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R1b and the People of Europe: An Ancient DNA Update
- 2. • Indirect approach – Examine patterns of genetic variation in extant humans and infer past • Direct approach – Recover DNA sequences from ancient material and compare across different time frames Allows assessment of whether contemporary people descend from long-term inhabitants of that region, or from people who arrived from elsewhere— replacing or admixing with previous inhabitants Importance of Ancient DNA in Reconstructing Population History
- 3. The R1b Controversy (2013) Haplogroup R-M269 is the most common European Y- chromosomal lineage, increasing in frequency from east to west, and carried by 110 million European men. 2013 Conference: discussed two studies that agreed origin in Europe was post- Paleolithic, but differed on whether it entered Europe with Neolithic farmers or more recently.
- 4. 1 2 3 5 6 7 2 I* 1 I2 1 I2a1b* 8 9 11 I2a2b 2 R1a1 1 R1b (M343) 10 1111 Mesolithic Hunter-Gatherers Motala, Sweden (8kya) 11 Mesolithic Hunter-Gatherers Motala, Sweden (8kya) 4 12 Mesolithic Hunter-Gatherer Loschbour, Luxembourg (8.2- 7.9kya) 12 Mesolithic Hunter-Gatherer Loschbour, Luxembourg (8.2- 7.9kya) 12 13 Mesolithic Hunter-Gatherer, La Brana Valdelugueros, Spain (7.0kya) 13 Mesolithic Hunter-Gatherer, La Brana Valdelugueros, Spain (7.0kya) 13 14 14 Pitted Ware Culture Gotland, Sweden (Mesolithic 4.8-4.0kya) 14 Pitted Ware Culture Gotland, Sweden (Mesolithic 4.8-4.0kya) 15 Vinkovci and Vukovar Croaita Starcevo Culture (7.6kya) (LBK)̌ 15 Vinkovci and Vukovar Croaita Starcevo Culture (7.6kya) (LBK)̌ 15 20 G2a 2 I2a 5 G2a 1 E1b1b1 1 G2a3 2 F*(xG,H,I,J,K) G2a2b 2 I2a 1 C1a2 1 G 1 I or J? 2 R1b (M269, M343) 2 R1a 1 I2a1b* 1 I2a 1 G2 3 G2a 4 G2a2b 2 F* 1 I 1 I1 2 G2a 1 I2a1 1 Cave 1 of Treilles at St-Jean et St Paul (Aveyron, France) 5kya (end of Neolithic) 1 Cave 1 of Treilles at St-Jean et St Paul (Aveyron, France) 5kya (end of Neolithic) 2 Abellaner Cave (Catalonia, Spain) 5kya (Epicardial Culture; end of Neolithic) 2 Abellaner Cave (Catalonia, Spain) 5kya (Epicardial Culture; end of Neolithic) 3 Derenburg Cave (Meerenstieg Germany) 7kya (LBK) 3 Derenburg Cave (Meerenstieg Germany) 7kya (LBK) 4 Ötzi Chalcolithic (5.3 kya) 4 Ötzi Chalcolithic (5.3 kya) 5 Starcevo Culture and LBǨ sites from Carpathian Basin Hungary (7.6-7.0kya) (Neolithic) 5 Starcevo Culture and LBǨ sites from Carpathian Basin Hungary (7.6-7.0kya) (Neolithic) 7 Chalcolithic Bell Beaker Kromsdorf, Germany (4.6kya Copper Age) 7 Chalcolithic Bell Beaker Kromsdorf, Germany (4.6kya Copper Age) 6 Dolmen of La Pierre Fritte, France (4.8kya) (Neolithic) 6 Dolmen of La Pierre Fritte, France (4.8kya) (Neolithic) 8 Corded Ware Eulau, Germany (4.6kya) 8 Corded Ware Eulau, Germany (4.6kya) 9 Lichtenstein Cave, Dorste, Germany Urnfield? (3.0kya Bronze Age) 9 Lichtenstein Cave, Dorste, Germany Urnfield? (3.0kya Bronze Age) 10 Jagodno, Poland Chalcolithic (4.8kya, Copper Age) 10 Jagodno, Poland Chalcolithic (4.8kya, Copper Age) Mesolithic HG Neolithic Farmers Metal Age F 2 C 1 I1 1 1 I*/I2 5 7 11 G 37 1 R1b 3 R1a 4 E 1 6 48 20 Ancient European Y Chromosomes (2014) N=74
- 5. Distribution of Hg G today Major Paternal Lineage of European Neolithic
- 6. 2014 Conference: Combined evidence supports hypothesis that the current distribution of Hg R lineages in western Europe is the result of major population movements occurring after the Neolithic agricultural transition—during the Metal Ages. Populations carrying R1b chromosomes appear to have nearly displaced western European Neolithic Y chromosomes (Different pattern for mtDNA) What conferred advantage to post-Neolithic men? aDNA Supports a Recent Spread of Hg R Lineages in Europe
