With better tools—like telephones, Facebook, e-mail, World of Warcraft guilds, and so on—you become slightly more efficient at maintaining relationships, so the number can be larger, but not much larger. Dunbar’s most recent research suggests even power-users of Facebook with 1,000 or more friends still communicate regularly with only around 150 people, and of that 150 they strongly communicate with a group of less than 20.
