females.

y-dna-mtdna-amazonia
MDS plots for mtDNA and NRY. Stress values (within parentheses) are indicated in percentages.

Looking more precisely at the different groups (even with the resampling approach), there are no significant differences between matrilocal and patrilocal groups. At best, as the study proposes, “this is just one of the factors at play in structuring the observed genetic variation”.

Interesting excerpts:

(…) we found evidence that the patterns of genetic differentiation depend on the geographical scale of the study. The magnitude of between-population differentiation in the NRY compared to the mtDNA is smaller when looking at the continental scale than in NWA (Figure 6). This is in agreement with the findings of Wilkins and Marlowe (2006), who showed that the excess of between-population differentiation for the NRY in comparison to the mtDNA decreases when comparing more geographically distant populations. Heyer et al. (2012) and Wilkins and Marlowe (2006) have proposed that at a local scale the patterns of genetic diversity reflect cultural practices over a relatively small number of generations, whereas at a larger geographic scale the genetic diversity reflects old migration and/or old common ancestry patterns(Heyer et al. 2012; Wilkins and Marlowe 2006).

y-dna-mtdna-amazon
BSPs for the mtDNA and NRY sequences from NWA. The dotted lines indicate the 95% HPD intervals. Ne was corrected for generation time according to (Fenner 2005), using 26 years for mtDNA and 31 years for NRY.

The BSP plots and the diversity statistics indicate that overall the Ne of males has been smaller than that of females. One tentative explanation for this difference is that it reflects larger differences in reproductive success among males than among females. Some support for this explanation comes from the shape of the phylogenies (Supplementary Figures 1 and 6), since differences in reproductive success and the cultural transmission of fertility lead to imbalance phylogenies (Blum et al. 2006; Heyer et al. 2015). We estimated a common index of tree imbalance (Colless index) and calculated whether the mtDNA and NRY trees were more unbalanced than 1000 simulated trees generated under a Yule process (Bortolussi et al. 2006) (i.e. a simple pure birth process that assumes that the birth rate of new lineages is the same along the tree). We found that the NRY tree is more unbalanced than predicted by the Yule model (p-value=0.001), whereas the mtDNA tree is not significantly different from trees generated by the Yule model (p-value=0.628). It has been suggested that highly mobile hunter-gatherer societies, such as those typical of most of human prehistory, were polygynous bands (Dupanloup et al. 2003); similarly, nomadic horticulturalist Amazonian societies exhibit strong differences in reproductive success due to the common practice of polygyny, especially among community chiefs, whose offspring also enjoy a high fertility (Neel 1970; 1980; Neel and Weiss 1975).

Furthermore, a more recent expansion can be observed in the BSP based on the NRY, but not in the mtDNA BSP (Figure 5), indicating an expansion specifically in the paternal line. The reasons behind this recent male-biased population expansion, which starts ~3.5 kya, are as yet unclear. However, similar male-biased expansions have been observed in other studies using high-resolution NRY sequences (Batini et al. 2017; Karmin et al. 2015).

Related:

Ancient human parallel lineages within North America contributed to a coastal expansion

americas-dispersal

New paper (behind paywall), Ancient human parallel lineages within North America contributed to a coastal expansion, by Scheib et al. Science (2018) 360(6392):1024-1027.

Abstract:

Little is known regarding the first people to enter the Americas and their genetic legacy. Genomic analysis of the oldest human remains from the Americas showed a direct relationship between a Clovis-related ancestral population and all modern Central and South Americans as well as a deep split separating them from North Americans in Canada. We present 91 ancient human genomes from California and Southwestern Ontario and demonstrate the existence of two distinct ancestries in North America, which possibly split south of the ice sheets. A contribution from both of these ancestral populations is found in all modern Central and South Americans. The proportions of these two ancestries in ancient and modern populations are consistent with a coastal dispersal and multiple admixture events.

americas-ancestry
Visual model of ancestry components and distribution of proportions in the Americas. (A) A model with four admixture events that offers a
good fit to the data (Z = 0.888) (15). (B) Scale of ANC-B ancestry from 0% in Anzick-1 to 100% in the ASO and modern Algonquian-speaking populations.

