Long Live the 25th March, 1821

Lactase persistence and pastoralism in Africa

AJHG doi:10.1016/j.ajhg.2014.02.009

Genetic Origins of Lactase Persistence and the Spread of Pastoralism in Africa

Alessia Ranciaro et al.

In humans, the ability to digest lactose, the sugar in milk, declines after weaning because of decreasing levels of the enzyme lactase-phlorizin hydrolase, encoded by LCT. However, some individuals maintain high enzyme amounts and are able to digest lactose into adulthood (i.e., they have the lactase-persistence [LP] trait). It is thought that selection has played a major role in maintaining this genetically determined phenotypic trait in different human populations that practice pastoralism. To identify variants associated with the LP trait and to study its evolutionary history in Africa, we sequenced MCM6 introns 9 and 13 and ∼2 kb of the LCT promoter region in 819 individuals from 63 African populations and in 154 non-Africans from nine populations. We also genotyped four microsatellites in an ∼198 kb region in a subset of 252 individuals to reconstruct the origin and spread of LP-associated variants in Africa. Additionally, we examined the association between LP and genetic variability at candidate regulatory regions in 513 individuals from eastern Africa. Our analyses confirmed the association between the LP trait and three common variants in intron 13 (C-14010, G-13907, and G-13915). Furthermore, we identified two additional LP-associated SNPs in intron 13 and the promoter region (G-12962 and T-956, respectively). Using neutrality tests based on the allele frequency spectrum and long-range linkage disequilibrium, we detected strong signatures of recent positive selection in eastern African populations and the Fulani from central Africa. In addition, haplotype analysis supported an eastern African origin of the C-14010 LP-associated mutation in southern Africa.

Link

Back-migration of Yeniseian into Asia from Beringia

PLOS One DOI: 10.1371/journal.pone.0091722

Linguistic Phylogenies Support Back-Migration from Beringia to Asia

Mark A. Sicoli, Gary Holton

Recent arguments connecting Na-Dene languages of North America with Yeniseian languages of Siberia have been used to assert proof for the origin of Native Americans in central or western Asia. We apply phylogenetic methods to test support for this hypothesis against an alternative hypothesis that Yeniseian represents a back-migration to Asia from a Beringian ancestral population. We coded a linguistic dataset of typological features and used neighbor-joining network algorithms and Bayesian model comparison based on Bayes factors to test the fit between the data and the linguistic phylogenies modeling two dispersal hypotheses. Our results support that a Dene-Yeniseian connection more likely represents radiation out of Beringia with back-migration into central Asia than a migration from central or western Asia to North America.

Link

Dark pigmentation of Eneolithic and Bronze Age kurgan groups from eastern Europe

This is a very exciting new study that seems to parallel some results from early west Europeans. The authors invoke selection as a possible cause for the massive change in frequency between the Bronze Age and present-day Ukrainians.

An invocation of selection as an explanation requires evidence population continuity, otherwise changes in allele frequency may involve migration of a new frequency-differentiated new population; for example, the massive change in pigmentation in North America over the last 500 years is not due to selection but to migration of Europeans. The authors cannot reject population continuity on the basis of mtDNA haplogroup frequencies, although autosomal data may be more informative for that purpose.

In any case, the fact that the limited sample from western Europe and the much more extensive sample from eastern Europe both show a darker pigmentation than modern Europeans does suggest that interesting changes happened in Europe over the last few thousand years and samples from more recent time periods may better determine the pace of this change.

From the paper:

In sum, a combination of selective pressures associated with living in northern latitudes, the adoption of an agriculturalist diet, and assortative mating may sufficiently explain the observed change from a darker phenotype during the Eneolithic/Early Bronze age to a generally lighter one in modern Eastern Europeans, although other selective factors cannot be discounted. The selection coefficients inferred directly from serially sampled data at these pigmentation loci range from 2 to 10% and are among the strongest signals of recent selection in humans.

UPDATE: 

The classical Greeks did of course notice that the inhabitants of the north Pontic hinterland, collectively known as Scythians, were extraordinarily light-pigmented. This would imply that major pigmentation change occurred in the steppe over a time span of Bronze Age-Classical Antiquity rather than Bronze Age-present; this would imply even higher selection coefficients (if selection over a population exhibiting continuity is at play).

