NPR has a short piece with an interesting historical story about old-time back-to-nature fitness fanatics: "Paleo Diet Echoes Physical Culture Movement Of Yesteryear"
As Hamilton Stapell, a historian at the State University of New York, New Paltz, found when he went digging into the archives of physical culture, there are striking resemblances to the paleo movement today. And, he argues, this shows that people seem to romanticize a healthier past in the midst of great societal upheaval: the Industrial Revolution, in the case of physical culture; and the digital revolution, in the case of paleo.
I don't think this specific link is very persuasive, there have been "go back to the good old days" movements since the dawn of time. Most of them have had no basis in anthropological science.