Salamanca: Roman Lusitania versus the Castilian narrative in Spain

Salamanca, between Roman Lusitania and the Castilian narrative

Salamanca is nothing like Burgos. It sounds like a tavern jab, but behind it lie genetic coordinates, admixture models and an uncomfortable question: what exactly does it miccionan to be of Castilian origin? Over the past few days, a group of population genetics enthusiasts has turned the province into a chessboard where G25 samples, medieval repopulations and centuries of badly told history collide. The provisional conclusion makes more than one person squirm: DNA does not respect administrative borders, and the word "Castilian" is more recent than the people who inhabit it.

What a G25 coordinate actually measures

The star tool of the debate is the G25 coordinates, those strings of numbers that some read as if they were a blood test. A sample from Valladolid starts with a value of 0.107753; the average of four people from León is around 0.103. Some claim this figure directly measures the percentage of North African ancestry of a province. It does not. That first coordinate is an axis of a principal component analysis: it places the population on a European geographic gradient, it does not quantify anything on its own.

To obtain a percentage, those coordinates must be fed into a model with reference populations. And here the real problem begins: the result depends on which sources you choose. An exercise circulating online attributes to Valladolid an 11% of Maghreb_East_Ancient within a breakdown antiestéticaturing 26.8% ancient Irish, 25.4% ancient Basque and 14% Etruscan. The fit lands at a distance of 0.7%. It sounds conclusive. It is also, the most critical voices point out, a weighting that changes completely if the sources are swapped.

From Roman Lusitania to the repopulation of the Duero

The hypothesis with the most traction about Salamanca is not genetic, it is historical. The province was part of Roman Lusitania, which links it to the western Iberian Peninsula, not to the northern plateau. From there, the affinity with Portugal is a step some take without qualms and others with a smirk: there are those who lament resembling their Portuguese neighbor and instead claim a southern French air.

The counterargument comes from history itself: the Duero valley was repopulated with Astur-Galicians and Mozarabs, the same human stock as Trás-os-Montes and the Beira. The Franks, they insist, barely set foot in those lands beyond the pilgrimage route to Santiago. And if we are talking origins, the founding of León is attributed to a legion with soldiers who came from the East.

The North African who arrived before Tariq

The most cited and worst understood figure is that of North African ancestry. The 11% some assign to Valladolid comes, according to another participant, from a 2013 study by Botigué published in PNAS, which placed the peak in the northwest of the peninsula, with Galicia hovering around that percentage. Transferring that regional maximum to the central plateau is, they say, a leap without a safety net.

The key lies in the layers. The North African footprint that appears in Paleolithic-Neolithic models entered between 6,000 and 8,000 years ago, with the first farming populations. It arrived before the Iberians, Romans and Phoenicians, and is spread across the whole peninsula. Burgos, Soria, Valladolid and Badajoz drink from the same well. What came with the conquest of 711 is another layer, a minority one, and it does not show on anyone's face.

Burgos, Basques and Franks: the purity that does not exist

The irony of the matter is that the province taken as the benchmark of pure Castilian identity also carries its own mixture. Burgos was repopulated with people from the north, Basques and Navarrese included, and the Way of St. James left documented Frankish colonies. There is no possible dispute there: the Duero was filled with northerners and pilgrims.

Attempts to identify lineages by physical appearance always hit the same wall. Phenotype is not genotype. There are dark-haired, dark-eyed people in Dublin who could pass for neighbors of Fez, and blond types in the Maghreb who would not look out of place in any Burgos village. A face does not prove a genealogy. If any of the cited examples took a DNA test, the profile would come out almost identical to that of the neighbor who brags about supposedly pure roots.

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Given all this, the predictable outcome is that the debate will not be settled. Recreational genetics tools will keep making headlines because their popular reading is light years away from their technical use. New models and new coordinates will likely appear that seem to confirm opposite theses, depending on who publishes them. Nobody with any sense should extract a hierarchy between provinces from a handful of numbers. But that, I antiestéticar, will not stop anyone.