Our Hunter Gatherer DNA Begs For More Physical Activity
We all know by now that if you spend time on moderate-to-vigorous physical activity (MVPA) you have a good chance of being heart healthy. But, most people don’t meet the recommended 150 min/week. That’s all of the people living in a modern, industrialized society with most sedentary work practices. But, researchers have long suggested that we come from a hunter gather backgrounded and that our modern lifestyle is a mismatch with our biology.
This study1set out to explore this mismatch by characterizing MVPA and cardiovascular health in the Hadza, a modern hunting and gathering population living in Northern Tanzania. Of the fewer than 1,000 Hadza left, an estimated 300 to 400 of them are full-time hunter-gatherers. They live a nomadic lifestyle, moving around every month or two but staying in the Lake Eyasi region of Eastern Africa. Although there have been attempts by the Tanzanian government and foreign missionaries to settle the Hadza, with the introduction of agriculture and Christianity, those efforts largely have failed, with the Hadza choosing to maintain their traditional lifestyle.
The Hazda men leave their huts on foot, armed with bows and poison-tipped arrows, to hunt for their next meal. Donner could be a small bird, a towering giraffe, or something in between. The women gather tubers, berries and other fruits. By the standards set down by the US Government, the Hazda live a very active physical life and are at extremely low risk of cardiovascular disease.
University of Arizona anthropologist David Raichlen and his collaborators, Brian Wood of Yale University and Herman Pontzer of Hunter College, spent several years studying the lifestyle of the Hadza, which they say provides a glimpse into how our ancestors lived tens of thousands of years ago, and how that way of life may have impacted human evolution, especially with regard to exercise and health.
"Our overall research program is trying to understand why physical activity and exercise improve health today, and one arm of that research program aims to reconstruct what physical activity patterns were like during the evolution of our physiology," said Raichlen, UA associate professor of anthropology. "The overarching hypothesis is that our bodies evolved within a highly active context, and that explains why physical activity seems to improve physiological health today."
"They have very low levels of hypertension," Raichlen said of the Hazda. "In the U.S., the majority of our population over the age of 60 has hypertension. In the Hadza, it's 20 to 25 percent, and in terms of blood lipid levels, there's virtually no evidence that the Hadza people have any kind of blood lipid levels that would put them at risk for cardiovascular disease."
While physical activity may not be entirely responsible for the low risk levels—diet and other factors may also play a role—exercise does seem to be important, Raichlen said. This is significant because humans' physical activity levels have drastically declined as we have transitioned from hunting and gathering to farming to the Industrial Revolution to where we are today.
While other studies on hunter-gatherer populations have relied on observational data, Raichlen and his colleagues gathered quantitative data using chest-strap heart rate monitors and GPS trackers to record how far and how fast the Hadza people travel on a daily basis. Hadza study participants put on the monitors at the beginning of the day and handed them over each night to the researchers, who lived amid the Hadza during the study period.
"Going forward, this helps us model the types of physical activity we want to be looking at when we explore our physiological evolution. When we ask what kinds of physical activity levels would have driven the evolution of our cardiovascular system and the evolution of our neurobiology and our musculoskeletal system, the answer is not likely 30 minutes a day of walking on a treadmill. It's more like 75-plus minutes a day."
The Hadza people, in north-central Tanzania, are among the last hunter-gatherers on Earth. (Photo: Brian Wood)
The results of the research suggests that our ancestors, who practiced hunting and gathering for ∼2.0 million years, were adapted to a lifestyle characterized by long periods of time spent in MVPA. It is important to note that diet plays a major role in cardiovascular disease risk.
The results also suggest the Hadza do a much larger amount of physical activity than people living in more industrialized societies. Using a very large accelerometry dataset from the National Health and Nutrition Examination Survey (NHANES), previous research had found that a geographically diverse sample of adults living in the United States engage in, on average, 45.1 ± 4.6 min/week of moderate physical activity and 18.6 ± 6.6 min/week of vigorous physical activity (i.e., just over an hour per week of MVPA). By comparison, the data in this study suggests Hadza participants engage in ∼805 min of moderate physical activity and ∼137 min of vigorous physical activity per week, ∼14.8 times higher than adults in the US.
Now that’s an eye opening statistic.
1. David A. Raichlen, Herman Pontzer, Jacob A. Harris, Audax Z. P. Mabulla, Frank W. Marlowe, J. Josh Snodgrass, Geeta Eick, J. Colette Berbesque, Amelia Sancilio, Brian M. Wood. Physical activity patterns and biomarkers of cardiovascular disease risk in hunter-gatherers. American Journal of Human Biology, 2016.