The Recurrent Laryngeal Nerve

Professor Richard Dawkins narrates as another biologist dissects the neck of a giraffe which had recently died in a zoo. The nerve they are studying serves the larynx and coordinates making sounds, breathing, and swallowing.

In our fish ancestors — as in modern fish — the nerve runs a very short distance from the brain to the gills, near the heart — “a couple of inches” in a fairly large fish. But when the fish began to develop necks and evolve into amphibians, reptiles, and finally mammals, and the heart moved downward in the body, the nerve was forced to loop down through the chest, around the aorta, and back up the neck to the larynx.

In humans this is just a few unnecessary inches, but how does it work in a giraffe?

The reason for dissecting the neck of this giraffe was to see how this particular nerve is routed. The experiment had been performed only once before, in 1838, so this was a confirmation of the original experiment.

Sure enough, the nerve wound down through the giraffe’s long neck, around the aorta, and all the way back up the neck to the larynx. As Dawkins concludes, it is easy to understand how this strange situation evolved, step by step. But it is not a situation any designer would have created.

 

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