The maternal genetic make-up of the Iberian Peninsula between the Neolithic and the Early Bronze Age

Genomic perspectives on human dispersals during the Holocene

Nearly 20 y ago, Jared Diamond and Peter Bellwood reviewed the evidence for the associated spread of farming and large language families by the demographic expansions of farmers. Since then, advances in obtaining and analyzing genomic data from modern and ancient populations have transformed our knowledge of human dispersals during the Holocene. Here, we provide an overview of Holocene dispersals in the light of genomic evidence and conclude that they have a complex history. Even when there is a demonstrated connection between a demographic expansion of people, the spread of agriculture, and the spread of a particular language family, the outcome in the results of contact between expanding and resident groups is highly variable. Further research is needed to identify the factors and social circumstances that have influenced this variation and complex history.

Kinship practices in the early state El Argar society from Bronze Age Iberia

The Early Bronze Age in Europe is characterized by social and genetic transformations, starting in the early 3rd millennium BCE. New settlement and funerary structures, artifacts and techniques indicate times of change with increasing economic asymmetries and political hierarchization. Technological advances in metallurgy also played an important role, facilitating trade and exchange networks, which became tangible in higher levels of mobility and connectedness. Archeogenetic studies have revealed a substantial transformation of the genetic ancestry around this time, ultimately linked to the expansion of steppe- and forest steppe pastoralists from Eastern Europe. Evidence for emerging infectious diseases such as Yersinia pestis adds further complexity to these tumultuous and transformative times. The El Argar complex in southern Iberia marks the genetic turnover in southwestern Europe ~ 2200 BCE that accompanies profound changes in the socio-economic structure of the region. To answer the question of who was buried in the emblematic double burials of the El Argar site La Almoloya, we integrated results from biological relatedness analyses and archaeological funerary contexts and refined radiocarbon-based chronologies from 68 individuals. We find that the El Argar society was virilocally and patrilineally organized and practiced reciprocal female exogamy, supported by pedigrees that extend up to five generations along the paternal line. Synchronously dated adult males and females from double tombs were found to be unrelated mating partners, whereby the incoming females reflect socio-political alliances among El Argar groups. In three cases these unions had common offspring, while paternal half-siblings also indicate serial monogamy or polygyny.

Neolithic genomic data from southern France showcase intensified interactions with hunter-gatherer communities

Archaeological research shows that the dispersal of the Neolithic took a more complex turn when reaching western Europe, painting a contrasted picture of interactions between autochthonous hunter-gatherers (HGs) and incoming farmers. In order to clarify the mode, the intensity, and the regional variability of biological exchanges implied in these processes, we report new palaeogenomic data from Occitanie, a key region in Southern France. Genomic data from 28 individuals originating from six sites spanning from c. 5,500 to c. 2,500 BCE allow us to characterize regional patterns of ancestries throughout the Neolithic period. Results highlight major differences between the Mediterranean and Continental Neolithic expansion routes regarding both migration and interaction processes. High proportions of HG ancestry in both Early and Late Neolithic groups in Southern France support multiple pulses of inter-group gene flow throughout time and space and confirm the need for regional studies to address the complexity of the processes involved.

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Genome-wide data from 28 individuals from Southern France (∼5,500–∼2,500 BCE)

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Small groups associated with the Neolithic expansion along the Mediterranean

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Early admixture between hunter-gatherers and Neolithic farmers in Southern France

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Multiple pulses of HG legacy introgression in Western Europe throughout Neolithic

Nutrition and Health in Human Evolution–Past to Present

Anyone who wants to understand the biological nature of humans and their special characteristics must look far back into evolutionary history. Today’s way of life is drastically different from that of our ancestors. For almost 99% of human history, gathering and hunting have been the basis of nutrition. It was not until about 12,000 years ago that humans began domesticating plants and animals. Bioarchaeologically and biochemically, this can be traced back to our earliest roots. Modern living conditions and the quality of human life are better today than ever before. However, neither physically nor psychosocially have we made this adjustment and we are paying a high health price for it. The studies presented allow us to reconstruct food supply, lifestyles, and dietary habits: from the earliest primates, through hunter-gatherers of the Paleolithic, farming communities since the beginning of the Anthropocene, to the Industrial Age and the present. The comprehensive data pool allows extraction of all findings of medical relevance. Our recent lifestyle and diet are essentially determined by our culture rather than by our millions of years of ancestry. Culture is permanently in a dominant position compared to natural evolution. Thereby culture does not form a contrast to nature but represents its result. There is no doubt that we are biologically adapted to culture, but it is questionable how much culture humans can cope with.

