In making sense of these ideas, the usual way to proceed has been to make use of a rich concept of biological function, in which the function of an entity derives from a history of natural selection (see Teleological Notions in Biology).  This move is familiar from the philosophy of mind, where similar problems arise in the explanation of the semantic properties of mental states (Millikan 1984). When an entity has been subject to and shaped by a history of natural selection, this can provide the grounding for a kind of purposive or normative description of the causal capacities of that entity. To use the standard example (Wright 1973), the function of a heart is to pump blood, not to make thumping sounds, because it is the former effect that has led to hearts being favored by natural selection. The hope is that a similar “teleofunctional” strategy might help make sense of the semantic properties of genes, and perhaps other biological structures with semantic properties.