Geckos have a hidden 'sixth sense' linked to hearing

Have you ever stopped to ponder how a gecko might experience the world? For the longest time, we believed that we had a good grasp on how animals like geckos hear and feel their surroundings.

But recent research from the University of Maryland is challenging that notion, revealing a surprise twist in our understanding of animal hearing.

Hearing mechanism of geckos

The research, published in the journal Current Biology, uncovers a hidden “sixth sense” in geckos.

This sixth sense enables geckos to detect low-frequency vibrations using a part of their inner ear called the saccule, previously associated only with maintaining balance and body positioning.

The intriguing discovery challenges long-standing theories about animal sensory systems, suggesting that this alternate hearing mechanism may not be exclusive to geckos, and could be present in other reptilian species as well.

Geckos detect vibrations

Study co-author Catherine Carr, a professor of biology at UMD, elaborated on the findings.

“The ear, as we know it, hears airborne sound. But this ancient inner pathway, which is typically linked to balance, helps geckos detect vibrations that travel through mediums like the ground or water,” said Professor Carr.

The saccule is sensitive enough to detect vibrations ranging from 50 and 200 Hz – well below what geckos usually perceive through their ears. This suggests that the saccule serves a distinctive, yet complementary role to the geckos’ regular auditory system.

Evolution of gecko hearing

Study lead author Dawei Han is a postdoctoral researcher and former graduate student at UMD.

“A lot of snakes and lizards were thought to be ‘mute’ or ‘deaf’ in the sense that they do not vocalize sounds or hear sounds well. But it turns out they could potentially be communicating via vibrational signals using this sensory pathway instead,” explained Han.

This shared sensory pathway in modern reptiles provides fascinating insights into the evolutionary history of vertebrate sensory systems.

It suggests that the transition from aquatic to terrestrial environments likely involved more intricate and gradual changes in hearing mechanisms than previously assumed.

Hearing and balance in humans

While these findings may not directly relate to humans, the researchers emphasize the potential for hidden complexities.

“Think about when you’re at a live rock concert,” said Carr. “It’s so loud that you can feel your whole head and body vibrate in the sound field.”

“You can feel the music, rather than just hearing it. That feeling suggests that the human vestibular system may be stimulated during those loud concerts, meaning our sense of hearing and balance may also be linked closely.” 

Carr and Han hope that their findings will trigger further research into mammalian hearing, especially in relation to this sensory pathway.

The researchers believe that recognizing the link between hearing and balance can lead to a better understanding of disorders related to human hearing and balance.

“The implications of this research extend beyond the world of reptiles,” said Han. “As we uncover these hidden mechanisms, we’re also gaining a richer and more nuanced picture of how animals perceive and interact with their environments – and potentially, new insights into our own sensory experiences.”

Implications for conservation

The research also has significant implications for conservation efforts and the study of animal hearing and behavior. Understanding the gecko’s unconventional sensory capabilities can lead to better strategies for conserving reptilian habitats.

By recognizing the importance of vibrational communication, researchers and conservationists can ensure that environments are preserved or restored with these sensory experiences in mind.

This knowledge could also influence the way we interpret interactions within ecosystems, offering new insights into how reptiles engage with their surroundings, potentially altering our approach to studying their behavior.

Expanding sensory research

The discovery prompts a widespread reconsideration of sensory research across various species. By exploring the evolutionary roots and biological functions of unique sensory pathways, scientists can uncover new dimensions of perception that may have been previously overlooked.

The research broadens the scientific community’s understanding of animal physiology. It also encourages interdisciplinary research, bringing together experts in biology, ecology, and physiology to further explore how these systems have evolved.

The hope is that such collaborations may inspire innovative applications in technology and medicine, simulating vibrational sensors for use in prosthetics or robotics.

Who would have thought that the humble gecko could teach us so much about animal hearing and sensory perception? This could be just the tip of the iceberg when it comes to our understanding of animal hearing.

The study is published in the journal Current Biology.

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