Where did domestic rats come from? - briefly
Domestic rats are descendants of the wild brown rat (Rattus norvegicus), which originated in Central Asia. Human trade and maritime transport spread the species worldwide, leading to its domestication.
Where did domestic rats come from? - in detail
Domestic rats belong to the species Rattus norvegicus, originally a wild, brown‑coated rodent that inhabited temperate regions of Eurasia. The first populations that later became pets and laboratory animals were captured from these wild stocks.
Archaeological and genetic data indicate that the species spread from its native range through human‑mediated transport. By the early 1700s, ships sailing between Europe and Asia routinely carried rats that disembarked at ports, establishing feral colonies in new continents. These colonies provided a readily available supply of individuals for early scientific experiments and for people who began keeping them as companions.
Key stages in the development of the domestic form include:
- 18th‑century Europe: Naturalists and physicians began breeding rats for observation, selecting for reduced aggression and tameness.
- Mid‑19th century: Laboratories in England and Germany standardized breeding lines, emphasizing rapid growth, uniform coat color, and predictable reproductive cycles.
- Early‑20th century: Pet trade emerged in the United States and Britain, with breeders focusing on distinct coat patterns, docile temperament, and health robustness.
- Late‑20th century onward: Genetic analyses revealed that modern domestic rats retain most of the wild genome, with only a few loci showing selection for behavior and coat traits.
The domestication process relied on three primary factors: continuous proximity to human settlements, intentional selective breeding for manageable behavior, and the species’ high reproductive rate, which allowed rapid fixation of desired traits. Consequently, today’s pet and laboratory rats are genetically close to their wild ancestors but exhibit markedly altered behavior, morphology, and physiology suited to human environments.