13,000 year old North American spear point
"The first clear evidence of human activity in North America are spear heads like this. They are called Clovis points. These spear tips were used to hunt large game. The period of the Clovis people coincides with the extinction of mammoths, giant sloth, camels and giant bison in North America. The extinction of these animals was caused by a combination of human hunting and climate change.
How did humans reach America?
North America was one of the last continents in the world to be settled by humans after about 15,000 BC. During the last Ice Age, water, which previously flowed off the land into the sea, was frozen up in vast ice sheets and glaciers so sea levels dropped. This exposed a land bridge that enabled humans to migrate through Siberia to Alaska. These early Americans were highly adaptable and Clovis points have been found throughout North America."