If you're keeping tabs on the history of human food - and keeping score on modern American diet books - there's a tuber-sized hole in the founding principle of the Paleo diet, with its avoidance of dairy, legumes, pulses, grains and starches. Apparently, ominivorous Old Stone Age people ate starchy cereals and roots whenever possible, drying tubers and acorns and grinding them into flour. "A lot of Paleo diets talk about health, but by this they mean weight loss. And I can’t think of a single human ancestor who wanted to lose weight," says Amanda Henry of Leiden University in the Netherlands.