<human>:  When did the first humans arrive in the Americas?
<bot>: The first humans arrived in the Americas about 12,000 years ago. The first humans were nomadic hunter-gatherers who lived in Africa and spread throughout the world. The first humans who migrated to the Americas were called Paleo-Indians. They were hunters and gatherers, but they also had a more sophisticated technology than their ancestors. They used bone tools and made spear points, which were made of stone, bone, and wood.