Inca and Spanish Empires had a profound impact on Peruvian demography


Open access Evolutionary genomic dynamics of Peruvians before, during, and after the Inca Empire by Harris et al., PNAS (2018) 201720798 (published ahead of print).

Abstract (emphasis mine):

Native Americans from the Amazon, Andes, and coastal geographic regions of South America have a rich cultural heritage but are genetically understudied, therefore leading to gaps in our knowledge of their genomic architecture and demographic history. In this study, we sequence 150 genomes to high coverage combined with an additional 130 genotype array samples from Native American and mestizo populations in Peru. The majority of our samples possess greater than 90% Native American ancestry, which makes this the most extensive Native American sequencing project to date. Demographic modeling reveals that the peopling of Peru began ∼12,000 y ago, consistent with the hypothesis of the rapid peopling of the Americas and Peruvian archeological data. We find that the Native American populations possess distinct ancestral divisions, whereas the mestizo groups were admixtures of multiple Native American communities that occurred before and during the Inca Empire and Spanish rule. In addition, the mestizo communities also show Spanish introgression largely following Peruvian Independence, nearly 300 y after Spain conquered Peru. Further, we estimate migration events between Peruvian populations from all three geographic regions with the majority of between-region migration moving from the high Andes to the low-altitude Amazon and coast. As such, we present a detailed model of the evolutionary dynamics which impacted the genomes of modern-day Peruvians and a Native American ancestry dataset that will serve as a beneficial resource to addressing the underrepresentation of Native American ancestry in sequencing studies.

Admixture among Peruvian populations. (A) Colors represent contributions from donor populations into the genomes of Peruvian mestizo groups, as estimated by CHROMOPAINTER and GLOBETROTTER. The label within parentheses for each Peruvian Native American source population corresponds to their geographic region where Ama, And, and Coa represent Amazon, Andes, and coast, respectively. (B) Admixture time and proportion for the best fit three-way ancestry (AP, Trujillo and Lima) and two-way ancestry (Iquitos, Cusco, and Puno) TRACT models [European, African, and Native American (NatAm) ancestries] for six mestizo populations. (C) Network of individuals from Peruvian Native American and mestizo groups according to their shared IBD length. Each node is an individual and the length of an edge equals to (1/total shared IBD). IBD segments with different lengths are summed according to different thresholds representing different times in the past (52), with 7.8 cM, 9.3 cM, and 21.8 cM roughly representing the start of the Inca Empire, the Spanish conquest and occupation, and Peruvian independence. IBD networks are generated by Cytoscape (98) and only the major clusters in the network are shown for different cutoffs of segment length. AP, Central Am, and Matsig are short for Afroperuvians, Central American, and Matsiguenka, respectively. The header of each IBD network specifies the length of IBD segments used in each network.

Interesting excerpts

The high frequency of Native American mitochondrial haplotypes suggests that European males were the primary source of European admixture with Native Americans, as previously found (23, 24, 41, 42). The only Peruvian populations that have a proportion of the Central American component are in the Amazon (Fig. 2A). This is supported by Homburger et al. (4), who also found Central American admixture in other Amazonian populations and could represent ancient shared ancestry or a recent migration between Central America and the Amazon.

Following the peopling of Peru, we find a complex history of admixture between Native American populations from multiple geographic regions (Figs. 2B and 3 A and C). This likely began before the Inca Empire due to Native American and mestizo groups sharing IBD segments that correspond to the time before the Inca Empire. However, the Inca Empire likely influenced this pattern due to their policy of forced migrations, known as “mitma” (mitmay in Quechua) (28, 31, 37), which moved large numbers of individuals to incorporate them into the Inca Empire. We can clearly see the influence of the Inca through IBD sharing where the center of dominance in Peru is in the Andes during the Inca Empire (Fig. 3C).

ASPCA of combined Peruvian Genome Project with the HGDP genotyped on the Human Origins Array. A.) European ancestry. B.) African ancestry. Samples are filtered by their corresponding ancestral proportion: European ≥ 30% (panel A) and African ≥ 10% (panel B). The two plots in each panel are identical except for the color scheme: reference populations are colored on the left and Peruvian populations are colored on the right. Each point is one haplotype. In the African ASPCA we note three outliers among our samples, two from Trujillo and one from Iquitos, that cluster closer to the Luhya and Luo populations, though not directly. It is likely that these individuals share ancestry with other regions of Africa in addition to western Africa, but we cannot test this hypothesis explicitly as we have too few samples.

