Distribution of Southern Iberian haplogroup H indicates exchanges in the western Mediterranean

Recent open access paper The distribution of mitochondrial DNA haplogroup H in southern Iberia indicates ancient human genetic exchanges along the western edge of the Mediterranean, by Hernández, Dugoujon, Novelletto, Rodríguez, Cuesta and Calderón, BMC Genetics (2017).

Abstract (emphasis mine):

Background
The structure of haplogroup H reveals significant differences between the western and eastern edges of the Mediterranean, as well as between the northern and southern regions. Human populations along the westernmost Mediterranean coasts, which were settled by individuals from two continents separated by a relatively narrow body of water, show the highest frequencies of mitochondrial haplogroup H. These characteristics permit the analysis of ancient migrations between both shores, which may have occurred via primitive sea crafts and early seafaring. We collected a sample of 750 autochthonous people from the southern Iberian Peninsula (Andalusians from Huelva and Granada provinces). We performed a high-resolution analysis of haplogroup H by control region sequencing and coding SNP screening of the 337 individuals harboring this maternal marker. Our results were compared with those of a wide panel of populations, including individuals from Iberia, the Maghreb, and other regions around the Mediterranean, collected from the literature.

Results
Both Andalusian subpopulations showed a typical western European profile for the internal composition of clade H, but eastern Andalusians from Granada also revealed interesting traces from the eastern Mediterranean. The basal nodes of the most frequent H sub-haplogroups, H1 and H3, harbored many individuals of Iberian and Maghrebian origins. Derived haplotypes were found in both regions; haplotypes were shared far more frequently between Andalusia and Morocco than between Andalusia and the rest of the Maghreb. These and previous results indicate intense, ancient and sustained contact among populations on both sides of the Mediterranean.

Conclusions
Our genetic data on mtDNA diversity, combined with corresponding archaeological similarities, provide support for arguments favoring prehistoric bonds with a genetic legacy traceable in extant populations. Furthermore, the results presented here indicate that the Strait of Gibraltar and the adjacent Alboran Sea, which have often been assumed to be an insurmountable geographic barrier in prehistory, served as a frequently traveled route between continents.

mtdna-h1-h3-europe-frequency
a, b, c. Interpolated frequency surfaces of clade H and its main sub-clades (H1 and H3). Frequencies (%) are showed in a colour scale. See information about the populations used in Additional files 4 and 5. Map templates were taken from Natural Earth free map repository (http://www.naturalearthdata.com/)

I usually find mtDNA data, especially studies like this one based on modern populations, very difficult to interpret for anthropological purposes. It is well-known that there are important differences in the pattern of Y-DNA and mtDNA expansion and distribution.

A paragraph in this respect caught my attention:

The patterns of variation in the Y-chromosome between western and eastern Andalusians, based on 416 males, have also been investigated for a set of Y-Short Tandem Repeats (Y-STRs) and Y-SNPs [53, 54, 55], Calderón et al., unpublished data] in combination to mtDNA analyses ([18, 19] and present study). In general, for both uniparental makers, Andalusians exhibit a typical western European genetic background, with peak frequencies of mtDNA Hg H and Y-chromosome Hg R1b1b2-M269 (45% and 60%, respectively). Interestingly, our results have further revealed that the influence of African female input is far more significant when compared to male influence in contemporary Andalusians. The lack of correspondence between the maternal and paternal genetic profiles of human populations reflects intrinsic differences in migratory behavior related to sex-biased processes and admixture, as well as differences in male and female effective population sizes related to the variance in reproductive success affected, for example, by polygyny [56, 57].

I think that the greater reduction in patrilineal lineages compared to maternal lineages we usually see during and after prehistoric or historic migrations have more to do with the renown Uí Néill family case and with war-related casualties (since combatants were usually men) than with other more popular explanations, such as enslavement of women or polygyny.

