The wings of cliff swallows in Nebraska are getting shorter – while female turtles in Chesapeake Bay are getting larger. On the Galapagos Islands, two species of finches are developing back into one. Increasing numbers of peregrine falcons are living in urban areas – and have adapted their behaviour: thanks to the city lights, they have learnt to hunt at night. What has happened to evolution? The answer is very simple: us. Life emerged three and a half billion years ago and since then has evolved into a dazzling variety of shapes and forms. Species that are better adapted to their environment survive, selected by nature to breed and pass on their genes to the next generation through a process called natural selection. Humans have played a part in this new development as well, as they have transformed our planet beyond recognition – turning grasslands and forests into fields and cities, and polluting the air and water, thus changing the environment of many animals. All of these changes have altered the course of evolution – in some surprising and unexpected ways. The process known as natural selection has now taken on another, quite different dimension: ‘Unnatural Selection’.