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Lazaridis, I.

Publications and source records attributed to Lazaridis, I..

At least 19 recordsLinked to original sources

The Pan-European Impact of the Balkan Hunter-Gatherers

During the Last Glacial Maximum (LGM) 26-19 thousand years ago (kya), Europe had three principal refugia not covered by ice: the Iberian, Italian, and Balkan peninsulas1,2. While the Iberian and Italian refugia have been studied with ancient DNA3-7, the legacy of the Balkan refugium has remained a mystery due to a lack of genetic data 30-12 kya. We present genome-wide data from nine newly reported individuals: three Epipaleolithic from Romania, one Epipaleolithic from Bosnia and Herzegovina, three Mesolithic from Greece, one Epipaleolithic from Southern Italy, and one Mesolithic from Sardinia. We find that the Epipaleolithic individuals from Romania and the Mesolithic individual from mainland Greece were from a previously unsampled population that was the primary source for later European hunter-gatherers. Westward expansion of Balkan Epipaleolithic people into the Italian Peninsula and mixture with a minority contribution from pre-LGM Italians, produced a population that then spread further west to become the primary ancestry of west-ern European Mesolithic people. Northeastward expansion, bypassing Italy, contributed the European ancestry source of Scandinavian and Eastern European hunter-gatherers. Southeastward expansion to the Aegean led to Anatolian-European mixtures before the spread of farming.

genetics↗

Buried in two places: Lineages from elite Maya tombs also found in distant caves

Classic Maya societies (250-900 CE) carved out urban centers in the rainforest reaching population heights and political complexity previously unknown in the Mesoamerican tropics. Kinship was a central feature of the social fabric, and rulership was legitimized through claims of direct descent from mythical ancestors. Mortuary practices kept the dead close to the living, and ancestor veneration sometimes produced complex deposits of disarticulated remains that are difficult to identify and whose biological relationships to one another cannot be understood without genetic data. We screened 487 human tooth and bone samples and successfully generated genome-wide data for 430 of them. Of these, 341 samples representing 107 distinct individuals were recovered from both elite and non-elite tombs in a Classic period kingdom (250-900) CE in the rugged Maya Mountains of Belize. Remarkably, 24 of these individuals have skeletal elements in both an elite tomb and in a ritual tooth cache in a distant cave located 26.5km away on the other side of the Maya Mountains. These results indicate that elite lineages created ancestors from their deceased relatives in geographically expansive ways and highlights the importance of caves in the belief system of Classic Maya elites.

genetics↗

Gothic Identity as Cultural Practice: Paleogenomic Evidence for Multi - Ethnic Assemblages Under Gothic Material Culture in Late Antique Bulgaria (4th - 6th centuries CE)

We report genome-wide ancient DNA from 38 individuals associated with Gothic-period mortuary contexts at two Bulgarian sites: the Aquae Calidae necropolis ([~]320 - 375 CE; n=23) and the Aul of Khan Omurtag (AKO; [~]350 - 489 CE; n=15). Although linked by closely similar Gothic-associated material culture and east - west Arian burial practices, the two assemblages are genetically distinct. Aquae Calidae individuals are modeled with predominantly Anatolian-related ancestry (50 - 85% in qpAdm), whereas AKO individuals are modeled with predominantly Wielbark/Chernyakhov-related northern ancestry (60 - 78%). Across the full assemblage, no single ancestry model fits all individuals, whose profiles range from nearly unadmixed Chernyakhov-like to predominantly Anatolian-related. DATES analysis places admixture between northern European and southern Balkan/Anatolian-related ancestry components approximately 11 - 13 generations before burial (point estimate [~]50 CE; 95% CI, 85 BCE - 183 CE; Z=5.26), raising the possibility that this mixture predated the earliest documented Gothic - Roman contacts ([~]170 CE). The convergence of dates across alternative southern proxies, together with reduced fit when Balkan and Anatolian sources are pooled into a single southern reference, favors admixture involving a pre-blended Balkan - Anatolian substrate over two temporally distinct southern admixture pulses. This signal was not recovered in the non-Gothic Roman-period Balkan populations tested as controls and is consistent with admixture in a trans-Danubian frontier setting, potentially including Roman Dacia after 106 CE. These findings support models in which Gothic affiliation in the Balkans operated as a cultural-political framework encompassing populations of diverse biological ancestry.

