Training unusual animals to serve human ends has proved surprisingly easy, in part because of the extensive research that scientists have done simply to find out why they do what they do. Lewis knew the wasp responded to smells it identified with food and with reproduction. Radio transmitters were too heavy, and although scientists had had some success gluing microchips on the bees, the process took too long. When the insects smell an odor, they duck their heads to receive the reward, tripping an electric eye. Lewis said such a device could work well searching for explosives at airports, cocaine at the border, or even traces of disease in odors from the human body.
Moths use their antennae to detect different odors.
The eventual goal is to put the antennae in a mobile cyborg that can both sense a land mine and flag the target. In the insect experiments, researchers are trying to pick one odor from a barrage of competing signals, but in Los Angeles, the University of Southern California's Baudry has reversed the approach by modeling hundreds of thousands of signals that describe a normal environment. The sophistication of the mammalian brain, coupled with modern computer capacity, has given this research almost unlimited potential, for once scientists assemble a library of responses, they can screen for practically anything, including testing thousands of chemicals to see if one might produce a novel medicine. One barrier to the practical exploitation of critter devices is the need to increase their life span. In simpler organisms, this hurdle can be lower.