This is an excerpt from the wonderful book “First Steps” by Jeremy DeSilva. It speaks to me in so many ways. I have always loved walking – it remains the only passion (of many) that I have done my entire life. It is obviously part of hiking and my spiritual side is found in nature. Spending time in the mountains of the Canadian Rockies, the interior of BC, and on Vancouver Island where I now live has been a passion since my university days.
I have made 37 trips to the desert Southwest of the USA always hiking everywhere to explore what I think may be one of the most beautiful places in the world.
Walking and trekking have always been a large part of my travel. I’ve walked over 2000 km of the Camino de Santiago, once walking 1750 km in a continuous walk over 64 days from Le Puy en Valey, France to Santiago.
I have Asperger’s syndrome, and although Mr. DeSilva doesn’t mention it, all the great thinkers mentioned in this book also had Asperger’s syndrome. There must be a connection.
I added a section at the end about the human foot. Again there is so much here that made a connection with me. Since starting travel in 2006, I have worn flip-flops almost 99% of the time (I only wear shoes when doing rough hiking), and often walk over 20 km per day. That is the way I have explored most of the cities I travel to. This is only possible with special flip-flops and I exclusively wear Chacos. I can’t help but think that they have made my feet very strong like the Tarahumara of the Copper Canyon of northern Mexico. Read the wonderful book on running “Born to Run” to see another discussion of the evils of modern footwear, clearly a conspiracy by running shoe manufacturers to sell shoes that may do more harm than good.
GAIT DIFFERENCES and WHAT THEY MEAN
The way each of us walks is unique and recognizable, whether it’s John Wayne’s slightly off-balance swagger, Dorothy’s skip toward Oz, Mae West’s exaggerated hip swivel, or the lope of Shaggy from Scooby-Doo. This observation is more than anecdotal.
One of the first experiments to test whether people could identify one another by the way they walk, recorded individuals walking and then converted their bodies into a series of small lights, similar to the motion-capture technology used in Hollywood and video games today. That way, study participants could not pick up on cues such as hair colour or body shape. Even when people were turned into a string of lights, their friends were pretty good at spotting them.
Repeated studies have confirmed that we are skilled at recognizing friends and family members solely by the way they walk. As it turns out, regions of our brains are fine-tuned to accomplish this.
A 2017 study had 19 participants lie in an MRI and watch videos of familiar people coming toward them. A region of the brain just behind their ears (the bilateral posterior superior temporal sulcus) activated when they recognized people from their walks. When the walkers were close enough for their faces to be recognized, a different area of the participants’ brains lit up.
But the way a person walks signals more than their identity. We are skilled at detecting moods, intentions, and even personality traits from the way someone walks. Slumped shoulders and a plodding gait are recognized as sadness. A bounce in one’s step communicates happiness. A loud stomp can signify anger. Research shows that these influences are not just a matter of intuition.
However, people aren’t always 100% accurate in interpreting these cues, and some of us are better at it than others. We perceive others as adventurous, warm, trustworthy, neurotic, extroverted, or approachable by the way they walk, but the walkers often don’t think of themselves that way at all. It appears that the inferences we draw this way are sometimes wrong.
But, as it turns out, some of those who are particularly good at it are psychopaths. When videos of undergraduates walking were shown to 47 maximum-security prisoners and they were asked how vulnerable the walkers were on a scale of one to ten. The prisoners – especially those characterize as psychopaths – revealed in follow-up questioning that they used gait cues to identify those who were frail or otherwise vulnerable to being preyed upon. Given the same task, undergraduate students were blind to these cues.
The implications were chilling. Ted Bundy, who confessed to raping and killing thirty women and girls in the 1970s, once boasted that he could “tell a victim by the way she walked down the street, the tilt of her head, the manner in which she carried herself.”
It makes evolutionary sense that all animals – including humans – would be fine-tuned to identify different species and different individuals within those species, and even to recognize their moods by the way they move.
Given the evidence that different hominin species walked differently from one another in the past, it would have been beneficial, and perhaps even a matter of life and death, to know whether a group of hominins foraging in the distance belonged to your species or another. Subtle gait cues might have helped with these identifications.
As it happens, our gaits aren’t the only things about walking that betray our identities. Footprints are like fingerprints. Omar Costilla-Reyes developed an algorithm that identifies individuals by the footprints they leave behind. He identified 24 ways in which footprints differ from one person to another and is accurate 99.3% of the time. In the last two decades the research community has by and large moved to facial recognition, deemed a superior approach. The wrong camera angle or variations in the walking surface or carrying a load are enough to alter gait and impact accuracy. Individual gait signatures would be difficult to extract from a crowd. Facial recognition is cheaper and more effective.
Gait analysis has possibilities for health professionals. One of the first symptoms to appear in dementia is a change in gait.
