Author’s note: This is Part Two in a series of conversations with Stuart Burgess, author of Ultimate Engineering: An Engineer Investigates the Biomechanics of the Human Body.
Q. Continuing our look at your Bristol University colleague Lucy Hyde’s essay asserting poor design in the human body, the anatomy professor writes that the configuration of the recurrent laryngeal nerve simply “makes no sense.” In your chapter on the nervous system, you have a section on this specific bundle of nerves. What’s she talking about there, and why is she misinformed?
A. The first point I would make is that engineers are in awe of the nervous system. Think of a spacecraft. It might have 50 miles of wiring. In contrast, the human body has an incredible 50,000 miles of wiring, 1,000 times more than a really sophisticated spacecraft. The whole wiring of the nervous system is just incomprehensible. An engineer understands this. I’ve wired spacecraft myself, and if you have wired a spacecraft, you look at the human nervous system and you think to yourself, I would not dare to criticize and nitpick this system.
When Ignorance Criticizes Blindly
To be blunt, you should resist the temptation to be an “armchair” critic of a super-complex engineering system like the nervous system. Imagine a child looking at the wiring of a Boeing 747 and proclaiming that it looks a mess. Such a judgment is a reflection of the ignorance of the child, not of any fault in the engineering. We see a similar situation with criticisms of the laryngeal nerve.
So, just to explain what this claimed bad design is about, there are two laryngeal nerves that go to the larynx, the voice box. One comes directly from the brain on a short path to the larynx. That’s called the superior laryngeal nerve. Then there’s a second one, the recurrent laryngeal nerve. Instead of going straight to the larynx, it loops down near the heart and then comes back up to the larynx. Lucy’s claim is very common among evolutionists. Basically, they say, “This looks like a silly detour. Why would it go down there? That must be bad design.”
To make a quick first point in response, evolutionists don’t give any reason why this wiring causes a problem. They’re only saying it looks bad. So immediately, there’s a weakness on their part. They’re not explaining any real problem with the design. Nerves hardly weigh anything, so the looping laryngeal nerve is not adding weight. Their only argument is that they think it looks silly.
Q. It’s a very shallow way of looking at something, isn’t it?
A. Yes.
As an engineer, when I look at the laryngeal nerve, I conclude this loop is just the kind of feature I would expect. I have put wiring loops on spacecraft that look exactly like the recurrent laryngeal nerve. Engineers often put loops in wiring. If you looked inside your car, your house, you would find loops of wires that help engineers to assemble and connect the wiring. Something very similar takes place when a baby’s growing in the womb. The organs are moving around, and the whole body is expanding. So sometimes loops can be used to make such movements possible.
But there are other probable reasons for loops as well. Engineers sometimes make a loop in a main cable in order for another smaller cable to piggyback on the main cable. I’ve done this on a spacecraft. I did a special loop for one of my power lines so that I could then get a sensor wire to piggyback on it and go to a certain place. It’s like a bus that does a special looping route around town in order to pick up more people. It doesn’t go on a direct route; it goes on a loop.
This is what you see with the recurrent laryngeal nerve. It has other nerves piggybacking on it. There’s a nerve to the esophagus, for example, and a nerve to the trachea. Those nerves need to be grouped with other nerves in the throat area to form a substantial bundle, and the recurrent laryngeal nerve fulfills this role. So with the laryngeal nerve being diverted, these other nerves could be piggybacked onto it.
Q. That doesn’t sound silly; it sounds efficient.
A. Yes. These are details that engineers see straight away. But Lucy Hyde and Richard Dawkins have not asked engineers to explain design strategies used in wiring systems, which is basically what the nervous system is.
Another important reason for the loop is that by having the superior laryngeal nerve coming from the top and the recurrent laryngeal nerve coming from the bottom, you have nerves on both sides of the larynx. This means you’ve got a redundant system that gives some tolerance in the event of failure of one nerve. I’ve done exactly the same thing when wiring a spacecraft — splitting a cable system into two separate paths.
There have been examples of soldiers who were shot in the throat and survived, only damaging one of those two laryngeal nerves. They could still speak, usually not so well, but they could still speak after being shot. If they’d only had one laryngeal nerve, they would not have been able to speak if they were shot through that nerve. So the recurrent laryngeal nerve gives you that important property of redundancy, just as in spacecraft design.
The Enfeebling “Lens of Evolution”
So engineers are not surprised by the detour of the recurrent laryngeal nerve, but once again, Lucy Hyde is just not thinking about the engineering rationale. As she says in her article, she is looking through the lens of evolution.
This is a really interesting term she uses, because she’s making an admission about a biased worldview. She has the worldview of evolution, which says, “Evolution must be correct. Therefore, I don’t need to ask, is there a reason behind this? I don’t need to speak to engineers, because I’m expecting bad design. I’m looking through the lens of evolution.” Had she spoken to an engineer, she would have found the laryngeal nerve is not a silly design at all. There are no problems with the design, and there are logical reasons for it.
There are many things we do not understand about the nervous system because the design is at such a higher level compared to human technology. So there could well be things that I haven’t even mentioned that explain the design rationale of the recurrent laryngeal nerve. But even if I couldn’t list anything, I would still be confident that there is a reason for what we see.
Q. Because you take the design approach.
A. Yes. So often we discover things that are a great surprise — the level of intricacy, the level of design sophistication. It is very common in academic research papers to read the phrase “we were very surprised to find this sophisticated design in this organism.” The design approach is a humble approach because you recognize that what you’re looking at is superior to what engineers do. If you don’t understand something, you look for a design rationale rather than assuming bad design. This is why a design approach is good for science, whereas an evolutionary worldview often hinders scientific progress.