NASA’s (ST5) nanosatellites, which are scheduled to start measuring Earth’s magnetosphere in late 2004, requires an antenna that can receive a wide range of frequencies regardless of the spacecraft’s orientation. Rather than leave such exacting requirements in the hands of a human, the engineers decided to breed a design using genetic algorithms and 32 Linux PCs. The computers generated small antenna-constructing programs (the genotypes) and executed them to produce designs (the phenotypes). Then the designs were evaluated using an antenna simulator.
Like strands of DNA, email messages have a standard data format that amounts to a genome for legitimate email. Spammers exploit and mutate email genes to obscure the origin or content of their messages, creating distinctive spam genes. The genetic approach has made it possible for Cloudmark to identify spam with better than 98 percent accuracy. And our system is continually improving: Whenever it mistakes a legit message for spam, a program called the Evolution Engine mutates the spam genes involved and sends the misidentified message back through the filter until it classifies the message correctly. Result: an increasingly precise definition of the spam genome, and thus increasingly effective filtering.
Research into artificial intelligence aims to make machines more responsive to their environments. The AI method, however, has been to program devices to react to specific events, creating machines that are unable to cope with unexpected circumstances. Complexity theory offers a different perspective. If a car were designed like a living thing – as a collection of components wired to regulate one another in response to external stimuli, like organs mediated by a nervous system – it would act more like a living thing.
Colonies of simulated ants laying down digital scent trails can find the best way to send delivery trucks through city streets or data packets through communication networks. More generally, ant algorithms can find minimum-cost solutions to a variety of problems in distribution and logistics. Unilever uses them to allocate storage tanks, chemical mixers, and packaging facilities. Southwest Airlines uses them to optimize its cargo operations. Numerous consulting houses, such as the Swiss firm AntOptima, have embraced them as an indispensable tool.