: American History The Earliest Americans
: Main Ideas 1. Climate changes allowed Paleo-Indians to begin the first migration to the Americas. 2. Early societies existed in Mesoamerica and South America.
: First Migration to the Americas Many scientists believed that the first people arrived in North America during the last Ice Age. At the start of the Ice Age, Earth's climate became intensely cold. Large amounts of water froze into huge, moving sheets of ice called glaciers. As a result, ocean levels dropped more than 300 feet lower than they are today. When the sea level fell, a land bridge between northeastern Asia and present-day Alaska was exposed.
: First Migration Con. Geographers call this strip of land the Bering Land Bridge. Although no one knows exactly when or how people crossed into North America, evidence suggests that people called Paleo-Indians crossed this bridge into Alaska between 38,000 and 10,000 BC. This migration-a movement of people or animals from one region to another-took place over a long time. It is believed that Paleo-Indians traveled south into Canada, the United States, and Mexico following herds of animals.
: Changes in Early Peoples' Migration About 8000 BC, Earth's climate grew warmer, and the Ice Age ended. Rising temperatures melted glaciers. Water levels in the oceans rose, and the Bering Land Bridge was covered in water. The warmer climate at the end of the Ice Age created new environments, climates and landscapes that surround living things. Large herds of animals such as buffalo and deer ate new short grasses that thrived in the warm climate.
: Climate in Early People's Migration Con. As the number of these animals grew, Paleo-Indians hunted these animals for survival. Varied environments influenced the development of different Native American societies, or groups that share a culture. Culture is a group's set of common values and traditions, including language, government and family relationships. Like all societies, Native American groups changed over time.
: Changes in Early Peoples' Migration Con. People planted seeds, and eventually they learned to breed animals, farm, and grow plants. Maize, or corn, was one of their most important early crops. Later, they learned to grow beans and squash. Farming allowed people to stop moving around looking for food and to settle in one place. With adequate food supplies, settlements could support larger populations. As populations grew, more advanced societies began to develop.