My understanding is that we're basically built to be walking ~8 hours most days. So yes, a long walk... but longer than most of us can fit in.
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?
Wherever food seemed to be, I imagine.
Google "wolf run hours per day". Where do they run?
"... 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."
http://www.sciencedaily.com/releases/2012/07/120725200304.ht...
More, if you go far enough back (not actually that far, frighteningly) and things like "respect for the life of others" drops out rather sharply.
So.... what, exactly, is the lesson here? My takeaway is that rose colored glasses can make even some of the most horrid of conditions (human history), somehow look good. Me? I'll take the present where I have a reasonable expectation that my kids will not die before me. By a long shot.