The Scythians were also thought to be recent arrivals from the east so it is not clear if they were descended from the Bronze Age population of eastern Europe; the crazy selection coefficients that would need to be assumed if there was indeed population continuity might imply that Herodotus got it right again, and the Scythians did in fact arrive from elsewhere. That would of course also imply that people from Central Asia and Siberia (where the Scythians may have come from) were originally lighter than Europeans which does find support from an older study on southern Siberian remains. Ironically, if that is the case, it would mean that the famous light-pigmented mummies of different parts of Inner Asia may not be long-lost European descendants -- as it has sometimes been presumed on the basis of modern-day clines of pigmentation. As usual, ancient DNA continues to surprise.

PNAS doi: 10.1073/pnas.1316513111

Direct evidence for positive selection of skin, hair, and eye pigmentation in Europeans during the last 5,000 y

Sandra Wilde et al.

Eye, hair, and skin pigmentation are highly variable in humans, particularly in western Eurasian populations. This diversity may be explained by population history, the relaxation of selection pressures, or positive selection. To investigate whether positive natural selection is responsible for depigmentation within Europe, we estimated the strength of selection acting on three genes known to have significant effects on human pigmentation. In a direct approach, these estimates were made using ancient DNA from prehistoric Europeans and computer simulations. This allowed us to determine selection coefficients for a precisely bounded period in the deep past. Our results indicate that strong selection has been operating on pigmentation-related genes within western Eurasia for the past 5,000 y.

Link

The place of the Armenian language in the Indo-European family

A very interesting talk at the Library of Congress making a good case for a Greek-Phrygian-Armenian clade within the Indo-European family.
 


Of course the testimony of Herodotus is -at least for me- the most convincing argument for an ultimately Balkan origin of the Phrygo-Armenians.

Modern Armenians are quite distinct from modern populations of the Balkans but who knows how both they and the populations of the Balkans have changed since the beginning of the Iron Age when the Phrygians established themselves in Asia Minor? The recent study by Hellenthal et al. did not find any good evidence for recent admixture in Armenians but this might be due to (i) Armenians being unmixed descendants of Proto-Armenians, (ii) Armenians being near-unmixed descendants of pre-Armenians, or (iii) the method not having enough power to detect admixture.

My guess is that the relative remoteness of the Armenian highlands coupled with the heterodox position of the Armenian church hindered substantial gene flow into the Armenian population over at least the last 1,500 years.

Green Arabia 2014 conference

The program of an upcoming conference that will take in about a month. I don't see abstracts but the list of talks seems interesting and hopefully there will be a twitter stream by attendees in April.

Chauvet cave art not the work of earliest Europeans

Many of you may have watched Cave of Forgotten Dreams, a great documentary about the paintings of Chauvet cave in France. It now turns out that the extraordinary art preserved in the cave may not date to ~36,000 years but rather to the Gravettian or Solutrean period.

 L'Anthropologie Available online 11 February 2014

New investigations into the cultural and stylistic identity of the Chauvet cave and its radiocarbon dating

Jean Combiera, Guy Jouve

The discovery of Chauvet cave, at Vallon-Pont-d’Arc (Ardèche), in 1994, was an important event for our knowledge of palaeolithic parietal art as a whole. Its painted and engraved figures, thanks to their number (425 graphic units), and their excellent state of preservation, provide a documentary thesaurus comparable to that of the greatest sites known, and far beyond what had already been found in the group of Rhône valley caves (Ardèche and Gard). But its study – when one places it in its natural regional, cultural and thematic framework – makes it impossible to see it as an isolated entity of astonishing precocity. This needs to be reconsidered, and the affinities that our research has brought to light are clearly incompatible with the very early age which has been attributed to it. And if one extends this examination to the whole of the Franco-Cantabrian domain, the conclusion is inescapable: although Chauvet cave displays some unique characteristics (like every decorated cave), it belongs to an evolved phase of parietal art that is far removed from the motifs of its origins (known from art on blocks and on shelter walls dated by stratigraphy to the Aurignacian, in France and Cantabrian Spain). The majority of its works are therefore to be placed, quite normally, within the framework of the well-defined artistic creations of the Gravettian and Solutrean. Moreover, this phase of the Middle Upper Palaeolithic (26,000–18,000) coincides with a particularly intensive and diversified local human occupation, unknown in earlier periods and far less dense afterwards in the Magdalenian. A detailed critique of the treatment of the samples subjected to AMS radiocarbon dating makes it impossible to retain the very early age (36,000 cal BP) attributed by some authors to the painted and engraved figures of Chauvet cave.

