Rats are our shadow selves. We live on the surface of the city; they generally live below. We mostly work by day; they mostly work by night. But nearly everywhere that people live, rats live too.
In Seattle, where I grew up, the rats excel at climbing sewer pipes—from the inside. Somewhere in my hometown right now, a long, wet Norway rat is poking its twitchy pink nose above the water surface in a toilet bowl. Seattle also has another species, roof rats, which nest in trees and skitter along telephone lines. In the Middle Ages, they may have transmitted plague.
From Seattle to Buenos Aires, urban rat populations are rising—as much as 15 to 20 percent in the past decade, according to one expert. Charismatic animals like elephants, polar bears, and lions are all in decline, yet inside our cities, we find it hard even with extraordinary efforts to keep rat populations in check.