New research on the daily exercise habits of one of the last remaining hunter-gatherer societies on the planet—the Hadza of East Africa—reaffirms the link between moderate-to-vigorous physical activity (MVPA) and a lower risk of cardiovascular disease. The November 2016 report was published yesterday in the American Journal of Human Biology.
The Hadza population resides in a remote area of north-central Tanzania. On a daily basis, the Hadza men hunt for sources of protein using bows and poison-tip arrows; while the women typically gather berries, tubers, and other fruits to feed the family and community. The everyday life of the Hadza people has been untouched by the technological advances of modern civilization.
For millennia, human beings relied on our physical ability to hunt and gather food as we foraged for our individual and collective survival. But, with the onset of industrialization and the subsequent digital age, our need to stay physically active to obtain daily sustenance evaporated. In the twenty-first century, the triple whammy of sedentarism, overly processed foods, and perceived social isolation have created a public health crisis in most industrialized nations.
Experts define sedentarism as being chronically inactive, which is marked by expending less than 10 percent of your daily energy in the performance of moderate- and high-intensity physical activities. There is a strong correlation between sedentarism and heart disease, which is the leading cause of death in the United States. “Sitting is the new smoking,” according to James Levine, author of, Get Up! Why Your Chair Is Killing You and What You Can Do About It, and inventor of the treadmill desk.
The U.S. Department of Health and Human Services guidelines recommend 150 minutes per week of moderate-intensity physical activity (about 30 minutes a day, five times a week) or 75 minutes per week of vigorous-intensity physical activity. Unfortunately, less than half of all Americans achieve these recommendations.
On the flip side, the Hadza typically engaged in about 75 minutes per day of MVPA and have exceptionally low levels of hypertension and cardiovascular disease, according to the researchers. In fact, the Hadza population engages in over 14 times as much MVPA as typical study participants in large epidemiological studies on exercise habits of populations in the United States.
The new study on the daily physical activity habits of the Hadza population was conducted by a team of researchers that included Brian Wood of Yale University, Herman Pontzer of Hunter College, and University of Arizona anthropologist David Raichlen.
The researchers lived collectively amid the Hadza in their camp throughout the study period. Whereas previous studies of hunter-gatherer populations relied on observational data, this team gathered daily quantitative data using heart rate monitors and GPS trackers. In a statement to University of Arizona, Raichlen described the study:
"This is the first study that's looked at their cardiovascular intensity throughout the day, so it helps us understand a little bit more about what cardiovascular intensity levels are like in this lifestyle.
Notably, Hadza adults' activity levels don't seem to fluctuate much over their lifespan. In the U.S., we tend to see big drop-offs in physical activity levels when people age. In the Hadza, we don’t see that. We see pretty static physical activity levels with age."
The new study by Raichlen et al. is a valuable contribution to a growing body of research by anthropologists who have studied indigenous cultures as a way to pinpoint how modern life might disrupt our evolutionary biology.
In the mid-twentieth century, a handful of American researchers began studying the lifestyle habits of indigenous populations and tribes in remote regions of the world who had remained untouched by industrialization. They were trying to identify which fundamental lifestyle habits were associated with human longevity and good health.
In the 1960s and '70s, legendary researchers such as Alexander Leaf of Harvard Medical School and René Dubos of Rockefeller University discovered that the triad of strong social bonds, regular physical activity, and an energy-balanced diet seemed to be a winning formula for protecting indigenous cultures from illness while fostering longevity.
Leaf was considered a trailblazer and pioneer for his work linking diet and exercise to the prevention of heart disease. Dubos, who wrote the 1969 Pulitzer-Prize winning book So Human an Animal, was more interested in the importance of close-knit human bonds. He warned that rapid advances in technology might dehumanize us over time—which could cause our minds and bodies to short circuit. (To read more on the importance of avoiding perceived social isolation in a digital age, check out my Psychology Today blog post, "Face-to-Face Social Participation Nourishes Quality of Life").
Obviously, when studying indigenous cultures that have been untouched by modernization, it's impossible to isolate one lifestyle choice that is the magic bullet for their sustained well-being and longevity. Correlation is not necessarily causation; all of the lifestyle factors and dietary habits must be taken together.
That being said, over the years, dozens of studies have confirmed a causal link between aerobic activity and a lower risk of heart disease. The Hadza researchers found optimal levels of biomarkers associated with cardiovascular health across the entire lifespan. Clearly, there is a correlation between moderate-to-vigorous physical activity and lower risk of cardiovascular disease.
Hopefully, these research findings will inspire you to be more physically active and eat less junk food. You don't have to eat a Paleo diet or live like a caveman to reap the benefits of making common-sense lifestyle choices that are deeply embedded in your evolutionary biology from the days when your ancestors were hunter-gatherers.
Research suggests that it's important to stay cognizant of the pitfalls of sedentarism, which include the potential social isolation that comes with living in a Facebook era. Remember, the simple triad of staying physically active, eating an energy-balanced diet, and maintaining face-to-face social connectedness is an easy way to protect yourself from the Future Shock of too much technological change, in too short a time.
Raichlen, D. A., Pontzer, H., Harris, J. A., Mabulla, A. Z. P., Marlowe, F. W., Josh Snodgrass, J., Eick, G., Colette Berbesque, J., Sancilio, A. and Wood, B. M. (2016), Physical activity patterns and biomarkers of cardiovascular disease risk in hunter-gatherers. Am. J. Hum. Biol.. doi:10.1002/ajhb.22919
Bernstein, M. S., Morabia, A., & Sloutskis, D. (1999). Definition and prevalence of sedentarism in an urban population. American Journal of Public Health, 89(6), 862–867.
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