Category Archives: Latin America
|Battle of Vertières (Haiti 1803)|
A very interesting study on Caribbean populations’ autosomal ancestry is in the oven (pre-publication at arXiv).
The Caribbean basin is home to some of the most complex interactions in recent history among previously diverged human populations. Here, by making use of genome-wide SNP array data, we characterize ancestral components of Caribbean populations on a sub-continental level and unveil fine-scale patterns of population structure distinguishing insular from mainland Caribbean populations as well as from other Hispanic/Latino groups. We provide genetic evidence for an inland South American origin of the Native American component in island populations and for extensive pre-Columbian gene flow across the Caribbean basin. The Caribbean-derived European component shows significant differentiation from parental Iberian populations, presumably as a result of founder effects during the colonization of the New World. Based on demographic models, we reconstruct the complex population history of the Caribbean since the onset of continental admixture. We find that insular populations are best modeled as mixtures absorbing two pulses of African migrants, coinciding with early and maximum activity stages of the transatlantic slave trade. These two pulses appear to have originated in different regions within West Africa, imprinting two distinguishable signatures in present day Afro-Caribbean genomes and shedding light on the genetic impact of the dynamics occurring during the slave trade in the Caribbean.
The most synthetic graph is the following one:
ADMIXTURE metrics at increasing K values
based on Log-likelihoods (A)
and cross-validation errors (B)
for results shown in Figure S2.
Using table B, the best fit is K=7:
|From Fig. S2 (ADMIXTURE results)|
AbstractNumerous studies of human populations in Europe and Asia have revealed a concordance between their extant genetic structure and the prevailing regional pattern of geography and language. For native South Americans, however, such evidence has been lacking so far. Therefore, we examined the relationship between Y-chromosomal genotype on the one hand, and male geographic origin and linguistic affiliation on the other, in the largest study of South American natives to date in terms of sampled individuals and populations. A total of 1,011 individuals, representing 50 tribal populations from 81 settlements, were genotyped for up to 17 short tandem repeat (STR) markers and 16 single nucleotide polymorphisms (Y-SNPs), the latter resolving phylogenetic lineages Q and C. Virtually no structure became apparent for the extant Y-chromosomal genetic variation of South American males that could sensibly be related to their inter-tribal geographic and linguistic relationships. This continent-wide decoupling is consistent with a rapid peopling of the continent followed by long periods of isolation in small groups. Furthermore, for the first time, we identified a distinct geographical cluster of Y-SNP lineages C-M217 (C3*) in South America. Such haplotypes are virtually absent from North and Central America, but occur at high frequency in Asia. Together with the locally confined Y-STR autocorrelation observed in our study as a whole, the available data therefore suggest a late introduction of C3* into South America no more than 6,000 years ago, perhaps via coastal or trans-Pacific routes. Extensive simulations revealed that the observed lack of haplogroup C3* among extant North and Central American natives is only compatible with low levels of migration between the ancestor populations of C3* carriers and non-carriers. In summary, our data highlight the fact that a pronounced correlation between genetic and geographic/cultural structure can only be expected under very specific conditions, most of which are likely not to have been met by the ancestors of native South Americans.
|Table 1. Correlation between Y-SNP haplogroup and language class.|
Overall distribution of Y-DNA C3* (yellow), which I understand to mean C3(xC3b) for this study:
|Figure 4. Prevalence of Y-SNP haplogroup C-M217 (C3*) around the Pacific Ocean.
Light blue: previous studies; dark blue: present study; yellow: relative frequency of C-M217 (C3*) carriers.
AbstractThere is a consensus that modern
humans arrived in the Americas 15,000–20,000 y ago during the Late
Pleistocene, most probably
from northeast Asia through Beringia.
However, there is still debate about the time of entry and number of
including apparent inconsistencies between
genetic and morphological data on Paleoamericans. Here we report the
of mitochondrial sequences belonging to
haplogroups characteristic of Polynesians in DNA extracted from ancient
the now extinct Botocudo Indians from
Brazil. The identification of these two Polynesian haplogroups was
confirmed in independent
replications in Brazil and Denmark,
ensuring reliability of the data. Parallel analysis of 12 other Botocudo
only the well-known Amerindian mtDNA
haplogroup C1. Potential scenarios to try to help understand these
results are presented
and discussed. The findings of this study
may be relevant for the understanding of the pre-Columbian and/or
peopling of the Americas.
For more than 40 y, there has been an active discussion over the presence and economic importance of maize (Zea mays) during the Late Archaic period (3000–1800 B.C.) in ancient Peru. The evidence for Late Archaic maize has been limited, leading to the interpretation that it was present but used primarily for ceremonial purposes. Archaeological testing at a number of sites in the Norte Chico region of the north central coast provides a broad range of empirical data on the production, processing, and consumption of maize. New data drawn from coprolites, pollen records, and stone tool residues, combined with 126 radiocarbon dates, demonstrate that maize was widely grown, intensively processed, and constituted a primary component of the diet throughout the period from 3000 to 1800 B.C.
Update: see the interesting comments below by Raimo Kangasniemi, who argues that several sites (Áspero, La Galgada, Caral, all them in Peru) are roughly contemporary of this one, indicating a growing dedication of resources to ritual/religious buildings already in the Pre-Ceramic Period V, also elsewhere.
Renato Kipnis, a respected archaeologist in São Paulo whom Vale hired to
survey the caves of Carajás, said that Vale had prohibited him from
discussing their archaeological significance, because of a
confidentiality agreement Vale had required him to sign. Later, a Vale
spokeswoman allowed Mr. Kipnis to be interviewed by e-mail, but only if
the company was allowed to vet his replies.
In written replies screened by Vale, he marveled at the importance of the caves.
|NASA image of the already existing Carajás mine|
|Xavantes (cc Agência Brasil)|
Characterization of population genetic variation and structure can be used as tools for research in human genetics and population isolates are of great interest. The aim of the present study was to characterize the genetic structure of Xavante Indians and compare it with other populations. The Xavante, an indigenous population living in Brazilian Central Plateau, is one of the largest native groups in Brazil. A subset of 53 unrelated subjects was selected from the initial sample of 300 Xavante Indians. Using 86,197 markers, Xavante were compared with all populations of HapMap Phase III and HGDP-CEPH projects and with a Southeast Brazilian population sample to establish its population structure. Principal Components Analysis showed that the Xavante Indians are concentrated in the Amerindian axis near other populations of known Amerindian ancestry such as Karitiana, Pima, Surui and Maya and a low degree of genetic admixture was observed. This is consistent with the historical records of bottlenecks experience and cultural isolation. By calculating pair-wise Fst statistics we characterized the genetic differentiation between Xavante Indians and representative populations of the HapMap and from HGDP-CEPH project. We found that the genetic differentiation between Xavante Indians and populations of Ameridian, Asian, European, and African ancestry increased progressively. Our results indicate that the Xavante is a population that remained genetically isolated over the past decades and can offer advantages for genome-wide mapping studies of inherited disorders.
|Fig. 2 three-dimensional global PCA with emphasis in American populations|
|Fig. 3 (edited by me: only the labeling): neighbor-joining global tree|