No living American alpinist is more respected for his climbing skills than Jack Tackle. The Exum mountain guide is 56 years old, sports a bushy salt-and-pepper mustache, and will tell you, in his mild-mannered way, that he wants to keep on climbing—bagging first ascents, conquering new lines—as long as age allows. Last year alone, he and a friend established four new routes in the jagged Alaska Range, atop snow-crusted peaks that hadn’t been touched by human feet in years.

For the past decade, studies have linked people like Tackle with the feel-good neurotransmitter dopamine. This research has fueled the perception of outdoor athletes as reckless adrenaline junkies who heedlessly put their lives at risk to trigger the next rush. But a new line of inquiry paints a very different picture. Far from risk-obsessed, people like Tackle are often careful planners, driven by success. "I hate being scared,” the climber admits. In fact, if risks are managed effectively, dopamine could be the key to a successful career both in and out of the mountains.