A recent DNA analysis has uncovered the fascinating history of a small, devout Christian community that survived the turbulent medieval period in isolation, living in a network of underground caves in Spain. This community, residing in what is now northern Spain, practiced endogamy—marrying within their own group—and managed to maintain their distinct way of life despite the sweeping changes and invasions that reshaped the Iberian Peninsula between the 8th and 11th centuries.
During this time, the Iberian Peninsula, comprising modern-day Spain and Portugal, was a battleground for religious and political dominance, particularly following the arrival of Muslim armies from North Africa, who established the territory of Al-Andalus. This era of upheaval saw dramatic shifts in population and power, laying the foundations for modern Europe. However, historical records and archaeogenetic studies from this period in Iberia are sparse, particularly concerning rural and isolated communities.
The new research, published in Science Advances, analyzed the remains of 33 individuals from Las Gobas, an ancient cemetery in northern Spain. This site, used between the 7th and 11th centuries AD, is remarkable for its church and living quarters carved directly into the rock. The DNA analysis revealed that the inhabitants were primarily of local Iberian ancestry, with minimal genetic input from North African populations, despite their proximity to the Muslim-controlled Al-Andalus.
“Our findings indicate that this community stayed relatively isolated for at least five centuries,” explained Rodríguez Varela, a co-author of the study. The analysis showed high levels of inbreeding among the cave dwellers, suggesting that they practiced endogamy. Some of the earliest male inhabitants were found to be close relatives, as indicated by the minimal variations in their Y-chromosomes, which are inherited from father to son.
The study also uncovered evidence of violence within the community, as some remains bore signs of sword blows to the head. This suggests that the early inhabitants may have had some military experience. Additionally, the community was not immune to disease; researchers found evidence of zoonotic diseases—those transmitted from animals to humans. For example, some individuals showed signs of infection with the bacterium Erysipelothrix rhusiopathiae, which can cause skin disease in humans and originates from domestic animals. Another individual was infected with a bacterium that spreads via contaminated meat, while yet another carried a variant of the smallpox virus similar to one known to have affected northern and eastern Europe.
The study’s findings challenge previous theories about how diseases like smallpox spread into Iberia. “By the 10th century, smallpox seems to have affected Las Gobas, likely spreading through Europe rather than via Islamic routes, as was previously theorized,” said Anders Götherström, another author of the study.
Despite the broader societal changes around them, the cave community remained relatively untouched by external influences, as evidenced by the lack of significant North African or Middle Eastern genetic markers in their DNA over time. This isolation, combined with their devout religious practices, shaped a community characterized by strong familial ties, resilience in the face of disease, and the ability to maintain their way of life despite external pressures.
The Las Gobas cave complex offers a rare and detailed glimpse into the lives of a rural Christian community during a period often overshadowed by the grand narratives of urban centers and ruling elites. As the researchers noted, “What started as a cave-dwelling group evolved into a typical rural village that endured its share of disease,” providing a unique window into the everyday lives of people living on the fringes of history.