I would find that a little tough to believe. I could see long walks occasionally, but sustained walks of ~8 hours a day just doesn't make sense. Where would we have been walking? Just giant circles?
"... the Hadza, a population of traditional hunter-gatherers living in the open savannah of northern Tanzania. Despite spending their days trekking long distances to forage for wild plants and game, the Hadza burned no more calories each day than adults in the U.S. and Europe. The team ran several analyses accounting for the effects of body weight, body fat percentage, age, and gender. In all analyses, daily energy expenditure among the Hadza hunter-gatherers was indistinguishable from that of Westerners."
