'Humans were never built to run': Harvard professor says walking beats workouts for a longer, healthier life

Renowned evolutionary biologist Daniel E. Lieberman, a professor at Harvard University, is turning heads — and slowing down treadmills — with his thought-provoking book Exercised. The core message? Contrary to popular belief, humans didn’t evolve to run marathons or grind through intense workouts. Instead, our ancestors spent far more time sitting, walking, and conserving energy than sprinting or strength training.

Speaking on the High Performance podcast, Lieberman debunks the modern fitness myth: “We have to do this weird thing called exercise, which is voluntary physical activity for the sake of health and fitness — something nobody did until very recently.”

Evolution Didn’t Design Athletes — It Designed Survivors
Lieberman explains that while physical activity is crucial, the kind we idolize today is historically unnatural. Our ancient relatives only moved as much as survival demanded — usually through moderate walking, hunting, gathering, or building shelter.

“Humans are unusually fat creatures,” Lieberman says with a smile, adding that biologically, our bodies are wired to store energy, not burn it off unnecessarily. From an evolutionary perspective, excessive exercise could even be seen as counterintuitive.

His studies challenge the modern “no pain, no gain” philosophy. While 150 minutes of activity a week — roughly 21 minutes a day — can reduce mortality by 30%, pushing beyond that can sometimes invite injury or burnout. “It’s not about running marathons. Just walking a bit more each day can do wonders,” Lieberman suggests.

A Culture of Overexertion
Lieberman warns against the growing culture of overtraining and pushing limits, especially among younger generations influenced by performance-driven social media. While elite athleticism is impressive, he emphasizes that the average human body simply wasn’t built to endure constant strain.

“The obsession with optimum performance is overrated,” he said during the podcast. “High performance is just achieving your goals and staying active — it doesn’t need to mean winning medals.”

Walk Before You Run — Literally
At the heart of Lieberman’s philosophy is the humble act of walking. More than a biological necessity, he presents it as a sustainable, natural form of exercise that aligns with how our bodies evolved. Ancient humans walked the equivalent of Los Angeles to New York every year — not because they wanted to, but because they had to.

In modern times, incorporating simple changes like walking an extra metro stop or opting for stairs over elevators is more aligned with our evolutionary design than lifting weights for hours or pushing through rigorous cardio regimens.

If you’ve ever felt guilty for not signing up for that spin class or skipping leg day, Lieberman’s research is a breath of fresh, science-backed air. His message is clear: being active is important — but balance is essential.

So before you lace up for your next run, consider his advice. Maybe it’s time we all gave our legs — and guilt — a little rest. After all, evolution might just be on your side.