The evolution of technology within a simple computer model

Technology-the collection of devices and methods available to human society-evolves by constructing new devices and methods from ones that previously exist, and in turn offering these as possible components-building blocks-for the construction of further new devices and elements. The collective of technology in this way forms a network of elements where novel elements are created from existing ones and where more complicated elements evolve from simpler ones. We model this evolution within a simple artificial system on the computer. The elements in our system are logic circuits. New elements are formed by combination from simpler existing elements (circuits), and if a novel combination satisfies one of a set of needs, it is retained as a building block for further combination. We study the properties of the resulting build out. We find that our artificial system can create complicated technologies (circuits), but only by first creating simpler ones as building blocks. Our results mirror Lenski et al.'s: that complex features can be created in biological evolution only if simpler functions are first favored and act as stepping stones. We also find evidence that the resulting collection of technologies exists at self-organized criticality. (c) 2006 Wiley Periodicals, Inc.