The employment of insecticides raises the relative fitness of resistant insects; the use of antibiotics applies selection pressure in favour of resistant strains of bacteria; lower limits on fish net mesh size raises the advantages of smaller adults. These are some of the many examples of the unintended impact of human activity upon biological evolution. Often this evolution has economic significance, as it does in the examples quoted. This paper examines some of the principles involved and provides a preliminary analysis of the extent to which the economically optimal inducement of evolution differs from that arising when changes in selection pressures are not anticipated.