A society of virtual "agents" - each with a remarkably realistic personality and the ability to learn and communicate - is being crafted by scientists from five European research institutes who hope to gain insights into the way human societies evolve.

Advanced computer simulations let epidemiologists unleash virtual plagues in real cities to see which interventions could best quell outbreaks of disease.

The Pentagon needs 21st-century analytical tools to replace the outmoded war games of yore, which, despite improvements in computer power, are still one-dimensional, culturally blinkered and of small use in devising strategies for asymmetric warfare. So it has earmarked over $100 million to determine whether the agent-based models used in commercial role playing games can advance the strategic game.

Agent-based modeling is an emerging computer technology that holds promise as a powerful tool for analyzing policy problems -- and experts in the field believe it has the potential to fundamentally change the way social scientists and economists test theories, examine data, and create new policies.

The new science of artificial societies suggests that real ones are both more predictable and more surprising than we thought. Growing long-vanished civilizations and modern-day genocides on computers will probably never enable us to foresee the future in detail?but we might learn to anticipate the kinds of events that lie ahead, and where to look for interventions that might work.