Stone Age plague accompanying migrants from the steppe, probably Yamna, Balkan EBA, and Bell Beaker, not Corded Ware

copper-age-late-bell-beaker

In the latest revisions of the Indo-European demic diffusion model, using the results from the article Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years Ago, by Rasmussen et al., Cell (2015), I stated (more or less indirectly) that the high east-west mobility of the Corded Ware migrants across related cultures might have been responsible for the spread of this disease, which seems to have been originally expanded from Central Eurasia.

New results appeared recently in the article The Stone Age Plague and Its Persistence in Eurasia, by Valtueña et al., Current Biology (2017), which may contradict that interpretation.

corded-ware-map
Diachronic map of Copper Age migrations ca. 3100-2600 BC – Corded Ware

Abstract:

Yersinia pestis, the etiologic agent of plague, is a bacterium associated with wild rodents and their fleas. Historically it was responsible for three pandemics: the Plague of Justinian in the 6th century AD, which persisted until the 8th century [ 1 ]; the renowned Black Death of the 14th century [ 2, 3 ], with recurrent outbreaks until the 18th century [ 4 ]; and the most recent 19th century pandemic, in which Y. pestis spread worldwide [ 5 ] and became endemic in several regions [ 6 ]. The discovery of molecular signatures of Y. pestis in prehistoric Eurasian individuals and two genomes from Southern Siberia suggest that Y. pestis caused some form of disease in humans prior to the first historically documented pandemic [ 7 ]. Here, we present six new European Y. pestis genomes spanning the Late Neolithic to the Bronze Age (LNBA; 4,800 to 3,700 calibrated years before present). This time period is characterized by major transformative cultural and social changes that led to cross-European networks of contact and exchange [ 8, 9 ]. We show that all known LNBA strains form a single putatively extinct clade in the Y. pestis phylogeny. Interpreting our data within the context of recent ancient human genomic evidence that suggests an increase in human mobility during the LNBA, we propose a possible scenario for the early spread of Y. pestis: the pathogen may have entered Europe from Central Eurasia following an expansion of people from the steppe, persisted within Europe until the mid-Bronze Age, and moved back toward Central Eurasia in parallel with human populations.

plague_phylogeny_eurasia
Maximum-Likelihood Tree and Percent Coverage Plot of Virulence Factors of Yersinia pestis. (A) Maximum-likelihood tree of all Yersinia pestis genomes, including 1,265 SNP positions with complete deletion. Nodes with support R95% are marked with an asterisk. The colors represent different branches in the Y. pestis phylogeny: branch 0 (black), branch 1 (red), branch 2 (green), branch 3 (blue), branch 4 (orange), and LNBA Y. pestis branch (purple). Y. pseudotuberculosis-specific SNPs were excluded from the tree for clarity of representation. In the light-colored boxes, discussed losses and gains of genomic regions and genes are indicated. Related

It seems that, notwithstanding the simplistic (white) arrows of steppe ancestry expansion shown in their map (see below), the actual expansion of Yersinia pestis might have in fact accompanied Yamna migrants from the Pontic-Caspian steppe into Early Bronze Age cultures from the Balkans, including Bell Beaker migrants, as the phylogenetic analysis and dates suggest – and as the potential arrows of the plague expansion in the map (in green) show.

Late Corded Ware migrants would have only later expanded the disease to eastern Europe, as shown in the second map, most likely because of their close contact with Bell Beaker migrants (but remaining culturally distinct from them), and indeed because of the mobility accross related Corded Ware cultures up to the Urals.

The cultural-historical community in the Late Neolithic between steppe peoples that would evolve into Uralic-speaking Sredni Stog/Corded Ware migrants in the western steppe, and Late Indo-European-speaking Yamna/SE EBA/Bell Beaker migrants originally from the eastern steppe, would allow for the spread of the disease first among steppe groups, and then from both distinct late groups into their respective expanded regions.

The phylogenetic tree of Y. pestis available right now (see above), however, seems to suggest a stronger initial link to Yamna migrants, i.e. an origin in the North Caspian steppe, and an expansion with Yamna into the north Pontic area, into the Caucasus, and with the Afansevo culture, spreading later with Balkan EBA cultures and the expansion of Bell Beaker peoples.

