Mission Impossible: Trying to Explain the Feather Without Teleology

In an article for National Geographic, "Your Inner Feather," Carl Zimmer writes: "Feathers started out as simple filaments, turning to fuzz, and then diversifying into a lot of different forms -- including the ones that eventually let birds take to the air." Touting a study in Molecular Biology, Zimmer points out that even humans have nearly all of the genetic requirements for feathers. How can this be?

"It may seem strange to consider the fact that you, as a mammal, have all the known genes...