genomics↗

Long-term hunter-gatherer continuity in the Rhine-Meuse region was disrupted by local formation of expansive Bell Beaker groups

The first phase of the ancient DNA revolution painted a broad-brush picture of European Holocene prehistory, whereby 6500-4000 BCE, farmers descending from western Anatolians mixed with local hunter-gatherers resulting in 70-100% ancestry turnover, then 3000-2500 BCE people associated with the Corded Ware complex spread steppe ancestry into north-central Europe. We document an exception to this pattern in the wider Rhine-Meuse area in communities in the wetlands, riverine areas, and coastal areas of the western and central Netherlands, Belgium and western Germany, where we assembled genome-wide data for 109 people 8500-1700 BCE. Here, a distinctive population with high hunter-gatherer ancestry ([~]50%) persisted up to three thousand years later than in continental European regions, reflecting limited incorporation of females of Early European Farmer ancestry into local communities. In the western Netherlands, the arrival of the Corded Ware complex was also exceptional: lowland individuals from settlements adopting Corded Ware pottery had hardly any steppe ancestry, despite a characteristic early Corded Ware Y-chromosome. The limited influx may reflect the unique ecology of the regions river-dominated landscapes, which were not amenable to wholesale adoption of the early Neolithic type of farming introduced by Linearbandkeramik, making it possible for previously established groups to thrive, and creating a persistent but permeable boundary that allowed transfer of ideas and low-level gene flow. This changed with the formation-through-mixture of Bell Beaker using populations [~]2500 BCE by fusion of local Rhine-Meuse people (9-17%) and Corded Ware associated migrants of both sexes. Their expansion from the Rhine-Meuse region then had a disruptive impact across a much wider part of northwest Europe, including Britain where its arrival was the main source of a 90-100% replacement of local Neolithic peoples.

genomics↗

Striatal Astrocytes Influence Dopamine Dynamics and Behavioral State Transitions

We demonstrate here that astrocytes in the striatum interact with striatal dopamine in bidirectional signaling with dopamine release actively driving surges in astrocytic Ca++, which in turn modulate and reduce subsequent dopamine release. These Ca++ surges accurately predict behavioral state changes from task-engaged to task-disengaged states, but fail to predict detailed action parameters. We propose that interactions between striatal astrocytes and dopamine are strong candidates to modulate nigro-striato-nigral loop function underlying on-going behavioral state dynamics.

neuroscience↗

Striosomes Target Nigral Dopamine-Containing Neurons via Direct-D1 and Indirect-D2 Pathways Paralleling Classic Direct-Indirect Basal Ganglia Systems

Balanced activity of canonical direct D1 and indirect D2 basal ganglia pathways is considered a core requirement for normal movement, and their imbalance is an etiologic factor in movement and neuropsychiatric disorders. We present evidence for a conceptually equivalent pair of direct-D1 and indirect-D2 pathways that arise from striatal projection neurons (SPNs) of the striosome compartment rather than from SPNs of the matrix, as do the canonical pathways. These S-D1 and S-D2 striosomal pathways target substantia nigra dopamine-containing neurons instead of basal ganglia motor output nuclei. They modulate movement oppositely to the modulation by the canonical pathways: S-D1 is inhibitory and S-D2 is excitatory. The S-D1 and S-D2 circuits likely influence motivation for learning and action, complementing and reorienting canonical pathway modulation. A major conceptual reformulation of the classic direct-indirect pathway model of basal ganglia function is needed, as well as reconsideration of the effects of D2-targeting therapeutic drugs. HIGHLIGHTSO_LIDirect S-D1 and Indirect S-D2 striosomal pathways target SNpc dopamine cells C_LIO_LIThe S-D2 indirect pathway targets a distinct central external pallidal zone (cGPe) C_LIO_LIStimulation of S-D2 increases, of S-D1 decreases, striatal dopamine and movement C_LIO_LIS-D1 SPNs activity brackets task, inverse to a mid-task peak of dopamine release C_LI