Instead of warring nature, close ties, and mobility of Corded Ware peoples (reasons I used to justify the rapid spread of the disease among CWC groups), I guess it was rather the higher population density of SE Europe compared to the regions north of the loess belt, as well as the greater admixture of Yamna migrants with native SE European populations, the factors which might have helped expand the disease.

plague-expansion-europe
Map of Proposed Yersinia pestis Circulation throughout Eurasia (A) Entrance of Y. pestis into Europe from Central Eurasia with the expansion of Yamnaya pastoralists around 4,800 years ago. (B) Circulation of Y. pestis to Southern Siberia from Europe. Only complete genomes are shown.

Nevertheless, lacking more data, it is unclear if the disease expanded with both steppe groups.

Related:

Review article on the origin of modern humans: the multiple-dispersal model and Late Pleistocene Asia

homo-sapiens-dispersal

Review article On the origin of modern humans: Asian perspectives, by Christopher J. Bae, Katerina Douka, and Michael D. Petraglia, Science (2017)

Abstract:

BACKGROUND
The earliest fossils of Homo sapiens are located in Africa and dated to the late Middle Pleistocene. At some point later, modern humans dispersed into Asia and reached the far-away locales of Europe, Australia, and eventually the Americas. Given that Neandertals, Denisovans, mid-Pleistocene Homo, and H. floresiensis were present in Asia before the appearance of modern humans, the timing and nature of the spread of modern humans across Eurasia continue to be subjects of intense debate. For instance, did modern humans replace the indigenous populations when moving into new regions? Alternatively, did population contact and interbreeding occur regularly? In terms of behavior, did technological innovations and symbolism facilitate dispersals of modern humans? For example, it is often assumed that only modern humans were capable of using watercraft and navigating to distant locations such as Australia and the Japanese archipelago—destinations that would not have been visible to the naked eye from the departure points, even during glacial stages when sea levels would have been much lower. Moreover, what role did major climatic fluctuations and environmental events (e.g., the Toba volcanic super-eruption) play in the dispersal of modern humans across Asia? Did extirpations of groups occur regularly, and did extinctions of populations take place? Questions such as these are paramount in understanding hominin evolution and Late Pleistocene Asian paleoanthropology.

ADVANCES
An increasing number of multidisciplinary field and laboratory projects focused on archaeological sites and fossil localities from different areas of Asia are producing important findings, allowing researchers to address key evolutionary questions that have long perplexed the field. For instance, technological advances have increased our ability to successfully collect ancient DNA from hominin fossils, providing proof that interbreeding occurred on a somewhat regular basis. New finds of H. sapiens fossils, with increasingly secure dating associations, are emerging in different areas of Asia, some seemingly from the first half of the Late Pleistocene. Cultural variability discerned from archaeological studies indicates that modern human behaviors did not simply spread across Asia in a time-transgressive pattern. This regional variation, which is particularly distinct in Southeast Asia, could be related at least in part to environmental and ecological variation (e.g., Palearctic versus Oriental biogeographic zones).

OUTLOOK
Recent findings from archaeology, hominin paleontology, geochronology, and genetics indicate that the strict “out of Africa” model, which posits that there was only a single dispersal into Eurasia at ~60,000 years ago, is in need of revision. In particular, a multiple-dispersal model, perhaps beginning at the advent of the Late Pleistocene, needs to be examined more closely. An increasingly robust record from Late Pleistocene Asian paleoanthropology is helping to build and establish new views about the origin and dispersal of modern humans.

homo-sapiens-dispersal
Map of sites with ages and postulated early and later pathways associated with modern humans dispersing across Asia during the Late Pleistocene.

Related:

Migrations painted by Irish and Scottish genetic clusters, and their relationship with British and European ones

ireland-britain-cluster

Interesting and related publications, now appearing in pairs…

1. The Irish DNA Atlas: Revealing Fine-Scale Population Structure and History within Ireland, by Gilbert et al., in Scientific Reports (2017).

Abstract:

The extent of population structure within Ireland is largely unknown, as is the impact of historical migrations. Here we illustrate fine-scale genetic structure across Ireland that follows geographic boundaries and present evidence of admixture events into Ireland. Utilising the ‘Irish DNA Atlas’, a cohort (n = 194) of Irish individuals with four generations of ancestry linked to specific regions in Ireland, in combination with 2,039 individuals from the Peoples of the British Isles dataset, we show that the Irish population can be divided in 10 distinct geographically stratified genetic clusters; seven of ‘Gaelic’ Irish ancestry, and three of shared Irish-British ancestry. In addition we observe a major genetic barrier to the north of Ireland in Ulster. Using a reference of 6,760 European individuals and two ancient Irish genomes, we demonstrate high levels of North-West French-like and West Norwegian-like ancestry within Ireland. We show that that our ‘Gaelic’ Irish clusters present homogenous levels of ancient Irish ancestries. We additionally detect admixture events that provide evidence of Norse-Viking gene flow into Ireland, and reflect the Ulster Plantations. Our work informs both on Irish history, as well as the study of Mendelian and complex disease genetics involving populations of Irish ancestry.

