Dawkins points out that at insect scale, flight isn't particularly interesting: in many environments, tiny organisms would have difficulty not flying. Thus, it

Dawkins points out that at insect scale, flight isn't particularly interesting: in many environments, tiny organisms would have difficulty not flying. Thus, it may be that wings started as little rudders to control how the wind is blowing you. From that point, it's easy to imagine a gradual evolution to self-powered flight. But I'm afraid this doesn't help us understand avian and mammalian evolution of flight. The example of the flying squirrel (that can't fly, but can direct his glide) may be a little instructive...