Prider: multiplexed primer design using linearly scaling approximation of set coverage

Background

Designing oligonucleotide primers and probes is one of the key steps of various laboratory experiments such as multiplexed PCR or digital multiplexed ligation assays. When designing multiplexed primers and probes to complex, heterogeneous DNA data sets, an optimization problem can arise where the smallest number of oligonucleotides covering the largest diversity of the input dataset needs to be identified. Tools that provide this optimization in an efficient manner for large input data are currently lacking.

Results

Here we present Prider, an R package for designing primers and probes with a nearly optimal coverage for complex and large sequence sets. Prider initially prepares a full primer coverage of the input sequences, the complexity of which is subsequently reduced by removing components of high redundancy or narrow coverage. The primers from the resulting near-optimal coverage are easily accessible as data frames and their coverage across the input sequences can be visualised as heatmaps using Prider’s plotting function. Prider permits efficient design of primers to large DNA datasets by scaling linearly to increasing sequence data, regardless of the diversity of the dataset.

Conclusions

Prider solves a recalcitrant problem in molecular diagnostics: how to cover a maximal sequence diversity with a minimal number of oligonucleotide primers or probes. The combination of Prider with highly scalable molecular quantification techniques will permit an unprecedented molecular screening capability with immediate applicability in fields such as clinical microbiology, epidemic virus surveillance or antimicrobial resistance surveillance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12859-022-04710-1.

Ancient DNA gives new insights into a Norman Neolithic monumental cemetery dedicated to male elites

By integrating genomic and archaeological data, we provide new insights into the Neolithic French monumental site of Fleury-sur-Orne in Normandy, where a group of selected individuals was buried in impressively long monuments. The earliest individuals buried at Fleury-sur-Orne match the expected western European Neolithic genetic diversity, while three individuals, designated as genetic outliers, were buried after 4,000 calibrated BCE. We hypothesize that different, unrelated families or clans used the site over several centuries. Thirteen of 14 of the analyzed individuals were male, indicating an overarching patrilineal system. However, one exception, a female buried with a symbolically male artifact, suggests that the embodiment of the male gender in death was required to access burial at the monumental structures.

The Middle Neolithic in western Europe is characterized by monumental funerary structures, known as megaliths, along the Atlantic façade. The first manifestations of this phenomenon occurred in modern-day France with the long mounds of the Cerny culture. Here, we present genome-wide data from the fifth-millennium BCE site of Fleury-sur-Orne in Normandy (France), famous for its impressively long monuments built for selected individuals. The site encompasses 32 monuments of variable sizes, containing the burials of 19 individuals from the Neolithic period. To address who was buried at the site, we generated genome-wide data for 14 individuals, of whom 13 are males, completing previously published data [M. Rivollat et al., Sci. Adv. 6, eaaz5344 (2020)]. Population genetic and Y chromosome analyses show that the Fleury-sur-Orne group fits within western European Neolithic genetic diversity and that the arrival of a new group is detected after 4,000 calibrated BCE. The results of analyzing uniparentally inherited markers and an overall low number of long runs of homozygosity suggest a patrilineal group practicing female exogamy. We find two pairs of individuals to be father and son, buried together in the same monument/grave. No other biological relationship can link monuments together, suggesting that each monument was dedicated to a genetically independent lineage. The combined data and documented father–son line of descent suggest a male-mediated transmission of sociopolitical authority. However, a single female buried with an arrowhead, otherwise considered a symbol of power of the male elite of the Cerny culture, questions a strictly biological sex bias in the burial rites of this otherwise “masculine” monumental cemetery.

