Does the prospect of enduring a second lockdown feel like deja vu all over again? And are you worried about its renewed effects on your body? I am. To cope with the monotony and strain of confinement, my family did a lot of stress-baking, but my biggest problem was being too sedentary. I tried to jog regularly, but my inability to go to work or other places curtailed my physical activity levels drastically. According to my iPhone, my average number of daily steps decreased by about half. Apparently, my experience was typical. Working from home and prohibitions on going out also kept people at their desks for nearly an extra hour a day, and surveys suggest that almost half of UK adults claimed to have put on weight during the lockdown.
How can we cope better with a second time round, especially in terms of exercise? Knowing the past helps us understand the present and plan for the future, and I study the evolution, biology and anthropology of human physical activity. In addition to doing experiments in my laboratory, I have travelled all over the world to observe the diverse ways that non-westernised, non-industrial people – that is most of humanity – use their bodies. My experiences and other research have helped me appreciate how recent decades have reduced and altered physical activity in places such as the UK and the US, lockdown or no. Fortunately, these perspectives also provide useful insights into how we can do better during the next lockdown and afterwards.
According to careful studies that have monitored hunter-gatherers in Tanzania and elsewhere, foragers typically engage in about two-and-a-quarter hours a day of moderate to vigorous physical activity. Every day, even in their 70s, hunter-gatherer women and men walk between five and nine miles, often carrying heavy loads, and they also spend hours doing other activities like digging. Farmers who don’t rely on tractors and other machines generally work even harder. Thanks to labour-saving inventions, billions of people never have to elevate their heart rate or break a sweat. Prior to the pandemic Britons averaged about half an hour a day of moderate to vigorous physical activity.
Does our newfound sedentism mean we have become lazier? Decidedly not. Avoiding physical activity that is neither necessary nor rewarding is a fundamental, universal instinct among adults. To be sure, in every culture children play, adults sometimes engage in sports, dance, or otherwise move for fun, but generally humans sit whenever possible. Even hunter-gatherers sit for almost 10 hours a day, the same as most westerners. From an evolutionary perspective, this inertia makes sense because in the past, when food was usually scarce, energy spent on discretionary activities, such as a five-mile jog, diverted precious calories from the only outcomes natural selection really cares about: taking care of the body’s needs and having as many babies as possible.
And therein lies a conundrum, because while it is profoundly normal to avoid unnecessary exertion, physical activity promotes health. Many of the salubrious effects of physical activity occur because the short-term stresses of exertion stimulate myriad maintenance and repair processes that increase the body’s capacity and slow its deterioration with age. Almost every organ and system of the body benefits, including muscles, bones, brains and immune systems. The problem is that we never evolved to stimulate these repair and maintenance mechanisms as effectively in the absence of physical activity because no one until recently was persistently sedentary. Long-term sedentism thus increases our vulnerability to dozens of widespread illnesses including obesity, respiratory tract infections, type 2 diabetes, heart disease, high blood pressure, osteoarthritis, some cancers, depression and more.
And so we invented exercise: planned, voluntary physical activity for the sake of health and fitness. While exercise began in ancient times to train soldiers to fight and also became the privilege of elites, its popularity exploded during the industrial revolution to help growing legions of clerks, bankers, administrators and other white-collar workers who needed to find new ways to move. Now, billions of people exercise by going for walks or runs, doing yoga, playing sports and visiting gyms. To help them, and to make money, we have also commodified, industrialised and medicalised exercise. I spend a small fortune on running gear, a coach, and even pay fees for the privilege of participating in races.
There is nothing wrong with commercialising and medicalising exercise, but these modern approaches evidently don’t work very well for most of us under normal circumstances, and they certainly don’t work well in a lockdown. Being told to “Just Do It” by Nike, your doctor or your prime minister, isn’t always effective for several reasons, not the least of which is that exercise is a newfangled, odd activity that we must choose to do in spite of deep-seated counter-instincts. Imagine trying to explain to your hungry caveman ancestors that you pay money to trudge in a gym on a treadmill that gets you nowhere, or lift weights whose sole purpose is to be lifted.
Instead of being deflating, I think the realisation that exercise is a modern, abnormal activity is empowering. Don’t feel bad if you struggle to exercise. You aren’t lazy, you’re normal. It is just as wrong to shame and blame people for being couch potatoes as it is for having trouble losing weight. We also don’t need much of it to enjoy its benefits. Our ancestors weren’t elite athletes who trained. Instead they mostly rested, and were physically active only a few hours a day. Some exercise is vastly better than none, and just 20 daily minutes can halve your risk of dying prematurely.
Finally, keep in mind that we evolved to be physically active only when it was necessary or fun. It follows that we are more likely to exercise when we make it both necessary and fun. Perhaps you enjoy meditating while walking or running, or listening to a podcast on a treadmill, but most people enjoy exercise most when it is social. So find ways to do it with friends, even if it’s on Zoom. And to make exercise necessary, consider making a commitment contract. Just as we often best learn difficult subjects by signing up for classes and being graded, ask a friend or relative to be your exercise referee: agree on a goal, report your progress and establish ways to make yourself accountable either with carrots or sticks.
Sadly, the social distancing required to keep Covid-19 at bay isn’t going away soon, and we need to adapt. Instead of being exercised by a lack of exercise, I hope evolutionary and anthropological perspectives can help us find new ways to keep moving.
• Daniel E Lieberman is professor of human evolutionary biology at Harvard University and author of EXERCISED: The science of physical activity, rest and the pursuit of health