Highly read on www.plosone.org in August

Despite their very different lifestyles, a hunter-gatherer expends about the same amount of energy each day as the average person in Europe or the United States.

For 11 days, Herman Pontzer of Hunter College in New York and his colleagues measured daily energy expenditure and physical activity levels in 30 adults from a Hadza hunter-gatherer group in Tanzania. Controlling for factors such as age, sex, body fat and body mass, the researchers compared their results to individual and population data from a spectrum of societies, including Western countries. Hadza individuals walk longer distances and forage for resources. So, unsurprisingly, they had higher physical-activity levels than Westerners. However, on average, both groups used the same amount of energy on a daily basis, as well as when walking or resting, suggesting that the rate of energy expenditure is an evolved trait that is independent of culture.

Obesity trends in Western populations could be unrelated to a sedentary lifestyle, the researchers suggest.

PLoS ONE 7, e40503 (2012)