In the past few decades evolutionary theorists E. O. Wilson of Harvard University and David Sloan Wilson (no relation) of Binghamton University are trying to give group selection full-fledged respectability. They are rebranding it as multilevel selection theory: selection constantly takes place on multiple levels simultaneously. And how do you figure the sum of those selections in any real-world circumstance? “We simply have to examine situations on a case-by-case basis,” Sloan Wilson says.The Wilsons think evolutionists must embrace multilevel selection to do fruitful research in sociobiology—“the study of social behavior from a biological perspective.” When doing so, other investigators can keep in mind the Wilsons’ handy rule of thumb: “Selfishness beats altruism within groups. Altruistic groups beat selfish groups.”