Question

Why do giraffes have a recurrent laryngeal nerve that is several meters longer than the shortest possible route?

1) Their ancestors were fish and did not have a larynx
2) The route of that nerve was inherited from their ancestors
3) The nerve makes more connections to their lungs than it did in their ancestors
4) The route that the nerve takes is the result of random processes

Answer 1

Giraffes have a long recurrent laryngeal nerve due to inherited anatomical features from their ancestors. The elongation of their necks over generations to reach high leaves also extended the nerve's length.Option 2 is the correct answer.

Step-by-step explanation:

The reason why giraffes have a recurrent laryngeal nerve that is significantly longer than the shortest possible route is because the route of that nerve was inherited from their ancestors. This nerve's trajectory is a result of the evolutionary history of giraffes. As their necks grew longer to help them reach higher leaves, so too did the recurrent laryngeal nerve because it has to loop around the aortic arch and go back up to the larynx. This path is not about making more connections to the lungs or being caused by random processes; it is simply a byproduct of anatomical development from the giraffe's ancestors.

LibreTexts explains how giraffes with longer necks had greater fitness, as they could reach leaves that others could not. Over time, this neck elongation would also affect the length of the nerve. Giraffes evolved from shorter-necked ancestors, and despite the seeming inefficiency, the existing developmental pathways in their ancestors laid the groundwork for this nerve's extended route.