Post by Admin on Oct 23, 2018 18:15:06 GMT
Dynamics of Female Mobility.
The most striking result of this study is the genetic difference between Early Medieval individuals buried in Bavaria with and without ACD. While both males and females with normal skulls were found to be a largely homogenous set of individuals with a common northern/central European ancestry (with two exceptions STR_300 and STR_502), females with deformed skulls sampled from the same cemeteries were very genetically diverse, demonstrating a wide range of both modern northern/central and southern/southeastern European ancestry, and even some samples with East Asian ancestry.
If the structure of modern genetic variation can be considered a suitable proxy for how genetic variation was approximately structured in Europe and the rest of Eurasia 1,500 y ago, then local Medieval Bavarian individuals were probably not practicing ACD with their own children. Instead, consistent with the suggestion of Hakenbeck (6), adult females with deformed skulls found in Medieval Bavaria likely migrated from southeastern Europe, a region that not only contains the earliest known European burials of males and females with ACD but also the largest accumulation (SI Appendix, Figs. S51 and S52). It also seems unlikely that mass migration of people from the southeast were involved, as there appears to be no major impact on the local Bavarian gene pool (ACD samples make up only a very small percentage of the local burials). Instead, given that ACD was a particularly involved and labor-intensive procedure that may indicate a certain role or status in Medieval society, these females may have moved as part of a system in which local Bavarian communities practiced exogamy to form strategic alliances with entities to the east.
The diversity of the genomic profile of the immigrant females with ACD suggest two primary models with regard to how, who, and to what extent these central European peoples interacted with people from the east. In the first, local populations in Early Medieval Bavaria may have had direct contacts with an extremely diverse set of people practicing ACD, ranging from southeastern European tribes such as the Gepids to those with probably even more Asian origins that moved into Europe such as Huns, which would explain the presence of East Asian ancestry in AED_1108 and possibly STR_328 and ALH_3. Alternatively, this pool of women may have origins exclusively in southeast Europe and more precisely the middle or lower Danube Basin area, which itself contained a long-standing mixture of people and where the custom of creating elongated skulls arose both locally and from interactions with groups from the east (not only Huns, but also predating Sarmatians and Alans), similar to the model proposed by Molnár et al. (24). The similar Central Asian genomic profiles of AED_1108 from Bavaria and VIM_2 from 6th century Serbia support this second scenario.
While the immigrant females would have been clearly distinguishable physically among the local population based on the combination of their enlarged crania as well as their different eye, hair, and perhaps even skin pigmentation patterns, it is noteworthy that their assemblies of grave goods appear to reflect both local customs and more distant material cultures (10). This not only indicates a potentially significant level of integration of these women into local life, but also cautions against inferring migration from material culture alone.
A Hunnic Spread for Skull Deformation in Europe?
The question arises of whether the observed East Asian ancestry in both our late 5th/early 6th century Bavarian and Serbian samples is consistent with an assumed ultimate Hunnic origin of skull deformation in both eastern and western Europe. Generally, it is assumed that the Huns were a diverse mixture of east European and Central Asian people, and that they integrated men and women from the local populations during their westward expansion (25).
Located ∼1,600 km away from VIM_2 and predating both this sample and AED_1108 by at least a century, our most easterly sampled deformed skull is KER_1 from the Crimea. The age of the sample and its archaeological context associate the skull with the Ostrogoth people but also with the ancient Greek city of Pantikapaion, which it is said was destroyed by the Huns in 370 AD (SI Appendix, section 1). Thus, we might hypothesize an exclusive “Hunnic” origin of skull deformation spreading from the Steppe and into Europe would be reflected in Central/East Asian ancestry in KER_1 similar to AED_1108 and VIM_2. However, KER_1 provided no evidence of such ancestry. Instead, it displays similarities to today’s Mediterranean populations, consistent with this being a Greek trading colony founded in the 6th century BCE. While clearly more samples are needed to support this assessment, the absence of any Central/East Asian ancestry in KER_1 but a significant proportion observed in AED_1108 and VIM_2 is nevertheless surprising and not in line with an exclusive Central/East Asian origin of ACD.
As a further “proxy” for a potential eastern origin of the individuals with ACD, we analyzed Sarmatian-associated genomes from southern Russia (400 BC). While there is some genetic evidence of an East Asian ancestry in these samples, it is limited and much less than that estimated in both AED_1108 and VIM_2. Their largest additional ancestry component is represented by modern Finnish individuals (much of which likely reflects their previously observed Yamnaya-like ancestry) (26), which is very low in all our other ancient samples (normal and deformed skulls). Overall we found no evidence for a higher amount of East Asian-related ancestry in the 10 deformed skull individuals relative to 29 individuals without deformed skulls (Wilcoxon rank-sum test two-sided P value = 0.84). When coupled with archaeological evidence of skull deformation in Romania as early as the 2nd century, it perhaps suggests any Hunnic or earlier Sarmatian-like influence in spreading the tradition of ACD from the Steppe may have been low, and their genetic impact even lower.
Lack of Mediterranean and Gallo-Roman Influence on Medieval Bavarian Genetic Structure.
Excluding individuals with ACD and two women with Greek/Anatolian ancestry, our samples from Early Medieval Bavaria can be genetically characterized as typically northern/central European. It is perhaps surprising that no local individual was found to share recent common genetic ancestry with a Roman soldier living in the same area ∼200 y earlier. The analysis of his genome identifies him to be of southwest European origin. Thus, our results, though only based on one sample, argue against significant admixture between any Roman populations from more southern parts of the former Roman Empire and our individuals buried in Bavaria around 500 AD.