In 2012, an app was developed that allows a smartphone to recognize the gait of its owner. Tiny gyroscopes and accelerometers inside smartphones can detect subtle differences in how someone walks. Since everyone has a unique gait, the phone will remain locked if it doesn’t recognize the speed and movement of the user.
Walking has always been about more than moving from one place to another. It is, and always has been, a social phenomenon. Today, we celebrate the solitary, cerebral Thoreau, Wordsworth, and Darwin, but rarely in our evolutionary history has walking alone been a. good idea. Until very recently, a lone, contemplative walk would have surely ended in the piercing grip of a leopard’s jaw.
Often, we walk collectively, like a school of fish, and it seems likely that our ancestors did too. It has been long known that people walking together subconsciously coordinate their gaits. One study had 14 middle school girls walk down a school hallway. When walking in pairs, the girls synchronized their gaits. Wearing blinders that blocked their views of one another did not seem to change the results. Synchronization was most easily achieved when the girls held hands. People walking on adjacent treadmills at the gym synchronize their gaits. All people, no matter where they are from, even complete strangers, synchronize their strides. Sometimes, however, synchronized walking comes at a cost.
At just 18 years of age, Stephen King wrote his first book, The Long Walk. In it, one hundred teenage boys and young men line up at the Maine-Canada border and walk south at four miles per hour. If they go under this speed threshold, they are issued a warning. Three warnings and they are executed by soldiers riding alongside them. Crowds lined the streets, cheering them on. The long walk ends when there is only one competitor left standing.
What makes The Long Walk so gripping is the speed threshold: 4 miles per hour. A cross-cultural study on over 2,000 people from thirty-one different countries found that human waking alone on flat city streets average almost exactly 3 miles per hour. The Irish and the Dutch tend to be slightly faster (3.6 miles per hour) and Brazilians and Romanians stroll at a more casual pace (2.5 miles per hour).
When walking speeds of 338 people of different ages were studied, an average of 2.8 miles per hour showed gradual slowing with age. At this speed, humans can walk and walk and walk without exhaustion.
But the cost to move our bodies increases with speed. Those boys in King’s novel were exhausted, mentally, emotionally and yes, physically. Having to sustain four miles per hour to stay alive is what makes The Long Walk horrifying.
There are many reasons, some cultural and some anatomical, for why people naturally walk at different speeds, but one of them involves basic principles of energetics. Try walking at your normal pace. Now accelerate and walk faster. It takes energy to do this. But if you slow to a snail’s pace, it also takes energy to resist your body’s preferred speed. Everyone has an optimal walking speed, so what happens when people with different optimal speeds walk together?
Picture two walkers, a fast one and a slow one. Does the slow one speed up and absorb all of the energetic costs, or does the fast one slow down and take on that burden? What happens in a large group of people who all have different optimal walking speeds? The answer appears to be that people tend to meet in the middle subconsciously settling into an optimal speed that minimizes energy costs for the entire group.
However, a twist occurs when two walkers are romantically involved. The male in a heterosexual relationship absorbs the entire cost. This may be chivalrous but not entirely fair from a physiologic point of view. Women’s wide hips also give a wider range of optimal walking speeds than men have. When women slow down or speed up, they don’t expend as much energy as men do.
Nevertheless, walking has always been something we do together. For 97% of our species’ history, and for 99% of the time that bipedal hominins have walked the Earth, we have been nomadic hunters and gatherers. We roamed the landscape, walking from one food source to the next. We established temporary camps, and when the resources were nearly exhausted, we packed up our few belongings and moved on together.
Some human populations, including the Hadza of Tanzania and the Tsimane of Bolivia, still live this way, but today most people live in permanent settlements and eat farm products. We drive cars and fly in airplanes. And many of our cities, where more than half of all humans live, are designed in a way that makes walking from place to place difficult or even dangerous. Walking – the thing that made us human – isn’t nearly as common as it used to be. There was a time when everybody walked; they did it because they had no choice. The moment they had a choice, they chose not to do it. As a result, our health has suffered.
MYOKINES and the COST of IMMOBILITY
Recent headlines promote “10 Reasons to Go for a Walk Right Now,” “9 Surprising Health Benefits of Walking,” and “Benefits of Walking: 15 Reasons to Walk.” Walking is a superfood. In terms of evolution, walking is our default. Throughout Our History, if we wanted to eat, we had to walk. What’s new is not walking.
Consider the effect that immobility has had on our bones. Our skeleton consists of two different kinds of bone. One, called cortical or compact, is the thick outer shell of our bones. The other, called trabecular, located in the joints where our bones meet, is a network of thinner, spongy bone arranged like a honeycomb. Compared to our ape cousins, humans have less of both kinds. We rely more on our trabecular skeleton to absorb, like a sponge, the high impact forces of bipedalism. Why, then, would we have so little of it?
