National Geographic's "Free Solo" this week won an Academy Award for best documentary feature after capturing the journey of 33-year-old Alex Honnold as he achieved the seemingly impossible: Scaling 3,000-feet of Yosemite National Park's El Capitan rock formation without so much as a rope.
The film left audiences reeling. Many were awestruck by what the New York Times described as "one of the great athletic feats of any kind, ever." Meanwhile others were more skeptical, questioning whether Honnold even possesses the primal instinct that has deterred so many before him: fear.
Indeed, in the face of such consternation, Honnold began to question it himself. To satisfy critics who labelled him a sociopath, the film sees him embark on a rigorous brain scan to test the functionality of his amydgala — the nodule responsible for such emotions.
But, according to Mark Synnott, a long-time friend of Honnold's and author of a new book chronicling the ascent, when the scan indicated that Honnold's amydgala was "perfectly normal," it revealed something altogether more interesting about humans' mental capacity to master their greatest fears.
"People want to explain him away, they want it to be something that doesn't place a demand on them," Synnott writes in his book, quoting J.B. MacKinnon, a Canadian writer who arranged Honnold's brain scan. "Because if Alex is just an ordinary guy who managed to transform himself into this superhuman figure of fearlessness ... then they should be able to do that too."
Honnold is an ordinary guy, however, Synnott says — just one who has managed to acutely control his emotions.
"The reason he is able to free solo huge rock walls is because he has meticulously trained his mind, over the course of decades, to control his innate fear response," the author of "The Impossible Climb: Alex Honnold, El Capitan, and the Climbing Life" told CNBC Make It.
Synnott, who is himself a climber, noted that he was not surprised when Honnold's fMRI (functional magnetic resonance imaging) test recorded no biological abnormalities yet failed to detect any response to typically fear-inducing stimuli. It was reflective of what Honnold had always argued, Synnott said.
"Over the past twenty years, he has focused intently on learning to control fear," said Synnott. "It's been a gradual process, something he once described to me as a 'slowly expanding the bubble around my comfort zone.'"
"(I've) worked on my climbing skills so much that my comfort zone is quite large. So these things that I'm doing that look pretty outrageous, to me they seem normal," Honnold told Synnott in a 2015 interview for National Geographic.
Honnold's is an approach mirrored by fellow extremists, such a Nik Wallenda, a famed aerialist who, in 2013, seemingly defied gravity by walking across the Grand Canyon on a tightrope.
"Fear is a choice," Wallenda told Synnott in the book, noting that he "chooses" to counter negative emotions with positives.
Synnott acknowledged that Honnold took that to a "rarified extreme" to conquer El Capitan. But he said everyone is capable of mastering their greatest fears to a "certain degree."
"Every day, we talk ourselves out of things that scare us," he said. "We all have mechanisms we use to get ourselves together when forced to speak in public, or when screwing up the nerve to ask someone out on a date."
"The difference is that these guys have made it their mission in life to take this to an extreme degree, and to be able to apply these coping mechanisms in situations where their lives are literally on the line."
Synnott's perspective is echoed by Joseph LeDoux, a neuroscientist at New York University who specializes in the study of the amygdala. LeDoux noted in Synnott's book: "By self-exposing, training himself in those situations, he's going to reduce the amygdala activity, because that's what exposure does."
It also draws parallels with the 10,000-hour rule made famous by Malcolm Gladwell and espoused by top leaders like Oprah Winfrey. The theory states that if you work on something for long enough — 10,000 hours to be precise — you can master it.
That mentality, said Synnott, is something that can be applied to other walks of life and challenges big and small.
"We all have our own El Capitan," said Synnott. "If (Honnold) can free climb El Capitan, what could we accomplish, if we truly set our minds to it?"
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