14 DAY TRIAL // You know how cats and dogs can move their ears to follow sounds? Well, it looks like there was a time when we humans could do the same. That's right, it would seem that we were once quite similar to these life companions of ours.
Then, evolution happened and we lost our ability to wiggle our ears around to our heart's desire. All the same, proof of this forgotten skill can still be found embedded in our anatomy.
New insights into our evolutionary history
In a recent study in the journal Psychophysiology, University of Missouri researcher Steven Hackley describes so-called vestigial muscles hidden within the posterior wall of the outer ear.
Like wisdom teeth, these muscles are part and parcel of our body but don't really do anything. They once served to orient our ears so that we could follow sounds, but evolution has made them obsolete.
According to specialist Steven Hackley, it was probably around 30 million years ago that our ancestors' ears shrunk, the musculature to go with them changed and so these muscles become useless.
“Everyone has noticed cats or dogs orienting their ears toward a surprising or otherwise interesting sound; we as humans, of course, don't make ear movements when we focus our attention.”
“Significant changes in the human auditory system began soon after the evolution of dry-nosed primates more than 30 million years ago. Ear size decreased and the associated musculature changed,” the researcher explain in an interview.
They might be useless, but they're not dead
It might be that these muscles embedded in our outer ear are no longer of any use to us, but Steven Hackley says this does not mean that they are completely dead.
On the contrary, experiments have shown that, deep in our brain, there's also a neural circuit to go with them. Even cooler, he says that, when we hear loud, sudden sounds, this neural circuit fires signals.
Admittedly, these signals are nowhere near strong enough for the muscles they are meant for to respond, but they do happen. So, the vestigial muscles still work.
Although too weak to make us move our ears around, Steven Hackley says these reflexes that we seem to still possess could nonetheless come in handy, albeit merely for research purposes.
Thus, the researcher says the muscles and the neural circuit operating them could help us better understand hearing deficits. Then, their study could also shed new light on our evolutionary history.