I am having a hard time putting my comment into a concise point, so I apologize if this doesn't come out well.

I think something that also needs to be considered is that food shortages are also caused not by lack of food and but the lack of safe delivery of it. Many 3rd world countries that have rampant starvation do not lack for food coming into to help them but the food is taken by the government or warlords, stolen or destroyed in transportation before it gets to the regions that depend on it for survival.

On that same token, in 3rd world countries, people are more beholden to tribal/historical lands and would never leave it regardless of starvation or drought, even knowing that if they moved from their village to the city they could get the food and water they need.

It's my 2 cents.