In technology, as in biology, we like to imagine evolution proceeding onward and upward. As new species and technologies appear, their primitive ancestors drop by the wayside, right? Not exactly. Mammals, birds, and flowering plants-all relatively recent innovations-might seem to rule the earth today. But far older designs, from barnacles to crocodiles, are doing just fine in their respective niches, thank you. New species don't always evolve to replace old ones; they also fill vacant niches, which in turn can actually solidify the standing of older species. So it is with technology.

Paper and bytes are the classic example. In the early 1980s, at the dawn of the PC age, high-volume electronic storage and transmission-360-kilobyte floppy disks! 14-kilobit-per-second modems!-were supposed to make paper superfluous and forests safe. Hah. Electronic data just begat more paper copies. Writers who used to carefully mark corrections on pecked-out manuscripts began printing out one revised version after another. Web surfers started printing out whatever looked interesting. Having data on-screen didn't stop people from wanting to read it, share it, and store it on paper.