neuroscience↗

The Genetic Origin of the Indo-Europeans

The Yamnaya archaeological complex appeared around 3300BCE across the steppes north of the Black and Caspian Seas, and by 3000BCE reached its maximal extent from Hungary in the west to Kazakhstan in the east. To localize the ancestral and geographical origins of the Yamnaya among the diverse Eneolithic people that preceded them, we studied ancient DNA data from 428 individuals of which 299 are reported for the first time, demonstrating three previously unknown Eneolithic genetic clines. First, a "Caucasus-Lower Volga" (CLV) Cline suffused with Caucasus hunter-gatherer (CHG) ancestry extended between a Caucasus Neolithic southern end in Neolithic Armenia, and a steppe northern end in Berezhnovka in the Lower Volga. Bidirectional gene flow across the CLV cline created admixed intermediate populations in both the north Caucasus, such as the Maikop people, and on the steppe, such as those at the site of Remontnoye north of the Manych depression. CLV people also helped form two major riverine clines by admixing with distinct groups of European hunter-gatherers. A "Volga Cline" was formed as Lower Volga people mixed with upriver populations that had more Eastern hunter-gatherer (EHG) ancestry, creating genetically hyper-variable populations as at Khvalynsk in the Middle Volga. A "Dnipro Cline" was formed as CLV people bearing both Caucasus Neolithic and Lower Volga ancestry moved west and acquired Ukraine Neolithic hunter-gatherer (UNHG) ancestry to establish the population of the Serednii Stih culture from which the direct ancestors of the Yamnaya themselves were formed around 4000BCE. This population grew rapidly after 3750-3350BCE, precipitating the expansion of people of the Yamnaya culture who totally displaced previous groups on the Volga and further east, while admixing with more sedentary groups in the west. CLV cline people with Lower Volga ancestry contributed four fifths of the ancestry of the Yamnaya, but also, entering Anatolia from the east, contributed at least a tenth of the ancestry of Bronze Age Central Anatolians, where the Hittite language, related to the Indo-European languages spread by the Yamnaya, was spoken. We thus propose that the final unity of the speakers of the "Proto-Indo-Anatolian" ancestral language of both Anatolian and Indo-European languages can be traced to CLV cline people sometime between 4400-4000 BCE. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/589597v1_ufig1.gif" ALT="Figure 1"> View larger version (91K): org.highwire.dtl.DTLVardef@127de98org.highwire.dtl.DTLVardef@87010aorg.highwire.dtl.DTLVardef@1554627org.highwire.dtl.DTLVardef@170dd63_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOSummary Figure:C_FLOATNO The origin of Indo-Anatolian and Indo-European languages. Genetic reconstruction of the ancestry of Pontic-Caspian steppe and West Asian populations points to the North Caucasus-Lower Volga area as the homeland of Indo-Anatolian languages and to the Serednii Stih archaeological culture of the Dnipro-Don area as the homeland of Indo-European languages. The Caucasus-Lower Volga people had diverse distal roots, estimated using the qpAdm software on the left barplot, as Caucasus hunter-gatherer (purple), Central Asian (red), Eastern hunter-gatherer (pink), and West Asian Neolithic (green). Caucasus-Lower Volga expansions, estimated using qpAdm on the right barplot as disseminated Caucasus Neolithic (blue)-Lower Volga Eneolithic (orange) proximal ancestries, mixing with the inhabitants of the North Pontic region (yellow), Volga region (yellow), and West Asia (green). C_FIG

genetics↗

A genomic history of the North Pontic Region from the Neolithic to the Bronze Age

