1. Migration theories

2. Clovis Theory
First humans came from N. Asia to the Americas via the Land Bridge.
They came in one migration about 12,000 years ago
They could travel through the gap in the glaciers that opened up about 12,000 years ago when ice age was ending.
Best evidence: the oldest remains were thought to be from Clovis, NM. Dated about 9000 years old.

3. Coastal Theory Clovis is not wrong, but not the whole story
Some people came the Clovis way, but others might have walked/used boats to go along the coast.
The coastal travelers might have done it even earlier than Clovis people, and from different parts of Asia
Thus, there were several migrations over time, not one main one
Best evidence: Skeletons at Monte Verde Chile that were older than 12,000 years old. (14,500)
Best Evidence #2: Kennewick people looked different from other Native Americans/ anscestors.

4. Europe Theory
Maybe some of the first people were actually from Europe.
It might be possible that they followed a coastal route from France/Spain along through the Northern Atlantic to the East Coast.
Best evidence: The spearheads found in Pennsylvania are very similar in design to the ones from the Solutreans from France/Spain.
Evidence against: no evidence that they built boats, and no evidence of other parts of their culture (cave art) in the Americas.
More evidence against: it is possible that similar spearhead could have been developed in 2 different places.