A new study has sequenced DNA from a Christian community in medieval Spain who lived in artificial caves carved into a rocky outcrop. This discovery sheds light on the lives of one of several known medieval cave communities in the Iberian Peninsula, encompassing both Portugal and Spain. The reasons why these groups chose caves over conventional village dwellings remain a subject of debate among archaeologists. While it’s tempting to speculate about hermits or religious groups, concrete evidence supporting these theories is scarce.
Our study, published in Science Advances, investigates the possibilities by combining genetic analysis with existing knowledge of the physical remains from the site’s cemetery. DNA analysis reveals the ancestry of this community, their familial relationships, and the diseases they endured. The combined information paints a picture of inbreeding, occasional violence, and disease during a fascinating period in history.
One intriguing possibility is that some of the earliest settlers had military experience, although it’s unclear whether they were professional soldiers. The settlement existed from the mid-sixth century to the 11th century A.D., a dynamic and tumultuous period in many parts of Europe, including the Iberian Peninsula. After the fall of the Western Roman Empire in A.D. 476, Iberia came under the rule of the Visigoths from northern Europe. The Visigothic kingdom collapsed following the Muslim conquest from North Africa in A.D. 711, establishing a territory known as Al-Andalus. While Al-Andalus eventually encompassed much of Iberia, Christian kingdoms persisted in the north, gradually reclaiming territory.
Our understanding of this period in Iberia has been largely shaped by events in major cities like Toledo, Granada, and Cordoba—hubs of trade, diplomacy, and power. However, the rural site of Las Gobas provides a glimpse into life away from these urban centers, specifically within one of the distinct cave-dwelling communities of this era. Located in Burgos province, northern Spain, near the village of Laño, Las Gobas features a cemetery used continuously from the seventh to the 11th century. It was initially connected to a church, also built within the cave complex. By the tenth century, the inhabitants had transitioned to a more typical rural village, although the cave church and cemetery remained in use until the 11th century.
Archaeological excavations at the cemetery have uncovered the remains of 41 individuals. Genetic analysis was conducted on 39 of them, with 33 providing enough DNA for sex identification (22 males and 11 females). Further investigation using various genetic techniques was possible on 28 of the remains.
Our analysis revealed that the inhabitants were overwhelmingly of local Iberian ancestry with minimal contribution from North Africans, despite their proximity to the northern edge of Al-Andalus. This aligns with historical records indicating limited genetic influence from North African populations in northern Iberia during the middle ages. Nevertheless, some migration did occur, evidenced by several individuals with higher North African ancestry following the Muslim conquest.
Two skeletons dating to the early phase of settlement exhibited signs of violence, likely resulting from sword blows to the head. Remarkably, one of them survived an injury that cut through the skull. These individuals were genetically closely related, and their injuries predate the Muslim conquest, indicating that they were not caused by conflicts along the Al-Andalus border.
This period saw elevated levels of inbreeding, with approximately 61% of the sample with enough genomic data showing signs of inbreeding (14 out of 23). This suggests that the population practiced endogamy, marrying only within the community. Further evidence for inbreeding is seen in the close kinship between several of the earliest males, as indicated by minimal variations in their Y-chromosome. This suggests that the site could have been populated in the seventh century A.D. by a small patrilocal group (where couples settle in the husband’s home or community) who may have had experience of warfare.
The early phase of the Las Gobas settlement also revealed several cases of the bacterium *Erysipelothrix rhusiopathiae*, which causes a skin disease in humans. This bacterium often originates in domestic animals. While present in the settlement’s later phase, it occurred at a lower frequency. The presence of this bacterium, commonly found in pigs, suggests that raising these livestock animals was an essential part of the community’s lifestyle. Additionally, one of the individuals infected with *E. rhusiopathiae* was also carrying *Yersinia enterocolitica*, a bacterium known to infect humans through contaminated meat or water.
Endogamy remained a strong feature throughout the population’s history, even as the community transitioned from cave dwellings to a more typical rural settlement in the tenth century. During this later phase, DNA from the variola virus, responsible for smallpox, was detected in a tenth-century individual. Smallpox, with its high mortality rate (30% without vaccination), has been suggested by some researchers to have reached Iberia via the Muslim conquest. However, the Las Gobas smallpox strain resembled those found in Scandinavia, Russia, and Germany during the same period. This suggests that at least one pandemic route was from the east.
Increased mobility, exemplified by the growing importance of the northern city of Santiago de Compostela for Christian pilgrims in the ninth and tenth centuries, may have even contributed to the spread of the virus.
In all these ways, Las Gobas stands out as a unique site spanning the turbulent early medieval period in Iberia. It reveals a community marked by isolation, violence, and devout worship. What began as a cave-dwelling group evolved into a typical rural village that endured its share of disease. As such, the site offers a rare and detailed glimpse into the lives of people whose stories are often overshadowed by the narratives of major urban centers and their elites.
