Why has increasing farm production failed to prevent malnutrition and famine in developing nations? i need all the answers

Looking back at how farms where run back in the times of the bible or when the colonist first migrated to the Americas from Europe you can see a huge difference in the quality of food being produced. However, we didn't have all the pollution we have now from power plants and carbon dioxide permeating the atmosphere. The low ph balances in the earth which believe it or not help with the amount of nutrients that enters the plants not to mention the chemicals that are constantly being sprayed on crops. When you factor all of those variables in you can see that even in developing nations this is a problem the more a nation developes the more people it can facilitate which means it must now speed up production on many things one of which is food that means over working the soil (Rich soil helps improve the nutrition in the crop) this can lead to famine because eventually the ground will become so over worked that you will no longer be able to grow anything there and just for fun lets through in global warming this is why many people are becoming malnourished because the food is being rushed produced which diminishes the nutrition in the crop.