The north Black Sea (Pontic) Region was the nexus of the farmers of Old Europe and the foragers and pastoralists of the Eurasian steppe1,2, and the source of waves of migrants that expanded deep into Europe3-5. We report genome-wide data from 78 prehistoric North Pontic individuals to understand the genetic makeup of the people involved in these migrations and discover the reasons for their success. First, we show that native North Pontic foragers had ancestry not only from Balkan and Eastern hunter-gatherers6 but also from European farmers and, occasionally, Caucasus hunter-gatherers. More dramatic inflows ensued during the Eneolithic, when migrants from the Caucasus-Lower Volga area7 moved westward, bypassing the local foragers to mix with Trypillian farmers advancing eastward. People of the Usatove archaeological group in the Northwest Pontic were formed ca. 4500 BCE with an equal measure of ancestry from the two expanding groups. A different Caucasus-Lower Volga group, moving westward in a distinct but temporally overlapping wave, avoided the farmers altogether, and blended with the foragers instead to form the people of the Serednii Stih archaeological complex7. A third wave of expansion occurred when Yamna descendants of the Serednii Stih forming ca. 4000 BCE expanded during the Early Bronze Age (3300 BCE). The temporal gap between Serednii Stih and the Yamna expansion is bridged by a genetically Yamna individual from Mykhailivka in Ukraine (3635-3383 BCE), a site of uninterrupted archaeological continuity across the Eneolithic-Bronze Age transition, and the likely epicenter of Yamna formation. Each of these three waves propagated distinctive ancestries while also incorporating outsiders during its advance, a flexible strategy forged in the North Pontic region that may explain its peoples outsized success in spreading their genes and culture across Eurasia3-5,8-10.

genetics↗

Postglacial genomes from foragers across Northern Eurasia reveal prehistoric mobility associated with the spread of the Uralic and Yeniseian languages

The North Eurasian forest and forest-steppe zones have sustained millennia of sociocultural connections among northern peoples. We present genome-wide ancient DNA data for 181 individuals from this region spanning the Mesolithic, Neolithic and Bronze Age. We find that Early to Mid-Holocene hunter-gatherer populations from across the southern forest and forest-steppes of Northern Eurasia can be characterized by a continuous gradient of ancestry that remained stable for millennia, ranging from fully West Eurasian in the Baltic region to fully East Asian in the Transbaikal region. In contrast, cotemporaneous groups in far Northeast Siberia were genetically distinct, retaining high levels of continuity from a population that was the primary source of ancestry for Native Americans. By the mid-Holocene, admixture between this early Northeastern Siberian population and groups from Inland East Asia and the Amur River Basin produced two distinctive populations in eastern Siberia that played an important role in the genetic formation of later people. Ancestry from the first population, Cis-Baikal Late Neolithic-Bronze Age (Cisbaikal_LNBA), is found substantially only among Yeniseian-speaking groups and those known to have admixed with them. Ancestry from the second, Yakutian Late Neolithic-Bronze Age (Yakutia_LNBA), is strongly associated with present-day Uralic speakers. We show how Yakutia_LNBA ancestry spread from an east Siberian origin [~]4.5kya, along with subclades of Y-chromosome haplogroup N occurring at high frequencies among present-day Uralic speakers, into Western and Central Siberia in communities associated with Seima-Turbino metallurgy: a suite of advanced bronze casting techniques that spread explosively across an enormous region of Northern Eurasia [~]4.0kya. However, the ancestry of the 16 Seima-Turbino-period individuals--the first reported from sites with this metallurgy--was otherwise extraordinarily diverse, with partial descent from Indo-Iranian-speaking pastoralists and multiple hunter-gatherer populations from widely separated regions of Eurasia. Our results provide support for theories suggesting that early Uralic speakers at the beginning of their westward dispersal where involved in the expansion of Seima-Turbino metallurgical traditions, and suggests that both cultural transmission and migration were important in the spread of Seima-Turbino material culture.