Interesting excerpts:

We modeled the population history of the Americas using qpGraph (15, 21) and found that the ASO and Mexican (Pima) populations were consistently outgroups to sets of clades formed by Anzick-1, SAM(Surui), and ESNpopulations in analyses that did not involve admixture (fig. S4) (15, 21). Fit between the data and the tree could be significantly improvedwhenmodeling ancient Californian, modern Pima, and Surui populations through admixture of two basal ancestries that we call ANC-A and ANC-B.

The clear separation of ANC-A and ANC-B ancestries is further supported by the sharing of unambiguous, derived haplotype segments in modern Surui and Pima populations (27) with both the ASO (CK-13) and Anzick-1 individuals (fig. S5) (15). The results of this analysis are consistent with ancient substructure and a separation of at least a few thousand years between the ANC-A and ANC-B populations prior to merging (fig. S6) (15). The summary of evidence presented here allows us to reject models of a panmictic “first wave” population from which the ASO diverged after the peopling of South America or in which solely the ANC-A population contributed to modern southern branch populations. Because populations vary in ANC-A and ANC-B proportions but do not differ significantly in their affinity to non-American populations (table S7) (15), it is possible that ANC-A and ANC-B split within America as opposed to Beringia where there would have been ongoing gene flow with Siberia.

Related:

Latin Americans show widespread Mediterranean and North African ancestry

Recent preprint Latin Americans show wide-spread Converso ancestry and the imprint of local Native ancestry on physical appearance, by Chacon-Duque et al. bioRxiv (2018).

Abstract:

Historical records and genetic analyses indicate that Latin Americans trace their ancestry mainly to the admixture of Native Americans, Europeans and Sub-Saharan Africans. Using novel haplotype-based methods here we infer the sub-populations involved in admixture for over 6,500 Latin Americans and evaluate the impact of sub-continental ancestry on the physical appearance of these individuals. We find that pre-Columbian Native genetic structure is mirrored in Latin Americans and that sources of non-Native ancestry, and admixture timings, match documented migratory flows. We also detect South/East Mediterranean ancestry across Latin America, probably stemming from the clandestine colonial migration of Christian converts of non-European origin (Conversos). Furthermore, we find that Central Andean ancestry impacts on variation of facial features in Latin Americans, particularly nose morphology, possibly relating to environmental adaptation during the evolution of Native Americans.

latin-america-finestructure
Reference population samples, fineSTRUCTURE groups and SOURCEFIND ancestry estimates for the five Latin American countries examined. (A) Colored pies and grey dots indicate the approximate geographic location of the 117 reference population samples studied. These samples have been subdivided on the world map into five major biogeographic regions: Native Americans (38 populations), Europeans (42 populations), East/South Mediterraneans (15 populations), Sub-Saharan Africans (15 populations) and East Asians (7 populations). The coloring of pies represents the proportion of individuals from that sample included in one of the 35 reference groups defined using fineSTRUCTURE (these groups are listed in the color-coded insets for each region; Supplementary Fig. 2). The grey dots indicate reference populations not inferred to contribute ancestry to the CANDELA sample. Panels (B) and (C) show, respectively, the estimated proportion of sub-continental Native American and European ancestry components in individuals with >5% total Native American or European ancestry in each country sampled (the stacked bars are color-coded as for the reference population groups shown in the insets of panel (A)). Panel (D) shows boxplots of the estimated sub-continental ancestry components for individuals with >5% total Sephardic/East/South Mediterranean ancestry. In this panel colors refer to countries as for the colored country labels shown in (A).

I don’t know how I missed this. It is probably the biggest sample of Latin American populations used for genetic analysis, and it seems it is due for publication soon.

