On pages 82-84 of Why Evolution is True I discuss the recurrent laryngeal nerve of humans (and other tetrapods) as an example of evolution. It’s evidence via “retrodiction”, which is what I call the situation when a previously unexplained and puzzling phenomenon can be understood only in light of a theory, thus supporting that theory—in this case, evolution.
Rather than describe it again, here are two videos showing it and explaining how the configuration of that nerve supports evolution.
Creationists have an explanation for it, too (there’s nothing they can’t explain via God’s will, except perhaps the peculiar species composition of oceanic islands), but the goddy story is unconvincing and less parsimonious. Whereas the evolutionary explanation tells us why only one of the twinned cranial nerves does its crazy loop, and why it’s completely comprehensible via the known evolution of tetrapods, the creationist explanation is based solely on how the nerve works: a post facto “functional” explanation of why the creator would create the nerve’s tortuous path. But it doesn’t explain why the creator made that big loop to enervate the larynx when he could have sent a branch directly to the larynx without the loop.
Here Dr. Rohin Francis, a cardiologist and researcher in London, uses his expertise to show how the nerve supports the “tinkering” aspect of evolution:
Below Richard Dawkins attends the dissection of a giraffe, which has an extraordinarily long (5 meter) recurrent laryngeal nerve. Rohin, however, notes above that some long-necked sauropod dinosaurs certainly had a recurrent laryngeal nerve about 28 meters (92 feet) long! I believe I’ve posted this video before, but it goes well with the video above:
In my only visit ever to a human anatomy lab (I get freaked out by corpses), I myself watched the dissection of this nerve by an anatomy professor. And it’s just like the one above, only shorter.