People had started growing plants and cattle-herding when they grow tired of moving from one place to another. Hunters and gatherers are nomads. They tend to move when they think that the resources are scarce in their location.They believed that if they could grow these foods instead, they would be able to feed their families and community.
Answer:
Self Interest or self-interested.
Defend until the North gave up--essentially the South believed they had more conviction than the North and that would win out.
The South had an idea to fight for and believed they could survive on their own. The South relied on their ports and did not have as many supplies as the North but they had something to fight for. The North lacked morale and a mission. It was also believed by some that the South had the right to leave and the North had no right to stop them through military action.
