Peter “Treeman” Jenkins doesn’t look like a monkey, at least not when he opens the door to his house on a quiet, pine-lined side street in Atlanta. A trim 55-year-old with frizzy gray hair and a bushy mustache, he could be a college professor on his day off as he pads around the kitchen in his Smartwool socks brewing Raspberry Zinger tea.

But get Jenkins in a tree, and the resemblance to our primate cousins becomes suddenly apparent. More than 20 years ago, Jenkins, a professional arborist, opened America’s first recreational tree-climbing school on a vacant lot in Atlanta. Since then, Tree Climbers International has taught more than 10,000 students to scale the heights, all without a single accident. To hear Jenkins tell it, he’s just as comfortable 100 feet up in the branches as he is on the ground-maybe even more so.

“I want to send the human race back to the trees,” he says. Jenkins believes that deep within our genes lies the primal instinct to seek sanctuary from predators high in the treetops, an urge left over from the days when most of the human race roamed the African savannah. “The human being is a climbing machine. That’s why there’s a feeling of peace in the trees.”

Fortunately for today’s tree climbers, climbing gear has advanced beyond fingers and toes. Though a former avid rock climber himself, Jenkins opposes free-climbing trees. Not that he thinks parents should keep their children from scrambling up the dogwood in the front yard. But when it comes to the 100-foot white oaks where he teaches in Atlanta, ropes are the rule.

First, Jenkins hauls out his ten-foot slingshot and fires a weighted rope up into the branches. When his aim is true, which it almost always is, the rope wraps around a high, sturdy bough. He pulls it the rest of the way to the ground with an attached fishing line.

Climbers tie the rope to their harnesses, which feature more padding than a typical rock climbing harness. Then it’s time to climb. Don’t worry: We’re not talking middle-school gym class here. Jenkins teaches climbers to use small metal devices called mechanical ascenders to slide up the rope. Alternately, he’ll teach the classic double-rope technique, a self-belaying system that relies on sliding friction knots to allow climbers to go as high as they want without fear of falling.

These methods don’t require a lot of strength, Jenkins says. Kids as young as five and as old as 80 have climbed with him. He’s developed rope systems that have enabled paraplegics and even quadriplegics to climb tall trees under their own power.

The ropes-only approach also protects the trees. “We never use leg spikes,” Jenkins says.

Once up in a tree, Jenkins will sometimes pull out a hammock and set up camp. “You can’t beat the bird watching from the top of a tree,” he reports. (A great horned owl in Colorado once came inches from using Jenkins as a perch.) On blustery days, he’ll tie in with a second rope and tree-surf, balancing on branches as the tree flexes as much as ten feet in either direction. (“You can see the wind rippling toward you through the canopy like waves.”)

Though students come from far and wide for Jenkins’ classes, tree climbing as a sport hasn’t caught on in America like it has in Germany and Japan. Jenkins wonders if that’s because the sport lacks a competitive edge.

“There’s not an ego thing like I sometimes saw in rock climbing,” he says. “Trees are social places. You want lots of people up there.”

Still, he remains optimistic. “It’s going to be ubiquitous, like bicycle riding,” he says. “One of my visions is to go to a park and see lots of ropes dangling from the trees and hear laughter in the treetops.”

For more information on classes, gear, and how to climb trees, visit Tree Climbers International at www.treeclimbing.com.

-Marcus Wohlsen