- 7. The Bronze Age: first use of metal specifically to create weapons. The sword, spear and shield were all invented in this period (warrior identity became a standard part of daily life) Post-Neolithic Turnover of W. European Y Chromosomes: Metal Weapons? The Iron Age: First true mass-production of metal tools and weapons. Revolutionizes both agriculture and warfare. 1200 to 1000 BCE: Celts most dominant iron-age warriors. Ranging over Europe, from the British Isles to Hungary, the Celts forged tough swords made of iron. (2014)
- 8. Indo-European Invasions from Steppes How well do our inferences from 2013 and 2014 at this conference, hold up in 2015? Spread of IE Languages Spread of Chariot (2014)
- 9. 2013 2014 2015 Number of Ancient YDNA Samples
- 10. Mitochondria (1000/cell) Where do we find DNA in the Cell? Nucleus Chromosomes Mitochondrial DNA (mtDNA) Cytoplasm Genome: the total amount of DNA in a typical cell
- 11. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 X Y We inherit one copy of each chromosomal pair from our mother and father 1-22 Autosomes 23rd pair: Sex Chromosomes Nuclear DNA: 6 Billion Nucleotides/46 chromosomes
- 12. A single nucleotide polymorphism (SNP)– an alteration at a single site in the DNA– is the most frequent type of variation in the genome. Currently, there are ~85 million SNPs that have been identified in the human genome. DNA microarray technology (SNP array) is used to detect SNPs within a population. SNP arrays are able to detect millions of different SNPs on all chromosomes in hundreds of samples in a single experiment. Single Nucleotide Polymorphism (SNP)
- 13. 1 hunter-gatherer (~8kya) 7 hunter-gatherers (~8 kya) 1 farmer (~7 kya) Complete Genomes from Nine Ancient Europeans Lazaridis et al. Nature (2014) First study to fully sequence genomes of Neolithic and Mesolithic Europeans
- 14. Order of Presentation 1. Autosomal/X DNA 2. Y Chromosome 3. mtDNA First: Results from Contemporary Samples, then ancient DNA
- 15. Genome-wide (Autosomal) Data Supported Europe as a Mixture of Two Populations Skoglund et al. (2012) Sikora et al. (2014)
- 16. Genes from a third source? • Genotyped >600K SNPs in >900 individuals from 53 diverse populations • Performed admixture tests and inferred proportions and dates of mixture • Found signal of Northeast Asian-related admixture in northern Europeans Patterson et al. (2012) “The ghost population of North Eurasia” Out of Africa Ancestry Ancient Levant Ancient North Eurasians Iceman Sardinia Ancient Siberia N. Europe Americas
- 17. The Ghost is Identified: Discovery of Ancient North Eurasian Meta-Population Raghavan et al. (2013) • Sequenced genome of ~24,000 year old Siberian individual (Mal’ta or MA1) • MA1 is genetically similar to Native Americans and West Eurasians (not close to East Asians) • Sequencing of another south-central Siberian (Afontova Gora-2) dating to ~17 kya revealed similar genetic signatures, suggesting the persistence of an ancient North Eurasian meta-population (ANE) • What is the relationship of ANE to ancient H-G and farming populations that contributed ancestry to contemporary Europeans? Rahavan et al. (2013)
- 18. • West European Hunter-Gatherer (WHG), based on an 8,000 year-old genome from Loschbour, Luxembourg. The WHG meta-population includes the Swedish hunter-gatherers and a Mesolithic individual from the La Brana Cave in Spain. • Early European Farmer (EEF), based on a 7,500 year-old genome from Stuttgart, Germany, belonging to the Neolithic Linearbandkeramik (LBK) culture. The EEF meta-population includes Oetzi the Iceman and a Neolithic Funnelbeaker farmer from Sweden. • Ancient North Eurasian (ANE), based on the 24,000 year-old genome from Mal'ta Siberia. The ANE meta-population includes Mal'ta (MA1) boy as well as the late Upper Paleolithic sample from Central Siberia called Afontova Gora-2 (AG2). European Ancestral Components: Rooted in Ancient DNA
