Why scientists need to stop worrying about whether or not everything in biology serves a purpose.

John Brockman, the publisher and science impresario who runs the online science and culture salon Edge.org [5], has asked his provocative, annual Edge question: What scientific idea is ready for retirement? "Few truly new ideas are developed without abandoning old ones first," Brockman writes. "What established scientific idea is ready to be moved aside so that science can advance?"

Here’s my candidate for forced retirement: The idea that we need to distinguish between things in biology that are there for a purpose and those that aren’t.