The other day, I listened on the radio to a piece by Daniel E Lieberman, who is a professor of human evolutionary biology at Harvard University. He was talking about exercise during the Covid-19 pandemic and how our ancestors were no great lovers of exercise.
Lots of research has shown that the closure of gyms and comfort eating has resulted in many piling on the pounds over the last six months of restrictions. How can we cope better with a second wave of the virus affecting so many countries?
The professor focuses on the past to help us understand the present and plan for the future, and study the evolution, biology and anthropology of human physical activity. In addition to doing experiments in his laboratory, he travelled all over the world to observe the diverse ways that non-westernised, non-industrial people use their bodies.
According to 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.
Thanks to labour-saving inventions, billions of people never have to elevate their heart rate or break a sweat.
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 sat for almost 10 hours a day. 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.
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.
Billions of people exercise by going for walks or runs, doing yoga, playing sports and visiting gyms. 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.
Don’t feel bad if you struggle to exercise. You aren’t lazy, you’re normal. Our ancestors weren’t elite athletes. They mostly rested and were physically active only a few hours a day. Some exercise is 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.