Great article. But I hesitate to call feathers one of evolution's cleverest inventions. The natural world is chock full of amazing evolved engineering from the huge (the hearts of blue whales) to the intricate (the brains of hominids) to the diverse (the various forms of eyes from compound to pinhole, to lensed), to the tiny (white blood cells). Everywhere you look there are feats of engineering that would awe anyone.