Rats have a complex and ancient relationship with humanity, spanning millennia. Their history is not marked by a single “discovery,” but by gradual interaction, unintentional global spread, and formal scientific recognition. These adaptable rodents have lived alongside humans for thousands of years, evolving and migrating as human civilizations expanded.
Early Coexistence and Initial Spread
The earliest evidence of rats coexisting with humans points to their origins in Asia. Archaeological findings suggest large rats lived alongside early humans on East Timor approximately 46,000 years ago. Evidence from central or northern China, dating back 7,000 to 9,000 years, indicates a commensal relationship between brown rats and humans, found with human refuse. This proximity allowed rats to benefit from human settlements, utilizing discarded food and shelter.
As human societies developed, rats spread by capitalizing on early human migration routes and trade networks. Unintentionally carried by people, these rodents traveled across continents as stowaways on early ships and caravans. This early diffusion laid the groundwork for their later, more significant global migrations.
The Great Migrations: Black and Brown Rats
Two species, the black rat (Rattus rattus) and the brown rat (Rattus norvegicus), became particularly widespread, each with distinct migratory histories. The black rat, also known as the roof rat or ship rat, originated in the Indian subcontinent or Southeast Asia. It spread to the Near East, Egypt, and throughout the Roman Empire, reaching Great Britain by the 1st century AD. Ancient DNA analysis shows black rats colonized Europe in two distinct waves, mirroring human trade and urbanism.
The black rat was prevalent across Europe until the 18th century, but its population declined with the arrival of the brown rat. The brown rat, also known as the common rat, originated in northern China or Mongolia. It reached Eastern Europe by the early 18th century and was present in Ireland by 1722, England by 1730, and France by 1735.
Brown rats arrived in North America around 1740-1755, typically as stowaways on ships. They often displaced black rats in human settlements, partly because they are larger and more aggressive. The shift from wooden structures to brick and tiled buildings also favored the burrowing habits of brown rats over the arboreal black rats, contributing to their widespread presence.
Formal Recognition and Scientific Understanding
The systematic classification of rats marked a significant shift from anecdotal observations to scientific understanding. Carl Linnaeus formally classified the black rat, Rattus rattus, in 1758. This established a standardized binomial name for the species.
In 1778, Peter Simon Pallas classified the brown rat, initially naming it Mus decumanus. Though Pallas’s name was widely used, John Berkenhout popularized the current binomial name, Rattus norvegicus, in 1769. This formal classification solidified rats’ place within biological studies.