npr.org – By Wynne Davis , Mallory Yu and Kelly McEvers – The Empire State building, pizza and Broadway are just a few things synonymous with New York City — and then there’s the rats. Like many other major metropolitan areas, New York City has a rat problem. But that doesn’t mean that all the rats are the same. Matthew Combs is a graduate student at Fordham University who studies rats. In a recently published paper of his, Combs shared his findings about the genetics of the city’s brown rats.