Darwinist Jerry Coyne ponders the circuitous course of the recurrent laryngeal nerve. He writes:
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.
The anatomy, embryology, and evolution of the recurrent laryngeal nerve are fascinating. The left recurrent nerve takes a loop down from the vagus nerve in the neck, slips under the aortic arch, and goes back up to the larynx (the voice box). The right recurrent nerve loops under the subclavian artery. They take these circuitous paths because both nerves develop from the 6th pharyngeal arch in the embryo, and several of the great vessels emerging near the heart also develop from the 6th (and 4th) pharyngeal arch. The vessels descend from the neck to the chest to join the heart during development, and trap and drag the recurrent laryngeal nerves with them.
So Coyne, appropriately, applies the design inference to the recurrent laryngeal nerve. “Would a designer have done it this way, or can unintelligent natural selection or chance best explain it?” He arrives at the conclusion that natural selection or chance are better explanations, which is a reasonable conclusion.
By Far the Best Explanation
This is good intelligent design science. We look at biological structure and function, and we ask: “Is this evidence for intelligent design, or is chance or unintelligent natural selection a better explanation?” For many things in biology — the genetic code, the intricate nanotechnology that powers intracellular metabolism, the astonishing functional complexity of the camera eye — intelligent design is by far the best explanation. Chance and unintelligent natural selection are powerless to create such remarkable functional complexity.
It is precisely this design science — evaluation of design and chance and biology according to the evidence — that Coyne uses to attribute the course of the recurrent laryngeal nerve to chance and unintelligent causes.
While I withhold opinion about the recurrent nerve (there is much we don’t understand about its physiology and I don’t want to fall victim to the “natural selection of the gaps” fallacy), I welcome Coyne to the exciting field of intelligent design research. I knew he’d come around.
Photo: Jerry Coyne interviewed by Dave Rubin on The Rubin Report (screen shot).