How rats became an inescapable part of city living

Brown rats likely originated on the Asian steppes, where they first learned they could eat well by hanging out with humans. They colonized today’s United States before it had that name, by the 1750s, and apparently from both the east and the west. Brown rats along the East Coast are descended mostly from European ancestors, but West Coast rats are a mix of European and Asian genetics.

Source: www.nationalgeographic.com