Link

Middle Neolithic European archers from France

Am J Phys Anthropol DOI: 10.1002/ajpa.22504

Bioarchaeology of the middle Neolithic: Evidence for archery among early european farmers

Aline Thomas

This article focuses on Neolithic skeletons associated with the first monumental cemeteries of Western Europe and specifically those of the Cerny culture (Paris Basin, France). While this cultural context is an agrarian one, numerous arrowheads derived from complete hunting equipment are present in numerous graves. The goal of this work is to evaluate the morphological and pathological differences among the individuals according to the presence of arrowheads in their graves. It is postulated that those buried with such artifacts practiced archery, unlike their counterparts. Only adult males were selected for study to limit the effect of non-mechanical factors such as age- and sex-related modifications. The corpus consists of 36 males reliably identified among the 101 Cerny adults currently available. Thirteen men are associated with arrowheads. Variations in morphology and robusticity are evaluated on the basis of the external geometric properties of the appendicular skeleton. Entheseal changes to fibrocartilaginous attachment sites of upper and lower limbs are also examined. Both nonpathological skeletal adaptations and pathological indicators are consistent and reveal significant differences between the two groups compared. Functional adaptation is observed in the forearm bones and the clavicle in response to mechanical loads, and enthesopathies suggest repeated forceful use of upper limb muscles. These osteological changes specifically reflect the higher intensity upper limb activity of the men buried with arrowheads and correspond with the medical data on known archers, suggesting that this specific forceful task is linked to the practice of archery.

Link

Admixture in US populations

An interesting blog post from 23andMe:

In an update to that work, our researcher Kasia Bryc found that about about 4 percent of whites have at least 1 percent or more African ancestry.

Although it is a relatively small percentage, the percentage indicates that an individual with at least 1 percent African ancestry had an African ancestor within the last six generations, or in the last 200 years. This data also suggests that individuals with mixed parentage at some point were absorbed into the white population.

Looking a little more deeply into the data, Kasia also found that the percentage of whites with hidden African ancestry differed significantly from state-to-state. Southern states with the highest African American populations, tended to have the highest percentages of hidden African ancestry. In South Carolina at least 13 percent of self-identified whites have 1 percent or more African ancestry, while in Louisiana the number is a little more than 12 percent. In Georgia and Alabama the number is about 9 percent. The differences perhaps point to different social and cultural histories within the south.

and:

Previous published studies estimate that on average African Americans had about 82 percent African ancestry and about 18 percent European ancestry. But in self-identified African Americans in 23andMe’s database, Kasia found the average amount of African ancestry was closer to 73 percent.

I don't think that is necessarily the average percentage in the general African American population as the subset of African Americans who take 23andMe tests may not be representative (e.g., it may come more from cities where African Americans may have more opportunity to admix with European Americans).

and:

On average Latinos had about 70 percent European ancestry, 14 percent Native American ancestry and 6 percent African ancestry. The remainder ancestry is difficult to assign because the DNA is either shared by a number of different populations around the world, or because it’s from understudied populations, such as Native Americans. Obviously that large “unassigned” percentage means that those “averages” could be higher. As with African Americans, looking at the regional and state-to-state numbers for self-identified Latinos, the differences are striking. 

...

For example, some Latinos have no discernible Native American ancestry, while in others have as much as 50 percent of the ancestry being Native American. Latinos in states in the Southwest, bordering Mexico — New Mexico, Texas, California and Arizona — have the greatest percentage of Native American ancestry. Latinos in states with the largest proportion of African Americans in their population — South Carolina, Louisiana and Alabama — have the highest percentage of African Ancestry.

23andMe may have a couple of orders of magnitude more sampled individuals than anything that appears in most published studies and it's great to see this being put to good use.

It'd be great if someone at 23andMe did some more analyses over their huge database. I can only imagine what a flashPCA with half a million individuals from around the world would look like; even if it told us nothing new about human history it would be quite a cool picture to look at.

