In his book Guns, Germs, and Steel, Jared Diamond is trying to explain why some nations prospered and some did not. Having enough food to feed all the people meant that more people would live through a winter and not starve, more babies would survive as their mothers could care for them, and the men and women would be strong enough to help their nation grow by the use of their labor. The book is saying that because this is one of Diamondd's main ideas in why a civilization grew. Labor could be divided and new ways found to help the nation expand. If the nation was always hungry, many people died of starvation which prevented the ability to prosper.