For the first time, scientists have sequenced the genomes of medieval Spanish Jews from a 1348 pogrom, revealing their genetic ties to ancient Canaanites and modern Jewish communities worldwide.
In 2007, archaeologists excavating a site in Tàrrega, Catalonia, made a grim discovery. Six mass graves containing the remains of at least 69 individuals, many with signs of violent head trauma, dated to the mid-14th century. Historical records from 1348 describe a massacre of the local Jewish community following the arrival of the Black Death.
But was this really a Jewish cemetery? Could the victims be identified as members of the medieval Jewish community of Tàrrega? For nearly two decades, the answer remained uncertain—until now.
A groundbreaking new study published in the journal Genes (MDPI) has for the first time sequenced the genomes of 11 individuals from the Roquetes necropolis in Tàrrega. The results are definitive: these were indeed medieval Jews, with genetic affinities to both ancient Canaanite populations and modern Jewish communities, particularly Sephardic and Ashkenazi Jews.
The study, titled “Uncovering a Medieval Pogrom: Genetic History of a Jewish Community in Catalonia (Spain),” represents the first genomic data ever reported for medieval Iberian Jews. It provides powerful evidence for the continuity of Jewish populations over millennia, while also revealing the unique genetic diversity of the Sephardic community.
The Historical Context: A Century of Violence
The 14th century was catastrophic for European Jewry. The Black Death (1347–1351) killed millions, and desperate, frightened populations sought scapegoats. Jewish communities across Europe were falsely accused of poisoning wells and spreading the plague. Pogroms—violent riots targeting Jews—erupted across the continent.
In the Crown of Aragon (eastern Iberian Peninsula), the most affected cities were Barcelona, Cervera, Lleida, Girona, and Tàrrega. Historical sources chronicle a massacre in Tàrrega in 1348, during which armed attackers entered the Jewish quarter, assaulted homes, destroyed property, and killed approximately 300 people.
This violence was not new. Discrimination against Jewish communities had been intensifying for centuries. After the 6th century, with Christianity established as the dominant religion, Jews frequently endured social marginalization, legal restrictions, forced conversions, and episodes of expulsion. A brief period of relative prosperity under early Islamic rule (700–1086 CE) ended with the arrival of more orthodox dynasties, leading to Jewish emigration to northern Christian kingdoms.
The discrimination worsened dramatically in the 14th century. The combined effects of plague, famine, war, and economic crisis created a climate of insecurity that translated into widespread antisemitism. The hostilities culminated in 1492, with the Edict of Expulsion forcing all unconverted Jews to leave the Crowns of Castile and Aragon—the end of a major Jewish presence in Spain.
The Roquetes mass graves are a physical testament to this history.
The Genetic Evidence: A Jewish Signature
The research team analyzed bone samples from 16 individuals exhumed from all six mass graves. After rigorous contamination screening, 11 individuals yielded high-quality ancient DNA sufficient for genome-wide analysis.
The researchers examined three types of genetic evidence: uniparental markers (mitochondrial DNA passed from mothers to children, and Y-chromosome DNA passed from fathers to sons), autosomal DNA (the 22 pairs of chromosomes that recombine each generation), and runs of homozygosity (stretches of identical DNA indicating relatedness or endogamy).
Mitochondrial DNA (maternal lineage) diversity was remarkably high. The researchers identified ten different mitochondrial haplogroups among the 11 individuals. This diversity contrasts sharply with medieval Ashkenazi communities in Germany (Erfurt and Norwich), which showed strong founder effects and limited diversity. The Roquetes pattern aligns more closely with modern Sephardic-descended communities (Bulgaria, Turkey, Morocco), which maintain substantial haplogroup diversity.
Table 1: Mitochondrial Haplogroups Identified in the Roquetes Individuals
| Haplogroup | Ancient Distribution | Present-Day Jewish Distribution |
|---|---|---|
| K1a1b1a | Present in medieval Erfurt Jews | Common in Ashkenazi |
| U5a2b | Present in medieval Erfurt Jews | Present in Ashkenazi |
| M1a1b1c | Not in ancient database | Present in Sephardic |
| J1c1 | Not in ancient database | Present in Ashkenazi/Sephardic |
| R0a4 | Not in ancient database | Present in Ashkenazi/Sephardic |
| H1bo | Not in ancient database | Present in Jewish populations |
| L2a1c+16129 | Rare in ancient record | Present in Sephardic |
| H20a | Present in ancient Iberia | Present in Jewish populations |
The presence of haplogroup L2a1c+16129 is particularly notable. This lineage has been found in ancient individuals from the Iberian Peninsula and the eastern Mediterranean, suggesting broader Mediterranean maternal ancestry.
Y-chromosome (paternal lineage) diversity also reflected Jewish diaspora patterns. Among the four males in the sample, researchers identified haplogroups J2a2a, E1b1b (specifically subclade E-CTS9507), and G1a1a. These lineages have deep Neolithic–Bronze Age roots in the Eastern Mediterranean and Levant and are frequent in Jewish diasporic contexts.
