American Scientist

When something is designed, decisions are necessarily made. Deliberate progress cannot proceed without choices—as to whether a part goes to the right or the left of another part, whether a component is larger or smaller. In some cases a clear historical record documents for us the evolutionary design process that brought us the thing that we contemplate. Looking into that record in detail can help us understand why certain things are the way they are and, perhaps more importantly, help us understand how things in general come to take the forms that they do. One case study that has these attributes encompasses the keypads of two familiar artifacts that most of us use daily: those of the telephone and the hand-held calculator.