Human beings fancy ourselves to be quite an intelligent species. With our relatively enormous brains and intricate handling of the five senses, we like to believe that the things we see, touch, smell, taste, and hear, define the boundaries of our universe. Yet, evidence of our shortcomings exists in plain sight on our own bodies. This becomes even more prominent when compared to the furry companions we often assume we are superior to. 

After living together for almost a decade, my dog is rather sick of me. While she is educated enough to know her name, I no longer even get a turn of a head when I call her. Often, the only response I receive is a wiggle of the ears as she turns them towards me. I, the source of sound, must wait as she considers whether my call for attention is worthy of her time. In this scenario, my dog’s ego might not be the only thing giving her superiority - in the realm of ear wiggling, her abilities are anatomically unattainable to us mere humans.

The muscles responsible for this skill are the auriculares, with the anterior controlling upwards and forwards movement, the superior controlling the upwards and downwards movement, and finally the posterior pulling them backwards (1). In other species such as dogs, cats and horses, these muscles have evolved to become intricate over generations, with dogs manoeuvring their ears using 18 muscles, and cats using more than 30 (2).

In most human beings, voluntary control of the ears has been almost entirely lost. For the 15 percent (3) of us who can wiggle our ears, the trait is vestigial – effectively useless, except for perhaps readjusting your glasses without using your hands. 

Despite this, ear wiggling was once a useful functional trait in our ancestral Homo species. Tracing back more than 150 million years (4), a common ancestor of mammals learnt to pivot and curl their ears for evolutionary advantage. It is theorised that before we walked upright, our own primate predecessors directed their ears in response to sound (5). This allowed them to pinpoint sources of danger that were hard to locate while moving on all fours. It was a mechanism comparable to when big cats, like those often featured in Attenborough documentaries, perk up their ears as they prowl through the grasslands. In fact, most of our mammalian relatives (6), other than our closest ape family, have preserved some level of ear wiggling ability, from foxes and wolves to lemurs and koalas. 

The deterioration of human ear-wiggling began with the emergence of bipedalism. As our ancestors lifted upright, off their knuckles and onto two feet, their entire centre of gravity shifted. This awarded them a wider scope of vision and diurnal activity (7), meaning they began to primarily operate during the day, so humans began relying on vision for many important things: hunting, protecting and surviving. Ear-wiggling's role in showing emotional expressions, such as anger or fear (8), was also replaced with gestures of the hands that were now free to be swung about. With no need for the sophisticated ear machinery that evolution had equipped us with, human beings’ ability to move our ears diminished, while our eyesight drastically improved.

It seems that over time, the ear-orienting ability in humans simply died out with evolution. 

We have not let go of it completely, though. Interestingly, Homo sapiens have retained the neural circuits that were once responsible for ear movement. In the journal Psychophysiology by Steve Hackley (9), a cognitive neuroscientist at the University of Missouri, remnants of this neural circuitry were observed in clinical studies. When stimulated by an unexpected sound, the muscles behind the corresponding ears twitched and curled. Similarly, distraction with sounds of bird songs while attempting a set task kick-started bursts of ear muscle activity. 

​While ear wiggling is no longer required for our survival, we exist as evolutionary fossils. As humans, we now have other options in well-established senses while hearing remains a dominant form of sensory input in other species – a very well-refined one too, if my dog’s ability to recognise the sound of her treat packet opening is anything to go by. While the only thing human ear-wigglers have is a cool party trick, our furry friends have mastered intricate ear control, giving them a paw up on us at least in this race.