Super long nerve cells are one hell of an interesting evolutionary accident!

One of my favorite “proofs” of evolution is the recurrent laryngeal nerve (RLN)—the nerve that innervates the larynx from the brain, helping us speak and swallow. It takes a very circuitous course, looping from the brainstem down around the aorta and then back up to the larynx. Here’s its course in humans:

It’s a prime example of “bad design”, that is, of the ham-handedness of any creator that was responsible for designing organisms. Of course, we aren’t designed, but evolved from very different ancestors. That’s why our bodies are full of glitches and kludges, and this nerve is one of them. It’s much longer than it need be, taking a tortuous route several feet longer than the direct path from brain to neck.