Human societies have developed from hunter-gatherers to agrarian to industrial. Hunter-gatherers lived nomadic lifestyles, depending on natural resources for food, shelter, and tools. They lived in small bands of 20-40 people. The development of agriculture led to more sedentary societies that grew crops and raised livestock. This allowed for larger settlements and specialization of labor. The Industrial Revolution saw a shift to manufacturing-based economies with machinery and new technologies. People migrated to cities near resources and transportation.