4.2 kiloyear event and the demise of Indus Valley megacities

From the paper:

The 4.2 ka aridification event is regarded as one of the most severe climatic changes in the Holocene, and affected several Early Bronze Age populations from the Aegean to the ancient Near East (Cullen et al., 2000; Weiss and Brad- ley, 2001). This study demonstrates that the cli- mate changes at that time extended to the plains of northwestern India. The Kotla Dahar record alone cannot fully explain the role of climate change in the cultural evolution of the Indus civilization. The Indus settlements spanned a diverse range of environmental and ecological zones (Wright, 2010; Petrie, 2013); therefore, correlation of evidence for climate change and the decline of Indus urbanism requires a comprehensive assessment of the relationship between settlement and climate across a sub- stantial area (Weiss and Bradley, 2001; Petrie, 2013). The impact of the abrupt climate event in India and West Asia records, and that observed at Kotla Dahar, on settled life in the Indus region warrants further investigation.

Plato (or rather the Egyptian priest speaking through Plato) may have been the first one to note the differential survival of people as a result of natural catastrophes. It is hard to imagine that such an extreme event would not unbalance agricultural economies leading to famine and also endanger the supply systems on which early cities were based. The failure of cities would in turn lead to a failure of governing elites centered on them and a power vacuum which new elites (armed with bronze weapons at this time) might take advantage of. Climate may have ended the Bronze Age civilization itself 1000 years later.

Geology doi: 10.1130/G35236.1

Abrupt weakening of the summer monsoon in northwest India ∼4100 yr ago

Yama Dixit et al.

Climate change has been suggested as a possible cause for the decline of urban centers of the Indus Civilization ∼4000 yr ago, but extant paleoclimatic evidence has been derived from locations well outside the distribution of Indus settlements. Here we report an oxygen isotope record of gastropod aragonite (δ18Oa) from Holocene sediments of paleolake Kotla Dahar (Haryana, India), which is adjacent to Indus settlements and documents Indian summer monsoon (ISM) variability for the past 6.5 k.y. A 4‰ increase in δ18Oa occurred at ca. 4.1 ka marking a peak in the evaporation/precipitation ratio in the lake catchment related to weakening of the ISM. Although dating uncertainty exists in both climate and archaeological records, the drought event 4.1 ka on the northwestern Indian plains is within the radiocarbon age range for the beginning of Indus de-urbanization, suggesting that climate may have played a role in the Indus cultural transformation.

Link

Recent radiation of R-M269 males in Europe

From the paper:

As such it is not possible to predict the subhaplogroup within R-M269 to which an individual belongs based on his YSTR haplotype, in contrast to the situation with higher level haplogroups for which haplotypes do have predictive power(Athey, 2005; Schlecht et al., 2008).

The explosion of R-M269 descendants who (seemingly) went from zero to a solid majority in much of Western Europe over the last few thousand years is probably one of the most interesting events in recent European history. Not many would have entertained such a possibility until a few years ago, but truth is often stranger than fiction.

Annals of Human Genetics DOI: 10.1111/ahg.12050

Recent Radiation within Y-chromosomal Haplogroup R-M269 Resulted in High Y-STR Haplotype Resemblance

Maarten H. D. Larmuseau et al.

Y-chromosomal short tandem repeats (Y-STRs) are often used in addition to Y-chromosomal single-nucleotide polymorphisms (Y-SNP) to detect subtle patterns in a population genetic structure. There are, however, indications for Y-STR haplotype resemblance across different subhaplogroups within haplogroup R1b1b2 (R-M269) which may lead to erosion in the observation of the population genetic pattern. Hence the question arises whether Y-STR haplotypes are still informative beyond high-resolution Y-SNP genotyping for population genetic studies. To address this question, we genotyped the Y chromosomes of more than 1000 males originating from the West-European regions of Flanders (Belgium), North-Brabant and Limburg (the Netherlands) at the highest resolution of the current Y-SNP tree together with 38 commonly used Y-STRs. We observed high resemblance of Y-STR haplotypes between males belonging to different subhaplogroups of haplogroup R-M269. Several subhaplogroups within R-M269 could not be distinguished from each other based on differences in Y-STR haplotype variation. The most likely hypothesis to explain this similarity of Y-STR haplotypes within the population of R-M269 members is a recent radiation where various subhaplogroups originated within a relatively short time period. We conclude that high-resolution Y-SNP typing rather than Y-STR typing might be more useful to study population genetic patterns in (Western) Europe.

Link

AIMs and fine structure in 15 European populations

This is an open access article.

European Journal of Human Genetics advance online publication 19 February 2014; doi: 10.1038/ejhg.2014.1

Using ancestry-informative markers to identify fine structure across 15 populations of European origin

Laura M Huckins et al.