The most successful paternal lines (anywhere in the world) were probably those who remained in power for a long time (be it a patriarchal society based on families, clans, or more complex organizational units), who were richer and thus more capable of having healthy offspring, who in turn were able to survive longer and have more children who inherited power, etc.

In case of recent migrations or population movements that disrupt the previously established organization, after a certain number of generations, successful patrilocal families (usually from incoming lineages) might slowly dominate over a whole region, with poorer families (usually of ‘indigenous’ lineages) suffering a greater – especially perinatal and child – mortality, without any obvious (pre)historic event associated to these gradual changes.

This gradual replacement of paternal lineages is compatible with the adoption of the native language by newcomers. If the number of migrants is greater that the native population, and especially if their technology is more advanced, then a more radical change including ethnolinguistic identification is more likely.

I don’t deny the (pre)historic existence of radical replacement of male populations with continuity of female lineages due to massacres of men, female slavery, or polygyny, but they are probably not the main explanation for most regional differences seen in paternal lineages, and should thus be used with caution.

Gradual replacement and founder effects are also the most logical explanation for why autochthonous continuity myths (that the modern regional prevalence of few successful lineages tended to create in the 2000s) haven’t been corroborated by ancient DNA; e.g. R1b-DF27 in Basques, N1c-M178 in Finnic populations, R1a-Z283 in Slavs, etc. There is nothing different in those areas from other recent founder effects and internal migratory flows seen everywhere in Europe in the past millennia.

Paper discovered via a link by Alberto Gonzalez on Facebook group Iberia ADN

Related:

mtDNA suggest original East Germanic population linked to Jutland Iron Age and Bell Beaker

antiquity_classical_Europe_przeworsk

Open Access article A mosaic genetic structure of the human population living in the South Baltic region during the Iron Age, by Stolarek et al., at Scientific Reports 8:2455 (2018).

About the site:

Kowalewko is a village in Wielkopolskie vojevodship, close to Poznan, in the middle reaches of the Samica Kierska river. Biritual Roman Age cemetery (site 12), dated from the mid-1st to the beginning of 3rd century AD, is located in the featureless arable fields at the South and West of the village

About the Wielbark culture:

Chronology spans almost all the Roman Iron Age, since ca. 20 AD to ca. 450 AD. The Wielbark culture is associated with the Goths and Gepids, who migrated from Scandinavia towards the Black Sea, and their successors, who, after several centuries, returned to the lands formerly occupied by their ancestors. Typical features of the culture include inhumation graves rich in goods of numerous ornaments frequently of noble metals, while no implements and weapons have been observed and iron objects very rarely. Less frequent cremations. Barrows recorded within cemeteries reflect emergence of elites. The Wielbark communities built stone constructions, including pebbled floors and circles. This culture is mainly known from cemeteries, as settlements, not fortified, are less recognized.

kowalewko
Location of Kowalewko and a scheme of the Kowalewko cemetery site 12, based on the Fig. 3 from the monograph by Tomasz Skorupka, Kowalewko 12. Biritual cemetery of a population of the Wielbark Culture (mid 1st to beginning of 3rd century AD), published in: Marek Chlodnicki [ed.], Archaeological rescue investigations along the gas transit pipeline, vol. II – Wielkopolska, part 3, Poznan 2001, generated using Corel Draw ver. 12.0, with the author permission. Sampled graves are marked with a red color. Europe and Poland maps were downloaded from Wikimedia Commons (https://commons.wikimedia.org), under the free licence, and modified with Corel Draw ver. 12.0.