Table 2: Y-Chromosome Haplogroups in Roquetes Males
| Individual | Haplogroup | Ancient Distribution | Jewish Context |
|---|---|---|---|
| ROQ1 | J2a2a1~* | Eastern Mediterranean, Neolithic | Frequent in Jewish diasporas |
| ROQ2 | E-CTS9507 (E1b1b) | Mediterranean, Near East | Present in medieval Erfurt & Norwich Jews |
| ROQ4 | G-PH1944 (G1a1a) | Chalcolithic Iran, Bronze Age Anatolia | Present in Jewish populations |
| ROQ7 | E2a | Rare; eastern Africa | Rare in Jewish contexts |
The recurrence of E1b1b lineages in medieval Jewish cemeteries (Erfurt, Norwich) and the presence of J and G among present-day Jewish groups further underscores continuity from Levantine–Mediterranean ancestry sources.
Autosomal DNA: Connecting to Ancient Canaanites and Modern Jews
The most powerful evidence came from autosomal DNA analysis. The researchers used several complementary methods:
Principal Component Analysis (PCA) placed the Roquetes individuals in close proximity to medieval Jewish samples from Erfurt (Germany) and Norwich (England), as well as to modern Sephardic Jews (e.g., Turkey, North Africa). Importantly, they were genetically distinct from non-Jewish medieval Iberians (Christians and Muslims).
ADMIXTURE analysis (which estimates ancestry proportions) revealed that the Roquetes population’s ancestry could be modeled as a mixture of Western hunter-gatherer, Steppe Bronze Age, Anatolian Neolithic, and Canaanite-related components, with a minor North African (Iberomaurusian) contribution in some individuals. This ancestral profile closely resembles that observed in Jewish individuals from medieval Erfurt.
Outgroup f3-statistics measured the shared genetic drift between the Roquetes population and other populations. The results showed that Roquetes individuals shared the highest genetic drift with:
- Non-Jewish, non-Islamic medieval Iberians
- Medieval Ashkenazi Jews from Erfurt (Germany)
- Present-day Ashkenazi Jews
- Present-day Sephardic Jews (Turkey)
Lower genetic affinity was observed with Islamic and Nazari (the last Islamic dynasty of Al-Andalus) individuals from the Iberian Peninsula, medieval Norwich Jews, and present-day Asian Jews (Cochin, Yemenite).
qpAdm modeling (a formal test of ancestry) was the most definitive. The researchers tested whether the Roquetes population could be modeled as a mixture of two source populations: ancient Canaanites (labeled as Israel Middle/Late Bronze Age) and a local Iberian population.
The model was statistically plausible (p = 0.158), with estimated ancestry proportions of 69% Canaanite and 31% non-Jewish, non-Islamic medieval Iberian.
This is a remarkable finding. It suggests that the medieval Jewish community of Tàrrega had preserved a strong genetic connection to the ancient Levant while also incorporating a significant minority of local Iberian ancestry over the preceding centuries.
Endogamy Without Close Kinship
The researchers also examined runs of homozygosity (ROH)—stretches of the genome that are identical from both parents, indicating relatedness or endogamy (marriage within a closed community).
The ROH analysis revealed that most individuals showed no evidence of close kinship (no first- or second-degree relatives among the 11 individuals). This indicates that the mass graves were not family burials but rather a communal catastrophe.
However, one individual (ROQ2) exhibited long ROH segments (20–300 cM), indicating background endogamy—mating patterns typical of relatively small or socially insular communities. This pattern mirrors other medieval Jewish contexts but is less extreme than the strong consanguinity reported in Norwich.
Why This Matters: Genetic Continuity Despite Persecution
This study has profound implications for understanding Jewish history and genetic continuity.
First, it confirms that the Jewish community of Tàrrega was indeed Jewish, as historical sources suggested. The genetic signature is unmistakable: Levantine ancestry, uniparental markers common in Jewish populations, and genetic affinity with other ancient and modern Jewish communities.
Second, it demonstrates that despite centuries of persecution, forced conversions, and eventual expulsion, Jewish genetic continuity persisted. The same genetic signatures found in medieval Tàrrega are found in modern Jewish populations today.
Third, it highlights the unique genetic diversity of Sephardic Jews compared to Ashkenazi Jews. The high mitochondrial diversity at Roquetes contrasts with the narrow mtDNA spectra of medieval Ashkenazi communities, which experienced strong founder effects and genetic drift.
Fourth, it provides a model for understanding Jewish ancestry: a core Levantine component (approximately 70%) combined with local admixture (approximately 30%). This is consistent with studies of modern Jewish populations, which also show substantial European admixture (30–60%).
Limitations and Future Directions
The study has several limitations. The sample size is relatively small (11 individuals), and the genomic coverage varies among samples. The research could not determine the specific cause of death (though perimortem cranial trauma was documented in at least one-third of the individuals). The study also cannot confirm the religious identity of the individuals (though genetic evidence strongly supports the historical attribution).
Future research should expand the sample size, include additional medieval Jewish sites across Iberia, and integrate genetic data with archaeological and historical evidence.
A Final Word of Remembrance
The Roquetes necropolis is not just a scientific site. It is a mass grave of individuals who were killed because of their religious identity. The study’s authors are careful to acknowledge this: the genomic data cannot identify the cause of death, but the archaeological context, dating, historical sources, and perimortem trauma strongly support attribution to the 1348 Tàrrega pogrom.
By sequencing their DNA, scientists have given these individuals a voice after 700 years of silence. Their genes tell a story of continuity, survival, and resilience. They remind us that Jewish communities have deep roots in Iberia—roots that were violently torn out but not erased.
As the study concludes: “This is the first study to report genomic data for medieval Iberian Jews. Our findings reveal genomic affinities of the Roquetes individuals with ancient and modern Jewish populations and corroborate the previous attribution of the burials to victims of the 1348 Tàrrega pogrom.”
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