european-ancestry-british-isles
The European ancestry profiles of 30 Irish and British clusters. (a) The total ancestry contribution summarised by majority European country of origin to each of the 30 Irish and British clusters. (b) (left) The ancestry contributions of 19 European clusters that donate at least 2.5% ancestry to any one Irish or British cluster. (right) The geographic distribution of the 19 European clusters, shown as the proportion of individuals in each European region belonging to each of the 19 European clusters. The proportion of individuals form each European region not a member of the 19 European clusters is shown in grey. Total numbers of individuals from each region are shown in white text. Not all Europeans included in the analysis were phenotyped geographically. The figure was generated in the statistical software language R46, version 3.4.1, using various packages. The map of Europe was sourced from the R software package “mapdata” (https://CRAN.R-project.org/package=mapdata).

2. New preprint on BioRxiv, Insular Celtic population structure and genomic footprints of migration, by Byrne, Martiniano et al. (2017).

Abstract:

Previous studies of the genetic landscape of Ireland have suggested homogeneity, with population substructure undetectable using single-marker methods. Here we have harnessed the haplotype-based method fineSTRUCTURE in an Irish genome-wide SNP dataset, identifying 23 discrete genetic clusters which segregate with geographical provenance. Cluster diversity is pronounced in the west of Ireland but reduced in the east where older structure has been eroded by historical migrations. Accordingly, when populations from the neighbouring island of Britain are included, a west-east cline of Celtic-British ancestry is revealed along with a particularly striking correlation between haplotypes and geography across both islands. A strong relationship is revealed between subsets of Northern Irish and Scottish populations, where discordant genetic and geographic affinities reflect major migrations in recent centuries. Additionally, Irish genetic proximity of all Scottish samples likely reflects older strata of communication across the narrowest inter-island crossing. Using GLOBETROTTER we detected Irish admixture signals from Britain and Europe and estimated dates for events consistent with the historical migrations of the Norse-Vikings, the Anglo-Normans and the British Plantations. The influence of the former is greater than previously estimated from Y chromosome haplotypes. In all, we paint a new picture of the genetic landscape of Ireland, revealing structure which should be considered in the design of studies examining rare genetic variation and its association with traits.

Here are some interesting excerpts (emphasis mine):

Population structure in Ireland

The geographical distribution of this deep subdivision of Leinster resembles pre-Norman territorial boundaries which divided Ireland into fifths (cúige), with north Leinster a kingdom of its own known as Meath (Mide) [15]. However interpreted, the firm implication of the observed clustering is that despite its previously reported homogeneity, the modern Irish population exhibits genetic structure that is subtly but detectably affected by ancestral population structure conferred by geographical distance and, possibly, ancestral social structure.

ChromoPainter PC1 demonstrated high diversity amongst clusters from the west coast, which may be attributed to longstanding residual ancient (possibly Celtic) structure in regions largely unaffected by historical migration. Alternatively, genetic clusters may also have diverged as a consequence of differential influence from outside populations. This diversity between western genetic clusters cannot be explained in terms of geographic distance alone.

In contrast to the west of Ireland, eastern individuals exhibited relative homogeneity; (…) The overall pattern of western diversity and eastern homogeneity in Ireland may be explained by increased gene flow and migration into and across the east coast of Ireland from geographically proximal regions, the closest of which is the neighbouring island of Britain.

Analysis of variance of the British admixture component in cluster groups showed a significant difference (p < 2×10-16), indicating a role for British Anglo-Saxon admixture in distinguishing clusters, and ChromoPainter PC2 was correlated with the British component (p < 2×10-16), explaining approximately 43% of the variance. PC2 therefore captures an east to west Anglo-Celtic cline in Irish ancestry. This may explain the relative eastern homogeneity observed in Ireland, which could be a result of the greater English influence in Leinster and the Pale during the period of British rule in Ireland following the Norman invasion, or simply geographic proximity of the Irish east coast to Britain. Notably, the Ulster cluster group harboured an exceptionally large proportion of the British component (Fig 1D and 1E), undoubtedly reflecting the strong influence of the Ulster Plantations in the 17th century and its residual effect on the ethnically British population that has remained.

