The lure of molecular computing: While marketable products seem decades away, researchers are crystallizing theories and devices that will give biological organisms the power to compute

A splinter suddenly punctures your finger and lodges beneath the skin. Harmful bacteria begin to enter your bloodstream. A white blood cell recognizes a molecular structure on the surface of one of the invaders as it brushes by, triggering an elaborate sequence of defensive actions. This sequence, a cascade of chemical reactions within and between cells, occurs without any electric signals from nerves. In time, your finger swells, a dramatic macroscopic readout of these chemical and cellular events.