Mondays Proof. Edited*
The recurrent laryngeal nerve is a proof of evolution that shows it occurs without any foresight. There are numerous blunders left as evidence of our gradual modification from simpler organisms. It shows that evolution is an unintelligent process.
The recurrent laryngeal nerve is a nerve that controls our larynx (voice box). It's not far from the brain. The best route for this nerve would be a direct route. This does not happen. The nerve takes a detour, as it exits the brain, the nerve travels down the neck, past its destination, and continues down to the heart, where it loops around an artery, and then proceeds back up the neck to the larynx. In humans this detour is a few feet. In Giraffes this detour is amazing, but in sauropods, the detour is ridiculous.
The reason for this detour is because all tetrapod's evolved from fish. In fish there is no neck, so the path from the brain to it destination is a direct route. But everything gets tangled when you grow a neck. It is impossible for an animal to 'regrow' the nerve to avoid the tangled artery, so we all live with it. To fix this would be a modification that cannot be done in small steps, therefore it is an unbreakable rule that all tetrapods have this mixup. And it's bad engineering.
Here is the nerve detour, shown in a human.
When it becomes advantageous to grow an even longer neck, the nerve must extend.
We can see below the reasons why the nerve gets tangled, everything is straight forward in our ancestors, the fish.
There are many other costs that a giraffe pays by becoming so tall, including the neck vertebrates, and are well covered in the Giraffe episode of the BBC docco, Inside Natures Giants, available on youtube. The following is a scene showin the dissection of the laryngeal nerve in a baby giraffe..