Interesting excerpts with emphasis added (and some stylistic changes for abbreviations):

Analysis of genetic distances (see Fig. 2b) showed that both Jutland Iron Age (JIA) and Kowalewko (Kow-OVIA), are the closest to the Central Europe Metapopulation (CEM). However, it should be mentioned that many of the resulting genetic proximities did not reach statistical significance at the alpha level 0.05 (mainly due to the multiple comparisons), thus they should be interpreted with caution. Higher prevalence of the mtDNA haplogroup H in Kowalewko and Jutland Iron Age(its high level is also characteristic for the Bell Beaker Culture) than in the preceding Corded Ware Culture (CWC) and Unetic Culture (UC) supports the hypothesis assuming significant demographic changes in Central Europe after the LN/EBA period. This hypothesis is additionally strengthened by the results of AMOVA analysis indicating that there is some inconsistency between genetic distances and the chronology of the appearance of the studied populations in Central Europe, i.e., the older populations (BBC, CWC) contributed more to the genetic structure of CEM than the younger ones (UC).

Changes in the occurrence of mtDNA haplogroups U5a/U5b in Central Europe are also worth noting. At LN and EBA, the prevailing haplogroup was U5a for BBC/CWC/UC. Next, there was a dominance of U5b for the Kow-OVIA/JIA during IA and now U5a is again more popular (CEM). The first alteration in the U5a/U5b prevalence between the LN/EBA and the IA supports the hypothesis of demographic changes right after the LN, proposed by Brandt et al (2013). The second conversion indicated by our results suggests another crucial demographic event that should occur between the IA and present.

On the basis of the above observations, one may assume that in the IA, specific genetic substructures were formed in Central Europe. Because the demographic history of fossil populations often has a local character33,34, it is worth considering the range of the observed changes. These considerations should also take into account the hypothesis on the migrations that most likely occurred between the 3rd and 6th century AD. In this context, it seems necessary to compare Kow-OVIA and JIA with other populations from the IA, in particular those located east of Vistula, and with the populations that inhabited this region during the Middle Ages.

kowalewko-mtdna
PCA2 vs. PCA3 on the haplogroup frequencies of ‘European Population Transect’ populations

Finally, we found that the genetic structures of female and male subpopulations of Kow-OVIA were significantly different. This fact cannot be explicitly determined based on the results of individual analyses; however, it is quite evident if one considers the whole set of data presented here including the Fisher test on haplogroup frequencies. The analyses of both mtDNA haplogroups and genetic distances indicated that women from Kowalewko were related closer to the EN/MN populations, and the men were closer to the CWC and UC. This observation may explain why the genetic relationships of Kow-OVIA with other ancient European populations were more complex and more difficult to define as it was in the case of JIA. In analyzing Kow-OVIA, we observed multiple overlapping effects of two subpopulations with different genetic affinities. One would speculate that the genetic profile of Kow-OVIA-F resulted from exogamy that was described for the CWC population. This is, however, not the case. We found that the genetic differences between women and men were maintained for the entire observation period, i.e., for 200 years (approximately 8 generations). Such a composition of the genetic structure of Kow-OVIA could exist only if at least one subgroup (Kow-OVIA-F or -M) was periodically exchanged. It would further mean that Kowalewko played some specific roles in that region. According to the recent archaeological studies, the colonization pattern in IA Greater Poland could be linked with the existence of a centralized organization system32. Kowalewko could have been one of the important elements of this system. For example, it could have functioned as a garrison for the population closely associated with the JIA, such that warriors stayed in the garrison for only a few years and were then replaced by others. Other scenarios are also possible; however, verification of any hypothesis requires more detailed studies.

All in all, we know that Wielbark probably represented the initial migration period of East Germanic tribes, traditionally believed to be from Northern Scandinavia, into territory later inhabited by Slavic tribes (and potentially earlier by a Balto-Slavic community).

Other than that, the results show some potential for a stable genomic situation in the Germanic homeland in terms of mtDNA, common after the Bell Beaker expansion, which probably brought Pre-Germanic to Scandinavia.

Nevertheless, only a comprehensive study of all Germanic regions from that period (whole genomic and Y-DNA) might shed light onto the real origin of East Germanic peoples, and thus their contended dialectal position, since we already know that certain modern Slavic and Germanic populations cluster closely to some Bronze Age communities of the same region, so differences during the Iron Age may be already quite subtle.

