Friday07 February 2025
korr.in.ua

Most people haven't used these muscles for 25 million years, yet some can still engage them.

Research indicates that approximately 10-20% of people worldwide have the ability to control muscles that others do not utilize.
Большинство людей не использовали эти мышцы последние 25 миллионов лет, но некоторые все еще способны это делать.

It is no secret that our distant ancestors had several body parts that became fairly useless over the course of evolution. Among these are wisdom teeth, tails present during the sixth week of pregnancy, and ear muscles. These muscles helped our ancestors reshape their outer ears millions of years ago, which enhanced their hearing abilities. However, around 10-20% of people worldwide can still control these muscles to wiggle their ears, as reported by Popular Science.

Now, scientists believe that these rudimentary ear muscles may actually be used more frequently than previously thought. In a recent study, researchers proposed that the ear muscles activate when people attempt to listen to competing sounds. It’s noteworthy that it was once believed these muscles only activated during ear wiggling.

According to co-author of the study, neurobiologist Andreas Schreer from Saarland University in Germany, there are three major muscles connecting the outer ear to the skull and scalp — they play a crucial role in the ear-wiggling process. The researchers also found that these muscles, particularly the superior auricular muscle, exhibit increased activity during demanding listening tasks. In simple terms, these muscles are engaged not merely as a reflex but potentially play a role in the attention enhancement mechanism, especially in complex auditory environments.

In the new study, the scientists employed a technique known as electromyography. This allowed them to gauge how intensely a person is listening without directly asking the participants. It's important to mention that the technique measures electrical activity in the muscle and can accurately pinpoint activity in the ear muscles associated with attentive listening. The results indicated that the largest muscles, the posterior and superior auricular muscles, respond during focused listening. In fact, these muscles pull the ears upward and backward — the researchers believe they historically assisted in moving the outer ear to capture sounds.

Schreer notes that it is extremely challenging to determine why these muscles eventually became rudimentary, but suggests it may be due to evolutionary pressures to move the ears that ceased as humans became more adept at utilizing visual and vocal systems.

Furthermore, the scientists sought to discover whether the muscles become more active during more complex listening tasks. The team studied 20 individuals with no documented hearing issues. In the first phase, electrodes were placed on the participants' ear muscles, and then an audiobook and several distracting podcasts were played from speakers positioned in front of or behind the listeners. All 20 participants underwent 12 five-minute trials covering three different difficulty levels.

In the easy mode, the podcast was quieter than the audiobook, while the speaker's voice contrasted more strongly with the audiobook. In the medium and hard modes, researchers added a podcast that sounded more like the audiobook and increased the volume of the distracting sounds. However, they had to ensure that even the most challenging situations remained achievable, as if participants gave up, the physiological effort would not register on the machines.

Next, the participants were asked to evaluate the level of their efforts and how often they lost track of what was happening while listening to the audiobooks during each trial. It’s noteworthy that participants were also surveyed about the audiobook materials.

The results showed that the two ear muscles responded differently to varying conditions. For instance, the posterior muscles changed direction, while the superior muscles reacted to the task's difficulty level. In comparison, the superior auricular muscles responded to the task's complexity. Participants’ self-assessment of how difficult it was to listen and how often they lost the audiobook also increased in accordance with the task's difficulty. Their accuracy in answering questions about the audiobook significantly decreased between the medium and hard modes.

The data suggest that the activity of the ear muscles could provide an objective measure of effort during listening. However, it remains unclear whether muscle activity genuinely aids people in hearing better.

The authors of the study note that ear movements in response to signals are extremely minimal and likely offer no real benefit. However, this indicates that our ear muscles, after 25 million years of being rudimentary, are trying their hardest, yet it seems to yield no advantage.