Sean Carroll in Preposterous Universe:
Evolution has equipped species with a variety of ways to travel through the air — flapping, gliding, floating, not to mention jumping really high. But it hasn’t invented jet engines. What are the different ways that heavier-than-air objects might be made to fly, and why does natural selection produce some of them but not others? Richard Dawkins has a new book on the subject, Flights of Fancy: Defying Gravity by Design and Evolution. We take the opportunity to talk about other central issues in evolution: levels of selection, the extended phenotype, the role of adaptation, and how genes relate to organisms.
More here.