Bioarchaeological evidence for hybridization between house mouse subspecies in early Neolithic Iran.

Abstract

House mice (Mus musculus) have been associated with humans since the beginning of sedentism, enabling them to become successful global colonisers. Three main subspecies originated ~0.5 myrs ago in a region extending from Southwest Asia to northern India. Molecular data suggest that a complex scenario of secondary admixture occurred thereafter in the Iranian region, leading to the formation of a Central Iranian Lineage, but this evidence was overlooked in previous bioarchaeological analysis. The early Neolithic settlement of Ganj Dareh is located in this cradle area. It delivered remains of commensal house mice formerly attributed to Mus musculus domesticus. A geometric morphometric analysis of the first lower molars is used here to characterize the signature of hybridization between M. m. musculus and M. m. domesticus. The subspecific attribution of the Ganj Dareh mouse remains is re-evaluated through the inclusion of modern specimens from Central Iran as a separate group in the reference dataset. The results indicate that, contrary to what was previously thought, the Ganj Dareh specimens are likely related to the Central Iranian Lineage. Their idiosyncrasy compared with modern representatives, however suggests a complex temporal dynamic of admixture, which may have been influenced by early human settlements and movements.