ireland-population-structure
Fine-grained population structure in Ireland. (A) fineSTRUCTURE clustering dendrogram for 1,035 Irish individuals. Twenty-three clusters are defined, which are combined into cluster groups for clusters that are neighbouring in the dendrogram, overlapping in principal component space (B) and sampled from regions that are geographically contiguous. Details for each cluster in the dendrogram are provided in S1 Fig. (B) Principal components analysis (PCA) of haplotypic similarity, based on ChromoPainter coancestry matrix for Irish individuals. Points are coloured according to cluster groups defined in (A); the median location of each cluster group is plotted. (C) Map of Irelandshowing the sampling location for a subset of 588 individuals analysed in (A) and (B), coloured by cluster group. Points have been randomly jittered within a radius of 5 km to preserve anonymity. Precise sampling location for 44 Northern Irish individuals from the People of the British Isles dataset was unknown; these individuals are plotted geometrically in a circle. (D) “British admixture component” (ADMIXTURE estimates; k=2) for Irish cluster groups. This component has the largest contribution in ancient Anglo-Saxons and the SEE cluster. (E) Linear regression of principal component 2 (B) versus British admixture component (r2 = 0.43; p < 2×10-16). Points are coloured by cluster group. (Standard error for ADMIXTURE point estimates presented in S11 Fig.)

On the genetic structure of the British Isles

The genetic substructure observed in Ireland is consistent with long term geographic diversification of Celtic populations and the continuity shown between modern and Early Bronze Age Irish people

Clusters representing Celtic populations harbouring less Anglo-Saxon influence separate out above and below SEE on PC4. Notably, northern Irish clusters (NLU), Scottish (NISC, SSC and NSC), Cumbria (CUM) and North Wales (NWA) all separate out at a mutually similar level, representing northern Celtic populations. The southern Celtic populations Cornwall (COR), south Wales (SWA) and south Munster (SMN) also separate out on similar levels, indicating some shared haplotypic variation between geographically proximate Celtic populations across both Islands. It is notable that after the split of the ancestrally divergent Orkney, successive ChromoPainter PCs describe diversity in British populations where “Anglo-saxonization” was repelled [22]. PC3 is dominated by Welsh variation, while PC4 in turn splits North and South Wales significantly, placing south Wales adjacent to Cornwall and north Wales at the other extreme with Cumbria, all enclaves where Brittonic languages persisted.

In an interesting symmetry, many Northern Irish samples clustered strongly with southern Scottish and northern English samples, defining the Northern Irish/Cumbrian/Scottish (NICS) cluster group. More generally, by modelling Irish genomes as a linear mixture of haplotypes from British clusters, we found that Scottish and northern English samples donated more haplotypes to clusters in the north of Ireland than to the south, reflecting an overall correlation between Scottish/north English contribution and ChromoPainter PC1 position in Fig 1 (Linear regression: p < 2×10-16, r2 = 0.24).

North to south variation in Ireland and Britain are therefore not independent, reflecting major gene flow between the north of Ireland and Scotland (Fig 5) which resonates with three layers of historical contacts. First, the presence of individuals with strong Irish affinity among the third generation PoBI Scottish sample can be plausibly attributed to major economic migration from Ireland in the 19th and 20th centuries [6]. Second, the large proportion of Northern Irish who retain genomes indistinguishable from those sampled in Scotland accords with the major settlements (including the Ulster Plantation) of mainly Scottish farmers following the 16th Century Elizabethan conquest of Ireland which led to these forming the majority of the Ulster population. Third, the suspected Irish colonisation of Scotland through the Dál Riata maritime kingdom, which expanded across Ulster and the west coast of Scotland in the 6th and 7th centuries, linked to the introduction and spread of Gaelic languages [3]. Such a migratory event could work to homogenise older layers of Scottish population structure, in a similar manner as noted on the east coasts of Britain and Ireland. Earlier communications and movements across the Irish Sea are also likely, which at its narrowest point separates Ireland from Scotland by approximately 20 km.