Genomic and dietary discontinuities during the Mesolithic and Neolithic in Sicily

Sicily is a key region for understanding the agricultural transition in the Mediterranean because of its central position. Here, we present genomic and stable isotopic data for 19 prehistoric Sicilians covering the Mesolithic to Bronze Age periods (10,700–4,100 yBP). We find that Early Mesolithic hunter-gatherers (HGs) from Sicily are a highly drifted lineage of the Early Holocene western European HGs, whereas Late Mesolithic HGs carry ∼20% ancestry related to northern and (south) eastern European HGs, indicating substantial gene flow. Early Neolithic farmers are genetically most similar to farmers from the Balkans and Greece, with only ∼7% of ancestry from local Mesolithic HGs. The genetic discontinuities during the Mesolithic and Early Neolithic match the changes in material culture and diet. Three outlying individuals dated to ∼8,000 yBP; however, suggest that hunter-gatherers interacted with incoming farmers at Grotta dell’Uzzo, resulting in a mixed economy and diet for a brief interlude at the Mesolithic-Neolithic transition.

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Genetic transition between Early Mesolithic and Late Mesolithic hunter-gatherers

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A near-complete genetic turnover during the Mesolithic-Neolithic transition

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Exchange of subsistence practices between hunter-gatherers and early farmers

Genomic transformation and social organization during the Copper Age-Bronze Age transition in southern Iberia

The emerging Bronze Age (BA) of southeastern Iberia saw marked social changes. Late Copper Age (CA) settlements were abandoned in favor of hilltop sites, and collective graves were largely replaced by single or double burials with often distinctive grave goods indirectly reflecting a hierarchical social organization, as exemplified by the BA El Argar group. We explored this transition from a genomic viewpoint by tripling the amount of data available for this period. Concomitant with the rise of El Argar starting ~2200 cal BCE, we observe a complete turnover of Y-chromosome lineages along with the arrival of steppe-related ancestry. This pattern is consistent with a founder effect in male lineages, supported by our finding that males shared more relatives at sites than females. However, simple two-source models do not find support in some El Argar groups, suggesting additional genetic contributions from the Mediterranean that could predate the BA.

Ten millennia of hepatitis B virus evolution

[Figure: see text].

Biomolecular insights into North African-related ancestry, mobility and diet in eleventh-century Al-Andalus

Historical records document medieval immigration from North Africa to Iberia to create Islamic al-Andalus. Here, we present a low-coverage genome of an eleventh century CE man buried in an Islamic necropolis in Segorbe, near Valencia, Spain. Uniparental lineages indicate North African ancestry, but at the autosomal level he displays a mosaic of North African and European-like ancestries, distinct from any present-day population. Altogether, the genome-wide evidence, stable isotope results and the age of the burial indicate that his ancestry was ultimately a result of admixture between recently arrived Amazigh people (Berbers) and the population inhabiting the Peninsula prior to the Islamic conquest. We detect differences between our sample and a previously published group of contemporary individuals from Valencia, exemplifying how detailed, small-scale aDNA studies can illuminate fine-grained regional and temporal differences. His genome demonstrates how ancient DNA studies can capture portraits of past genetic variation that have been erased by later demographic shifts-in this case, most likely the seventeenth century CE expulsion of formerly Islamic communities as tolerance dissipated following the Reconquista by the Catholic kingdoms of the north.

Human Genomic Diversity Where the Mediterranean Joins the Atlantic

Throughout the past few years, a lively debate emerged about the timing and magnitude of the human migrations between the Iberian Peninsula and the Maghreb. Several pieces of evidence, including archaeological, anthropological, historical, and genetic data, have pointed to a complex and intermingled evolutionary history in the western Mediterranean area. To study to what extent connections across the Strait of Gibraltar and surrounding areas have shaped the present-day genomic diversity of its populations, we have performed a screening of 2.5 million single-nucleotide polymorphisms in 142 samples from southern Spain, southern Portugal, and Morocco. We built comprehensive data sets of the studied area and we implemented multistep bioinformatic approaches to assess population structure, demographic histories, and admixture dynamics. Both local and global ancestry inference showed an internal substructure in the Iberian Peninsula, mainly linked to a differential African ancestry. Western Iberia, from southern Portugal to Galicia, constituted an independent cluster within Iberia characterized by an enriched African genomic input. Migration time modeling showed recent historic dates for the admixture events occurring both in Iberia and in the North of Africa. However, an integrative vision of both paleogenomic and modern DNA data allowed us to detect chronological transitions and population turnovers that could be the result of transcontinental migrations dating back from Neolithic times. The present contribution aimed to fill the gaps in the modern human genomic record of a key geographic area, where the Mediterranean and the Atlantic come together.