In my humble opinion, too many hypotheses in the paper for few interesting data – as is more and more usual in genetic papers. I guess journals expect that to get more attention, although serious reviewers should actually encourage the opposite, and only informal blogs like this one should come up with far-fetched theories, instead of rebutting them…

Related:

Modern Hungarian mtDNA more similar to ancient Europeans than to Hungarian conquerors

middle-ages-europe

New preprint at BioRxiv, MITOMIX, an Algorithm to Reconstruct Population Admixture Histories Indicates Ancient European Ancestry of Modern Hungarians, by Maroti et al. (2018).

hungarian-shared-mtDNA
The estimated age distribution of the shared mt Hgs between Hungarians (Hun), the best hypothetical admix (mixFreq) and the populations contributing to this admix: Belgian/Dutch (BeN), Danish (Dan), Basque (Bsq), Croatian/Serbian (CrS), Baltic Late Bronze Age culture (BalBA), Bell Beaker culture (BellB), Slovakian (Slo). The numbers in parentheses indicate the contributions to the best hypothetical admix.

Abstract (emphasis mine)

By making use of the increasing number of available mitogenomes we propose a novel population genetic distance metric, named Shared Haplogroup Distance (SHD). Unlike FST, SHD is a true mathematical distance that complies with all metric axioms, which enables our new algorithm (MITOMIX) to detect population-level admixture based on SHD minimum optimization. In order to demonstrate the effectiveness of our methodology we analyzed the relation of 62 modern and 25 ancient Eurasian human populations, and compared our results with the most widely used FST calculation. We also sequenced and performed an in-depth analysis of 272 modern Hungarian mtDNA genomes to shed light on the genetic composition of modern Hungarians. MITOMIX analysis showed that in general admixture occurred between neighboring populations, but in some cases it also indicated admixture with migrating populations. SHD and MITOMIX analysis comply with known genetic data and shows that in case of closely related and/or admixing populations, SHD gives more realistic results and provides better resolution than FST. Our results suggest that the majority of modern Hungarian maternal lineages have Late Neolith/Bronze Age European origins (partially shared also with modern Danish, Belgian/Dutch and Basque populations), and a smaller fraction originates from surrounding (Serbian, Croatian, Slovakian, Romanian) populations. However only a minor genetic contribution (<3%) was identified from the IXth Hungarian Conquerors whom are deemed to have brought Hungarians to the Carpathian Basin. Our analysis shows that SHD and MITOMIX can augment previous methods by providing novel insights into past population processes.

hungarian-hierarchic-cluster
Unrooted hierarchic cluster of modern and archaic populations based on the SHD matrix.

It is interesting to keep receiving data as to how language does not correlate well with Genomics, whether admixture or haplogroups, even though it is already known to happen in regions such as Anatolia, the Baltic, South-Eastern or Northern Europe.

Thorough anthropological models of migration or cultural diffusion are necessary for a proper interpretation of genetic data. There is no shortcut to that.

hungarian-mtdna
Co-occurrence of Hungarian Bronze Age mt Hgs Distribution of mt Hgs found in Hungarian Bronze Age archaic samples in the analyzed populations. The fixation dates are based on Behar et al [6].

Images made available under a CC-BY-NC-ND 4.0 International license.
See also:

mtDNA haplogroup frequency analysis from Verteba Cave supports a strong cultural frontier between farmers and hunter-gatherers in the North Pontic steppe

eneolithic-forest-zone

New preprint paper at BioRxiv, led by a Japanese researcher, with analysis of mtDNA of Trypillians from Verteba Cave, Analysis of ancient human mitochondrial DNA from Verteba Cave, Ukraine: insights into the origins and expansions of the Late Neolithic-Chalcolithic Cututeni-Tripolye Culture, by Wakabayashi et al. (2017).

