Tools, drugs, and signals in the road from evolution to money

The problem of the biology of money is twofold: It subsumes both the identification of behavioral mechanisms that account for the power of money as an incentive, and the elucidation of the phylogeny of such mechanisms. The drugs-tool distinction, as articulated by Lea & Webley (L&W) in their fascinating synthesis, is a welcome step toward their solution. Compared to the direct invocation of instinctual drives, however, conditioning processes provide a conceptually and empirically clearer road from evolution to money.