If you regularly ignored a playground’s monkey bars, seesaw and slide — and instead made a beeline straight to the merry-go-round — you’re likely familiar with the intoxicatingly dizzy feeling that accompanies a good spin session.
The light-headedness may come with a touch of vertigo, causing the world to tilt around you, or even bring on feelings of sudden elation. Sufi whirling dervishes take advantage of these effects, in fact, as a form of meditation and to induce spiritual experiences.
Others undergo extensive training to suppress dizziness while spinning: Professional ballet dancers complete countless pirouettes with ease, for example, and circus performers often dangle gracefully from ropes dozens of feet in the air.
There’s no doubt that humans have found many creative ways to incorporate spinning into our everyday lives. But at what point in our evolution did we begin spinning to induce that characteristic altered mental state? And what purpose does it serve?
Read More: How Did Humans Evolve?
The Science of Spin
When a person twists and twirls, the fluid inside their inner ears is moving, too. Actually, the fluid continues to move — bumping into minuscule hair cells and sending messages to the brain — even after the rest of the body comes to a stop.
This miscommunication between brain and body is typically what causes that dizzy feeling, and can even bring on physiological “highs” at high enough speeds. So go ahead, take a few extra turns in your office computer chair when no one is watching!
Other benefits, particularly for autistic people, include the abilities to increase or reduce sensory stimuli, according to the British National Autistic Society. But disrupting the vestibular system with some lighthearted swirling can be helpful for those not on the spectrum, too.
Adriano Lameira, a primatologist and evolutionary psychologist at the University of Warwick in England, says spinning and similar forms of play are commonly believed to help children sharpen their proprioception and even monitor unconscious physiological mechanisms like breathing and digestion.
“For [other] highly intelligent animals,” he adds, “we could expect similar advantages associated with the exploration of their ‘inner landscapes.’”
The Evolution of Dizziness
Those other highly intelligent animals Lameira is speaking of are orangutans, gorillas, chimpanzees and bonobos.
Last month, he and fellow researcher Marcus Perlman, a lecturer in English language and linguistics at the University of Birmingham in England, published a paper on the prevalence of spinning in these primates, our evolutionary cousins — and what the behavior may reveal about humans.
In other words, if other great apes are also big fans of spinning round and round, it’s safe to assume our desires for dizziness originated in a distant, common ancestor.
“Whether altered state experiences within the hominid family shaped the emergence and evolution of the modern human mind remains one of the major and most thought-provoking unknowns in cognitive science,” the authors write.
Their paper focused specifically on videos of primates hanging on to the bottoms of ropes or vines while twirling through the air. “Being suspended, this allowed great apes to achieve faster spinning revolutions and longer spinning time,” Lameira explains.
The researchers report that the primates spun at an average rotational velocity of 1.43 revolutions per second. (Though, in the case of one daredevil, the fastest sustained rotational speed clocked in at an impressive 3.3 revolutions per second.)
After letting go, they tended to topple over — a clear sign of dizziness — before returning for another few rounds. “This is perhaps the most solid evidence thus far that great apes are experiencing similar physiological ‘highs’ as humans [do] during and after spinning,” Lameira says.
And as it turns out, there’s good supporting evidence at play: Great ape inner ear anatomy is comparable to humans’. “Indeed, it is the most similar among any living nonhuman primate or nonhuman animal, including overall size,” Lameira says.
Inside the Mind
Of course, even with this shared physiology, deciphering the apes’ underlying reasons for getting sloshed — if only for a few minutes — and comparing them to human motivations is difficult.
“There seems to be a higher prevalence and frequency of the behavior in captivity,” Lameira says. “This does indeed hint at spinning playing an important role against boredom and under-stimulation that highly intelligent animals like great apes tend to experience in captivity.”
But beyond these observations, he says, we have no means to assess subjective experience in animals that cannot speak about their experiences. Are the apes experiencing the same altered state of consciousness that humans do? Do they find it as pleasurable as we do, or is it simply a way to combat boredom?
The answers to these questions could reveal how the self-induced altered mental states of our common ancestors shaped modern human behavior and cognition — but it will take further research to find them.
Read More: How Closely Related Are Humans to Apes?