 As can be seen from the letter to Asa Gray of March 1870 (Burkhardt et al. 2010 18: 68) , Darwin was particularly exercised by the issue of ethics in preparing the Descent. His published treatment focused the long chapter three of the Descent on the issue of the “moral sense”. In approaching ethics “exclusively from the side of natural history” (Descent 1871: vol 1: 71), he offered some innovations that do not easily map on to standard ethical positions formulated around the familiar categories of Utilitarianism and the Kantian heritage of Deontology. The closest connections might be drawn with certain aspects of contemporary virtue ethics and some aspects of Natural Law theory, although there are many specific differences that prevent assimilation to these traditions as well (Sloan 1999). His closest historical affinities are with the Scottish moral sense tradition of Adam Smith, David Hume, and particularly as this was developed in the writings of Darwin’s distant relative, Sir James Macintosh (1765–1832) (R.J. Richards 1987, 1999, 2003, .