Depending on species, lineage, and whether or not they are captive, rats live between one and four years. The average pet rat lives two or three years, while wild rats rarely live past one year. Pet rats from certain lineages live longer due to good breeding.
There are two common species of rat: the black rat and the brown or Norway rat. Black rats have an average life expectancy of one year in the wild and four years in captivity.
Norway rats have been domesticated for use in research and the pet trade. They have a two-year lifespan in the wild, but their lifespan in captivity is about the same as black rats. Norway rats sold as live feed for reptiles, known as feeder rats or pinkies, tend to be less healthy when raised to maturity and are more susceptible to tumors than other rat lines. The longest-lived rat on record as of 2014 is a domesticated Norway rat from Japan named Rodney, who lived seven years and four months, dying on May 25, 1990.