To the field of stars: Stable isotope analysis of medieval pilgrims and populations along the Camino de Santiagoin Navarre and Aragon, Spain

•The radiocarbon dating results corroborate the use of the pilgrim's shell since at least the 11th century CE.•The data suggest that the pilgrimage was mainly an urban phenomenon for populations from the northern Iberian Peninsula.•The pilgrimage was conducted equally by women and men.•Female pilgrims may have had greater access to animal protein than their male counterparts.•The individuals buried with the scallop shell had δ15N and δ13C indicative of a heterogeneous group.