- 19. WHG (indigenous Europeans) 0-50% EEF (Near Eastern origin) 32-93% ANE (like ancient Siberians) 1-18% Geographic Variation in European Ancestral Components • EEF component increases towards the South, peaking at just over 80% among Sardinians • In contrast, WHG component increases towards the North, peaking in the East Baltic region at ~50%.No detectable WHG ancestry in the Near East • ANE ancestry is present in nearly all Europeans today at lower levels, peaking in Estonians & Scots at just over 18% (absent in Sardinians) • Importantly, ANE component is not found in either farmers or HGs from central and western Europe during the Neolithic First Farmers only a mixture of 2 source populations N S ANE WHG EEF
- 20. S. Europeans inherited their hunter-gatherer ancestry mostly via EEF ancestors, whereas N. Europeans retain up to 50% of WHG ancestry above and beyond what they received through mixing with more recent EEF ancestors. ANE ancestry component entered the broader European gene pool after the Neolithic Three Source Migration Model for Europe Anatomically modern hunter-gatherers first migrated into Europe ~45 kya from Africa through the Levant Second major infusion of people comes with expansion of agriculture—also from the Levant—beginning ~8 kya
- 21. Who were the ANE and how did they make such a large contribution to the European Gene Pool? • Turns out that the spread of R1b into Europe can be traced to the ANE • Can we associate the initial entry of R1b into Europe with the innovation of the chariot, production of new weapons and training of horses, and the spread of the Indo-European languages in the Bronze Age (2700 BCE to 500 BCE)? • Two laboratories published papers in the same issue of Nature this past June- both reaching the same conclusion. Massive migrations from the Russian Steppe in the Bronze Age represents the third major source of genetic material found in Europeans today • They extracted genetic material from bones and teeth collected from across Europe and as far east as Lake Baikal in Siberia. The age of the bones spanned five millennia, from 6,000 to 900 BCE • To get the 170 samples, they had to test >700 samples for DNA quality. All of the samples that they ultimately used for analysis had a well-documented archaeological context with radio carbon dates
- 22. Massive migration from the steppe was a source for Indo-European languages in Europe Haak et al. Nature 522, 207–211 (11 June 2015) Used novel technique to enrich ancient DNA for a set of ~400,000 SNPs and generate genome-wide data from 69 ancient Europeans David Reich
- 23. Population genomics of Bronze Age Eurasia Allentoft et al. Nature 522, 207–211 (11 June 2015) Eske Willerslev Used improved methods to generate low-coverage genomes from 101 ancient Eurasians
- 24. low-coverage genomes from 101 ancient Eurasians genome-wide data from 69 ancient Europeans
- 25. • Neolithic Europe populations composed of mixture of the hunter-gatherer and Neolithic farmer groups • Bronze Age European populations have added ‘Caucasian’ component suggested to derive from Yamnaya culture from the Pontic-Caspian steppe • Neolithic farmer component is absent in Yamnaya and at very low levels in present-day Norwegians and Lithuanians • Yamnaya component is absent in present-day Sardinians Genomics Supports Steppe Contribution to Bronze Age Europe HG component Farmer component Caucasian component Allentoft et al.
