The following two books will be of interest to those studying the "evolution of morality" and its possible skeptical implications:
Peter Singer, The Expanding Circle: Ethics, Evolution, and Moral Progress, with a new afterword by the author (Princeton University Press, 2011). More information can be found here.
Daniel Kelly, Yuck! The Nature and Moral Significance of Disgust (MIT Press, 2011). For information, go here.