s I think Jack LaLane has been saying since the 50's.... if man made it don't eat it! Truer words have never been spoken on the subject of basic nutrition, I'll go so far and say things like grains of any sort are by default man made, in nature, especially before the selective cultivation of various strains, grains were inedible... lets see what else, fruits were smaller and more nutrient dense crab apples vs. plump modern apples, etc etc. But you don't have to go that far if you dont want to just ditch the obviously processed foods
I understand your point here, and it is good advice for sound nutrition (from LaLane), however, it is kind-of sentimental, and is not a recipe for future progress. If the entire current human race turned to a paleo diet the natural world would be ravaged in a manner of days. Modern agricultural practices and even GM foods (including everything that has been bred, hybridized, and domesticated for the last few thousand years) are needed to sustain the current population. Also, lifespan has been increasing over the last century in spite of all the processed (unnatural) foods. Even the expected lifespan after 50 has increased by 9 years.
I am not saying people should be eating more processed foods, large fruit, and high-glycemic grains, just that this component is needed to avoid mass starvation.