Genomes and evolution Deciphering the genomic palimpsest

www.sciencedirect.com Introduction A genome is a great compendium of interwoven texts written at different times by different authors (we speak, of course, metaphorically). Some genomes are prolix whereas others are terse. The original text may be supplemented by epigenetic annotations or overwritten by the graffiti of parasitic elements. Sometimes an insertion from another story becomes incorporated into a new and unintended message. An organism’s evolutionary history lies hidden within the multiple layers of this document if only we knew how to decipher a text without a unifying narrative or single coherent plot. Several of these compendia have now been published, and many more are in press, but the problem of interpretation has just begun. This issue of Current Opinion in Genetics and Development provides an anthology of commentaries on these documents and their interpretation. A single story-line may be hard to discern, but there are several recurrent themes.