Cost-effective straightforward method for captured whole mitogenome sequencing of ancient DNA

Working with mitochondrial DNA from highly degraded samples is challenging. We present a whole mitogenome Illumina-based sequencing method suitable for highly degraded samples. The method makes use of double-stranded library preparation with hybridization-based target enrichment. The aim of the study was to implement a new user-friendly method for analysing many ancient DNA samples at low cost. The method combines the Swift 2S™ Turbo library preparation kit and xGen® panel for mitogenome enrichment. Swift allows to use low input of aDNA and own adapters and primers, handles inhibitors well, and has only two purification steps. xGen is straightforward to use and is able to leverage already pooled libraries. Given the ancient DNA is more challenging to work with, the protocol was developed with several improvements, especially multiplying DNA input in case of low concentration DNA extractions followed by AMPure® beads size selection and real-time pre-capture PCR monitoring in order to avoid cycle-optimization step. Nine out of eleven analysed samples successfully retrieved mitogenomes. Hence, our method provides an effective analysis of whole mtDNA, and has proven to be fast, cost-effective, straightforward, with utilisation in population-wide research of burial sites.

Ancient Rome: A genetic crossroads of Europe and the Mediterranean

Ancient Rome was the capital of an empire of ~70 million inhabitants, but little is known about the genetics of ancient Romans. Here we present 127 genomes from 29 archaeological sites in and around Rome, spanning the past 12,000 years. We observe two major prehistoric ancestry transitions: one with the introduction of farming and another prior to the Iron Age. By the founding of Rome, the genetic composition of the region approximated that of modern Mediterranean populations. During the Imperial period, Rome's population received net immigration from the Near East, followed by an increase in genetic contributions from Europe. These ancestry shifts mirrored the geopolitical affiliations of Rome and were accompanied by marked interindividual diversity, reflecting gene flow from across the Mediterranean, Europe, and North Africa.

A massacre of early Neolithic farmers in the high Pyrenees at Els Trocs, Spain

Violence seems deeply rooted in human nature and an endemic potential for such is today frequently associated with differing ethnic, religious or socio-economic backgrounds. Ethnic nepotism is believed to be one of the main causes of inter-group violence in multi-ethnic societies. At the site of Els Trocs in the Spanish Pyrenees, rivalling groups of either migrating early farmers or farmers and indigenous hunter-gatherers collided violently around 5300 BCE. This clash apparently resulted in a massacre of the Els Trocs farmers. The overkill reaction was possibly triggered by xenophobia or massive disputes over resources or privileges. In the present, violence and xenophobia are controlled and sanctioned through social codes of conduct and institutions. So that, rather than representing an insurmountable evolutionary inheritance, violence and ethnic nepotism can be overcome and a sustainable future achieved through mutual respect, tolerance and openness to multi-ethnic societies.

The genomic history of the Iberian Peninsula over the past 8000 years

We assembled genome-wide data from 271 ancient Iberians, of whom 176 are from the largely unsampled period after 2000 BCE, thereby providing a high-resolution time transect of the Iberian Peninsula. We document high genetic substructure between northwestern and southeastern hunter-gatherers before the spread of farming. We reveal sporadic contacts between Iberia and North Africa by ~2500 BCE and, by ~2000 BCE, the replacement of 40% of Iberia's ancestry and nearly 100% of its Y-chromosomes by people with Steppe ancestry. We show that, in the Iron Age, Steppe ancestry had spread not only into Indo-European-speaking regions but also into non-Indo-European-speaking ones, and we reveal that present-day Basques are best described as a typical Iron Age population without the admixture events that later affected the rest of Iberia. Additionally, we document how, beginning at least in the Roman period, the ancestry of the peninsula was transformed by gene flow from North Africa and the eastern Mediterranean.

Spatially explicit analysis reveals complex human genetic gradients in the Iberian Peninsula

The Iberian Peninsula is a well-delimited geographic region with a rich and complex human history. However, the causes of its genetic structure and past migratory dynamics are not yet fully understood. In order to shed light on them, here we evaluated the gene flow and genetic structure throughout the Iberian Peninsula with spatially explicit modelling applied to a georeferenced genetic dataset composed of genome-wide SNPs from 746 individuals belonging to 17 different regions of the Peninsula. We found contrasting patterns of genetic structure throughout Iberia. In particular, we identified strong patterns of genetic differentiation caused by relevant barriers to gene flow in northern regions and, on the other hand, a large genetic similarity in central and southern regions. In addition, our results showed a preferential north to south migratory dynamics and suggest a sex-biased dispersal in Mediterranean and southern regions. The estimated genetic patterns did not fit with the geographical relief of the Iberian landscape and they rather seem to follow political and linguistic territorial boundaries.

