Another “leftover” “vestigial” piece of anatomy turns out to be useful after all.
The muscles around the outer ear are unquestionably used by most mammals. We can see a dog or cat moving both ears to listen in various directions. The outer ears are also used for emotional signaling, showing fear or alertness or curiosity if you know how to read them.
Until now scientists assumed our auricular muscles were vestigial. We can move each ear voluntarily, and we can practice to do it more flexibly. But our flat ears aren’t good reflectors or focusers, so the ability must not be actively used.
Oops.
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But in 2020, Daniel Strauss at Saarland University in Germany and his colleagues found that they actually become activated in response to hearing sounds from different directions, prompting them to wonder whether this also happens when people are concentrating on listening.
To explore this, the researchers got 20 people with typical hearing, all aged between 22 and 37, to take three hearing tests of varying difficulty. They all involved focusing on a 5-minute audiobook clip narrated by a female voice while skin sensors measured electrical activity in their auricular muscles.
The researchers found that the largest auricular muscle, the superior auricular muscle, became most activated during the difficult test.
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As usual the researchers proposed ways to use this knowledge in designing hearing aids, and closed with the automatic finale “More research is needed” which means “More money, please!”
The hearing aid idea makes sense. One big problem with aids is that they eliminate localization. When all the sound is piped directly into the canal, we lose the directional filtering of the outer ear. The variously shaped channels damp different frequencies, and we interpret this shaping to determine whether a sound is coming from above or below or behind.
Since every muscle has a kinesthetic feedback sensor as well, we probably have sensors to provide control feedback for this motion. The aid could move the ear a bit to focus on direction, and the brain might sense this feedback as coming from the real motion.
Nature is a hoarder and saver. Everything is stored and ready for use, and the more we use it the more it develops. Nature doesn’t play modern destructive games like just-in-time inventory or Quantitative Easing.
Until recently science followed the Endarkenment model of Tabula Rasa. Every person is an identical passive machine, ready to be shaped and molded by “benevolent” schools and robber barons. The genome is constant and only determines trivial differences like eye color. We couldn’t recognize the vast majority of genes as VARIABLE and responsive because variability and feedback can’t exist by official definition. Feedback is junk by official definition.
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