E.O. Wilson explains why multi-level models of evolution that allow for group selection have of become more accepted in recent times. He writes: “Multilevel selection is gaining in favor among evolutionary biologists because of a recent mathematical proof that kin selection can arise only under special conditions that demonstrably do not exist, and the better fit of multilevel selection to all of the two dozen known animal cases of eusocial evolution.” Read the full article “The Riddle of the Human Species on NYTimes.com.