- 26. All European populations can be modelled as a three-way mixture of WHG, Early Neolithic, and Yamnaya Yamnaya related ancestry is lower in southern Europe and higher in northern Europe Support steppe as a source for Indo- European languages in Europe, with massive migration ~4,500 years ago Yamnaya genetic contribution to Neolithic European Gene Pool Haak et al. Western European Hunter-Gatherer Early Neolithic Farmer Yamnaya Pastoralist
- 27. • Three groups of hunter-gatherers initially populated Europe: Western; Eastern, and Scandinavian HG • Early farmers of Europe migrated into Europe ~9,000-7,000 years ago. • Yamnaya pastoralists arrived in central Europe from the Russian steppe during the Late Neolithic ~4,500 years ago. • The resulting Corded Ware culture in Europe was the result of admixture with the local Neolithic people. Allentoft & Haak Studies Agree Proposed routes of migration by early farmers into Europe ~9,000−7000 years ago. Arrival of steppe ancestry in central Europe during the Late Neolithic ~4,500 years ago
- 28. Resurgence of hunter-gatherer ancestry during the Middle Neolithic 7,000−5,000 years ago Middle Neolithic Resurgence of HG Ancestry throughout Europe Haak et al. (2015)
- 29. Connecting the Dots: What does the new model of European ancestry based on autosomal DNA mean for the NRY and mtDNA? • Which population(s) carried the most common contemporary NRY haplogroups into Europe and when? • How does the Caucasian/Yamnaya ancestry component seen in autosomal DNA correspond to the NRY and mtDNA? Pie chart of NRY haplogroups of individuals in Lazaridis et al. study and present day Germans. While only haplogroup I was found in Mesolithic hunter-gatherers, this haplogroup is a minority in present-day Europeans from Germany. Mesolithic Hgs Contemporary Hgs
- 30. Mesolithic Neolithic Metal Present Thousands of Years Ago 8 7 6 5 4 3 2 1 0 2014: Ancient & Modern NRY Hg Frequencies N=6 N=48 N=20
- 31. 2015: NRY Haplogroups in Ancient & Modern Europeans WHG: 6.0-4.6 EN: 6.5-4.4 MN: 4.0-3.1 CA: 3.4-2.6 BA: 2.8-0.5 Kya BCE I2 G2a G2a I2 R1a/R1b R1b Increase in Hg I may reflect resurgence in WHG lineages in Middle Neolithic, consistent with autosomal data
- 32. • In Europe, only a single R1b individual found before Late Neolithic • By contrast, R1a and R1b found in 60% of Bronze Age Europeans • Highest frequency of R1b found in Copper Age Yamnaya of the Russian Steppe - the same population that contributed the autosomal ‘Caucasian’ component to Bronze Age Europeans • Combined results suggest that R1b spread into central and western Europe from the steppe after 3,000 BCE (in agreement with our inferences here in 2013 and 2014!) The origin of European R1b Europe Yamnaya Asia & Russian Steppe Bronze Age R1b R1b R1a G2a I/I2 I/I2 I/I2 R1b R1a C I/I2
- 33. 2014: NRY & mtDNA Discontinuities Mesolithic Neolithic Metal Ages Present-day
- 34. Off with their heads and onto their women!
- 35. Haak et al.Key mtDNA Results • Hunter-gatherers carry predominantly U-haplotypes • Early farmers predominantly carry haplotypes T2, K, HV, H, V, X and N1a • Middle Neolithic farmers exhibit a similar mitochondrial profile as early farmers but show an increase in the frequency of U- haplotypes (providing mitochondrial DNA based evidence of the resurgence of hunter-gatherer lineages that was documented from autosomal data) • Late Neolithic individuals mark a second major turnover, highlighted by the appearance of I, T1, and increase of U2, U4, U5a, H and W haplotypes
- 36. mtDNA haplogroup N1a and Y chromosome haplogroup G2a, common in early central European farmers, almost disappear during the Late Neolithic and Bronze Age, when they are largely replaced by Y haplogroups R1a and R1b and mtDNA haplogroups I, T1, U2, U4, U5a, W, and subtypes of H14, 23, 24. The uniparental data not only confirm a link to the steppe populations but also suggest that both sexes participated in the migrations. Haak et al.
