Is there a logic to life? To look at the drunks in the park, the teenage gangs gone wild, or the spread of sexually transmitted diseases because people don't use condoms, you'd be forgiven for concluding there is not. Think again.

The evidence for life's logic is coming from an unexpected source: economics. Turning their backs on the study of inflation or the stockmarket, a new breed of young economists is trying to unlock the secrets of love and sex, crime and office politics. And they will do whatever it takes to find out the truth, whether putting subjects into a brain scanner, or persuading corporations to run huge social experiments.

They have discovered that the most unlikely people in the most unlikely circumstances are often responding rationally to incentives, subconsciously weighing up risks and rewards. Once you see the hidden incentives behind the oddities of life, you start to see the world in a new way. The picture isn't always pretty, but it is constantly fascinating.