ireland-britain-genetic-geography
Genes mirror geography in the British Isles. (A) fineSTRUCTURE clustering dendrogram for combined Irish and British data. Data principally split into Irish and British groups before subdividing into a total of 50 distinct clusters, which are combined into cluster groups for clusters that formed clades in the dendrogram, overlapped in principal component space (B) and were sampled from regions that are geographically contiguous. Names and labels follow the geographical provenance for the majority of data within the cluster group. Details for each cluster in the dendrogram are provided in S2 Fig. (B) Principal component analysis (PCA) of haplotypic similarity based on the ChromoPainter coancestry matrix, coloured by cluster group with their median locations labelled. We have chosen to present PC1 versus PC4 here as these components capture new information regarding correlation between haplotypic variation across Britain and Ireland and geography, while PC2 and PC3 (Fig 4) capture previously reported splitting for Orkney and Wales from Britain [7]. A map of Ireland and Britain is shown for comparison, coloured by sampling regions for cluster groups, the boundaries of which are defined by the Nomenclature of Territorial Units for Statistics (NUTS 2010), with some regions combined. Sampling regions are coloured by the cluster group with the majority presence in the sampling region; some sampling regions have significant minority cluster group representations as well, for example the Northern Ireland sampling region (UKN0; NUTS 2010) is majorly explained by the NICS cluster group but also has significant representation from the NLU cluster group. The PCA plot has been rotated clockwise by 5 degrees to highlight its similarity with the geographical map of the Ireland and Britain. NI, Northern Ireland; PC, principal component. Cluster groups that share names with groups from Fig 1 (NLU; SMN; CLN; CNN) have an average of 80% of their samples shared with the initial cluster groups. © EuroGeographics for the map and administrative boundaries, note some boundaries have been subsumed or modified to better reflect sampling regions.

Genomic footprints of migration into Ireland

Quite interesting is that it is haplogroups, and not admixture, that which defines the oldest migration layers into Ireland. Without evidence of paternal Y-DNA lineages we would probably not be able to ascertain the oldest migrations and languages broght by migrants, including Celtic languages:

Of all the European populations considered, ancestral influence in Irish genomes was best represented by modern Scandinavians and northern Europeans, with a significant single-date one-source admixture event overlapping the historical period of the Norse-Viking settlements in Ireland (p < 0.01; fit quality FQB > 0.985; Fig 6). (…) This suggests a contribution of historical Viking settlement to the contemporary Irish genome and contrasts with previous estimates of Viking ancestry in Ireland based on Y chromosome haplotypes, which have been very low [25]. The modern-day paucity of Norse-Viking Y chromosome haplotypes may be a consequence of drift with the small patrilineal effective population size, or could have social origins with Norse males having less influence after their military defeat and demise as an identifiable community in the 11th century, with persistence of the autosomal signal through recombination.

European admixture date estimates in northwest Ulster did not overlap the Viking age but did include the Norman period and the Plantations

The genetic legacies of the populations of Ireland and Britain are therefore extensively intertwined and, unlike admixture from northern Europe, too complex to model with GLOBETROTTER.

ireland-admixture-estimates
All-Ireland GLOBETROTTER admixture date estimates for European and British surrogate admixing populations. A summary of the date estimates and 95% confidence intervals for inferred admixture events into Ireland from European and British admixing sources is shown in (A), with ancestry proportion estimates for each historical source population for the two events and example coancestry curves shown in (B). In the coancestry curves Relative joint probability estimates the pairwise probability that two haplotype chunks separated by a given genetic distance come from the two modeled source populations respectively (ie FRA(8) and NOR-SG); if a single admixture event occurred, these curves are expected to decay exponentially at a rate corresponding to the number of generations since the event. The green fitted line describes this GLOBETROTTER fitted exponential decay for the coancestry curve. If the sources come from the same ancestral group the slope of this curve will be negative (as with FRA(8) vs FRA(8)), while a positive slope indicates that sources come from different admixing groups (as with FRA(8) vs NOR-SG). The adjacent bar plot shows the inferred genetic composition of the historical admixing sources modelled as a mixture of the sampled modern populations. A European admixture event was estimated by GLOBETROTTER corresponding to the historical record of the Viking age, with major contributions from sources similar to modern Scandinavians and northern Europeans and minor contributions from southern European-like sources. For admixture date estimates from British-like sources the influence of the Norman settlement and the Plantations could not be disentangled, with the point estimate date for admixture falling between these two eras and GLOBETROTTER unable to adequately resolve source and proportion details of admixture event (fit quality FQB< 0.985). The relative noise of the coancestry curves reflects the uncertainty of the British event. Cluster labels (for the European clustering dendrogram, see S4 Fig; for the PoBI clustering dendrogram, see S3 Fig): FRA(8), France cluster 8; NOR-SG, Norway, with significant minor representations from Sweden and Germany; SE_ENG, southeast England; N_SCOT(4) northern Scotland cluster 4.

