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.
Clovis spear point c. 11,000 B.C.E., found Arizona, flint, 2.98 x 8.5 x 0.7 cm
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. It is remarkable that over such a vast area, the distinctive characteristics of the points hardly vary.
Typical Clovis points, like the example above, have parallel to slightly convex edges which narrow to a point. This shape is produced by chipping small, parallel flakes off both sides of a stone blade. Following this, the point is thinned on both sides by the removal of flakes which leave a central groove or "flute." These flutes are the principal feature of Clovis or "fluted" points. They originate from the base which then has a concave outline and end about one-third along the length. The grooves produced by the removal of the flutes allow the point to be fitted to a wooden shaft of a spear.
The people who made Clovis points spread out across America looking for food and did not stay anywhere for long, although they did return to places where resources were plentiful.
Clovis points are sometimes found with the bones of mammoths, mastodons, sloth and giant bison. As the climate changed at the end of the last Ice Age, the habitats on which these animals depended started to disappear. Their extinction was inevitable but Clovis hunting on dwindling numbers probably contributed to their disappearance.
Although there are arguments in favor of pre-Clovis migrations to America, it is the "Paleo-Indian" Clovis people who can be most certainly identified as the probable ancestors of later Native North American peoples and cultures.