genomics↗

Local recurrent circuits modulate visual center and surround interactions in the mouse superior colliculus

Center-surround interactions are fundamental to visual saliency computation, but debate continues over whether and how subcortical visual circuits actively contribute. To address this, we developed an optogenetic approach to delineate the visual center and surround zones of individual neurons in the superficial layer of the superior colliculus (SCs) using only retinal ganglion cell input. Using whole-cell recordings, we demonstrate that surround network activation suppresses center excitability, indicating that SCs circuitry is self-sufficient in driving center-surround dynamics. Through cell-type-specific trans-synaptic tracing and large-scale modeling, we identified an SCs-based circuit with two key motifs driving surround modulation: recurrent excitation and feedback inhibition. We propose that subcortical visual circuits in the SCs have evolved to perform surround suppression alongside retinal and cortical suppression, facilitating the distribution of parallel saliency computations across different levels. Significance statementThis study questions the notion that the superior colliculus (SC) merely acts as a passive recipient of saliency information from upstream circuits. We demonstrate that the SC can independently generate center-surround interactions that could contribute to visual saliency through local circuits without top-down input. This ability represents a computation that has been conserved since the dawn of vertebrate evolution. By mapping these interactions, we reveal that the mouse SC actively induces visual surround suppression. These findings suggest that phylogenetically older circuits in the SC may play a more independent role in active vision than previously acknowledged, prompting a reevaluation of visual saliency processing across subcortical brain regions.

neuroscience↗

Social and genetic diversity in first farmers of central Europe

The Linearbandkeramik (LBK) Neolithic communities were the first to spread farming across large parts of central Europe, settling fertile regions from Ukraine to France during the second half of the 6th millennium BCE. The LBK had a high degree of material culture uniformity, albeit with regional differences in settlement patterns, subsistence, and mortuary practices. To date, ancient DNA data from LBK individuals have been generated for a limited number of locations and often in small sample sizes, making it challenging to study variation within and across sites. We report genome-wide data for 178 LBK individuals, from the Alfold Linearbankeramik Culture (ALPC) eastern LBK site of Polgar-Ferenci-hat in Hungary, the western LBK site of Nitra in Slovakia, and the enclosed western LBK settlement and massacre site of Schletz in Austria, as well as 42 LBK individuals from 18 other sites. We also report genome-wide data for 28 Early Neolithic Koros and Star[c]evo individuals from 13 sites, viewed as the predecessors of the LBK. We observe a higher percentage of western hunter-gatherer (WHG) admixture among individuals in the eastern LBK than in the far more widely distributed western LBK, showing that these two archaeologically distinct cultures also had different genetic trajectories. Most WHG-farmer mixture occurred just before the dawn of the LBK culture and there is no evidence that the WHG ancestry came systematically more from males or females. However, we do find strong genetic evidence for patrilocality among the LBK, extending previous findings based on isotopic analysis, with more genetic structure across sites on the male than on the female line, and a higher rate of within-site relatives for males. At Schletz we detect almost no first-degree relatives despite reporting data from almost every skeleton present at the site, showing that this massacre involved people from a large population, not a small community.

genetics↗

The Allen Ancient DNA Resource (AADR): A curated compendium of ancient human genomes

More than two hundred papers have reported genome-wide data from ancient humans. While the raw data for the vast majority are fully publicly available testifying to the commitment of the paleogenomics community to open data, formats for both raw data and meta-data differ. There is thus a need for uniform curation and a centralized, version-controlled compendium that researchers can download, analyze, and reference. Since 2019, we have been maintaining the Allen Ancient DNA Resource (AADR), which aims to provide an up-to-date, curated version of the worlds published ancient human DNA data, represented at more than a million single nucleotide polymorphisms (SNPs) at which almost all ancient individuals have been assayed. The AADR has gone through six public releases since it first was made available and crossed the threshold of >10,000 ancient individuals with genome-wide data at the end of 2022. This note is intended as a citable description of the AADR.

genomics↗

Esr1+ hypothalamic-habenula neurons shape aversive states.

