This document summarizes several sources related to big history and the development of civilization. It discusses how early humans shared information through oral traditions and innovations like the printing press. It also summarizes Spencer Wells' work tracing human migration patterns out of Africa using genetic markers in DNA. The document then summarizes sources on natural disasters like the Krakatoa volcano eruption in 535 CE that caused global climate change and civilization collapses. Finally, it summarizes theories from Guns, Germs and Steel about how geographic factors contributed to European dominance and discussions of the role of trade, particularly the search for spices, in motivating European exploration like Columbus' voyages.