CT scans can be used to calculate trabecular bone density in the skeletons of humans, apes and fossil hominins. Chimpanzees, fossil Australopithecus, Neanderthals, and even Pleistocene Homo sapiens had the same density of trabecular bone in their joints: 30 to 40%. But humans today have less – 20 to 30%. This drop in bone density appeared to occur suddenly in the last 10,000 years. It has been suggested this happened because we don’t move around as much as our ancestors did.
Another study of four human populations – two nomadic groups and two farming communities – found that nomadic people have denser bones than farmers. While diet might have something to do with this, most scientists agree that bones are less dense in people that don’t move around as much. In fact, humans have lost as much bone density in the last 10,000 years as an astronaut loses in a trip through the low gravity conditions of space.
As we age, our bones naturally thin as levels of bone-stimulating estrogens fall, especially in postmenopausal women. But because we already have such low-density bone, this further reduction can lead to osteoporosis and broken bones in our aging population. But osteoporosis might be the least of our worries.
After age forty, what can we do to live longer and healthier? The answer could be as simple as a daily walk. A decade’s worth of data on 650,000 people found that those who did the exercise equivalent of a 25-minute daily walk – as long as they were not obese – lived close to four years longer than their more immobile counterparts. Even a 10-minute daily walk could make a two-year difference in life span.
In a study of 300,000 Europeans, inactivity caused twice as many deaths as obesity. A 20-minute walk daily cut the risk of dying by one-third. It is better to fit and fat than lean and lazy. To understand, one has to dive deeper into the science of physiology.
Walking affects the complex dance of molecules in our bodies in significant ways. A lot of the research has been done in breast cancer, especially estrogen-receptor-positive breast cancer, which occurs in two-thirds of all cases. Breast cancer is exceedingly complex.
Estrogen circulating in the bloodstream causes the cells of the breast tissue to grow and divide as part of the normal physiology of a woman. Every time a cell divides, it copies its DNA, and every time it does so, there is a chance of a mistake – a mutation. Usually, that is no big deal, but if a mutation occurs in a gene that limits how fast cells grow and divide, uncontrollable growth can produce a cluster of cells called a tumor. A mutation in a gene that keeps those cells in the breast where they belong could cause some to stray into the bloodstream and settle in the lungs, liver, bone, or brain. This process is called metastasis, and the result is stage IV breast cancer.
One in eight American women will be diagnosed with breast cancer in their lifetimes. Nearly 3,000 men are diagnosed annually as well. It kills 40,000 Americans and over half a million people globally every year.
But a daily walk reduces the chances of developing breast cancer. How? One possible explanation is that exercise lowers the levels of estrogen circulating in the blood. Exercise increases the body’s production of a molecule called sex hormone binding globulin. This molecule attaches itself to estrogen, reducing its concentration in the blood by 10 to 15%, thereby reducing the chance of a mutation in the DNA of breast cancer.
Even if a mutation occurs, exercise appears to help the damaged DNA repair itself. Exercising at least 20 minutes a day had a slight (1.6%) better ability to repair DNA copying mistakes, although it’s unclear how this works.
If the copying mistakes don’t get fixed and cancer results, walking still helps. Exercise – even just an hour of walking a week – decreased the chances of dying by about 40%. A Saudi Arabia study put the number at 50% for estrogen-positive breast cancer. Exercise reduced the chance of cancer recurring after remission by 24%. Similar reductions in recurrence have been found in men with prostrate cancer who routinely walk after diagnosis. A 2016 study of 1.5 million people found that moderate exercise lowers the risk of developing thirteen different cancers.
While cancer claims too many lives, the number one killer in industrialized nations is cardiovascular disease. In its various forms, it is responsible for one in four deaths, or 60,000 Americans a year. Walking can help stave that off, too. Frequent walkers have lower heart rates and lower blood pressure than sedentary individuals. A study of 40,000 American men found that a daily 30 minute walk lowered the risk for coronary heart disease by 18%.
Coronary heart disease is all but unheard of among hunter-gatherers. The Hadza of northern Tanzania are fourteen times more active than the average American. They also have lower blood pressure as they age, lower cholesterol, and not a hint of cardiovascular disease. Bolivia’s Tsimane people similarly have low levels of coronary heart disease and five times less blockage of their arteries than the average person in the industrialized world.
Diet has a lot to do with this, but there is evidence that physical activity plays a critical role. Perhaps, though, not in the way you think.
Everyone figured that the Hadza used more energy than the typical American as the adults walk between 6-9 miles a day while the average American spends six hours a day staring at screens. What was found was shocking and forces us to think about our bodies in a different way. The total daily energy used by active Hadza and couch-potato Americans is the same. How is this possible? A clue is hidden in the one thing that walking does not help use do: lose weight. Humans are so efficient at walking that a 150-pound person would have to walk at least 70 miles to lose a pound. So the extra steps the Hazda take compared to the typical Americans don’t burn much energy. But the Hazdas don’t just walk. They dig, climb, and run. Surely, they should be using more energy.