Excitatory projections from the lateral hypothalamic area (LHA) to the lateral habenula (LHb) drive aversive responses. We used Patch-seq guided multimodal classification to define the structural and functional heterogeneity of the LHA-LHb pathway. Our classification identified six glutamatergic neuron types with unique electrophysiological properties, molecular profiles, and projection patterns. We found that genetically-defined LHA-LHb neurons signal distinct aspects of emotional or naturalistic behaviors: Esr1+ LHA-LHb neurons induce aversion, whereas Npy+ LHA-LHb neurons control rearing behavior. Repeated optogenetic drive of Esr1+ LHA-LHb neurons induces a behaviorally persistent aversive state, and large-scale recordings showed a region-specific neural representation of the aversive state in the prelimbic region of the prefrontal cortex. We further found that exposure to unpredictable mild shocks induced a sex-specific sensitivity to develop a stress state in female mice, which was associated with a specific shift in the intrinsic properties of bursting-type Esr1+ LHA-LHb neurons. In summary, we describe the diversity of LHA-LHb neuron types, and provide evidence for the role of Esr1+ neurons in aversion and sexually dimorphic stress sensitivity.

neuroscience↗

Sst+ GPi output neurons provide direct feedback to key nodes of the basal ganglia and drive behavioral flexibility.

The internal globus pallidus (GPi) is a basal ganglia output nucleus with separate projections to the thalamus and the lateral habenula (LHb). Here, we show a GPi subtype with projections to LHb (GPi-LHb), genetically defined based on glutamate/GABA co-transmission and somatostatin (Sst) expression, also projects back to key nodes in the basal ganglia: the external globus pallidus (GPe), the striatal striosomes, and dopamine neurons in the substantia nigra. We found that the Sst+ GPi population showed strong movement and direction-specific selectivity in a goal-directed choice task, but not during self-paced exploration, and did not signal prediction errors or outcome modulation. During goal-directed behavior, the Sst+ GPi activity slowly evolved with learning of correct choice actions and genetic silencing disrupted the ability to update choice behavior following a task rule reversal. In summary, we have found that Sst+ GPi neurons establish a wide feedback network in the basal ganglia and drive behavioral flexibility.

neuroscience↗

Cosmopolitanism at the Roman Danubian Frontier, Slavic Migrations, and the Genomic Formation of Modern Balkan Peoples

The Roman Empire expanded through the Mediterranean shores and brought human mobility and cosmopolitanism across this inland sea to an unprecedented scale. However, if this was also common at the Empire frontiers remains undetermined. The Balkans and Danube River were of strategic importance for the Romans acting as an East-West connection and as a defense line against "barbarian" tribes. We generated genome-wide data from 70 ancient individuals from present-day Serbia dated to the first millennium CE; including Viminacium, capital of Moesia Superior province. Our analyses reveal large scale-movements from Anatolia during Imperial rule, similar to the pattern observed in Rome, and cases of individual mobility from as far as East Africa. Between [~]250-500 CE, we detect gene-flow from Central/Northern Europe harboring admixtures of Iron Age steppe groups. Tenth-century CE individuals harbored North-Eastern European-related ancestry likely associated to Slavic-speakers, which contributed >20% of the ancestry of todays Balkan people.

evolutionary biology↗

Complete representation of action space and value in all striatal pathways.

