Again, the science disagrees. Perhaps going straight from a modern, industrial, likely sedentary lifestyle to two weeks of extended physical exertion for its ow

Again, the science disagrees. Perhaps going straight from a modern, industrial, likely sedentary lifestyle to two weeks of extended physical exertion for its own sake is not equivalent to people spending their whole lives in a hunter-gatherer setting. Further, there's nothing inherently good about things being natural. Again, your patterns of exercise, your nutrition, and virtually every other aspect of your health is quite different from that of a hunter-gatherer, it would not be surprising if behavioral changes to adapt to differing circumstances would be beneficial.