PNAS March 12, 2018. 201719880; published ahead of print March 12, 2018.
The most striking result of this study is the genetic difference between Early Medieval individuals buried in Bavaria with and without ACD. While both males and females with normal skulls were found to be a largely homogenous set of individuals with a common northern/central European ancestry (with two exceptions STR_300 and STR_502), females with deformed skulls sampled from the same cemeteries were very genetically diverse, demonstrating a wide range of both modern northern/central and southern/southeastern European ancestry, and even some samples with East Asian ancestry.
If the structure of modern genetic variation can be considered a suitable proxy for how genetic variation was approximately structured in Europe and the rest of Eurasia 1,500 y ago, then local Medieval Bavarian individuals were probably not practicing ACD with their own children. Instead, consistent with the suggestion of Hakenbeck (6), adult females with deformed skulls found in Medieval Bavaria likely migrated from southeastern Europe, a region that not only contains the earliest known European burials of males and females with ACD but also the largest accumulation (SI Appendix, Figs. S51 and S52). It also seems unlikely that mass migration of people from the southeast were involved, as there appears to be no major impact on the local Bavarian gene pool (ACD samples make up only a very small percentage of the local burials). Instead, given that ACD was a particularly involved and labor-intensive procedure that may indicate a certain role or status in Medieval society, these females may have moved as part of a system in which local Bavarian communities practiced exogamy to form strategic alliances with entities to the east.
The diversity of the genomic profile of the immigrant females with ACD suggest two primary models with regard to how, who, and to what extent these central European peoples interacted with people from the east. In the first, local populations in Early Medieval Bavaria may have had direct contacts with an extremely diverse set of people practicing ACD, ranging from southeastern European tribes such as the Gepids to those with probably even more Asian origins that moved into Europe such as Huns, which would explain the presence of East Asian ancestry in AED_1108 and possibly STR_328 and ALH_3. Alternatively, this pool of women may have origins exclusively in southeast Europe and more precisely the middle or lower Danube Basin area, which itself contained a long-standing mixture of people and where the custom of creating elongated skulls arose both locally and from interactions with groups from the east (not only Huns, but also predating Sarmatians and Alans), similar to the model proposed by Molnár et al. (24). The similar Central Asian genomic profiles of AED_1108 from Bavaria and VIM_2 from 6th century Serbia support this second scenario.
While the immigrant females would have been clearly distinguishable physically among the local population based on the combination of their enlarged crania as well as their different eye, hair, and perhaps even skin pigmentation patterns, it is noteworthy that their assemblies of grave goods appear to reflect both local customs and more distant material cultures (10). This not only indicates a potentially significant level of integration of these women into local life, but also cautions against inferring migration from material culture alone.
A Hunnic Spread for Skull Deformation in Europe?
The question arises of whether the observed East Asian ancestry in both our late 5th/early 6th century Bavarian and Serbian samples is consistent with an assumed ultimate Hunnic origin of skull deformation in both eastern and western Europe. Generally, it is assumed that the Huns were a diverse mixture of east European and Central Asian people, and that they integrated men and women from the local populations during their westward expansion (25).
Located ∼1,600 km away from VIM_2 and predating both this sample and AED_1108 by at least a century, our most easterly sampled deformed skull is KER_1 from the Crimea. The age of the sample and its archaeological context associate the skull with the Ostrogoth people but also with the ancient Greek city of Pantikapaion, which it is said was destroyed by the Huns in 370 AD (SI Appendix, section 1). Thus, we might hypothesize an exclusive “Hunnic” origin of skull deformation spreading from the Steppe and into Europe would be reflected in Central/East Asian ancestry in KER_1 similar to AED_1108 and VIM_2. However, KER_1 provided no evidence of such ancestry. Instead, it displays similarities to today’s Mediterranean populations, consistent with this being a Greek trading colony founded in the 6th century BCE. While clearly more samples are needed to support this assessment, the absence of any Central/East Asian ancestry in KER_1 but a significant proportion observed in AED_1108 and VIM_2 is nevertheless surprising and not in line with an exclusive Central/East Asian origin of ACD.
As a further “proxy” for a potential eastern origin of the individuals with ACD, we analyzed Sarmatian-associated genomes from southern Russia (400 BC). While there is some genetic evidence of an East Asian ancestry in these samples, it is limited and much less than that estimated in both AED_1108 and VIM_2. Their largest additional ancestry component is represented by modern Finnish individuals (much of which likely reflects their previously observed Yamnaya-like ancestry) (26), which is very low in all our other ancient samples (normal and deformed skulls). Overall we found no evidence for a higher amount of East Asian-related ancestry in the 10 deformed skull individuals relative to 29 individuals without deformed skulls (Wilcoxon rank-sum test two-sided P value = 0.84). When coupled with archaeological evidence of skull deformation in Romania as early as the 2nd century, it perhaps suggests any Hunnic or earlier Sarmatian-like influence in spreading the tradition of ACD from the Steppe may have been low, and their genetic impact even lower.
Lack of Mediterranean and Gallo-Roman Influence on Medieval Bavarian Genetic Structure.
Excluding individuals with ACD and two women with Greek/Anatolian ancestry, our samples from Early Medieval Bavaria can be genetically characterized as typically northern/central European. It is perhaps surprising that no local individual was found to share recent common genetic ancestry with a Roman soldier living in the same area ∼200 y earlier. The analysis of his genome identifies him to be of southwest European origin. Thus, our results, though only based on one sample, argue against significant admixture between any Roman populations from more southern parts of the former Roman Empire and our individuals buried in Bavaria around 500 AD.
PNAS March 12, 2018. 201719880; published ahead of print March 12, 2018.