The dorsal striatum plays a central role in motor and decision programs, such as the selection and execution of particular actions and the evaluation of their outcomes. A standard model has emerged where distinct output pathways encode separate motor-action signals, including selection-evaluation division in the matrix versus patch compartments. We used large-scale cell-type specific calcium imaging during motor and decision behaviors to determine and contrast the activity of individual striatal projection neurons (SPNs) belonging to one of the three major output pathways in the dorsomedial striatum - patch Oprm1+ SPNs versus the D1+ direct and A2A+ indirect pathway. We found that Oprm1+ SPNs were tuned to a number of different behavioral categories, such as to different movements, or to discrete actions and decisions in a two-choice task, and these complex representations were found to the same extent in all three striatal output pathways. The sharp tuning of individual SPNs was highly stereotyped over time while performing a specific task, but the tuning profile remapped between different behavioral contexts. In addition to action representations, SPNs showed pathway-independent representation of decision-variables such as the trial strategy and the action value. We propose that all three major output pathways in the dorsomedial striatum share a similarly complete representation of the entire action space, including task- and phase-specific signals of action value and choice.

neuroscience↗

Interactions between earliest Linearbandkeramik farmers and central European hunter gatherers at the dawn of European Neolithization

Archaeogenetic research over the last decade has demonstrated that European Neolithic farmers (ENFs) were descended primarily from Anatolian Neolithic farmers (ANFs). ENFs, including early Neolithic central European Linearbandkeramik (LBK) farming communities, also harbored ancestry from European Mesolithic hunter gatherers (WHGs) to varying extents, reflecting admixture between ENFs and WHGs. However, the timing and other details of this process are still imperfectly understood. In this report, we provide a bioarchaeological analysis of three individuals interred at the Brunn 2 site of the Brunn am Gebirge-Wolfholz archeological complex, one of the oldest LBK sites in central Europe. Two of the individuals had a mixture of WHG-related and ANF-related ancestry, one of them with approximately 50% of each, while the third individual had approximately all ANF-related ancestry. Stable carbon and nitrogen isotope ratios for all three individuals were within the range of variation reflecting diets of other Neolithic agrarian populations. Strontium isotope analysis revealed that the ~50% WHG-ANF individual was non-local to the Brunn 2 area. Overall, our data indicate interbreeding between incoming farmers, whose ancestors ultimately came from western Anatolia, and local HGs, starting within the first few generations of the arrival of the former in central Europe, as well as highlighting the integrative nature and composition of the early LBK communities.

genetics↗

The Arrival of Steppe and Iranian Related Ancestry in the Islands of the Western Mediterranean

A series of studies have documented how Steppe pastoralist-related ancestry reached central Europe by at least 2500 BCE, while Iranian farmer-related ancestry was present in Aegean Europe by at least 1900 BCE. However, the spread of these ancestries into the western Mediterranean where they have contributed to many populations living today remains poorly understood. We generated genome-wide ancient DNA from the Balearic Islands, Sicily, and Sardinia, increasing the number of individuals with reported data from these islands from 3 to 52. We obtained data from the oldest skeleton excavated from the Balearic islands (dating to [~]2400 BCE), and show that this individual had substantial Steppe pastoralist-derived ancestry; however, later Balearic individuals had less Steppe heritage reflecting geographic heterogeneity or immigration from groups with more European first farmer-related ancestry. In Sicily, Steppe pastoralist ancestry arrived by [~]2200 BCE and likely came at least in part from Spain as it was associated with Iberian-specific Y chromosomes. In Sicily, Iranian-related ancestry also arrived by the Middle Bronze Age, thus revealing that this ancestry type, which was ubiquitous in the Aegean by this time, also spread further west prior to the classical period of Greek expansion. In Sardinia, we find no evidence of either eastern ancestry type in the Nuragic Bronze Age, but show that Iranian-related ancestry arrived by at least [~]300 BCE and Steppe ancestry arrived by [~]300 CE, joined at that time or later by North African ancestry. These results falsify the view that the people of Sardinia are isolated descendants of Europes first farmers. Instead, our results show that the islands admixture history since the Bronze Age is as complex as that in many other parts of Europe.

genomics↗