[Turing_Machine]

"Diet was hardly their only problem."

In terms of growth, it was definitely the major problem.

People did not evolve to get the majority of their calories from carbs.

Now, the "carbs are absolute evil!!!!" people do take it to an extreme, but it's just a fact that signs of nutritional deficiency (e.g., stunted growth) appear in the archeological record as soon as a group of people move from a high-protein, hunter-gatherer lifestyle to a high-carb agricultural lifestyle.

If there are any exceptions to this, I'm unaware of them.