They wiggle, though they dont do much else. Thats what weve long thought about the auricular muscles the useless ear muscles that once helped our ancient ancestors hear. But recent research in Frontiers in Neuroscience reveals that these muscles are still trying hard to help us, activating during difficult listening situations.There are three large muscles [that] connect the auricle [the outer ear] to the skull and scalp, said Andreas Schrer, a study author and a neuroscientist at Saarland University in Germany, in a press release. These muscles, particularly the superior auricular muscle, exhibit increased activity during effortful listening tasks.Made For More Than WigglingIn modern humans, auricular muscles arent all that useful. We use them to wiggle our ears (or, some of us do), and thats about all. (Wiggling, as it turns out, isnt a universal skill.) But millions of years ago, our distant ancestors employed these muscles to move their ears around, twisting and turning them towards sound.The exact reason these became vestigial is difficult to tell, as our ancestors lost this ability about 25 million years ago, Schrer said in the release. One possible explanation could be that the evolutionary pressure to move the ears ceased because we became much more proficient with our visual and vocal systems. While we cant contort our ears in the same way today, some of us sure can wiggle them, suggesting that these muscles are still active. Testing their abilities in 2020, Schrer and a team of researchers demonstrated that these muscles activated during listening tasks that featured sounds from different directions. But what about during difficult listening, when several sounds occur at once? To determine whether the activity of these muscles depends on the difficulty of the task, Schrer and a team turned to electromyography, a method that uses electrodes to monitor the electrical activity in muscle tissues. Their results revealed that the more difficult the task, the more active the muscles, at least for the superior auricular muscles.This suggests that these muscles are engaged not merely as a reflex but potentially as part of an attentional effort mechanism, Schrer said in the release, especially in challenging auditory environments.Read More: How Similar Are Humans and Monkeys? When Hearing Is HardTo arrive at their results, the researchers enlisted the help of 20 hearing participants. Applying electrodes to their auricular muscles, the team measured their muscle activity as they listened to an audiobook and a podcast at the same time. The audio played from separate speakers, placed in front of the participants or behind, and each participant listened to 12 trials, separated into three different levels of difficulty. The audiobook was a lot louder than the podcast in the easy trials, and the speakers voices were distinct. But in the moderate and difficult trials, the audiobook was only a little louder than the podcast, and the speakers voices were similar.As the difficulty level of the task increased, so, too did the activity of the superior auricular muscles. Though they remained relatively inactive during the easy and medium trials, the difficult trials saw a surge in their activity. According to the researchers, their activation also correlated with the participants self-assessments and comprehension scores. When the participants were asked to assess the amount of listening effort that they expended in the trials, they reported their effort increased with trial difficulty. And when they were asked to take tests on the audiobooks content, their scores declined in step with the incline in the difficulty of the task.Effort in ListeningFurther research is required to confirm the teams results, and to conclude whether the activity is tied to any actual improvements in listening (though Schrer says that it probably isnt). The ear movements that could be generated by the signals we have recorded are so minuscule that there is probably no perceivable benefit, said Schrer in the press release. Our auriculomotor system probably tries its best after being vestigial for 25 million years, but does not achieve much. Though it isnt likely that this activity helps hearing, it could help hearing research, as the superior auricular muscles could serve, the team says, as an indicator for increased levels of effort in listening.Investigating the possible effects of muscle strain itself or the ears miniscule movements on the transmission of sound is something we want to do in the future, Schrer said in the release. The effect of these factors in people with hearing impairments would also be interesting to investigate.Read More: How Did Humans Evolve?Article SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:Frontiers in Neuroscience. Electromyographic Correlates of Effortful Listening in the Vestigial Auriculomotor SystemSam Walters is a journalist covering archaeology, paleontology, ecology, and evolution for Discover, along with an assortment of other topics. Before joining the Discover team as an assistant editor in 2022, Sam studied journalism at Northwestern University in Evanston, Illinois.