Another study that strengthens the need to ascertain haplogroup-admixture differences between Yamna/Bell Beaker and Sredni Stog/Corded Ware.

Text and images from preprint article under a CC-BY-NC-ND 4.0 International license.

Featured image, from the article on Science Reports: The clustering of individuals with Irish and British ancestry based solely on genetics. Shown are 30 clusters identified by fineStructure from 2,103 Irish and British individuals. The dendrogram (left) shows the tree of clusters inferred by fineStructure and the map (right) shows the geographic origin of 192 Atlas Irish individuals and 1,611 British individuals from the Peoples of the British Isles (PoBI) cohort, labelled according to fineStructure cluster membership. Individuals are placed at the average latitude and longitude of either their great-grandparental (Atlas) or grandparental (PoBI) birthplaces. Great Britain is separated into England, Scotland, and Wales. The island of Ireland is split into the four Provinces; Ulster, Connacht, Leinster, and Munster. The outline of Britain was sourced from Global Administrative Areas (2012). GADM database of Global Administrative Areas, version 2.0. www.gadm.org. The outline of Ireland was sourced from Open Street Map Ireland, Copyright OpenStreetMap Contributors, (https://www.openstreetmap.ie/) – data available under the Open Database Licence. The figure was plotted in the statistical software language R46, version 3.4.1, with various packages.
Related:

Ancient Di-Qiang people show early links with Han Chinese

china-genetics-peoples

Bernard Sécher reports on a recent article, Ancient DNA reveals genetic connections between early Di-Qiang and Han Chinese, by Li et al., BMC Evolutionary Biology (2017).

Abstract:

Background
Ancient Di-Qiang people once resided in the Ganqing region of China, adjacent to the Central Plain area from where Han Chinese originated. While gene flow between the Di-Qiang and Han Chinese has been proposed, there is no evidence to support this view. Here we analyzed the human remains from an early Di-Qiang site (Mogou site dated ~4000 years old) and compared them to other ancient DNA across China, including an early Han-related site (Hengbei site dated ~3000 years old) to establish the underlying genetic relationship between the Di-Qiang and ancestors of Han Chinese.

Results
We found Mogou mtDNA haplogroups were highly diverse, comprising 14 haplogroups: A, B, C, D (D*, D4, D5), F, G, M7, M8, M10, M13, M25, N*, N9a, and Z. In contrast, Mogou males were all Y-DNA haplogroup O3a2/P201; specifically one male was further assigned to O3a2c1a/M117 using targeted unique regions on the non-recombining region of the Y-chromosome. We compared Mogou to 7 other ancient and 38 modern Chinese groups, in a total of 1793 individuals, and found that Mogou shared close genetic distances with Taojiazhai (a more recent Di-Qiang population), Hengbei, and Northern Han. We modeled their interactions using Approximate Bayesian Computation, and support was given to a potential admixture of ~13-18% between the Mogou and Northern Han around 3300–3800 years ago.

Conclusions
Mogou harbors the earliest genetically identifiable Di-Qiang, ancestral to the Taojiazhai, and up to ~33% paternal and ~70% of its maternal haplogroups could be found in present-day Northern Han Chinese.

chinese-ancient-modern-genetics-pca
MDS plot of genetic distance Fst between 3 ancient and 38 modern Chinese groups

Interesting times now for the investigation of potential migrations associated with the expansion of Sino-Tibetan and Altaic languages

Related:

Coexistence of two different populations in Gotland during the Middle Neolithic

neolithic

New insights on cultural dualism and population structure in the Middle Neolithic Funnel Beaker culture on the island of Gotland, by Fraser et al., in Journal of Archaeological Science: Reports (2017).

Abstract (emphasis mine):

In recent years it has been shown that the Neolithization of Europe was partly driven by migration of farming groups admixing with local hunter-gatherer groups as they dispersed across the continent. However, little research has been done on the cultural duality of contemporaneous foragers and farming populations in the same region. Here we investigate the demographic history of the Funnel Beaker culture [Trichterbecherkultur or TRB, c. 4000–2800 cal BCE], and the sub-Neolithic Pitted Ware culture complex [PWC, c. 3300–2300 cal BCE] during the Nordic Middle Neolithic period on the island of Gotland, Sweden. We use a multidisciplinary approach to investigate individuals buried in the Ansarve dolmen, the only confirmed TRB burial on the island. We present new radiocarbon dating, isotopic analyses for diet and mobility, and mitochondrial DNA haplogroup data to infer maternal inheritance. We also present a new Sr-baseline of 0.71208 ± 0.0016 for the local isotope variation. We compare and discuss our findings together with that of contemporaneous populations in Sweden and the North European mainland.