A similar policy of large-scale consolidation of multiple Native American populations was continued during Spanish rule through their program of reducciones, or reductions (31, 32), which is consistent with the hypothesis that the Inca and Spanish had a profound impact on Peruvian demography (25). The result of these movements of people created early New World cosmopolitan communities with genetic diversity from the Andes, Amazon, and coast regions as is evidenced by mestizo populations’ ancestry proportions (Fig. 3A). Following Peruvian independence, these cosmopolitan populations were those same ones that predominantly admixed with the Spanish (Fig. 3B). Therefore, this supports our model that the Inca Empire and Spanish colonial rule created these diverse populations as a result of admixture between multiple Native American ancestries, which would then go on to become the modern mestizo populations by admixing with the Spanish after Peruvian independence.

Further, it is interesting that this admixture began before the urbanization of Peru (26) because others suspected the urbanization process would greatly impact the ancestry patterns in these urban centers (25). (…)


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


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.


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.

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.


Population structure in Argentina shows most European sources of South European origin


Open access Population structure in Argentina, by Muzzio et al., PLOS One (2018).

Abstract (emphasis mine):

We analyzed 391 samples from 12 Argentinian populations from the Center-West, East and North-West regions with the Illumina Human Exome Beadchip v1.0 (HumanExome-12v1-A). We did Principal Components analysis to infer patterns of populational divergence and migrations. We identified proportions and patterns of European, African and Native American ancestry and found a correlation between distance to Buenos Aires and proportion of Native American ancestry, where the highest proportion corresponds to the Northernmost populations, which is also the furthest from the Argentinian capital. Most of the European sources are from a South European origin, matching historical records, and we see two different Native American components, one that spreads all over Argentina and another specifically Andean. The highest percentages of African ancestry were in the Center West of Argentina, where the old trade routes took the slaves from Buenos Aires to Chile and Peru. Subcontinentaly, sources of this African component are represented by both West Africa and groups influenced by the Bantu expansion, the second slightly higher than the first, unlike North America and the Caribbean, where the main source is West Africa. This is reasonable, considering that a large proportion of the ships arriving at the Southern Hemisphere came from Mozambique, Loango and Angola.

Principal component analysis.
On the x axis is PC 1 while PC2 is the y axis. Plus symbols represent Argentinian samples and circles are for reference panels. Fig 2a (left) Argentinians with YRI and LWK for African references (“African”), IBS and TSI for European references (“European”) and the PEL, MXL, PUR and CLM as a Latin American references. Fig 2b (right) samples from Argentina with IBS, MXL, CLM and PEL.


Paternal lineages mainly from migrants, maternal lineages mainly from local populations in Argentina

New paper (behind paywall) Genetic variation in populations from central Argentina based on mitochondrial and Y chromosome DNA evidence, by García, Pauro, Bailliet, Bravi & Demarchi, J. Hum. Genet (2018) 63: 493–507.

Abstract (emphasis mine):

We present new data and analysis on the genetic variation of contemporary inhabitants of central Argentina, including a total of 812 unrelated individuals from 20 populations. Our goal was to bring new elements for understanding micro-evolutionary and historical processes that generated the genetic diversity of the region, using molecular markers of uniparental inheritance (mitochondrial DNA and Y chromosome). Almost 76% of the individuals show mitochondrial lineages of American origin. The Native American haplogroups predominate in all surveyed localities, except in one. The larger presence of Eurasian maternal lineages were observed in the plains (Pampas) of the southeast, whereas the African lineages are more frequent in northern Córdoba. On the other hand, the analysis of 258 male samples reveals that 92% of them present Eurasian paternal lineages, 7% carry Native American haplogroups, and only 1% of the males show African lineages. The maternal lineages have high genetic diversity homogeneously distributed throughout central Argentina, probably as result of a recent common origin and sustained gene flow. Migratory events that occurred in colonial and recent times should have contributed to hiding any traces of differentiation that might have existed in the past. The analysis of paternal lineages showed also homogeneous distribution of the variation together with a drastic reduction of the native male population.

Maps showing continental mtDNA haplogroups frequencies in 20 population samples from central Argentina. References for populations abbreviated names are from the tables.

Interesting excerpts:

The immigration waves had less impact in the north–central and northwestern regions, the most populated areas of the country in pre-Hispanic times. The spatial structure of genetic diversity has its origins in historical factors. It is possible to distinguish different stages in migratory processes from abroad, with a heterogeneous regional impact. The genetic composition of central Argentina gives account of these processes. On one hand, the political boundaries between provinces influenced the configuration of the genetic structure of the populations that were formed. In this sense, Córdoba—an important economic and commercial center since colonial times—has a greater component of foreign lineages than the populations of San Luis and Santiago del Estero. On the other hand, the genetic structure of central Argentina also accounts for other processes related to different migration phases and occupations of space over the last 500 years.