- 37. 1.83 Estonian 0.93 Belarusian 0.53 Croatian 1.59 Spanish (N) 0.87 Ukranian 0.43 Bulgarian 2.25 Spanish (S) 1.00 Lithuanian 1.08 Tuscan 1.71 French 0.93 AVE 1.15 Albanian 1.64 English 0.67 Greek 1.35 Czech 0.77 AVE 1.28 Hungarian 0.81 Norwegian 1.06 Scottish 1.59 AVE Ratio of Bronze Age Y to ANE Contribution to Modern Europeans Varies by Location Male Bias High Low
- 38. Bronze Age FtDNA Y chromosomes in Europeans >25% ancY Slovakia Switzerland Portugal Belgium Spain Austria
- 39. Bronze Age Y chromosomes in FtDNA Database N & Iberia S & Scandinavia
- 40. S N WHG Y Chromosomes in FtDNA Database
- 41. Middle Neolithic Y chromosomes (FtDNA) S N
- 42. Ancient Y Haplogroups by Cultural Periods WHG 8.0-6.6 kya Middle Neolithic 8.5-5.1 kya Bronze Age 4.8-2.5 kya P37.2 L178 M423 V20 L596 L597 M269, L265, L773, L265, L500, L482 L483, L150.1, M512, M459, M417, P310 P217, P218, L181, CTS9183, CTS616, L596, L597, L26 M17, M198, Z91, L51, U106, P312 U152, M170, L146, M420, M173, P241 P215, M343 P15 P37.2 L158 M26 PF3146 L91 L281 P96 L284 L285 L286 M170 Z161
- 44. The frequency of haplogroup I, Europe's Mesolithic paternal marker, was strongly affected by incoming farmers in the early Neolithic—made a comeback in the Middle Neolithic—only to be partially replaced again during the Metal Ages. Haplogroup G2a, Europe’s Neolithic marker, had a very different fate: it’s predominance in the Neolithic contrasts sharply with it’s near absence in the subsequent ancient DNA record and it’s limited distribution today in the southern Europe and the eastern Mediterranean In contrast, the predominant haplogroup in western Europe today, R1b, made a late entrance– nearly absent from the ancient DNA record until the Bronze age when it swept into central Europe with the entry of Asian/Eastern European steppe invaders While it is clear that the post-Neolithic arrival of steppe invaders across much of Europe led to major upheavals during the Early Bronze Age— this was a period that saw the introduction of metal weapons and a new social organization across most of the continent—a further assessment is needed to determine the degree to which there was a sex-bias in the replacement process A Y Chromosome Roller Coaster
- 45. Contemporary populations from across great parts of western, northern and central Europe show greater genetic affinities with local Bronze Age groups in the Russian steppes than with earlier Mesolithic and Neolithic groups living in Europe. Much of the basis of the Eurasian genetic landscape of today was formed during the complex patterns of expansions, admixture and replacements during a relatively short period of time Subsequent increases in population size combined with continuing gene flow between populations led to diffusion of genetic material generating much lower differentiation among contemporary populations compared with the Bronze Age. A cautionary tale for interpreting patterns of contemporary variation
- 46. Several ‘centers of renewed expansion’ are visible across Europe in the archeological record, and several of these areas map closely to the centers of Y chromosome subclade foci Population Turnover: A continuing process L21 U152U106
- 47. A Big Thanks to Rui Hu
- 48. Copper Age Russian Steppe Western HG European Neolithic European Bronze Age Contemporary Europe
- 49. Distribution of Early Bronze Age cultures with arrows showing the Yamnaya expansions Black markers represent chariot burials (2000–1800 BC) with similar horse cheek pieces, as evidence of expanding cultures • By 3000 BC, Neolithic farming cultures in Eastern Europe appear to be largely replaced by Early Bronze Age Yamnaya culture, which is associated with completely new perception of family, property and personhood, rapidly stretching from Hungary to the Urals. • By 2800 BC Corded Ware, Single Grave or Battle Axe cultures with new social and economic formations developed in Europe, culturally replacing the remaining Neolithic farmers • From the beginning of 2000 BC, new class of master artisans known as the Sintashta culture emerged in the Urals, building chariots, breeding and training horses, and producing sophisticated new weapons. These innovations quickly spread across Europe and into Asia Archeology & Genomics Converge: Post-Neolithic Cultural Expansion
- 50. Opposite Trends: European Frequencies of R1b & R1a R1b R1a
Editor's Notes
- Importance of aDNA approach: To determine whether present day inhabitants of a region descend from long term inhabitants of that region, or from people who arrived from elsewhere—during periods of technological or cultural change—replacing or admixing with previous inhabitants.
- Lazaridis et al. on absence of R1b in their Neolithic sample “The absence of Y-haplogroup R1b in our two sample locations is striking given that it is, at present, the major west European lineage. Importantly, however, it has not yet been found in ancient European contexts prior to a Bell Beaker burial from Germany (4.8-4.0 kya), while the related R1a lineage has a first known occurrence in a Corded Ware burial from Germany (4.6 kya). This casts doubt on early suggestions associating these haplogroups with Paleolithic Europeans, and is more consistent with their Neolithic entry into Europe at least in the case of R1b. More research is needed to document the time and place of their earliest occurrence in Europe. Interestingly, the Mal’ta boy (MA1) belonged to haplogroup R* and we tentatively suggest that some haplogroup R bearers may be responsible for the wider dissemination of Ancestral North Eurasian ancestry into Europe, as their haplogroup Q relatives may have plausibly done into the Americas.”
