Our genetic closet holds skeletons. The bones of long-dead genes--known as pseudogenes--litter our chromosomes. But like other fossils, they illuminate the evolutionary history of today's more familiar forms, and emerging evidence indicates that a few of these DNA dinosaurs may not be quite so dead after all. Signs of activity among pseudogenes are another reminder that although the project to sequence the human genome (the complete set of genetic information in the nuclei of our cells) was officially finished, scientists are still just beginning to unravel its complexities.
It is already clear that a whole genome is less like a static library of information than an active computer operating system for a living thing. Pseudogenes may analogously be vestiges of old code associated with defunct routines, but they also constitute a fascinating record contained within the overall program of how it has grown and diversified over time. As products of the processes by which genomes remodel and update themselves, pseudogenes are providing new insights into those dynamics, as well as hints about their own, possibly ongoing, role in our genome.