The currently accepted hypothesis for this mystery is that human bodies all over the world have the same daily energy allowance. How they spend that energy varies from culture to culture and from person to person. The Hazda use energy getting from one place to another, gathering food, fighting off illness, carrying children and growing new ones. Americans do many of the same things, but because we aren’t as active, our bodies spend the excess energy on something else, ramping up our body’s inflammation response. Here’s why that. Is a health problem.
The inflammation response refers to the way our bodies recruit large, vigilant, amoeba-looking cells called macrophages to ward off infections or repair injuries. These cells, whose name means “big eaters,” are key components of our immune system. They make an infection-fighting protein called tumor necrosis factor (TNF). Among a variety of roles in the body, TNF tells the hypothalamus to crank up the body temperature when we are overrun by a virus or bacteria – a fever.
But chronically high levels of TNF have been linked to heart disease. Walking can downshift the production of TNF by 5% after a brisk 20-minute walk. How? The answer appears to involve a whole class of proteins that weren’t even in textbooks a few years ago.
Interleukin-6 is a protein white blood cells use to communicate with one another. Interleukin-6 levels in marathon runners are a hundred times higher at the end of a race than at the start. Muscles make interleukin-6 and release it into the bloodstream. Many organs in our bodies make molecules and release them into our bloodstreams as a way to talk with other organs. These endocrine organs include the pancreas, the pituitary gland, the ovaries, and the testes. But few had thought of muscle as an endocrine organ. Over a hundred molecules that our muscles make are released into the blood as we walk. One of these, oncostatin M, shrinks breast tissue tumors in mice and could be yet another reason why exercise is beneficial to humans with breast cancer. This amazing family of molecules is called myokines.
As a myokine, interleukin-6 is an anti-inflammatory. Among other roles, it helps shut down the problematic tumor necrosis factor. It is the body’s natural ibuprofen. Interleukin-6 can mobilize cells called “natural killers” to attack and destroy cancerous tumors, at least in mice. For some reason, this myokine needs to be produced by muscles during exercise in order to work. But that does not require walking. Can the 3 million Americans in wheelchairs generate myokines? After wheelchair half-marathons and basketball games, interleukin-6 is elevated and TNF lowered.
Myokines, however, are not magic potions. They cannot be injected or swallowed. They are made only when the body is in motion, and in modern societies, if often is not. On average, Americans take 5,117 steps a day, which is a third of what the average Hazda takes. How much should we walk to ward off heart disease, certain cancers, and type 2 diabetes?
The answer is 10,000 steps a day. Pedometer smartphone apps use that to change colour from a disappointed red or orange to a happy green. Where does this magical 10,000 step threshold come from? In the 1964 Tokyo Summer Olympic Games, Abebe Bikila of Ethiopia defended his gold medal in the marathon, setting a new world record in 2:12:11:2. American sprinter and future NFL Hall of Famer Bob Hayes raced a hundred meters down a cinder track in only 10.06 seconds, tying the world record. And Soviet gymnast Larisa Latynina, competing in her last Olympics, took home six more medals, bringing her total to 18 and making her the most decorated of any Olympian until American Michael Phelps swam along.
The Olympics inspired the people of Japan. For the first time, the games were broadcast live on television, and by 1964, 90% of Americans had a TV. Researchers in Japan were concerned with how sedentary the Japanese public had become and with the rising prevalence of obesity in Japan. It was shown that Japanese were walking between 3,500 and 5,000 steps per day but that was not enough to be healthy.
The following year, a device that hooked onto people’s waists counted the steps they took. It was called Manpo-kei which means “10,000”, po is “step”, and keii is “meter”. Thus the 10,000-step meter.
Smartphone walking apps default to 10,000 steps as a daily goal. Most fitbits do the same. Though the 10,000-step goal was based on some research, it was mostly a marketing gimmick. Yet over a half-century later, it is still with us. How many daily steps should we take?
From 2011 to 2015, 17,000 women whose age averaged 72 wore an accelerometer for a week. As a group, they averaged 5,499 steps a day, a shade more than the number a typical American adult takes. In the slightly over four years that followed, 504 of these women died. The number of daily steps was a good predictor for those who were still alive and who were not. Women who averaged at least 4,400 steps fared much better than those who took only 2,700. With daily steps up to 7,500, women continued to be better off those walking fewer steps. But that’s where it plateaued – going beyond 7,500 steps did not make a difference.
For a younger population, the plateau may not occur at 7,500 steps. The amount of walking required to yield health benefits, depends on age and activity level. It is recommended that everyone should take 2,000 more steps a day than currently average.