- Metal Ages: Copper Age (c. 3200–2300 bce), the Bronze Age (2300–700 BCE), the Iron Age (700–1 BCE) The Bronze Age: first use of metal specifically to create weapons The sword, spear and shield were all invented in this period (warrior identity became a standard part of daily life) The transition to the iron age was critical because iron is more abundant than copper and tin. First true mass-production of metal tools and weapons. Both agriculture and warfare were thereby revolutionized, since metal implements are far more effective than stone in both endeavors. Around 1200 to 1000 BCE, the most dominant iron-age warriors were the Celts. Ranging all over Europe, from the British Isles to Hungary, the Celts forged tough swords made of iron and backed with a ferocious tenacity that allowed them to dominate for centuries
- Nuclear DNA is located within the nucleus while mitochondrial DNA is located in the mitochondria and contains 100-1,000 copies per cell. The structure of nuclear DNA chromosomes is linear with open ends and includes 23 pairs of chromosomes containing 6 billion nucleotides 3 billion nucleotides per haploid genome). Mitochondrial DNA chromosomes have closed, circular structures, and contain 16,569 nucleotides. As I will explain in the next slides, nuclear DNA is diploid, inheriting the DNA from both mother and father, while mitochondrial DNA is haploid, coming only from the mother.
- In the nucleus at fertilization, we get 23 chromosomes each from our mother and our father. 22 of these chromosome pairs are called Autosomes, and a single pair of chromosomes is called the Sex chromosomes. This is because the Y chromosome carries a gene that triggers the development of male sexual characteristics. Males have an X and a Y chromosome whereas females have 2 X chromosomes.
- It's the first study to fully sequence genomes of Neolithic and Mesolithic Europeans, and report Y-chromosome haplogroups from Mesolithic Europe. Five out of the five successfully tested Mesolithic Y-chromosomes, one from Luxembourg and four from Motala, Sweden, belonged to haplogroup I. This probably won't come as a surprise to many people, as this haplogroup was always the main candidate for Europe's Paleolithic paternal marker. Interestingly, three of the results fell into haplogroup I2a1b, and none into the presently locally more common I1.
- Nuclear DNA is located within the nucleus while mitochondrial DNA is located in the mitochondria and contains 100-1,000 copies per cell. The structure of nuclear DNA chromosomes is linear with open ends and includes 23 pairs of chromosomes containing 6 billion nucleotides 3 billion nucleotides per haploid genome). Mitochondrial DNA chromosomes have closed, circular structures, and contain 16,569 nucleotides. As I will explain in the next slides, nuclear DNA is diploid, inheriting the DNA from both mother and father, while mitochondrial DNA is haploid, coming only from the mother.
- Complete nuclear genome of a Siberian boy who died 24,000 years ago is the oldest complete genome of a modern human sequenced to date The new findings are consistent with a report published in Genetics last year (and almost entirely ignored at the time) that used modern DNA to conclude that Native Americans have significant and ancient ties to Europeans. Reich’s team found that populations they identified as Native American ancestors in Asia apparently also contributed genes to populations in northern Europe. Thus, both studies suggest a source population in Asia whose genes made their way east all the way to the Americas, and west, all the way to Europe. “Mal’ta might be a missing link, a representative of the Asian population that admixed both into Europeans and Native Americans”, Reich says. “If so, he adds, “it shows the value of ancient DNA in peeling back history and resolving mysteries that are difficult to solve using only present day samples.”
- Complete nuclear genome of a Siberian boy who died 24,000 years ago is the oldest complete genome of a modern human sequenced to date The new findings are consistent with a report published in Genetics last year (and almost entirely ignored at the time) that used modern DNA to conclude that Native Americans have significant and ancient ties to Europeans. Reich’s team found that populations they identified as Native American ancestors in Asia apparently also contributed genes to populations in northern Europe. Thus, both studies suggest a source population in Asia whose genes made their way east all the way to the Americas, and west, all the way to Europe. “Mal’ta might be a missing link, a representative of the Asian population that admixed both into Europeans and Native Americans”, Reich says. “If so, he adds, “it shows the value of ancient DNA in peeling back history and resolving mysteries that are difficult to solve using only present day samples.”
