If you’ve regularly ignored the playground swings, swings and slides – and headed straight for the merry-go-round instead – you’re probably familiar with the intoxicating giddy feeling that accompanies a good spin session.
Vertigo can come with a tinge of vertigo, making the world tilt around you, or even causing a feeling of sudden elation. Sufi Whirling Dervishes take advantage of these effects actually as a form of meditation and to induce spiritual experiences.
Others undergo extensive training for suppress vertigo while spinning: professional ballet dancers perform countless pirouettes with ease, for example, and circus performers often hang gracefully on ropes dozens of feet in the air.
There is no doubt that people have found many creative ways to incorporate spinning into their daily lives. But at what point in our evolution did we start spinning to induce this characteristically altered mental state? And what purpose does it serve?
Read more: How did humans evolve?
The science of back
When a person twists and turns, the fluid in their inner ears also moves. In fact, the fluid keeps moving — bumping into tiny hair cells and sending messages to the brain — even after the rest of the body stops.
This miscommunication between the brain and the body is usually what causes the feeling of dizziness and can even lead to a physiological “high” at high enough speeds. So go ahead, do a few extra spins in the office computer chair when no one’s looking!
Other benefits, especially for people with autism, include the ability to increase or decrease sensory stimuli, according to British National Autistic Society. But disrupting the vestibular system with a little carefree spinning can be beneficial 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 generally thought to help children sharpen their proprioception and even observe unconscious physiological mechanisms such as breathing and digestion.
“For [other] highly intelligent animals,” he adds, “we might expect similar advantages associated with exploring their ‘inner landscapes’.”
The evolution of vertigo
These other highly intelligent animals that Lameira talks about are orangutans, gorillaschimpanzees and bonobos.
Last month, he and fellow researcher Marcus Perlman, a professor of English and linguistics at the University of Birmingham in England, published a report about the prevalence of spinning in these primates, our evolutionary cousins—and what the behavior might reveal about humans.
In other words, if the other great apes are too big fans of spinning in circles, it’s safe to assume that our desires for vertigo originate from a distant, common ancestor.
“Whether altered states in the hominid family shaped the emergence and evolution of the modern human mind remains one of the fundamental and most thought-provoking unknowns in cognitive science,” the authors write.
Read more: Humans aren’t the only primates to ‘share for the sake of sharing’
Going Ape
Their paper focused specifically on videos of primates hanging from the bottom of ropes or vines while spinning through the air. “Being suspended, this allowed the great apes to achieve faster spin rates and longer spin times,” explains Lameira.
The researchers report that the primates spin at an average rotational speed of 1.43 revolutions per second. (Although in the case of a Daredevil, the fastest sustained spin rate is an impressive 3.3 revolutions per second.)
After being released, they tended to roll over — a clear sign of dizziness — before returning for a few more rounds. “This is perhaps the strongest evidence yet that great apes experience similar physiological ‘highs’ as humans [do] during and after rotation,” says Lameira.
And as it turns out, there’s good supporting evidence: Great ape inner ear anatomy is comparable to that of humans. “Indeed, it is the most similar of any living non-human primate or non-human animal, including overall size,” says Lameira.
Inside the mind
Of course, even with this shared physiology, deciphering the monkeys’ underlying reasons for being spanked—even if only for a few minutes—and comparing them to human motives is difficult.
“There seems to be a higher prevalence and frequency of the behavior in captivity,” says Lameira. “This does suggest that rotation plays an important role against the boredom and understimulation that highly intelligent animals such as great apes tend to experience in captivity.”
But beyond these observations, he says, we have no means of assessing subjective experience in animals that cannot talk about their experiences. Do monkeys experience the same altered states of consciousness as humans? Do they find it as enjoyable as we do, or is it just 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 further research will be needed to discover them.
Read more: How closely related are humans to apes?