One way to add that many steps to your routine is to get a dog. Dogs were the first animals domesticated by our species. Ancient DNA from a canine’s rib found in Siberia reveals that humans and the wolf ancestors of dogs started hanging out together 30,000 years ago. In comparison, pigs and cows were domesticated closer to 10,000 years ago. As humans migrated around the globe, our dogs walked alongside us.
Even today, dog owners average almost 3,000 more daily steps than non-dog owners and are more likely to reach the recommended 150 minutes of walking per week.
In addition to preventing some cancers and reducing the risk of dying from cardiovascular diseases, a daily walk can prevent autoimmune diseases and can help ward off type 2 diabetes by lowering blood sugar levels. It improves sleep and lowers blood pressure. It decreases circulating cortisol levels, which helps reduce stress. In 40,000 women over 45, a thirty-minute daily walk reduced the risk of stroke by 27%. Despite these health benefits and admirable attempts to get our sedentary population on its feet, it is an uphill battle. Many futurists predict that our walking days are behind us. Could it be that humans will stop doing the very thing that defined us from the beginning?
WOMEN
Wide hips are not a detriment to a woman’s gait. They are adaptive. They also affect how many women walk. Having wider hips causes more rotation, or swivel, when walking. This allows women, who typically have shorter legs than men, to take longer strides than one might expect. Wider hips don’t make a woman’s walk less efficient. They just make it mechanically different.
Especially in endurance athletics, the gap between men and women is closing. Some studies show that women’s leg muscles tend to be more resistant to fatigue than men’s. In sports that test endurance rather than strength and speed, women may have an advantage.
The wrongheaded notion that female walking is compromised remains pervasive. It has been called the hangover from Genesis. Walking is related to both thinking and freedom and that historically men have thought women “deserve less of each.” In a culture that has been heavily influenced by interpretations of the book of Genesis, the obstetrical dilemma may be a flawed hypothesis, but difficult labour, dangerous childbirth, and helpless babies are not Eve’s fault, but evolutions. What happens to a woman’s gait and posture during pregnancy? As gestation reaches the third trimester, a sizable amount of baby, placenta and amniotic fluid accumulates in the front of the body, pulling the center of mass forward, Quadrupedal animals don’t have the same problem since weight gain during pregnancy wouldn’t alter the center of mass. Why don’t women tip over? The answer lies in the small of the lower back. Men and women both have five lumbar vertebrae. In men, the bottom two are shaped like wedges, producing a curve in the spine that brings the torso over the hips. But, in women, the bottom three vertebrae are wedge-shaped, giving them a larger curve. This helps women bring the shifting center of mass back over the hip joints, keeping them balanced as they walk. This sex difference in the shape of the third-to-last lumbar vertebrae occurred early in our evolutionary past. Australopithecus had it over two million years ago.
Women and Pregnancy
It has been shown that women walk as efficiently as men. But in some circumstances, they are even better at it. We don’t walk only in straight lines or on flat surfaces, and neither did our early ancestors. We don’t always walk empty-handed, either, and neither did they. With hands freed by bipedal walking, they carried food, water, tools, and babies. Walking while carrying an object roughly the same size as a human infant, can increase the amount of energy expended by nearly 20%. But the energy required is significantly reduced in individuals with wide hips from side to side – the kind often found in women. Women are, by all measures, better carriers than men. Wide hips are not about childbearing, they are about child carrying.
When waking, humans can settle at their most efficient pace and walk great distances without using too much energy. But walking with a group, especially one that includes children, often means slowing down, stopping, and speeding back up. When men vary speeds, they use more energy. Wider hips make it easier for women.
Women use their hips as a shelf, perching babies there they walk around the house. When men try it, the babies slide down their thighs. With no bony shelf, men’s arms tire. Carrying squirming kids is not easy, never mind if you are walking six miles a day as modern hunters and gatherers do.
WHY WALKING HELPS US THINK
Moreover, you must walk like a camel, which is said to be the only beast that ruminates when walking. Henry David Thoreau, “Walking” 1861
Charles Darwin was an introvert. Granted, he spent almost five years traveling around the world on the Beagle recording observations that produced some of the most important scientific insights ever made. But he was in his twenties then, embarking on a privileged, 19th– century naturalist’s version of backpacking around Europe during a gap year. After returning home in 1836, he never again stepped outside the British Isles.
He avoided conferences, parties, and large gatherings. They made him anxious and exacerbated an illness that plagued much of his adult life. Instead, he passed his days at Down House, his quiet home almost 20-miles southeast of London, doing most of his writing in the study. He occasionally entertained a visitor or two but preferred to correspond with the world by letter. He installed a mirror in his study so he could glance up from his work to see the mailman coming up the road – the 19th-century version of hitting the Refresh button on email.
Darwin’s best thinking, however, was not done in his study. It was one outside, on a lowercase d-shaped path on the edge of his property that he called the Sandwalk. Today, it is known as Darwin’s thinking path.
