A colleague of mine boasted long ago that he got an hour’s exercise every day by walking through SM Megamall, and he did it as soon as it opened, when it wasn’t too crowded yet. “And I don’t get bored,” he said.

I tried it once, but I felt extremely exhausted. I could sense something was really off. Now I know what exactly is the matter, and it’s not just because I breathe stale air recycled a hundred, even a thousand times a day.

A recent blog post in The New York Times’ online edition cites a study published in The British Journal of Sports Medicine that provides empirical evidence in support of theories and anecdotal claims that walking through parks, forests, and tree-lined plazas refreshes one’s mind and energizes the body even as much as sleep does. On the other hand, walking through a city [or a mall] saps your energy.

Thanks to modern, miniaturization technology, researchers at the University of Edinburgh can now wire more than a dozen volunteers with portable devices whose purpose is to measure and store their electroencephalographs (EEG), which in turn measure the brain’s electrical activity, as the subjects walk alternatively through urban streets and through the city’s parks.

The subjects’ states of mind could thus be determined, with the neuroscientists mapping certain EEG patterns.

The researchers find out that while the subjects walk through busy streets, their brain activities show patterns associated with frustration, a phenomenon they call “engagement”, roughly the equivalent of the mind’s “busy-ness” when it is working on a difficult math problem. It is that state of “engagement” that exhausts the mind and tires the body, since the brain, although it accounts for only 2 percent of a human’s weight, consumes 25 percent of its glucose utilization.

As the brain tires, your concentration is easily broken, i.e. you get less sharp.

When the subjects walk through the park though, the patterns of their brain activities are the same as those associated with calm and rest. And a calmer and rested mind essentially means a smarter you.

“Natural environments will engage the brain, but the attention demanded is effortless, states The New York Times, quoting a professor at that university. “It’s called involuntary attention in psychology. It holds our attention while at the same time allowing scope for reflection.”

Those into Eastern spiritual disciplines will immediately recognize that description as the sought-after state of meditation, as in the Indian vipasana technique in which one rests the mind observing the breath and thoughts as they pass through one’s attention field.

The study’s findings are supported by past researches. A 2004 experiment at the University of Illinois concluded that children with attention deficit problems performed better in mental tests after a 20-minute walk through a park or an arboretum. A 2012 study, also conducted by the University of Edinburgh, found out that those who live near trees and parks have lower levels of cortisol, a stress hormone, in their saliva than those who live in “concrete jungles”.

I haven’t read an explanation why living amidst trees and plants makes one calmer, more rested and meditative. Probably our brain still retains the structure it had a million years ago when home to our ancestors were jungles and savannas. After all, humans started to live in vast cities barely two hundred years ago. Our brain therefore —deep down—interprets the city as an alien environment, where it is continually on the alert for enemies. Or perhaps deep in our DNA, we still identify with other living organisms, rather than the concrete artifacts of modern civilization.

Other than the fact that humans—like all mammals— each require a certain territorial space, the denial of which makes him hostile, the lack of greenery in crowded urban areas, I would think, explains why urbanites seem to be more belligerent than those living in rural areas.

That greenery rests the mind is probably known to planners and managers of the developed countries’ great cities. For instance, a big chunk of Manhattan, a part of the world’s busiest city, is occupied by the 340-hectare Central Park. There are also mini-parks all over the metropolis. Greater London has eight huge Royal parks, the biggest of which is the 955-hectare Richmond Park.

Indeed, even as early as the late 19th century, one of the things that troubled our national hero, the well-traveled Rizal, in his personification as Ibarra in Noli Me Tangere, deplored, when he arrived from his sojourn in Europe, the pathetic state of Manila’s small parks: “The sight of the botanical garden (near Escolta) drove away his happy reminiscences; the devil of comparisons placed him before the great botanical gardens of Europe, in the countries where much gold are needed to make a leaf bloom or a bud open..” (Page 51, Locsin’s translation.)

And Metro Manila? It is its horrendous lack of parks and green spaces that justifies Dan Brown’s description of it as “gates of hell” in Inferno. The absence of cooling green trees and plants recalls a feature of hell’s barrenness as depicted in medieval paintings.

There are fewer than a dozen sizeable parks in a metropolis of more than 10 million souls, the biggest of which are Rizal Park in Manila and the Ninoy Aquino Parks and Wildlife Center in Quezon City.

Blame our elite for their wanton disregard for the human soul’s need for greenery.

In its original urban plan, the Ayala complex was supposed to be dotted with so many parks, emulating the great urban centers of the world. So little of green spaces are left now, with the billions of pesos to be made from condominiums and shopping centers. “Greenbelt” is a cruel sarcastic misnomer: the only large patch of green there is a rooftop grass garden.

I admire Henry Sy for building the biggest shopping malls in the world. I can’t understand though why he seems to hate green spaces—maybe because shopping stalls couldn’t be put there.

Green spaces in metropolitan Manila that could make a human smarter and even live longer lives are reserved—off-limits to the hoi poloi—for two of our country’s elite: the military brass who live in the huge tree-lined police and military camp with golf courses, right in the center of Quezon City, and the money elite who live in posh subdivisions with parks at their centers, and playing in the three golf courses in the metropolis.

Yes, a walk in the park invigorates the mind. Does that include playing golf? When the boss calls while you’re on the fairway, just tell him you read in this newspaper that spending time outdoors in the midst of trees and greenery makes you a smarter employee.