Most humans haven’t moved these muscles in 25 million years

Throughout evolution, our distant ancestors developed body parts that have become obsolete in modern humans, such as wisdom teeth, tails present during gestation, and auricular muscles in our ears. These muscles, once used for changing the shape of the ear shell and enhancing listening abilities, are still active in a small percentage of people who can wiggle their ears.

Recent research suggests that these vestigial auricular muscles may play a role in attentional efforts during challenging listening tasks, not just ear-wiggling. This study, published in the journal Frontiers in Neuroscience on January 31, sheds light on the potential functions of these muscles.

Andreas Schröer, a neuroscientist from Saarland University and co-author of the study, explains that these auricular muscles, particularly the superior auricular muscle, show increased activity during tasks requiring attentive listening. This suggests a potential role in attentional mechanisms, especially in challenging auditory environments.

Sounds vying for attention

Using electromyography, researchers found that the auricular muscles are activated during attentive listening without the need for self-reporting. The largest muscles, posterior and superior auricular muscles, react during focused listening, indicating their historical involvement in capturing sounds by moving the pinna.

The study participants underwent listening tasks of varying difficulty levels, revealing that the auricular muscles responded differently based on task complexity. The superior auricular muscles showed increased activity during more challenging tasks, suggesting a correlation between muscle activity and listening effort.

Further research is needed to validate these findings and explore practical applications. While the muscles may not significantly improve hearing abilities, they could provide insights into auditory attention. Understanding the role of these vestigial muscles after millions of years of disuse remains a fascinating area for future investigations.

“Our auriculomotor system may be doing its best after 25 million years of dormancy, but its impact on hearing remains uncertain,” says Schröer. Additional studies with larger and more diverse participant groups are necessary to fully comprehend the functions of these intriguing auricular muscles.