Where did mice and rats originate? - briefly
Mice and rats evolved in Asia, with the house mouse (Mus musculus) and the brown rat (Rattus norvegicus) originating in South‑East and East Asian regions before spreading worldwide through human activity. Archaeological records date their diversification to roughly 2–3 million years ago, and subsequent human trade and settlement propelled their global distribution.
Where did mice and rats originate? - in detail
Mice and rats belong to the family Muridae, a lineage that emerged in the early Eocene, approximately 55 million years ago. Fossil evidence places the earliest murid ancestors in Asia, where primitive forms such as Pseudocricetomys and Pseudomys have been recovered from sedimentary deposits in China and Mongolia. These early rodents exhibit dental and skeletal characteristics that link them to later members of the subfamily Murinae, which includes the modern house mouse (Mus musculus) and the brown rat (Rattus norvegicus).
Subsequent diversification occurred during the Oligocene and Miocene, as murines spread across the Eurasian continent. Phylogenetic analyses based on mitochondrial and nuclear DNA indicate two major clades: an Asian–European branch that gave rise to Mus species, and an African–Asian branch that produced Rattus lineages. The expansion into Africa and later into North America was facilitated by land bridges and later by human-mediated transport.
Key milestones in the global distribution of these rodents include:
- Emergence of Mus in the Mediterranean region during the late Miocene, followed by rapid colonization of temperate zones.
- Appearance of Rattus in Southeast Asia around the Pliocene, with subsequent spread to the Indian subcontinent and East Africa.
- Introduction to the Americas via European ships in the 16th century, establishing commensal populations in urban environments worldwide.
Modern Mus and Rattus species exhibit remarkable adaptability, thriving in diverse habitats from arid deserts to temperate forests. Their evolutionary success is reflected in a rich fossil record and extensive genetic data, confirming an Asian origin followed by extensive radiations driven by climatic shifts and anthropogenic dispersal.