The radiocarbon dating and Strontium isotopic ratios show that the dolmen was used between c. 3300–2700 cal BCE by a population which displayed local Sr-signals. Mitochondrial data show that the individuals buried in the Ansarve dolmen had maternal genetic affinity to that of other Early and Middle Neolithic farming cultures in Europe, distinct from that of the contemporaneous PWC on the island. Furthermore, they exhibited a strict terrestrial and/or slightly varied diet in contrast to the strict marine diet of the PWC. The findings indicate that two different contemporary groups coexisted on the same island for several hundred years with separate cultural identity, lifestyles, as well as dietary patterns.

gotland-funnel-beaker-culture
“Map indicating distribution of TRB-North group megalithic tombs (Blomqvist, 1989; Midgley, 2008; Sjögren, 2003; Tilley, 1999) and PWC areas (Larsson, 2009) modified from (Malmström et al., 2009). Swedish megalithic TRB burial sites included in the analyses: 1. Gökhem passage grave, Falköping, Västergötland, 2. Alvastra dolmen, Östergötland, 3. Mysinge passage grave, Resmo, Öland, 4. Ansarve dolmen, Tofta, Gotland, and 5. the Ostorf TRB burial ground, Mecklenburg-Vorpommern, Germany.”

If you are interested in knowing more details about settlements on the island, I recommend you to read Early Holocene human population events on the island of Gotland in the Baltic Sea (9200-3800 cal. BP), by Jan Apel, downloadable here.

It is important to remember cases like this one when speaking about the steppe as representing a single culture and people, speaking the same language, no matter the period in question and the archaeological cultures involved…

Related:

Featured image: Diachronic map of Early Neolithic migrations ca. 5000-4000 BC.

Related:

Expansion of peoples associated with spread of haplogroups: Mongols and C3*-F3918, Arabs and E-M183 (M81)

iron-age-migrations

Two recent interesting papers on the potential expansion of cultures associated with haplogroups:

1. Whole Y-chromosome sequences reveal an extremely recent origin of the most common North African paternal lineage E-M183 (M81), by Solé-Morata et al., Scientific Reports (2017).

Abstract:

E-M183 (E-M81) is the most frequent paternal lineage in North Africa and thus it must be considered to explore past historical and demographical processes. Here, by using whole Y chromosome sequences from 32 North African individuals, we have identified five new branches within E-M183. The validation of these variants in more than 200 North African samples, from which we also have information of 13 Y-STRs, has revealed a strong resemblance among E-M183 Y-STR haplotypes that pointed to a rapid expansion of this haplogroup. Moreover, for the first time, by using both SNP and STR data, we have provided updated estimates of the times-to-the-most-recent-common-ancestor (TMRCA) for E-M183, which evidenced an extremely recent origin of this haplogroup (2,000–3,000 ya). Our results also showed a lack of population structure within the E-M183 branch, which could be explained by the recent and rapid expansion of this haplogroup. In spite of a reduction in STR heterozygosity towards the West, which would point to an origin in the Near East, ancient DNA evidence together with our TMRCA estimates point to a local origin of E-M183 in NW Africa.

haplogroup-E-M183-subclade-distribution
Distribution of E-M183 subclades among North Africa, the Near East and the Iberian Peninsula. Pie chart sectors areas are proportional to haplogroup frequency and are coloured according to haplogroup in the schematic tree to the right. n: sample size. Map was generated using R software.