- WHG: based on an 8,000 year-old forager from the Loschbour rock shelter in Luxembourg (belonging to I2a1b). The WHG meta-population includes the Loschbour sample and two Mesolithic individuals from the La Brana Cave in Spain. However, today the WHG component peaks among Estonians and Lithuanians, in the East Baltic region, at almost 50%. EEF: apparently this is a hybrid component, the result of mixture between "Basal Eurasians" and a WHG-like population possibly from the Balkans. It's based on the aforementioned LBK farmer from Stuttgart, but today peaks at just over 80% among Sardinians. Apart from the Stuttgart sample, the EEF meta-population includes Oetzi the Iceman and a Neolithic Funnelbeaker farmer from Sweden. ANE: a component based on a previously reported genome of a 24,000 year-old Upper Paleolithic forager from South Central Siberia, belonging to Y-hg R*, and known as Mal'ta boy or MA-1. This component was very likely present in Southern Scandinavia since at least the Mesolithic, but only seems to have reached Western Europe after the Neolithic. At some point it also spread into the Americas. In Europe today it peaks among Estonians at just over 18%, and, intriguingly, reaches a similar level among Scots. The ANE meta-population includes Mal'ta boy as well as a late Upper Paleolithic sample from Central Siberia, dubbed Afontova Gora-2 (AG2). Scandinavian Hunter-Gatherer (SHG): this is a meta-population made up of Swedish Mesolithic and Neolithic forager samples from Motala and Gotland, respectively. It's a more easterly variant of WHG, with probable ANE admixture.
- Fitting present-day Europeans into the model, we find that few populations can be fit as two-way mixtures, but nearly all are compatible with three-way mixtures of ANE–EEF–WHG. Southern Europeans inherited their European hunter-gatherer ancestry mostly via EEF ancestors, whereas northern Europeans acquired up to 50% of WHG ancestry above and beyond what they received through their EEF ancestors. Europeans have a larger proportion of WHG than ANE ancestry in general. By contrast, in the Near East there is no detectable WHG ancestry, but up to 29% ANE in the Caucasus. A striking feature of these findings is that ANE ancestry is inferred to be present in nearly all Europeans today (with a maximum of 20%), but was absent in both farmers and hunter-gatherers from central and western Europe during the Neolithic transition. However, ANE ancestry was not completely absent from the larger European region at that time: we find that it was present in 8,000-years-old Scandinavian hunter-gatherers, as MA1 shares more alleles with Motala12 (SHG) than with Loschbour, and Motala12 fits as a mixture of 81% WHG and 19% ANE.
- Given absence of ANE ancestry in both farmers and hunter-gatherers from central and western Europe during the Neolithic transition, it is inferred that this component entered the broader European gene pool after the Neolithic.
- Europeans created by three migrations The last few years were an intense race between Willerslev and Reich to be the first to map and analyse the European’s ancient genetic material.They have already shown that modern Europeans share the genetic components of the early hunters but with the arrival of farming culture about 8500 years ago, there was a mixing with new genetic components. This shows up as a genetic difference between southern and northern Europe. Neolithic people (4000-1700 BC) resemble us more but there is still something missing, and last year it became clear to scientists that there must have been a third wave of migration. This was a migration to northern Europe, which could explain the genetic differences between northern and southern Europeans today. The researchers discovered that the early European Bronze Age skeletons had a new genetic component that was not inherited from the early farmers or hunters."Whether the sample was taken in Germany, Poland, Denmark or Sweden, we see the same component, and we can show that it comes from the Caucasus," says Allentoft. The component matches that of the relatively unknown steppe people, the Yamnaya, who were nomads from thousands of kilometres north of the Caucasus between the Black Sea and the Caspian Sea. Reichs and Willerslev's research groups agree that the Yamnaya tribe migrated west into northern Europe around 5,000 years ago. Previous archaeological findings have shown that changes occurred in northern Europe around the same time.
- Following the central European chronology, these included 19 hunter-gatherers (~43,000–2,600 BC) 28 Early Neolithic farmers (~6,000–4,000 BC) 11 Middle Neolithic farmers (~4,000–3,000 BC) including the Tyrolean Iceman 9 Late Copper/Early Bronze Age individuals (Yamnaya: ~3,300–2,700 BC) 15 Late Neolithic individuals (~2,500–2,200 BC) 9 Early Bronze Age individuals (~2,200–1,500 BC) 2 Late Bronze Age individuals (~1,200–1,100 BC) 1 Iron Age individual (~900 BC).