One of its most interesting finds is the eastern Mediterranean and North African ancestry found in almost a quarter of the individuals sampled all over Latin America, which the authors attribute to Sephardic Jews or Conversos.

Although these Conversos were forbidden from migrating to the colonies, historical records document that some individuals made the journey, in an attempt to avoid persecution14. Since this was a clandestine process, the extent of Converso migration to Latin America is poorly documented. Genetic studies have provided suggestive evidence that certain Latin American populations, arguably with a peculiar history, could have substantial Converso ancestry1,18. Our findings indicate that the genetic signature of Converso migration to Latin America is substantially more prevalent than suggested by these special cases, or by historical records.

However, strictly speaking, Converso refers to a recent convert, while this ancestry could have also been part of older Sephardic (and obviously other North African) admixture found in Iberian populations during the Reconquista.

latin-america-native-spanish-conversos
Geographic variation of Native American (A), European (B), and East/South Mediterranean (C) ancestry sub-components in Latin American individuals. Each pie represents an individual with pie location corresponding to birthplace. Since many individuals share birthplace, jittering has been performed based on pie size and how crowded an area is. Pie size is proportional to total continental ancestry and only individuals with >5% of each continental ancestry are shown. Coloring of pies represents the proportion of each sub-continental component estimated for each individual (color-coded as in Fig. 1; Chaco2 does not contribute >5% to any individual and was excluded). Pies in panel (C) have been enlarged to facilitate visualization.

Discovered via Lizzie Wade’s article Latin America’s lost histories revealed in modern DNA, Science (2018).

Related:

Ancient mtDNA from Central America and Mexico

pre-columbian-central-america-mexico

New article, Successful reconstruction of whole mitochondrial genomes from ancient Central America and Mexico, by Morales-Arce et al., Scientific Reports (2017).

Abstract:

The northern and southern peripheries of ancient Mesoamerica are poorly understood. There has been speculation over whether borderland cultures such as Greater Nicoya and Casas Grandes represent Mesoamerican outposts in the Isthmo-Colombian area and the Greater Southwest, respectively. Poor ancient DNA preservation in these regions challenged previous attempts to resolve these questions using conventional genetic techniques. We apply advanced in-solution mitogenome capture and high-throughput sequencing to fourteen dental samples obtained from the Greater Nicoya sites of Jícaro and La Cascabel in northwest Costa Rica (n = 9; A.D. 800–1250) and the Casas Grandes sites of Paquimé and Convento in northwest Mexico (n = 5; A.D. 1200–1450). Full mitogenome reconstruction was successful for three individuals from Jícaro and five individuals from Paquimé and Convento. The three Jícaro individuals belong to haplogroup B2d, a haplogroup found today only among Central American Chibchan-speakers. The five Paquimé and Convento individuals belong to haplogroups C1c1a, C1c5, B2f and B2a which, are found in contemporary populations in North America and Mesoamerica. We report the first successfully reconstructed ancient mitogenomes from Central America, and the first genetic evidence of ancestry affinity of the ancient inhabitants of Greater Nicoya and Casas Grandes with contemporary Isthmo-Columbian and Greater Southwest populations, respectively.

mesoamerica-ancient-mtdna
Archaeological sites location and corresponding culture areas as noted in the text. ArcGIS 10.4 software (http://www.esri.com/software/arcgis) was used to generate the figure. Service layer credits Esri, ArcGIS Online, TerraColor (Earthstar Geographics) 1999; Vivid – Mexico (Digital Globe) 2005, 2009, 2010, 2011, 2012, 2013, 2014, 2015; Metro (Digital Globe) 2016; Vivid Caribbean (Digital Globe) 2013, 2014, 2015, 2016, Vivid (Digital Globe) 2015, Vivid – Mexico (Digital Globe) 2012 and the GIS User Community.

Discovered via Bernard Sécher’s blog.

Featured image: From Wikipedia, author Juan Miguel, “Mesoamérica y toda América Central prehispanica en el siglo XVI (16) — antes de la llegada de los españoles.”

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