Robert Farris Thompson, the groundbreaking scholar of African art at Yale University, has recently published a splendid new book, "Tango: The Art History of Love" (Pantheon). On this very special episode of Afropop Worldwide's Hip Deep, Thompson talks to Afropop's own Ned Sublette, author of "Cuba and Its Music: From the First Drums to the Mambo," about the erotic Afro-Argentine dance whose Kikongo-derived name he renders as "moving in time to a beat." With musical examples galore.