- 101 Eurasian individuals spanning the entire Bronze Age, including individuals from: Copper Age Middle Neolithic Late Neolithic Early Bronze Age Middle Bronze Age Late Bronze Age Iron Age Battle Axe culture Corded Ware culture focused mainly on sampling human remains dating from the third and early to mid-second millennia BC. In cultural terms this corresponds to the period from Corded Ware/Yamnaya into the full European Bronze Age. The geographical cover is broad, stretching from Scandinavia, Central and Southern Europe over Eastern Europe, Southern Ural to Central Siberia
- In summary, our results suggest the following interpretations: - Predominantly West Eurasian ancestry for BAE, with the exception of some later BA individuals from Asia, which show influence of ancestry related to present-day Siberians - A gradual decrease in West-Asia / Neolithic farmer related ancestry from Southern and Central BA Europeans towards the North, which is also present in Armenians but absent from the Northern Caucasus (Yamnaya). - An opposing gradient in Caucasus / steppe related ancestry, maximized in the Yamnaya and distantly related to Native Americans. Possibly due to the presence of MA1-related ancestry in the Northern Caucasus. - A genetic link between the Kalash and the steppe through Yamnaya-related people. - Native American-related ancestry in the Okunevo, possibly due to shared ancestry with paleolihic hunter-gatherers from Mal’ta.
- Results make a compelling case for the steppe as a source of at least some of the Indo-European languages in Europe by documenting a massive migration ~4,500 years ago associated with the Yamnaya and Corded Ware cultures
- Our results support a view of European pre-history punctuated by two major migrations: first, the arrival of the first farmers during the Early Neolithic from the Near East, and second, the arrival of Yamnaya pastoralists during the Late Neolithic from the steppe. Our data further show that both migrations were followed by resurgences of the previous inhabitants: first, during the Middle Neolithic, when hunter-gatherer ancestry rose again after its Early Neolithic decline, and then between the Late Neolithic and the present, when farmer and hunter-gatherer ancestry rose after its Late Neolithic decline. This second resurgence must have started during the Late Neolithic/Bronze Age period itself, as the Bell Beaker and Unetice groups had reduced Yamnaya ancestry compared to the earlier Corded Ware, and comparable levels to that in some present-day Europeans (Fig. 3).
- All 5 of the male individuals in this study belonged to the I haplogroup. Among present-day Germans, this is found at a frequency of ~24%. At present, the limited number of ancient samples for which Y chromosome data is available makes it difficult to assess how statistically surprising it is that the Y haplogroup group occurs in all five of the ancient Mesolithic males but in only a quarter of present-day German males.
- It is tempting to speculate that haplogroup I might be the dominant European Y chromosome haplogroup in Palaeolithic Europe, that is, the male counterpart of maternally inherited mitochondrial haplogroup U. Y chromosome haplogroup I as well as mitochondrial haplogroup U, have also been identified in Neolithic Europeans, and are found throughout Europe in present-day populations. Thus, both maternally- and paternally-inherited genetic components of present-day Europeans may reflect a history of admixture: a genetic contribution from both the hunter-gatherers and early farmers of Europe. Y chromosome haplogroup I is scarce in the Near East today, with only sporadic occurrences of this haplogroup in the North Caucasus (~3% in frequency), consistent with limited gene flow from Europe into this area. This finding is also consistent with the near absence of haplogroup U in the Near East and our findings from the autosomal data.
- This study raises two questions that are important to address in future research. A first is where the EEF picked up their WHG ancestry. Southeastern Europe is a candidate as it lies along the geographic path from Anatolia into central Europe, and hence it should be a priority to study ancient samples from this region. A second question is when and where ANE ancestors admixed with the ancestors of most present-day Europeans. Based on discontinuity in mtDNA haplogroup frequencies in Central Europe, this may have occurred during the Late Neolithic or early Bronze Age ~5,500-4,000 years ago. A central aim for future work should be to collect transects of ancient Europeans through time and space to illuminate the history of these transformations. The absence of Y-haplogroup R1b in our two sample locations is striking given that it is, at present, the major west European lineage. Importantly, however, it has not yet been found in ancient European contexts prior to a Bell Beaker burial from Germany (2,800-2,000BC), while the related R1a lineage has a first known occurrence in a Corded Ware burial also from Germany (2,600BC). This casts doubt on early suggestions associating these haplogroups with Paleolithic Europeans, and is more consistent with their Neolithic entry into Europe at least in the case of R1b. More research is needed to document the time and place of their earliest occurrence in Europe. Interestingly, the Mal’ta boy belonged to haplogroup R* and we tentatively suggest that some haplogroup R bearers may be responsible for the wider dissemination of Ancient North Eurasian ancestry into Europe, as their haplogroup Q relatives may have plausibly done into the Americas.