We were bipedal before we were human. But science still has much to explore about how we evolved—body and brain—to be walkers.
Forget CrossFit and high-intensity interval training; walking is America’s most popular form of exercise. Today, more than 145 million people include it as part of a physically active lifestyle, according to the Centers for Disease Control and Prevention.
And the numbers continue to rise: Recreational walking has surpassed pre-pandemic levels. The activity brings many known benefits: weight loss, heart health and lower blood sugar. But lately, scientists are discovering much more. A Stanford study of 176 adults found that walking boosted creativity by 60%. Another study, published in Frontiers in Public Health, linked bipedalism and brain power, making the argument that walking and the development of the human brain are profoundly interlinked.
That’s something UW Anthropology Professor Patricia Kramer, ’98, an expert in physical and biological anthropology, thinks about when she’s strolling across campus to her lab. She’s mulling more than her immediate health; she’s considering how humans evolved over millions of years to be very good walkers. At the Primate Evolutionary Biomechanics Lab, she and her team study it from an engineering as well as anthropological point of view. “We were born to do it,” she says. “This is something that truly fascinates me. It has for my entire career. It’s this quintessential thing that we do, and we do it all the time from our first steps as babies to old age. And when you can’t walk, it can really change your quality of life.
“Our story, the story of the genus Homo, is about bipedal movement,” Kramer adds. Evidence has early humans walking upright about 6 million years ago, give or take a few million years. Our early human ancestor, Australopithecus afarensis, was bipedal with long thighs and strong knees that allowed her to support her weight on one leg at a time. The foot particularly intrigues Kramer. The way it is built with a high arch and ability to move from heel to toe is especially suited to walking.
“We’re actually very energetically efficient at walking and standing. That’s a good clue that selection has worked on us for millions of years to make us good at this.”
Patricia Kramer, UW Anthropology Professor
Three to 4 million years ago came Lucy, whose fossilized skeleton was discovered in Africa in 1974. The first scientists to study her quickly realized that her normal mode of movement was walking upright. Her foot, arched and stiff, is very similar to ours. Around that time—3.6 million years ago—our predecessors made the Laetoli footprint trail, a site in Tanzania of about 30 yards where three sets of feet once crossed wet volcanic ash. Those walkers were bipedal with human-like feet. They too stepped from heel to toe.
Our ability to walk on two limbs came first, before our larger brains, Kramer explains. “We’re actually very energetically efficient at walking and standing,” she says. “That’s a good clue that selection has worked on us for millions of years to make us good at this.” It made it easier to maneuver through different environments and move across landscapes. Free hands allowed humans to carry tools, food and babies, and to gather fruit from trees.
Kramer bristles that so many of us today are deskbound. “We were not adapted to be sedentary critters, and we are not adapted to sit on our couches and look at our screens,” she says. Common mythology has humans divided into hunters and gatherers, but the reality is that by the time you get into our genus, all individuals in the group were walkers. “The fossil record bears that out,” she says. Around 100,000 years ago, our species began migrating out of Africa and, in short time on the geological scale, had moved into Europe and Asia. She points to the peopling of the Americas around 16,000 years ago, “once we arrive, all of a sudden—by that I mean a couple of thousand years—we’re everywhere. I think it is because we are adapted to move.”
Our understanding of the benefits of walking is still evolving, says Dr. Cindy Lin, a clinical associate professor of Sports & Spine Medicine in the Department of Rehabilitation Medicine. Only recently have researchers explored how many steps a day are best for us. For the past few decades, conventional wisdom said we needed to walk 10,000 steps a day. But that number was a marketing strategy by a pedometer manufacturer, as it sounded good and was easy to remember, Lin says. Thanks to recent medical studies, we now know the real target for most adults is a much more attainable 7,000 to 7,500 steps. Lin cites a University of Massachusetts, Amherst study that associated that number with a 50% to 70% smaller chance of early death. “That study targeted middle-aged people. But older adults showed similar findings,” says Lin. “And I would say this is a general recommendation for the whole population.”
Walking has many benefits. For people with diabetes, even a 15-minute walk after a meal can help reduce blood sugar. It’s also great for breaking up prolonged sitting time. “If you sit longer than six hours a day, it’s not good for your health,” says Lin, who suggests getting up and moving every half-hour. “It all adds up to your overall step-count goal. People have traditionally thought that to exercise, you need to get sweaty or go to a gym. But we need to be more inclusive about activity, and not everybody has the time or resources to do a 30-minute gym workout daily, nor do they necessarily have to. Being creative and building in little bites of movement throughout the day contributes to your step-count goal.”
The practitioners in the Department of Rehabilitation Medicine and members of The Sports Institute at UW Medicine encourage their patients to find what works for them to stay active, Lin says. Wearables and digital-health tools might work for some people; many do not realize that our iPhones and Androids are already counting steps for us. Also, there are multiple free apps that map your walks and runs as well as offer incentives and social-media challenges. “We have a lot of tools to support taking more steps,” Lin says. “It all depends on what motivates you.”
Walking became a habit for Neil Smith about 50 years ago when he moved to Seattle. His motivation was exploring the city’s neighborhoods on foot. He kept up walking all through his time as a civil engineering student at the UW and then over 26 years as a Boeing engineer. Fifteen years ago, he joined a just-formed group called Sound Steppers and today leads sojourns through neighborhoods and parks throughout the Puget Sound region.
“I’m a planner and I love planning walks,” he says as we meet in front of the light rail station on Brooklyn Avenue Northeast at the start of a stroll through campus. Smith sports a bright yellow rain jacket and a fresh pair of Merrell sneakers. “I get a new pair every six months,” he says. His excursions, usually two-hour and 6-mile events once or twice a week, can quickly wear out his footwear. Every Thursday he leads a group of 10 to 14 walkers, mostly regulars who are accustomed to his fast clip. He also joins other groups on weekend strolls, exploring neighborhoods from Samish Island to Seward Park.
