In his fascinating debut book, “On Trails,” Robert Moor considers how and why living organisms make trails, from the paths of tiny prehistoric creatures to the many routes blazed over the earth by humans.

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‘On Trails — An Exploration’

by Robert Moor

Simon & Schuster, 341 pp., $25

On his first day as a volunteer shepherd on the Navajo Reservation in Arizona, Robert Moor lost his entire flock by 10 a.m. Some sheep went one way and some another, following paths irresistible to them but invisible to Moor. Not an auspicious beginning for a man whose curiosity about trails, how they form and how we use them eventually consumed seven years of writing time.

What had triggered his interest initially was having “thru-hiked” the Appalachian Trail, that is, having walked more than 2,000 miles in five months of 2009. In the freedom hiking provided, he began to wonder who creates trails. And why? Why do some persist while others fade? Why do animals move about? How do they make sense of their worlds?

In his fascinating debut book, Moor, an award-winning magazine writer, travels from Newfoundland to Morocco, to Botswana and Tanzania, into the forest near his British Columbia home, to distant Borneo and Iceland and beyond searching for “the wisdom of trails.” Sometimes he walks alone; other times, with companions. Sometimes he leads but other times, he follows, learning that “from microscopic cells to herds of elephants, creatures can be found relying on trails to reduce an overwhelming array of options to a single expeditious route. Without trails, we would be lost.”

Perhaps this observation seems obvious. And yet his quest to unravel a deceptively simple question is both fun and intriguing, an exploration filled with both learning and missteps, like any journey. Early in the book, Moor goes to the northern rim of a glacial fjord in Canada’s easternmost province. There, at Mistaken Point, he meets Oxford researcher Alexander Liu, who discovered traces left some 565 million years ago by ancient Ediacarans, early life-forms so strange, it’s hard to tell if they were plants or animals. But one thing’s clear: these tiny bizarre things resembling bags of mud moved across the sea floor, leaving trails.

Trails have destinations, whether for food, shelter or other reasons. When a trail loses purpose — say, for example, when ants have exhausted a food source — use dwindles and the trail disappears. What the Ediacarans’ “inscrutable old scribbles” led to, we can only guess.

Snails leave slime trails; tent caterpillars, pheromone paths. Landscape architects, such as Frederick Law Olmsted did in New York’s Central Park, let an area’s users create “desire lines” that develop over time. Ants, which live in large, leaderless communities, nevertheless find resources and cooperate with each other, refining their routes. Interestingly, they never get stuck in traffic jams; unlike humans at rush hour, some stop and form lanes.

Another thing about trails: good ones are increasingly efficient. For instance, as people moved from walking to riding horses to driving cars, always wanting to go faster, trails became straighter, flatter and harder.

Scientific exploration is another kind of trail use. Experiments refine knowledge, which brings about progress and new demands. The internet has become so complex and filled with options, it’s often difficult to find our way around. That’s when a single clear trail could trump the information maze, streamlining our pursuits.

We change the trails we make, Moor finds, and they change us. At the end of the Appalachian Trail, “I was as trim and clearheaded as a wild animal.” But then the “path of least resistance” — living in a box of possessions, staring at a computer screen — returned him to the “old rut.” Following Moor’s trails in this book opens many fascinating vistas.