Key Concept 6.1 Rapid advances in science altered the understanding of the universe and the natural world and led to the development of new technologies. These changes enabled unprecedented population growth, which altered how humans interacted with the environment and disrupted ecological balances at local, regional, and global levels.
Key Concept 6.2 At the beginning of the 20th century, a European-dominated global political order existed, which also included the United States, Russia, and Japan. Over the course of the century, peoples and states around the world challenged this order in ways that sought to redistribute power within the existing order and to restructure empires, while those peoples and states in power attempted to maintain the status quo. Other peoples and states sought to overturn the political order itself. These challenges to, and the attempts to maintain, the political order manifested themselves in an unprecedented level of conflict with high human casualties. In the context of these conflicts, many regimes in both older and newer states struggled with maintaining political stability and were challenged by internal and external factors, including ethnic and religious conflicts, secessionist movements, territorial partitions, economic dependency, and the legacies of colonialism. Key Concept 6.3 The 20th century witnessed a great deal of warfare and the collapse of the global economy in the 1930s. In response to these challenges, the role of the state in domestic economies uctuated, and new institutions of global governance emerged and continued to develop throughout the century. Scienti c breakthroughs, new technologies, increasing levels of integration, changing relationships between humans and the environment, and the frequency of political con ict all contributed to global developments in which people crafted new understandings of society, culture, and historical interpretations. Institutions of global governance both shaped and adapted to these social conditions.