“I often tell our patients that our brain needs blood too, and our heart and brain work together and need each other to be healthy.”
Carolyn Parsey, neuropsychologist
Sound Steppers is part of a national effort called Volkswalking, he explains. It is a big deal here in Washington, where more than 20 groups are registered with the American Volkssport Association. The movement started in Germany in the 1960s and came to the U.S. in the late 1970s with enthusiastic participation from military veterans who had encountered it while stationed in Germany. The sport is about walking for walking’s sake, with the goal of reaching a specific distance, usually 6.2 miles, through neighborhoods, parks and countryside. It is for all ages, though Smith’s crowd mostly consists of retirees who enjoy being outside, raising their heart rates and making social connections.
“For me, walking is about maintaining better health and keeping my blood pressure down,” Smith says. “I also like the group thing, the camaraderie and the friendships.” During the worst parts of the pandemic, Smith sorely missed the organized walks, but he managed to keep a few Sound Steppers together for smaller outings. It was the one thing that helped him not feel totally isolated, he says. Once the COVID-19 vaccines became available, the Sound Steppers’ attendance surged.
The benefits of walking include healthy aging and extend beyond the body to the brain—playing a role in staving off cognitive decline. “Research shows that the earlier we start walking, the better our chances are for healthy aging,” says Carolyn Parsey, a neuropsychologist at UW Medicine’s Memory and Brain Wellness Center. But “starting any time will improve your health.”
A Colorado State University study of older men and women published last fall found that exercise, particularly brisk walking, improved the amount of white matter in the brain. The study also looked at a control group and a dancing group and found the people who took a brisk 40-minute walk three times a week had the most prevalent improvements in their white matter, with brains looking larger and tissue lesions appearing to diminish.
While interesting, these findings may not be conclusive, Parsey says. When it comes to white-matter research, we still have much to explore. “But if you zoom out and ask, is exercise going to impact vascular health broadly—by that I mean the heart and the brain—then the answer is yes.” Walking can also play a role in the preservation of brain volume overall, she says. “I often tell our patients that our brain needs blood too, and our heart and brain work together and need each other to be healthy. If we do those good interventions for heart health, we might very well see improvements in brain health.”
Walking also helps with balance, reducing risk of falls and preserving muscle strength. That’s really important from a neurological perspective, Parsey says. “The last thing we want is for someone to fall and hit their head.”
This summer, the Memory and Brain Wellness Center is taking part in a walking and dementia study out of Oregon Health & Science University. The SHARP study (Sharing History through Active Reminiscence and Photo Imagery) combines memory sharing and social engagement on walks through historically Black neighborhoods. In February, a Seattle team held two focus groups in Seattle’s Central District. The team devised walks with the help of African American community members to focus on people, events and landmarks throughout the neighborhood. “It’s not just walking, but social and cognitive engagement,” says Parsey. The aim is to mitigate memory loss or improve cognitive health.
Parsey offered a final thought—older adults need about 150 minutes of moderate-intensity exercise per week. “You don’t have to do a 65-minute spin class. It doesn’t have to be huge blocks of time. Just 20 or 30 minutes a day five to six days a week will get you there.” She describes moderate intensity as “walking with a friend and talking. You may be breathy, but you can still hold a conversation.”
Mavis Tsai, ’82, clinical psychologist and UW research scientist at the Center for the Science of Social Connection, has built her practice around conversation. On a recent afternoon, she and Falkor, her small white pup, cross Eastlake Avenue East to meet me for a walk-and-talk along Lake Union. Tsai views walking as essential to physical and mental well-being. “We weren’t designed to sit for long periods of time,” she says, echoing her colleagues’ comments. She adds that she uses a treadmill desk. She can type comfortably at a pace of 1.4 mph.
Even better, walking outside and walking with another person can do more for you, she says. Tsai has built a practice around addressing isolation, loneliness and disconnection. “Social isolation can increase a person’s risk of death from all causes,” she says. Walking provides opportunities for contact and can strengthen neighborhood social ties. Simply acknowledging others as you go past or waving hello to your neighbors can bring some feelings of connection. It also might improve your mood and quell anxiety, she says.
Working with her patients, Tsai found that the act of taking a walk opened them up to sharing more than they might when sitting for face-to-face therapy. The stimuli of the outdoors and the work of walking may help them overcome some barriers to expressing themselves, she says.
Walking with a companion provides you with an opportunity to create more meaningful interactions. “If you want to connect more deeply, go for a walk,” she says. As we navigate the sidewalk together, Tsai suggests that we connect with our surroundings by naming things that we see—clouds, colorful clover, a blossoming weed. “I’m noticing this family of ducklings is going really fast,” she says. I point out a thick rope framing a bed erupting with flowers. “I never noticed that rope before,” Tsai says, adding, “There are no rules. We are just getting into our senses of the moment. As you get into your conversation, you have to be willing to be more vulnerable. Be openhearted and self-disclosing.” Then she dives into deeper, more personal questions in order to create a more meaningful connection.
Walking and communicating is certainly something we humans evolved to do, notes Kramer, the anthropologist. “As primates, we’re social and we want to see and smell and touch others. Our brains are programmed to want that.”
While connecting and communicating during walking has not changed over the millennia, how and where we walk has. We’re not built for strolling in a straight line or on a flat surface, Kramer says. We have evolved to move up and down hills, on slopes, in snow. “When you’re out walking, you’re getting a lot of sensory input. You’re feeling the breeze on your face, you’re seeing the building or hill in the distance, you’re hearing a bird, you’re feeling the ground with your feet,” she says. “Walking engages our senses in ways we find rewarding.”