Abstract:

Background: The Eneolithic (~5,500 yrBP) site of Verteba Cave in Western Ukraine contains the largest collection of human skeletal remains associated with the archaeological Cucuteni-Tripolye Culture. Their subsistence economy is based largely on agro-pastoralism and had some of the largest and most dense settlement sites during the Middle Neolithic in all of Europe. To help understand the evolutionary history of the Tripolye people, we performed mtDNA analyses on ancient human remains excavated from several chambers within the cave.

Results: Burials at Verteba Cave are largely commingled and secondary in nature. A total of 68 individual bone specimens were analyzed. Most of these specimens were found in association with well-defined Tripolye artifacts. We determined 28 mtDNA D-Loop (368 bp) sequences and defined 8 sequence types, belonging to haplogroups H, HV, W, K, and T. These results do not suggest continuity with local pre-Eneolithic peoples, but rather complete population replacement. We constructed maximum parsimonious networks from the data and generated population genetic statistics. Nucleotide diversity (π) is low among all sequence types and our network analysis indicates highly similar mtDNA sequence types for samples in chamber G3. Using different sample sizes due to the uncertainly in number of individuals (11, 28, or 15), we found Tajima’s D statistic to vary. When all sequence types are included (11 or 28), we do not find a trend for demographic expansion (negative but not significantly different from zero); however, when only samples from Site 7 (peak occupation) are included, we find a significantly negative value, indicative of demographic expansion.

Conclusions: Our results suggest individuals buried at Verteba Cave had overall low mtDNA diversity, most likely due to increased conflict among sedentary farmers and nomadic pastoralists to the East and North. Early Farmers tend to show demographic expansion. We find different signatures of demographic expansion for the Tripolye people that may be caused by existing population structure or the spatiotemporal nature of ancient data. Regardless, peoples of the Tripolye Culture are more closely related to early European farmers and lack genetic continuity with Mesolithic hunter-gatherers or pre-Eneolithic groups in Ukraine.

Genetic finds keep supporting the long-lasting cultural and linguistic frontier that Anthony (2007) – among others – asserted existed in the North-West Pontic steppe in the Mesolithic and Neolithic, between western steppe cultures and farmers, while it disproves Kristiansen’s theories of Sredni Stog expansion in Kurgan waves with a mixture of GAC and Trypillia within the Corded Ware culture:

Previous ancient DNA studies showed that hunter-gatherers before 6,500 yrBP in Europe commonly had haplogroups U, U4, U5, and H, whereas hunter-gatherers after 6,500 yrBP in Europe had less frequency of haplogroup H than before. Haplogroups T and K appeared in hunter-gatherers only after 6,500 yrBP, indicating a degree of admixture in some places between farmers and hunter-gatherers. Farmers before and after 6,500 yrBP in Europe had haplogroups W, HV*, H, T, K, and these are also found in individuals buried at Verteba Cave. Therefore, our data point to a common ancestry with early European farmers. Our data also suggest population replacement. Mathieson et al. analyzed a number of Neolithic Ukrainian samples (petrous bone) from several sites in southern, northern, and western Ukraine, dating to ~8,500 – 6,000 yrBP, and found exclusively U (U4 and U5) mtDNA lineages. It should be noted that ‘Neolithic’ in this context does not mean the adoption of agriculture, but rather simply coinciding with a change in material culture. They also analyzed several Trypillian individuals from Verteba Cave (different samples from the those included in this study). Similar to our findings, they found a wider diversity of mtDNA lineages, including H, HV, and T2b. These data, combined with our results, appear to confirm almost complete population replacement by individuals associated with the Tripolye Culture during the Middle to Late Neolithic.

