Deep genetic affinity between coastal Pacific and Amazonian natives evidenced by Australasian ancestry.

Different models have been proposed to elucidate the origins of the founding populations of America, along with the number of migratory waves and routes used by these first explorers. Settlements, both along the Pacific coast and on land, have been evidenced in genetic and archeological studies. However, the number of migratory waves and the origin of immigrants are still controversial topics. Here, we show the Australasian genetic signal is present in the Pacific coast region, indicating a more widespread signal distribution within South America and implicating an ancient contact between Pacific and Amazonian dwellers. We demonstrate that the Australasian population contribution was introduced in South America through the Pacific coastal route before the formation of the Amazonian branch, likely in the ancient coastal Pacific/Amazonian population. In addition, we detected a significant amount of interpopulation and intrapopulation variation in this genetic signal in South America. This study elucidates the genetic relationships of different ancestral components in the initial settlement of South America and proposes that the migratory route used by migrants who carried the Australasian ancestry led to the absence of this signal in the populations of Central and North America.

Population Histories and Genomic Diversity of South American Natives.

South America is home to one of the most culturally diverse present-day native populations. However, the dispersion pattern, genetic substructure, and demographic complexity within South America are still poorly understood. Based on genome-wide data of 58 native populations, we provide a comprehensive scenario of South American indigenous groups considering the genomic, environmental, and linguistic data. Clear patterns of genetic structure were inferred among the South American natives, presenting at least four primary genetic clusters in the Amazonian and savanna regions and three clusters in the Andes and Pacific coast. We detected a cline of genetic variation along a west-east axis, contradicting a hard Andes-Amazon divide. This longitudinal genetic variation seemed to have been shaped by both serial population bottlenecks and isolation by distance. Results indicated that present-day South American substructures recapitulate ancient macroregional ancestries and western Amazonia groups show genetic evidence of cultural exchanges that led to language replacement in precontact times. Finally, demographic inferences pointed to a higher resilience of the western South American groups regarding population collapses caused by the European invasion and indicated precontact population reductions and demic expansions in South America.

Genomic insight into the origins and dispersal of the Brazilian coastal natives.

In the 15th century, ∼900,000 Native Americans, mostly Tupí speakers, lived on the Brazilian coast. By the end of the 18th century, the coastal native populations were declared extinct. The Tupí arrived on the east coast after leaving the Amazonian basin ∼2,000 y before present; however, there is no consensus on how this migration occurred: toward the northern Amazon and then directly to the Atlantic coast, or heading south into the continent and then migrating to the coast. Here we leveraged genomic data from one of the last remaining putative representatives of the Tupí coastal branch, a small, admixed, self-reported Tupiniquim community, as well as data of a Guaraní Mbyá native population from Southern Brazil and of three other native populations from the Amazonian region. We demonstrated that the Tupiniquim Native American ancestry is not related to any extant Brazilian Native American population already studied, and thus they could be considered the only living representatives of the extinct Tupí branch that used to settle the Atlantic Coast of Brazil. Furthermore, these data show evidence of a direct migration from Amazon to the Northeast Coast in pre-Columbian time, giving rise to the Tupí Coastal populations, and a single distinct migration southward that originated the Guaraní people from Brazil and Paraguay. This study elucidates the population dynamics and diversification of the Brazilian natives at a genomic level, which was made possible by recovering data from the Brazilian coastal population through the genomes of mestizo individuals.

A multidisciplinary overview on the Tupi-speaking people expansion.

The cultural and biological diversity of South American indigenous groups represent extremes of human variability, exhibiting one of the highest linguistic diversities alongside a remarkably low within-population genetic variation and an extremely high inter-population genetic differentiation. On top of that, this region has seen some of the most dramatic demographic events in human history unleashed by the European colonization of the Americas. As a result of this process, the distribution of indigenous populations has been radically changed. In this review we focus on the Tupi, the largest and most widespread linguistic family in eastern South America. Tupi are believed to have originated in southwestern Amazon, from where some of its subfamilies expanded into other parts of the Amazon and, in the case of the Tupi-Guarani, beyond its borders. Recent evidence from archaeology, linguistics, and genetics aligns with José Brochado's Tupi Expansion model. He proposed that the gradual development of agricultural systems within the Amazon resulted in population growth and, eventually, territorial expansion. This model also supports separate Tupi Expansion branches: Tupinambá (Atlantic coast) and Guarani (south, midwest Brazil). Although being the most populous group on Brazil's Atlantic coast, which was the most affected by European colonization, the Tupi still account for roughly 20% of the country's overall indigenous population. Finally, despite its importance and more than a century of research on the Tupi and their expansion history, many key questions remain unanswered, which we attempt to summarize and explore here.

A diversidade cultural e biológica dos grupos indígenas sul-americanos representam extremos da variabilidade humana, abrangendo uma das maiores diversidades linguísticas e uma das menores diversidades genéticas intrapopulacionais do mundo, assim como uma das maiores diferenciações genéticas interpopulacionais. Além disso, esta região presenciou alguns dos eventos demográficos mais dramáticos da história da humanidade, desencadeados pela colonização européia das Américas. Como resultado desse processo, a distribuição das populações indígenas mudou radicalmente. Nesta revisão, focamos nos Tupi, o maior e mais difundido grupo linguístico do leste da América do Sul, dentre as sete principais famílias linguísticas do continente. Acredita-se que os Tupi tenham se originado no sudeste da Amazônia, de onde algumas de suas subfamílias se expandiram para outras partes da Amazônia e, no caso dos Tupi-Guarani, para além de suas fronteiras. Evidências recentes da arqueologia, linguística e genética alinham-se com o modelo de Expansão Tupi de José Brochado. Ele propôs que o desenvolvimento gradual dos sistemas agrícolas na Amazônia resultou no crescimento populacional e, eventualmente, na expansão territorial. Esse modelo também apóia ramos separados da Expansão Tupi: Tupinambá (costa atlântica) e Guarani (sul e centro-oeste do Brasil). Embora sejam o grupo mais populoso da costa atlântica do Brasil, que foi a mais afetada pela colonização europeia, os Tupi ainda representam cerca de 20% da população indígena total do país. Finalmente, apesar de sua importância e de mais de um século de pesquisa sobre os Tupi e sua história de expansão, muitas questões-chave permanecem sem solução, as quais tentamos resumir e explorar aqui.