The Wellcome Trust Case Control Consortium 3 anorexia nervosa genome-wide association scan includes 2907 cases from 15 different populations of European origin genotyped on the Illumina 670K chip. We compared methods for identifying population stratification, and suggest list of markers that may help to counter this problem. It is usual to identify population structure in such studies using only common variants with minor allele frequency (MAF) >5%; we find that this may result in highly informative SNPs being discarded, and suggest that instead all SNPs with MAF >1% may be used. We established informative axes of variation identified via principal component analysis and highlight important features of the genetic structure of diverse European-descent populations, some studied for the first time at this scale. Finally, we investigated the substructure within each of these 15 populations and identified SNPs that help capture hidden stratification. This work can provide information regarding the designing and interpretation of association results in the International Consortia.

Link

Evolution equally efficient in removing deleterious variants in Europeans and West Africans

...but apparently not in Denisovans who accumulated deleterious mutations at a higher rate than modern humans. This may account for the fact that we haven't been able to find many Denisovans in the archaeological record as they may simply be a population that "failed" -- although apparently some distant relatives of the single Denisovan genome did admix into Australasians.

arXiv:1402.4896 [q-bio.PE]

No evidence that natural selection has been less effective at removing deleterious mutations in Europeans than in West Africans

Ron Do et al.

Non-African populations have experienced major bottlenecks in the time since their split from West Africans, which has led to the hypothesis that natural selection to remove weakly deleterious mutations may have been less effective in non-Africans. To directly test this hypothesis, we measure the per-genome accumulation of deleterious mutations across diverse humans. We fail to detect any significant differences, but find that archaic Denisovans accumulated non-synonymous mutations at a higher rate than modern humans, consistent with the longer separation time of modern and archaic humans. We also revisit the empirical patterns that have been interpreted as evidence for less effective removal of deleterious mutations in non-Africans than in West Africans, and show they are not driven by differences in selection after population separation, but by neutral evolution.

Link

mtDNA of Okladnikov Neandertal

PNAS February 11, 2014 vol. 111 no. 6

Separating endogenous ancient DNA from modern day contamination in a Siberian Neandertal

Pontus Skoglund et al.

One of the main impediments for obtaining DNA sequences from ancient human skeletons is the presence of contaminating modern human DNA molecules in many fossil samples and laboratory reagents. However, DNA fragments isolated from ancient specimens show a characteristic DNA damage pattern caused by miscoding lesions that differs from present day DNA sequences. Here, we develop a framework for evaluating the likelihood of a sequence originating from a model with postmortem degradation—summarized in a postmortem degradation score—which allows the identification of DNA fragments that are unlikely to originate from present day sources. We apply this approach to a contaminated Neandertal specimen from Okladnikov Cave in Siberia to isolate its endogenous DNA from modern human contaminants and show that the reconstructed mitochondrial genome sequence is more closely related to the variation of Western Neandertals than what was discernible from previous analyses. Our method opens up the potential for genomic analysis of contaminated fossil material.

Link

AAPA 2014 abstracts

The program of the 83rd Annual Meeting of the American Association of Physical Anthropologists is online (pdf). I list some interesting titles:

• Ancient DNA sequencing on the Ion Torrent PGM and Proton Platforms: Genetic diversity of haplotype D4b1a2a1a at Nuvuk, an ancient Thule Village
• Preliminary analysis of ancient DNA on a late Neolithic population in Northeast China
• Ancient DNA analysis of human remains from Halahaigou, a Neolithic cemetery in China
• Mitochondrial DNA analysis reveals substantial population structure in Hecun, a shell mound in South China
• Kinship analysis of ancient samples in the Noble Family cemetery of the Yuan Dynasty
• Ancient DNA analysis of an infant from Sudanese Nubia (ca 500-1400 C.E.)
• Ancient DNA analysis of human skeletal remains from pre-Columbian Puerto Rico
• Ancient DNA from Early to Mid-Holocene Burials in Northwestern Argentina: Implications for understanding the colonization and early populations of South America
• Ancient DNA from the Schild site in Illinois: Implications for the Mississippian transition in the Lower Illinois River Valley
• Patterns of sequence variation at the pigmentation loci ASIP and OCA2 in Melanesian and African populations
• Evolution of the HERC2 eye color gene in Europeans using linkage disequilibrium analysis in four human populations
• Whole genome sequencing of Turkish genomes reveals functional private alleles and impact of genetic interactions with Europe, Asia and Africa
• The Qesem Cave mandibular premolars and molar from a morphometric perspective.
• Exploring the relationship of Neanderthals and modern humans at various population levels through an analysis of body proportion indices
• Early human dispersal from Africa: A model-based test of two hypotheses