As a businessman, he would pile up a mound of flints at the turn of the path and knock one away every time he passed to ensure he made a predetermined number of circuits without having to interrupt his train of thought. Five turns around the path amounted to half a mile or so. The Sandwalk was where he pondered. In this soothing routine, a sense of place became preeminent in Darwin’s science. It shaped his identity as a thinker.
Darwin circled the Sandwalk as he developed his theory of evolution, by means of natural selection. He walked to ponder the mechanism of movement in climbing plants and to imagine what wonders pollinated the fantastically shaped colorful orchids he described. He walked as he accumulated evidence for human ancestry. His final walks were done with his wife Emma as he thought about earth worms and their role in gradually remodeling the soil.
Today, the desk in his study is still cluttered with books, letters, and small specimen boxes containing pinned insects. Hanging from a nearby chair is his black jacket, black bowler hat, and a wooden walking stick, the bottom of which is well worn – evidence of the miles on the Sandwalk. Walk out the back kitchen of the cream-coloured home, pass the green trellis and vine-covered columns holding up Darwin’s back porch, dross the beautifully groomed garden, and enter the Sandwalk. It is easy to imagine that it was 1871 and that you are taking a walk with Darwin himself. Stack 5 flat flints at the entrance for 5 laps and begin the walk, first along the meadow and then counterclockwise into the woods. The Sandwalk is alive. Underfoot, fungi decompose wet leaves, emitting the smell of wet earth. With each step, the gravel crunched, and your shoes occasionally slip on damp stones worn smooth by thousands of footsteps, including some taken by Darwin himself.
Down House is not a place of magic, nor is it a place of worship. Looping the Sandwalk one flint at a time doesn’t endow you with the wisdom to continue your scientific pursuits. It turns out, any walk outdoors has the potential to unlock our brains. The Sandwalk just happened to be where the unlocking of one 19th-century brain helped change the world and our place in it. But why? Why does walking help us think?
Walking and thinking. You are undoubtedly familiar with this situation: You’re struggling with a problem – a tough work or school assignment, a complicated relationship, the prospects of a career change – and you cannot figure out what to do. So, you decide to take a walk, and somewhere along that trek, the answer comes to you.
The 19th-century English poet William Wordsworth is said to have walked 180,000 miles in his life. Surely on one of those walks, he discovered his dancing daffodils. French philosopher Jean-Jacques Rousseau once said, “There is something about walking which stimulates and enlivens my thoughts. When I stay in one place I can hardly think at all; my body has to be on the move to set my mind going.” Ralph Waldo Emerson’s and Henry David Thoreau’s walks in the New England woods inspired their writing, including “Walking,” Thoreau’s treatise on the subject. John Muir, Jonathan Swift, Immanuel Kant, Beethoven, Henry Cavendish, and Frederick Nietzsche were obsessive walkers. Nietzsche, who walked with his notebook every day between 11 am and 1 pm, said, “All truly great thoughts are conceived by walking.” Charles Dickens preferred to take long walks through London at night. “The road was so lonely in the night, that I fell asleep to the monotonous sound of my own feet, doing their regular four miles an hour,” Dickens wrote, “Mile after mile I walked, without the slightest sense of exertion, dozing heavily and dreaming constantly.” More recently, walks became an important part of the creative process of Apple cofounder Steve Jobs.
It is important to pause and reflect on these famous walkers. They were all guys and virtually all had Asperger’s syndrome. Little has been written about famous women who regularly walked. Virginia Woolf is one exception. She apparently walked quite a bit. More recently, Rob Davidson trekked with her dog and four camels across Australia and wrote about it in her book Tracks. In 1999, Dorris Haddock, an 89-year-old grandmother from Dublin, New Hampshire, walked 3,200 miles from coast to coast to protest United States campaign finance laws.
Historically, however, walking has been the privilege of white men. Black men were likely to be arrested, or worse. Women just out for a walk were harassed, or worse. And, of course, rarely in our evolutionary history was it safe for anyone to walk alone.
Perhaps it is a coincidence that so many great thinkers were obsessive walkers. There could be many brilliant thinkers who never walked. Did Willian Shakespeare, Jane Austen, or Toni Morrison walk every day? What about Frederick Douglass, Marie Curie, or Isaac Newton? Surely the astoundingly brilliant Stephen Hawking did not walk after ALS paralyzed him. So walking is not essential to thinking, but it certainly helps.
Marily Oppezzo, a Stanford University psychologist, used to walk around campus with her Ph.D. advisor to discuss lab results and brainstorm new projects. One day they came up with an experiment to look at the effects of walking on creative thinking. Was there something to the age-old idea that walking and thinking are linked?
