Why does the recurrent laryngeal nerve take a circuitous route?
– The laryngeal nerve originates in the brainstem and supplies motor function and sensation to our voice box, also helping us speak and swallow. It takes a circuitous route into the thorax before rising back up to the neck, while it could just as easily go straight from A to B. This circuit comes at a price – it is why when we are punched in the chest, we may have difficulty speaking or swallowing. One can see why the laryngeal nerve is a much bigger problem for the giraffe – being 15 feet longer than it needs to be! In the light of evolution, we can explain why the laryngeal nerve takes such a strange route. Our ancestors took an evolutionary pathway which produced the laryngeal nerve in such a way. Natural selection acted upon that, and there is no undo button. As the giraffe’s neck got longer, the nerves had to grow longer, too. It couldn’t reconnect itself or fix the bad ‘design’. 4. Why do fetuses (and some premature babies) grow hair, and then lose it? – We are pretty much hairle
