The distinction between function and role is a vexed and difficult one. While the distinction appears to be useful, in practice it is hard to apply; this can be even worse when applying this distinction to biology. In this paper, I take an evolutionary approach, considering a series of examples, to develop and generate definitions for these concepts. I test them in practice against work performed on the Ontology for Biomedical Investigations (OBI). Finally, I give an axiomatisation and discuss methods for applying these definitions in practice
