As the world continues the fight against the novel coronavirus, other public health battles continue to be fought. Take physical inactivity and obesity. Before the emergence of COVID-19, global data suggested both were significant enough to be labelled “epidemics”, as they have created significant health, social and economic burdens in many countries. In response, health agencies around the world have mobilised with a clear and simple message…

“We don’t move as much as we should, and it’s making us sick”.

Due to the seriousness of the problem, health and behavioural scientists have been wrestling with questions related to the causes and cures of physical inactivity and obesity. Some health disciplines – like nutrition, exercise science, psychology, and sociology – have obvious expertise and have led the development of national and global health promotion guidelines.

A paradox

Despite all the good work undertaken in the last 30 years, successful health behaviour change remains an elusive goal for many people. When it comes to exercise, a paradox exists: most people know it’s good for them but they struggle to do it. We fail to act in our self-interest.

Whilst it’s not an obvious place to go for answers, the field of evolutionary biology has an interesting perspective on the exercise paradox.

Evolutionary biology is focused on the origins of life and the evolution of species. They look at health behaviours by looking at human evolution and, specifically, types of physical activity that emerged slowly over time. Take, for example, this significant turn in human evolution…

Baby, we were born to run!

The progression of human species towards bipedalism (transport on two legs) brought with it anatomical and physiological changes that gave humans advantages over mammals that moved around on four legs (quadrupeds). This was the very development of human athleticism, where we developed advantages like spring-like ligaments in our feet, enlarged leg muscles, and the ability to control body temperature via sweating.

A practical benefit of this was that it helped humans to run very economically and outperform other animals over long distances. For humans who lived before the invention of spears, this meant they could run and track prey for many hours (i.e. persistence hunting), long enough to exhaust them and secure nutritious sources of food. This, in turn, supported the development of a larger brain.

Whilst Christopher McDougall’s popular book on ultramarathon running has previously suggested humans are “born to run”, Harvard University evolutionary biologist Daniel Lieberman would likely argue we have been shaped for running…over a very, very long time.

Baby, we were born to rest!

Interestingly, researchers like Daniel Lieberman are also interested in types of physical inactivity that humans have become well adapted for over time. Having noted that early humans were endurance athletes, it should not be surprising that behaviours that minimised and conserved effort would have been highly adaptive too.

Because successful hunter-gathering would rely on a good energy balance (to fuel hours of running or walking), early humans are likely to have been very keen to avoid physical activity wherever they could. Indeed, one could say it is natural and normal to be physically lazy!

But, our inactivity is making us sick

Studies of traditional hunter-gather communities show little signs of modern medical conditions that plague more developed societies (e.g., heart disease, diabetes). In these communities, people act in ways that match their environment. They use their bodies to good effect, walking and running just enough to meet their needs, and being careful not to waste energy.

In contrast, more modern societies place few demands on people to be active. All too often physical activity is seen as discretionary, with many only doing it if it’s fun (e.g. playing frisbee at the beach) or absolutely necessary (e.g. running to catch a train). For an evolutionary biologist, living in low-activity environments is problematic because we have not evolved to be physically inactive.

Evolutionary medicine refers to as a “mismatch” and considers it a driver of many modern illnesses.

Two urgent challenges

As life in high-convenience societies is unlikely to become much more physical, ways need to be found to reduce mismatch. Daniel Lieberman suggests two ways of doing this:

1. Make physical activity more enjoyable. Human beings start life in a highly active way. Much of the fun we have as children is through play, which also helps us learn about the world and develop ourselves physically and mentally. As such, inactive adults can be encouraged to either (i) identify forms of physical activity that they have intrinsic interest in, and/or (ii) look for ways of making physical activity fun and enjoyable.

2. Restructure environments to require more physical activity. Encouragingly, many workplaces and schools are already doing this. In many cases the changes are low- or no-cost, such as schools that get students to exercise before classes, or companies that encourage employees to increase incidental activity levels at work (e.g., by promoting the use of stairwells).

A silver lining?

The COVID-19 pandemic has been a tragic experience for the many millions of people touched by the deadly virus. Likewise, the lockdowns imposed in many countries have created financial hardship, social disconnection and widespread mental ill-health. Yet, it would also appear that the constrained living of the last 18 months has made people acutely aware of their evolved physical selves.

Forced to live within the confines of apartment blocks, houses or suburbs, people have turned towards physical activity as a coping mechanism. As a result, social media platforms have lit up with stories of long-distance walking or running in backyards and on balconies. On-line exercise classes and dance lessons have taken off. Whole families can be seen walking, running or cycling together. Sports watch manufacturers have reported spikes in GPS tracked physical activity levels.

And then there’s the story of Tom Moore. A 99-year old retired Army captain, who walked 100 circuits of his garden as his 100th birthday approached, as a charity fun-raiser! His story has inspired people across the globe, including Queen Elizabeth II, who promptly knighted him Sir Tom.

If there’s any silver lining to the pandemic, perhaps it’s the reconnection people have had with their physical selves, and the value they place upon that? Perhaps the pandemic is the jolt many people have needed, to help break the exercise paradox and trigger sustained behaviour change?

Only time will tell.

In the meantime, Sir Tom reminds us that old age need not weary us. He’s shown us that, with a some motivation and a sturdy walker, it’s still possible to do remarkable things!

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