Human admixture common in human history (Hellenthal et al. 2014)

A string of recent papers argued for admixture in human populations at time scales from the Middle Pleistocene to recent centuries. A new paper in Science makes the point convincingly for extensive admixture in humans over the last few thousand years. The authors include the creators of Chromopainter/fineStructure software; the new "Globetrotter" method appears to be a natural extension of that method that seemed to work wonderfully well except for the limitation of producing only a tree of the studied populations.

The paper has a companion website in which you can look up the admixture history of individual populations.

While reading this study, it is important to remember its limitations. Two are immediately obvious: (i) admixture events can only be detected for the last few thousand years, as this method depends on pattern of linkage disequilibrium which decays exponentially with time due to recombination, and (ii) detection of admixture seems to depend on the presence of maximally differentiated populations from the edges of the human geographical range; for example, the Japanese appear unadmixed even though they are clearly of dual Jomon/Yayoi ancestry. On the other hand, the method does detect the admixture present in the San at a similar time scale.

The case of Northwestern Europe appears especially striking as none of the populations from the region show evidence of admixture. This may be because the mixtures taking place there (e.g., between "Celts" and "Anglo-Saxons" in Great Britain) involved populations that were not strongly differentiated. Alternatively, population admixture history may have preceded the last few thousand years and is thus beyond the temporal scope of this method.

An exception to the rule that populations at the edges of the human range appear to be unadmixed are the Armenians who appear to be the only * between the Atlantic and Pacific in Figure 2D (shown at the beginning of this post). The companion site lists their status as "uncertain".

Other results are more questionable; for example, the authors assert that Sardinians are an admixed population with one side being "Egyptian-like" and the other "French-like" whereas the ancient DNA evidence as it stands would rather indicate that Sardinians are the best approximation of Neolithic Europeans currently in existence and so are more likely to (mostly) possess a gene pool that traces back to ~8-9 thousand years in Europe. It will be quite the surprise if so many Europeans from 5kya or earlier look like modern Sardinians and ancient Sardinians don't!

The analysis of Eastern Europe is particularly interesting as it documents three way admixture (Northern/Southern/NE Asian) in most populations but two way admixture (Northern/Southern) in Greeks, estimated at ~37%. The authors claim that this is related to the Slavs, which seems reasonable given the 1,054AD age estimate. On the other hand, according to the companion website, the southern element in Greeks is inferred to be Cypriot-like and it's far from clear that the pre-Slavic population of Greece was Cypriot-like or indeed represented by any of the populations in the authors' dataset.

The three-way admixture in much of eastern Europe is not particularly surprising as history furnishes ample evidence for groups of steppe origin in the region during historical times. Some bequeathed their both language and name (e.g., Magyars), others only their name (e.g., Bulgarians) on the local Europeans, but records indicate a widespread presence of "eastern" groups in Europe from the time of the Huns to that of the Ottomans. A study of late Antique eastern Europeans from the Baltic to the Aegean may help better document how the twin phenomena of the eastern invasions and the spread of the Slavs shaped the present-day genetic diversity of the region.

I suspect that a few ancient samples will be far more informative for understanding the recent history of our species than the most sophisticated modeling of modern populations. Nonetheless, it's great to have a new method that maximizes what can be learned about the past from the messy palimpsest of the present.

Science 14 February 2014: Vol. 343 no. 6172 pp. 747-751 DOI: 10.1126/science.1243518

A Genetic Atlas of Human Admixture History

Garrett Hellenthal et al.

Modern genetic data combined with appropriate statistical methods have the potential to contribute substantially to our understanding of human history. We have developed an approach that exploits the genomic structure of admixed populations to date and characterize historical mixture events at fine scales. We used this to produce an atlas of worldwide human admixture history, constructed by using genetic data alone and encompassing over 100 events occurring over the past 4000 years. We identified events whose dates and participants suggest they describe genetic impacts of the Mongol empire, Arab slave trade, Bantu expansion, first millennium CE migrations in Eastern Europe, and European colonialism, as well as unrecorded events, revealing admixture to be an almost universal force shaping human populations.

Link