As every picnicker knows, if you spill strawberry jam in the grass, it will be swarming with ants in no time at all. The ants arrive quickly because they always find the shortest route from their nests to the spill -- but how? That question is one that fascinates cutting-edge engineers, computer programmers, and other scientists, who study nature in order to design better and more efficient technology -- a quest compellingly described in Peter Bentley's new book, Digital Biology. Digital Biology By Peter J. Bentley Simon and Schuster, 271 pages, 2002 Take the example of the ants: Everywhere an …