From the Unselfish Gene ... "Nobel laureate Gary Becker argued in 1968 that the calculus of criminals is best understood as a set of rational trade-offs between the benefits of crime and the costs of punishment, discounted by the probability of detection. Imposing harsher punishments and increasing police enforcement, people concluded, are the obvious ways to tackle crime. The same year, Garrett Hardin described the tragedy of the commons—the parable about farmers who shared a piece of land with no restrictions on the number of cattle each could graze on it. They kept letting more cattle graze on the commons until the grass was gone, leaving nothing for anyone. No one stopped grazing animals, Hardin argued, for fear of losing out to the other farmers, who would continue overexploiting the commons. The conclusion was that as self-interested actors, human beings will inevitably destroy shared resources unless the latter are subject either to regulation or to property rights.  Like biology, however, the discipline of economics has changed over the years. In 2009, Elinor Ostrom was awarded the Nobel Prize in economics for showing how commons can -- and do -- sustain themselves for centuries as well-functioning systems. The most striking example is in Spain, where thousands of farmers have been managing their access to water through self-regulated irrigation districts for more than five centuries. To take another example, 75% of U.S. cities with populations of more than 50,000 have successfully adopted some version of community policing, which reduces crime not by imposing harsher penalties but by humanizing the interactions of the police with local communities."