1. Various innovations in technology and social organization allowed early complex civilizations to develop, including agriculture, irrigation systems, construction techniques, writing systems, and advanced medical practices. These innovations made societies more stable and productive.
2. Specific innovations discussed include bronze-casting in ancient China, which brought advances like horse-drawn chariots and new social hierarchies, and cuneiform writing invented by the Sumerians, which allowed record keeping and transmission of ideas.
3. Technologies like mummification in ancient Egypt played important social roles, while innovations like Hammurabi's Code systematized laws in ancient Mesopotamia. Overall, these advances supported more populous, organized societies.