Less like a Ferrari and more like a junkyard go-kart, the arrangements of organs within our vertebrate bodies are far from well-ordered. This is especially true of our internal wiring, specifically the network of nerves present in all animal bodies.
There is no better example than giraffes and the curious case of their recurrent laryngeal nerve – the nerve that helps mammals to swallow, and in humans assists with speech.
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Rather than passing from brain to neck, however, the nerve travels circuitously from the brain, looping around the aorta situated above the heart before heading back up into the larynx. It makes a loop where one is not needed, a result of organs evolving alongside one another, working to their own aims without a general ‘manager’ overseeing the project as it evolves.
In giraffes, the inefficiency of this arrangement is exposed to a staggering degree. The recurrent laryngeal in these mammals takes a 4.5m detour around the heart before heading back up into the neck.
It’s a famous example of so-called evolutionary ‘bad design’. The laryngeal nerve exposes natural selection as little more than an unskilled electrician that, rather than fitting a new set of plug sockets into a wall, chooses to buy a cheap extension lead and hide it under the carpet. In the case of giraffes, it’s become an expensive job that almost appears unfit for purpose.