Oppezzo designed an elegant experiment. A group of Stanford students was asked to list as many creative uses for common objects as they could. A Frisbee, for example, can be used as a dog toy, but it can also be used as a hat, a plate, a bird bath, or a small shovel. The more novel uses a student listed, the higher the creativity score. Half the students sat for an hour before they were given their test. The others walked on a treadmill. The results were staggering. Creativity scores improved by 60% after a walk.
Another study of brain connectivity recruited 65 couch-potato volunteers aged 55 – 80 and imaged their brains in an MRI machine. For the next year, half of her volunteers took 45-minute walks three times a week. The other participants kept spending their days watching Golden Girls reruns and only participated in stretching exercises as a control. After a year, they were put back in the MRI machine and imaged their brains again. Not much had happened to the control group, but the walkers had significantly improved connectivity in regions of the brain understood to play an important role in our ability to think creatively.
Walking changes our brains, and it impacts not only creativity but also memory.
A study involving 18,766 women aged 70 to 81 showed that even walking as little as 90 minutes per week reduced the rate at which cognition declined over time. As cognitive decline is what occurs in the earliest stages of dementia, walking might ward off that neurodegenerative condition. But correlation does not equal causation. Maybe mentally active people were simply more likely to go for a walk?
One source of information comes from medical students dissecting cadavers in first-year anatomy. Paleontologists need to know anatomy. A fossil could be from any one of more than 200 different bones in the body and from one of dozens of different animals often found along with human fossils. The brain is accessed by sawing off the top of the head. Students are awed when they hold the brain. The brain is the person. The brain is cut into left and right halves. Sitting on top of the brain stem is a thick loop of tissue about the length of a pinky finger. It is called the hippocampus and is the memory center of the brain. Old memories are often retained, but new ones aren’t. This puzzles and frustrates them and they get angry. This should make us want to do everything we can to maintain this region of our brain. Other kinds of memories are stored elsewhere – the ability to recognize faces, so-called implicit memories like how to ride a bike, and so-called explicit memories such as the date WWII began. But the hippocampus is the depository of our life stories.
As we get old, our brain gets smaller and in later years, the hippocampus shrinks at a clip of 1 to 2% per year, and it becomes more and more difficult to recall things that used to come to us instantly. What are we to do about this? Walk.
A study of 120 aging but otherwise healthy people had MRIs that measured the size of their hippocampus. Half were asked to walk forty minutes three times a week. The other half just did stretches but did not take the long walks. After a year, the stretching group had lost between 1 and 2% of the volume of the hippocampus. That was expected. But something extraordinary happened with the walkers. They gained some. The walking group, on average, had grown the hippocampus by 2%. Accordingly, their memory had improved.
The hippocampus, it turns out, can regenerate, and even with just a daily walk can promote growth. Walking can not only delay some effects of aging but can reverse them. But how?
One explanation is that walking, or any exercise, helps get the blood flowing, and, indeed this happens.
MRI brain scans of people who walked for 10 minutes every half hour or so and others who sat all day showed that those who walked had significantly greater blood flow in the middle cerebral and carotid arteries. But blood flow is just the vehicle. It must be carrying something of critical importance to the brain.
MYOKINES. Those molecules released by contracting muscles target the brain, and blood flow delivers them. One of those myokines is called irisin, named after Iris, the Greek goddess of rainbows and Hera’s personal messenger. Alarmingly low levels of irisin have been found in humans with Alzheimer’s, a disease that impacts one in ten people over 65.
When the production of irisin is blocked in mice, they performed terribly trying to remember where the cheese was in a maze. When the irisin flowed again, the same mice recovered. The mice that performed the best were the ones that exercised. In mice, at least, irisin goes straight to the hippocampus where it protects neurons from degeneration.
Another myokine is called brain-derived neurotrophic factor (BDNF). It may be even more important than irisin. The walkers whose hippocampus increased by 2% also had higher levels of BDNF than the non-walking group. BDNF has been called “Miracle-Gro for your brain.”
Depression. There is some evidence that walking helps relieve symptoms of depression and anxiety. They may believe they weren’t walking because they were depressed and enervated, but perhaps they are depressed because they weren’t walking. Those who struggle with depression describe it as an exhausting abyss of hopelessness. When you are in it, you feel like you’ll never get out. One in twelve Americans knows this feeling. While many studies have shown that a regular walk can alleviate symptoms of depression and anxiety, it doesn’t work for everybody. Furthermore, the benefits appear to depend on where you walk.
When you examine the brain, the folds and fissures of the brain seem randomly distributed. To a neurologist, they are a map that reveals the workings of our most magnificent organ. The folds in the back of the brain are where visual cues are processed. A strip of nervous tissue across the top helps coordinate movement. The bulge in the front of the brain is where we make plans. 52 different regions of the brain were identified and named in the early 20th-century by German neurologist Kobinian Brodmann, and each one now bears his name. Brodmann area 22 processes sound. Brodmann 44 and 45 help you talk.
