In the Tangled Bank, I wrote about how life has to evolve within constraints--constraints of physics, development, and history. One of the examples I used was the laryngeal nerve in giraffes. It travels down the giraffe's neck, takes a U turn, and then heads back up again. It seems ridiculous, but makes sense if you think about how it was laid down in fish without necks, and was then gradually modified--rather than re-engineered outright--as tetrapods grew necks, and then taken to surreal extremes in the long-necked giraffe. Youtube has an excellent snippet of Richard Dawkins hanging out with an anatomist as she dissects a giraffe's neck, to show what this remarkable evolutionary legacy really looks like. Warning: it's bloody, like all dissections. But it's worth the gore! (PS: Anybody know what show this came from?) (PPS: Turns out, it's from "Inside Nature's Giants." Wish I could see it from the States!)