The oldest mule in the western Mediterranean. The case of the Early Iron Age in Hort d’en Grimau (Penedès, Barcelona, Spain)

• Genetic and radiocarbon analyses confirm the Hort d'en Grimau mule as the oldest hybrid in the western Mediterranean and continental Europe. • Dated between the mid-8th and mid-6th century BCE. • The mule skeleton was found in a silo alongside the skeletal remains of a woman. This indicates a close relationship between equines and humans. • Pathological bone alterations and isotopic results suggest that the animal may have been used for riding and fed with forages containing cereals. Mules, first generation hybrids between a horse mare ( Equus caballus ) and a donkey jack ( Equus asinus ), are rarely documented in the western Mediterranean prior to Roman times. They may have been bred earlier in the Iberian Peninsula where domestic horses and donkeys had coexisted for at least a millennium. In this study, we use ancient DNA to identify a female mule from Hort d’en Grimau, an archaeological site located in the Prelitoral of the northeastern Iberian Peninsula dated to the First Iron Age (8 th -6 th century BCE). The animal was small in size and found in anatomical connection with the partially burnt remains of a woman, deposited inside a silo. Zooarchaeological analysis confirmed that the equid skeleton belonged to an adult-senile female exhibiting both horse and donkey morphological traits, with maxillary and mandibular pathologies consistent with riding. Stable carbon and nitrogen isotope analyses suggest a diet rich in cultivated cereals. This individual represents the earliest genetically confirmed mule in western Europe. Further research is needed to determine whether it was bred locally or introduced via Phoenician exchange networks.