This month we're taking a look at the world of top models - not the kind that won't get out of bed for less than ten grand, but the model organisms used by researchers all over the world to answer some of the most challenging questions in biology. We'll also be hearing about the origins of polar bears, the extinction of Tasmanian tigers, fitter frogs with faster-changing genomes and promiscuous bees. And move over Beyonce, because our gene of the month is the curvaceous Callipyge - Greek for beautiful buttocks.