Mitochondrial ancestry of medieval individuals carelessly interred in a multiple burial from southeastern Romania

The historical province of Dobruja, located in southeastern Romania, has experienced intense human population movement, invasions, and conflictual episodes during the Middle Ages, being an important intersection point between Asia and Europe. The most informative source of maternal population histories is the complete mitochondrial genome of archaeological specimens, but currently, there is insufficient ancient DNA data available for the medieval period in this geographical region to complement the archaeological findings. In this study, we reconstructed, by using Next Generation Sequencing, the entire mitochondrial genomes (mitogenomes) of six medieval individuals neglectfully buried in a multiple burial from Capidava necropolis (Dobruja), some presenting signs of a violent death. Six distinct maternal lineages (H11a1, U4d2, J1c15, U6a1a1, T2b, and N1a3a) with different phylogenetic background were identified, pointing out the heterogeneous genetic aspect of the analyzed medieval group. Using population genetic analysis based on high-resolution mitochondrial data, we inferred the genetic affinities of the available medieval dataset from Capidava to other ancient Eurasian populations. The genetic data were integrated with the archaeological and anthropological information in order to sketch a small, local piece of the mosaic that is the image of medieval European population history.

The multiple maternal legacy of the Late Iron Age group of Urville-Nacqueville (France, Normandy) documents a long-standing genetic contact zone in northwestern France

The compilation of archaeological and genetic data for ancient European human groups has provided persuasive evidence for a complex series of migrations, population replacements and admixture until the Bronze Age. If the Bronze-to-Iron Age transition has been well documented archaeologically, ancient DNA (aDNA) remains rare for the latter period and does not precisely reflect the genetic diversity of European Celtic groups. In order to document the evolution of European communities, we analysed 45 individuals from the Late Iron Age (La Tène) Urville-Nacqueville necropolis in northwestern France, a region recognized as a major cultural contact zone between groups from both sides of the Channel. The characterization of 37 HVS-I mitochondrial sequences and 40 haplogroups provided the largest maternal gene pool yet recovered for the European Iron Age. First, descriptive analyses allowed us to demonstrate the presence of substantial amounts of steppe-related mitochondrial ancestry in the community, which is consistent with the expansion of Bell Beaker groups bearing an important steppe legacy in northwestern Europe at approximately 2500 BC. Second, maternal genetic affinities highlighted with Bronze Age groups from Great Britain and the Iberian Peninsula regions tends to support the idea that the continuous cultural exchanges documented archaeologically across the Channel and along the Atlantic coast (during and after the Bronze Age period) were accompanied by significant gene flow. Lastly, our results suggest a maternal genetic continuity between Bronze Age and Iron Age groups that would argue in favour of a cultural transition linked to progressive local economic changes rather than to a massive influx of allochthone groups. The palaeogenetic data gathered for the Urville-Nacqueville group constitute an important step in the biological characterization of European Iron age groups. Clearly, more numerous and diachronic aDNA data are needed to fully understand the complex relationship between the cultural and biological evolution of groups from the period.

Ancient DNA of Phoenician remains indicates discontinuity in the settlement history of Ibiza

Ibiza was permanently settled around the 7th century BCE by founders arriving from west Phoenicia. The founding population grew significantly and reached its height during the 4th century BCE. We obtained nine complete mitochondrial genomes from skeletal remains from two Punic necropoli in Ibiza and a Bronze Age site from Formentara. We also obtained low coverage (0.47X average depth) of the genome of one individual, directly dated to 361-178 cal BCE, from the Cas Molí site on Ibiza. We analysed and compared ancient DNA results with 18 new mitochondrial genomes from modern Ibizans to determine the ancestry of the founders of Ibiza. The mitochondrial results indicate a predominantly recent European maternal ancestry for the current Ibizan population while the whole genome data suggest a significant Eastern Mediterranean component. Our mitochondrial results suggest a genetic discontinuity between the early Phoenician settlers and the island's modern inhabitants. Our data, while limited, suggest that the Eastern or North African influence in the Punic population of Ibiza was primarily male dominated.