The aim of this book is to examine and challenge the boundaries so often drawn in philosophy, as elsewhere, between humans and other animals, drawing on philosophical, legal and scientific perspectives in order to question the legitimacy and utility of such distinctions and thereby to explore the moral and philosophical meanings of humanity and being human.

A century and half ago, Darwin's theory of evolution challenged the notion of absolute species boundaries, showing that humans were related to animals rather than created unique amongst living creatures and putting us on a continuum...