About three inches behind the bridge of your nose is Brodmann 25, or what modern neurologists call the subgenual prefrontal cortex (sgPFC). It plays an important role in regulating our moods, displaying increased activity during periods of sadness and rumination.
One study had 38 people fill out a survey that included questions about their mood and negative self-reflection. The survey was tallied into what was called a rumination score. MRI scans of the sgPFC accessed the blood flow to this region. Then they were sent out for a walk. Half took a 3 ½ mile walk through greenspace on a university. There was fresh air, the shade of coast live oak trees, and screeches from western scrub jays. The other half walked the same distance on a sidewalk along a busy, multilane street through the heart of the city. There, they had to be alert for cars coming and going from gas stations, hotels, parking lots, and fast-food restaurants. When the participants returned, they had another survey and another MRI scan.
Those that had walked along the busy road showed no change in their rumination scores or in the blood flow to the sgPFC. But those that had walked through the woods had lowered their rumination scores, and blood flow to the sgPFC had reduced significantly.
For our mental health, it seems, we should walk where there are trees, birds, and the soft whispers of the wind.
When treadmill walkers did better than non-walkers on creativity tests, a test group took its walk outside. The ones on footpaths performed even better than the treadmill walkers at coming up with original ideas.
Unfortunately, we are not only walking less but, with so many of us living in urban areas, we are doing it in places that erase some of the health benefits.
Perhaps Ray Bradbury was right about what the future may hold. In his 1951 short story “The Pedestrian,” set a hundred years in the future, a writer named Leonard Mead goes for his nightly walk. Bradbury writes: To enter out into that silence that was the city at eight o’clock of a misty evening in November, to put your feet upon that buckling concrete walk, to step over grassy seams and make your way, hands in pockets, through the silences, that was what Mr. Leonard Mead most dearly loved to do.
As usual, Mead walks alone as his city neighbors watch TV, their windows aglow. A robotic police officer stops him and asks what he is doing. “Just walking,” he responds.
“Walking where? For what?” the police officer wants to know.
“For air, and to see, and just to walk,” he responds.
“Have you done this often?”
“Every night for years,” Mead says.
“Get in,” orders the officer.
The story ends with Mead in the back of a police car that is taking him to the Psychiatric Centre for Research on Regressive Tendencies.
The Human Foot and Shoes
Many foot ailments – plantar fasciitis, collapsed arches, bunions, hammer toes, high ankle strains, and all sorts of other maladies – are exacerbated by the very technology that allowed humans to inhabit the globe: shoes.
Footwear helped humans spread into northern latitudes and eventually the Americas. Today, shoes allow one to play blacktop basketball and hike in the woods after a nor’easter. High ankle boots protect against snakebites in the grasslands of Australia and sub-Saharan Africa. Footwear protects against broken glass at the beach or along city sidewalks. Or it simply allows one to buy something at the store since “no shirt, no shoes, no service.” Without shoes, humans wouldn’t have summited Mt. Everest or walked on the moon. There were and remain an important technological innovation. But as is true for many of our cleaver inventions, there are costs that accompany these benefits.
The bottom of your foot contains ten muscles, arranged in four layers. Some of these muscles maintain the foot’s arch while others are critical for propelling us into our next steps. But most shoes, even the wholesome-sounding “arch-supporting” ones can weaken these muscles. The result is a foot more prone to injury.
The Tarahumara are an indigenous people in Mexico known for their exceptional distance-running abilities. Their sandals are usually made from a piece of car tire rubber and held to the foot with string. Human evolutionists studying the Tarahumara to see how they walk and run also used ultrasound to measure the size of their foot muscles. The Tarahumara have higher arches, stiffer feet, and larger foot muscles than the typical American.
Maybe the Tarahumara are just genetically predisposed to have strong foot muscles? The size of two-foot muscles was measured in 33 runners. Half of the runners trained in their normal, cushioned running shoes. The other half transitioned slowly to a minimalist shoe – more like the Tarahumara wear. After only 12 weeks, the minimalist shoe-wearers had increased the size of the two-foot muscles by 20% and their arch was stiffer by a whopping 60%. Our feet change because of the shoes we wear, or don’t wear.
Not only that, but without strong foot muscles, the plantar aponeurosis – that band of tissue that spans the bottom of the foot – can become over-strained, resulting in the stabbing pain of plantar fasciitis. We have lulled ourselves into thinking that our feet need cushioning to survive.
To boot, shoes no longer just protect the feet. They are gendered symbols of social status, wealth, and power. Our feet pay the price. High-heeled shoes shorten the calf muscles and tighten the Achilles tendon, changing how we walk. Repeatedly squeezing the end of our feet into the narrow, pointed shoe box of a shoe increases the chances of developing bunions and hammertoes. These damaging effects disproportionately impact women’s feet and sometimes require surgical intervention.