An anonymous reader writes "What is cancer? It's not an invader; it's spawned from our own bodies. And it bears striking resemblance to early multicellular life from 1 billion years ago. This has led astrobiologists and cosmologists Paul Davies and Charlie Lineweaver to suggest that cancer is driven by primitive genes that govern cellular cooperation (abstract), and which kick in when our more recently evolved genes that keep them in check break down. So, far from being rogue cells that mutate out of control, cancers are actually cells that revert to a more ancient level of programming, like booting in Safe Mode. The good news is this means cancers have only finite variation. Once we figure out the ancient genes, we'll know how it works. It's unlikely to evolve any new defense mechanisms, meaning curing cancer might be not quite as mammoth a task as commonly thought."