Over the last 25 years, scientists have discovered an exquisite world of nanotechnology within living cells. Inside these tiny labyrinthine enclosures, scientists have found functioning turbines, miniature pumps, sliding clamps, complex circuits, rotary engines, and machines for copying, reading and editing digital information-hardly the simple "globules of plasm" envisioned by Darwin's contemporaries.
Moreover, most of these circuits and machines depend on the coordinated function of many separate parts. For example, scientists have discovered that bacterial cells are propelled by miniature rotary engines called flagellar motors that rotate at speeds up to 100,000 rpm. These engines look for all-the world as if they were designed by the Mazda corporation, with many distinct mechanical parts (made of proteins) including rotors, stators, O-rings, bushings, U-joints, and drive shafts.
Is this appearance of design merely illusory? Could natural selection have produced this appearance in a neo-Darwinian fashion one tiny incremental mutation at a time? Biochemist Michael Behe argues 'no.' He points out that the flagellar motor depends upon the coordinated function of 30 protein parts. Yet the absence of any one of these parts results in the complete loss of motor function. Remove one of the necessary proteins (as scientists can do experimentally) and the rotary motor simply doesn't work. The motor is, in Behe's terminology, "irreducibly complex."