Humans have evolved to be active creatures, shaped by millennia of movement and survival. Yet, despite this evolutionary background, many of us today lead sedentary lifestyles. Why do we often avoid physical activity, even though it's essential for our health? To understand this, we must examine our evolutionary history and the biological forces that shaped our bodies and behaviors.

Renowned anthropologists Herman Pontzer and Daniel Lieberman have conducted groundbreaking research on human energy expenditure and evolutionary adaptations. Their work offers key insights into why we might be inclined to avoid exercise despite its benefits in the modern world.

Pontzer’s Research: The Constrained Energy Model

Pontzer’s research, particularly his work on energy expenditure, has reshaped our understanding of human metabolism. Contrary to traditional views, Pontzer discovered that while humans are indeed more active than most other primates, the amount of energy we expend through physical activity is not as variable as once believed. His "constrained energy model" suggests that, regardless of how active we are, our bodies adjust overall energy use to remain within a narrow range. This efficiency in energy use, though advantageous for survival, may reduce the perceived benefit of physical activity in the short term, making it harder to stay motivated to exercise.

Lieberman’s Research: Built for Endurance, Not Bursts

Lieberman focuses on how evolutionary pressures shaped human bodies for endurance and consistent, moderate activity, like that of our hunter-gatherer ancestors. He argues that humans are not naturally adapted for high-intensity, short-duration exercise (like modern gym workouts) but rather for activities spread throughout the day. His research suggests that our ancestors engaged in long bouts of walking, light running, and other moderate activities necessary for foraging and hunting. This could explain why intense, modern workouts may feel unnatural or daunting to many.

The Evolutionary Roots of Sedentary Behavior

When we combine these two perspectives, a clearer picture emerges. Pontzer’s research emphasizes our bodies' efficiency in conserving energy, even during moderate physical activity. This may reduce the motivation to exercise because we might not feel like we're expending enough energy to make the effort worthwhile. Lieberman's work, on the other hand, highlights how our bodies are built for sustained, low-to-moderate intensity movement throughout the day, not the intense, short bursts common in many fitness regimes.

Together, these insights suggest that our modern aversion to physical activity is not a sign of laziness but rather a reflection of our evolutionary design. Our bodies evolved to balance energy expenditure carefully, avoiding unnecessary exertion to conserve resources. In an environment of food scarcity, this was critical to survival. However, this predisposition can lead to sedentary behavior and poor health in today’s world, where food is abundant for most people and physical activity is often optional.

Rethinking Exercise for Modern Life

Understanding these evolutionary factors can help us rethink our approach to exercise. Awareness is the first step toward developing strategies that align more closely with our natural tendencies. If the usual modern fitness routines discourage you, find out what works. Perhaps try this:

• Instead of focusing solely on intense, short workouts, engage in consistent, moderate activity throughout the day, like walking or cycling.

• Incorporate movement into daily routines, such as standing while working or taking regular breaks to move around, as our ancestors likely did. For more ideas, check out Don't Sit, Get Fit by The University of New Mexico’s exercise science department.

• Try exercise snacking. The Cleveland Clinic defines exercise snacking as a brief high-intensity movement or exercise that typically lasts no more than two minutes. And it’s something that you can and should do at various points in your daily life.

Our bodies are energy-saving machines designed to keep us going for as long as possible. We should concentrate on long-term health benefits instead of getting discouraged when we don’t see immediate results from our workouts.

Overcoming Evolutionary Barriers to Stay Active

By acknowledging our evolutionary heritage, we can better appreciate the importance of physical activity in modern life and work towards overcoming our natural tendencies toward inactivity. This understanding can help us develop healthier habits and improve our overall well-being.

More Resources

• Lieberman, D. E. (2013). The story of the human body: Evolution, health, and disease. Pantheon Books.

• Lieberman, D. E. (2020). Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding. Pantheon Books.

• Pontzer, H. (2021). Burn: New research blows the lid off how we really burn calories, lose weight, and stay healthy. Avery.