Hypotheses of modern disease, stop number 5: processed foods are killing us. We need to eat more in accord with Nature.
OK, I admit that this is the least scientific of the hypotheses that we have discussed so far, but it is by far the most prevalent. Some people become vegetarians for this reason. Some start eating organic produce. Some become locovores. Some join the whole food movement. Some just cut back on "cured" meats (I have an issue with this one, but that will have to be a different post).
It is understandable. In a country where it is difficult to buy heavy cream whose ingredients are, "Cream" and it is perfectly legal to list, "Orange Juice" as the only ingredient in a laboratory derived cocktail, processed foods comprise the vast majority of available foodstuffs. The vast majority of this vast majority of processed foods contains wheat and/or sugar.
There are a lot of differing opinions about exactly what it is in these frankenfoods that is bad for us. But we don't have to know the right answer if we can just avoid them entirely. A paleo diet lends itself to processed food avoidance pretty well. Eat your meat. Eat your veggies. Leave the frankenfoods for someone else.