The findings also hint to potential contacts of Yamna with Usatovo as predicted by Anthony (2007), or alternatively (lacking precise dates) to contacts with Corded Ware migrants:

Trypillians were very much a distinct people who most likely displaced 1 local hunter-gatherers with little admixture. Haplogroup W was also observed in several specimens deriving from Site G3. Although we are unsure if all of these haplogroups come from a single or multiple individuals, this observation is interesting in that it is relatively rare and isolated among Neolithic samples. It has, however, been found in samples dating to the Bronze Age. In the study by Wilde et al. [35], they found haplogroup W present in two samples from the Early Bronze Age associated with the Yamnaya and Usatovo cultures. The Usatovo culture (~ 3500 – 2500 BC) was found in Romania, Moldova, and southern Ukraine. It was the conglomeration of Tripolye and North Pontic steppe cultures. Therefore, this individual could link the Trypillian peoples to the Usatovo peoples and perhaps to the greater Yamnaya steppe migrations during the Bronze Age that lead to the Corded Ware Culture.

On the other hand, an article written in terms of mtDNA haplogroup frequencies seems to offer too little proof of anything today. The lack of Y-DNA haplogroups and data on admixture makes their interpretations provisional, subject to change when these further data are published. Also, radiocarbon dating is only confident for individuals of one site (site 7), dated ca. 5,500 cal BP, while “other chambers in the cave are not as confidently dated”…

verteba-cave-mtDNA
“Based on the 8 sequence types of the mtDNA D-loop, a maximum parsimonious phylogenetic network was constructed. Circles represent the sequence types, and the size of the circle is proportional to the number of samples. Numbers on the branches between the circles are nucleotide position numbers (+16,000) of the human mitochondrial genome sequence (rCRS). Information about the location (chamber within the cave) where the specimen was excavated is also provided. Areas 2 and 17 are part of Site 7, and these are defined as a separate chamber, although they are located in close proximity within Site 7. The other chambers, Site 20, G2, and G3, are independent and separate locations within the cave. ‘Undefined’ chamber describes an unknown location within the cave. Specimens from each chamber showed deviation for the sequence type distribution observed in the sample set. For example, specimens excavated from Site 7 had five unique sequence types, (I, II, III, IV, and VIII), while specimens excavated from chamber G 21 had mainly one sequence type (V)”. Made available by the authors under a CC-BY-NC-ND 4.0 International license.

We had also seen signs of conflict between Trypillian and steppe cultures in a recent article, Violence at Verteba Cave, Ukraine: New Insights into the Late Neolithic Intergroup Conflict, by Madden et al. (2017):

Many researchers have pointed to the huge “megasites” and construction of fortifications as evidence of intergroup hostilities among the Late Neolithic Tripolye archaeological culture. However, to date, very few skeletal remains have been analyzed for the types of traumatic injury that serve as direct evidence for violent conflict. In this study, we examine trauma on human remains from the Tripolye site of Verteba Cave in western Ukraine. The remains of 36 individuals, including 25 crania, were buried in the gypsum cave as secondary interments. The frequency of cranial trauma is 30-44% among the 25 crania, six males, four females and one adult of indeterminate sex displayed cranial trauma. Of the 18 total fractures, 10 were significantly large and penetrating suggesting lethal force. Over half of the trauma is located on the posterior aspect of the crania, suggesting the victims were attacked from behind. Sixteen of the fractures observed were perimortem and two were antemortem. The distribution and characteristics of the fractures suggest that some of the Tripolye individuals buried at Verteba Cave were victims of a lethal surprise attack. Resources were limited due to population growth and migration, leading to conflict over resource access. It is hypothesized that during this time of change burial in this cave aided in development of identity and ownership of the local territory.

Related:

Correlation does not mean causation: the damage of the ‘Yamnaya ancestral component’, and the ‘Future American’ hypothesis

New Ukraine Eneolithic sample from late Sredni Stog, near homeland of the Corded Ware culture

The concept of “outlier” in studies of Human Ancestry, and the Corded Ware outlier from Esperstedt

Marija Gimbutas and the expansion of the “Kurgan people” based on tumulus-building cultures