Wednesday, October 3, 2012

Debunking the Hunter-Gatherer Workout

The current levels of obesity and obesity-related health issues are epidemic in the United States and in other developed countries. While there are numerous debates occurring in the healthcare, politics, economics, and cultural areas of society about what the causes are for this obesity crisis, evolutionary genetics has a debate of its own going on regarding the causes of obesity. When we look at Darwin’s theory of evolution, it is clear that obesity must have some roots in the fact that our lives are radically different from how they were for our hunter-gatherer ancestors. However, the point of contention lies in what aspect of this difference is to blame for our epidemic—is it the fact that our activity has changed, or that our diet has changed?

According to Debunking the Hunter Gatherer Workout, a New York Times article written by scientist Pontzer, the key is the change in our diet. Pontzer cites his own study, published in the PLoS ONE journal, as evidence. He and his colleagues went to Tanzania to get data from a tribe of hunter-gatherers—one of the few left in existence. The Hadza people live simple lives and their daily activity consists of just that—women are on the move scavenging over hilly terrain for food (sometimes while holding children and water), and men are traveling 15-20 miles a day hunting game. There is no obesity, diabetes, or heart disease in the tribe.

Pontzer measured the Hadza’s physical activity level and how many kcal/day they burned, comparing the data with that of a typical American or European, and accounting for age, sex, body mass, and fat mass. His results were interesting: they showed essentially no correlation between physical activity level and BMI. An idea that the Hadza people might have more efficient bodies was ruled out through other data. Therefore, Pontzer and his team reached the conclusion that Hadza tribesman’s bodies must have adjusted over time to account for their intense physical activity, possibly by expending less energy in behind-the-scenes cellular processes that the majority of our energy expenditure consists of.

The implications of this study and article for obesity are that America must encourage a change in diet over activity. This is the most key aspect of our lives that has changed from the time we were hunter gatherers to our current status as modern human beings. It is certainly necessary to educate our country about this study and to encourage healthy eating habits in order to improve the well-being of our fellow citizens. 


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