The forbidden occupies a special place in the imaginations of young children, so it’s no surprise that a vital role in parenting (and grandparenting) resides in the task of setting clear boundaries—that process of delineating what is and isn’t allowed. That stove is hot. That knife is sharp. That street isn’t to be crossed.

But curiosity is the fuel that stokes childhood development, and the desire to explore and understand the unknown is at the very heart of learning. I was reminded of this fact on a recent outing to the zoo with my 4-year-old grandson, Barrett.

Like many frequent visitors, we have a specific circuit for navigating the sprawling zoo, one that invariably begins in the Lied Jungle. It’s a place of great adventure for Barrett, but perhaps not for the reason that one might expect.

The attention span of a 4-year-old is about as fleeting as the fame of most reality TV “stars” (Snooki, anyone?), and the trickiest part of any zoo excursion is to get my grandson to focus on the featured attractions—the animals.

Tapirs? Meh. Monkeys of every stripe? Ho hum. Exotic birds in a rainbow of colors? Save it for a box of Froot Loops.

No, what really turns him on are those emergency exits, utility closets, and entrances to hidden passageways situated along the path that wends its way through the dank environs of the jungle. You know the ones, those doors whose cleverly crafted facades are designed to blend seamlessly into the craggy, vine-draped space. They have the power to send Barrett into a frenzy of unquenchable, just-gotta-know-what’s-behind-there curiosity.

“Secret door!” he squeals with every new (and frequent) encounter with these camouflaged barriers. The magnificence of a planet’s flora and fauna is at his feet, but all Barrett seems to care about is imagining what double-super-secret wonders must lie just beyond those doors— those portals to the mysterious and the unknowable.

The same rang true in both “The Spooky Place” (Barrett’s name for the moonlit swamps of the Kingdom of the Night exhibit) and the shark-infested waters of what he calls “The Fishy Place.”

I’m glad that Barrett is curious. I’m happy that he has the ability to conjure visions of some alternate reality lurking just beyond his comprehension. Such inquisitiveness is a great asset and bodes well for a growing mind. And I also take comfort in knowing that the time will soon come when the zoo’s critters will take their rightful place as the center of his attention.

Omaha’s Henry Doorly Zoo and Aquarium is on every list of the nation’s best zoos, and deservedly so. But I feel that the place is ready for a minor makeover, one where every door is…well, just a door. Remove those faux finishes. Paint them a boring green or black or beige. And please don’t stop there. Install one of those audio box thingies at every door to play a recorded message.

“Move along,” the gentle voice should drone in a continuous loop. “Nothing to see here. Move along.”

Grandpas everywhere will be grateful.