An interesting excerpt, from the discussion:

Regarding the geographical origin of E-M183, a previous study suggested that an expansion from the Near East could explain the observed east-west cline of genetic variation that extends into the Near East. Indeed, our results also showed a reduction in STR heterozygosity towards the West, which may be taken to support the hypothesis of an expansion from the Near East. In addition, previous studies based on genome-wide SNPs reported that a North African autochthonous component increase towards the West whereas the Near Eastern decreases towards the same direction, which again support an expansion from the Near East. However, our correlations should be taken carefully because our analysis includes only six locations on the longitudinal axis, none from the Near East. As a result, we do not have sufficient statistical power to confirm a Near Eastern origin. In addition, rather than showing a west-to-east cline of genetic diversity, the overall picture shown by this correlation analysis evidences just low genetic diversity in Western Sahara, which indeed could be also caused by the small sample size (n = 26) in this region. Alternatively, given the high frequency of E-M183 in the Maghreb, a local origin of E-M183 in NW Africa could be envisaged, which would fit the clear pattern of longitudinal isolation by distance reported in genome-wide studies. Moreover, the presence of autochthonous North African E-M81 lineages in the indigenous population of the Canary Islands, strongly points to North Africa as the most probable origin of the Guanche ancestors. This, together with the fact that the oldest indigenous inviduals have been dated 2210 ± 60 ya, supports a local origin of E-M183 in NW Africa. Within this scenario, it is also worth to mention that the paternal lineage of an early Neolithic Moroccan individual appeared to be distantly related to the typically North African E-M81 haplogroup30, suggesting again a NW African origin of E-M183. A local origin of E-M183 in NW Africa > 2200 ya is supported by our TMRCA estimates, which can be taken as 2,000–3,000, depending on the data, methods, and mutation rates used.

The TMRCA estimates of a certain haplogroup and its subbranches provide some constraints on the times of their origin and spread. Although our time estimates for E-M78 are slightly different depending on the mutation rate used, their confidence intervals overlap and the dates obtained are in agreement with those obtained by Trombetta et al Regarding E-M183, as mentioned above, we cannot discard an expansion from the Near East and, if so, according to our time estimates, it could have been brought by the Islamic expansion on the 7th century, but definitely not with the Neolithic expansion, which appeared in NW Africa ~7400 BP and may have featured a strong Epipaleolithic persistence. Moreover, such a recent appearance of E-M183 in NW Africa would fit with the patterns observed in the rest of the genome, where an extensive, male-biased Near Eastern admixture event is registered ~1300 ya, coincidental with the Arab expansion. An alternative hypothesis would involve that E-M183 was originated somewhere in Northwest Africa and then spread through all the region. Our time estimates for the origin of this haplogroup overlap with the end of the third Punic War (146 BCE), when Carthage (in current Tunisia) was defeated and destroyed, which marked the beginning of Roman hegemony of the Mediterranean Sea. About 2,000 ya North Africa was one of the wealthiest Roman provinces and E-M183 may have experienced the resulting population growth.

2. The Y-chromosome haplogroup C3*-F3918, likely attributed to the Mongol Empire, can be traced to a 2500-year-old nomadic group, by Zhang et al., Journal of Human Genetics (2017)

Abstract:

The Mongol Empire had a significant role in shaping the landscape of modern populations. Many populations living in Eurasia may have been the product of population mixture between ancient Mongolians and natives following the expansion of Mongol Empire. Geneticists have found that most of these populations carried the Y-haplogroup C3* (C-M217). To trace the history of haplogroup (Hg) C3* and to further understand the origin and development of Mongolians, ancient human remains from the Jinggouzi, Chenwugou and Gangga archaeological sites, which belonged to the Donghu, Xianbei and Shiwei, respectively, were analysed. Our results show that nine of the eleven males of the Gangga site, two of the eight males of Chengwugou site and all of the twelve males of Jinggouzi site were found to have mutations at M130 (Hg C), M217 (Hg C3), L1373 (C2b, ISOGG2015), with the absence of mutations at M93 (Hg C3a), P39 (Hg C3b), M48 (Hg C3c), M407 (Hg C3d) and P62 (Hg C3f). These samples were attributed to the Y-chromosome Hg C3* (Hg C2b, ISOGG2015), and most of them were further typed as Hg C2b1a based on the mutation at F3918. Finally, we inferred that the Y-chromosome Hg C3*-F3918 can trace its origins to the Donghu ancient nomadic group.

mongol-expansion-y-dna-haplogroup
The development of Mongolia and the frequencies of haplogroup C3* in modern Eurasians. a The development of Mongolia. b The frequencies of haplogroup C3 in modern Eurasians. The dotted line represents the approximate boundary between the Xiongnu and the Donghu. The black and grey arrows denote the migration of the Donghu and Mongolians, respectively

The expansion of peoples is known to be associated with the spread of a certain admixture component, joint with the expansion and reduction in variability of a haplogroup. In other words, few male lineages are usually more successful during the expansion.

Other known examples include:

Featured image: Diachronic map of Iron Age migrations ca. 750-250 BC.

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