Maternal continental contribution (in percentages), and Native American haplogroup frequencies, by population

Similarly, negative values observed in the neutrality tests (Tajima’s D and Fu’s FS), indicate relatively recent population growth, probably associated with technological and organizational changes leading to new lifestyles and important demographic and territorial expansion [75]. In conclusion, the molecular markers of maternal inheritance shows large genetic diversity homogeneously distributed throughout central Argentina, probably as result of a recent common origin and sustained gene flow between sub-populations. In addition, migratory events that occurred in colonial and recent times should have contributed to hiding any traces of differentiation that might have existed in the past. The analysis of paternal lineages showed also homogeneous distribution of the variation across the region but also a drastic reduction of the native male population, with a large prevalence of haplogroups of European origin.

Y chromosome haplogroups frequencies in three provinces from central Argentina and other 19 samples from Argentina, Chile, and Paraguay


Earliest modern humans outside Africa and ancient genomic history


Interesting new paper at Science, The earliest modern humans outside Africa, by Hershkovitz et al., Science (2018) Vol. 359, Issue 6374, pp. 456-459


Recent paleoanthropological studies have suggested that modern humans migrated from Africa as early as the beginning of the Late Pleistocene, 120,000 years ago. Hershkovitz et al. now suggest that early modern humans were already present outside of Africa more than 55,000 years earlier (see the Perspective by Stringer and Galway-Witham). During excavations of sediments at Mount Carmel, Israel, they found a fossil of a mouth part, a left hemimaxilla, with almost complete dentition.

The sediments contain a series of well-defined hearths and a rich stone-based industry, as well as abundant animal remains. Analysis of the human remains, and dating of the site and the fossil itself, indicate a likely age of at least 177,000 years for the fossil—making it the oldest member of the Homo sapiens clade found outside Africa.


To date, the earliest modern human fossils found outside of Africa are dated to around 90,000 to 120,000 years ago at the Levantine sites of Skhul and Qafzeh. A maxilla and associated dentition recently discovered at Misliya Cave, Israel, was dated to 177,000 to 194,000 years ago, suggesting that members of the Homo sapiens clade left Africa earlier than previously thought. This finding changes our view on modern human dispersal and is consistent with recent genetic studies, which have posited the possibility of an earlier dispersal of Homo sapiens around 220,000 years ago. The Misliya maxilla is associated with full-fledged Levallois technology in the Levant, suggesting that the emergence of this technology is linked to the appearance of Homo sapiens in the region, as has been documented in Africa.

Beautifully complementing this anthropological research, the open access review Insights into Modern Human Prehistory Using Ancient Genomes, by Melinda A. Yang and Qiaomei Fu, Trends in Genetics (2018), depicts potential later migrations:

Key Figure: Schematic of Populations in Eurasia and the Americas (Bottom Right) during Ancient Modern A (AMA, ∼45–35 ka), Ancient Modern B (AMB, ∼34–15 ka), and Ancient Modern C (AMC, ∼14–7.5 ka).

Abbreviations: AMER, ancestry related to present-day Native Americans and Anzick 1; ANE, ancestry related to ancient North Eurasians represented by Mal’ta 1; EAS, ancestry related to present-day East Asians and the Tianyuan and Devil’s Gate individuals; EUR, ancestry related to ancient Europeans and found partially in present-day Europeans; NE, ancestry related to an unsampled population known as Basal Eurasian and found in partial amounts in ancient and present-day populations of the Near East and in present-day Europeans. Broken lines indicate no ancient genetic samples have been found for a population with the inferred ancestry. Colors loosely indicate genetic groupings between or within a region, with color gradients showing the connections (i.e., gene flow) that may exist between different ancient populations. A summary of major events in each of the time periods is on the left.


Eurasia ∼45–35 ka shows the presence of at least four distinct populations: early Asians and Europeans, as well as populations with ancestry found hardly or not at all in present-day populations.

Europeans from around 34–15 ka show high internal population structure.

Approximately 14–7.5 ka, populations across Eurasia shared genetic similarities, suggesting greater interactions between geographically distant populations.

Ancient modern human genomes support at least two Neanderthal admixture events, one ∼60–50 ka in early ancestors of non-African populations and a second >37 ka related to the Oase 1 individual.

A gradual decline in archaic ancestry in Europeans dating from ∼37 to 14 ka suggests that purifying selection lowered the amount of Neanderthal ancestry first introduced into ancient modern humans.

The genetic relationship of past modern humans to today’s populations and each other was largely unknown until recently, when advances in ancient DNA sequencing allowed for unprecedented analysis of the genomes of these early people. These ancient genomes reveal new insights into human prehistory not always observed studying present-day populations, including greater details on the genetic diversity, population structure, and gene flow that characterized past human populations, particularly in early Eurasia, as well as increased insight on the relationship between archaic and modern humans. Here, we review genetic studies on ∼45 000- to 7500-year-old individuals associated with mainly preagricultural cultures found in Eurasia, the Americas, and Africa.

(Both articles discovered via Iosif Lazaridis Twitter account).

See also: