The core of ethics runs deep in our species and is common to human beings everywhere. It survives the most appalling hardships and the most ruthless attempts to deprive human beings of their humanity. Nevertheless, some people resist the idea that his core has a biological basis which we have inherited from our pre-human ancestors.

Chapter 2, The Biological Basis Of Ethics, p. 27 - The Expanding Circle: Ethics, Evolution, and Moral Progress (1981)