Q: There is this theory that all the people (natives) in North and south America come from a group (small or even big) of people that crossed the Bering Strait about 12,000 years ago. But if it is so, Are 12.000 years enough to have all this morphologically different native peoples in the Americas? From North American Indians to the Amazon tribes? I mean maybe different groups (morphologically) of peoples arrived and colonized Prehistoric America in different places. Maybe some came from the sea or something like that
A: Monte Verde in Southern Chile has occupancy dates of 16,000 years ago. As does Medowcroft in Pennsylvania and Cactus Hill in Virgina. The Savanna River site has a supposed date of 50,000 years and one in Brazil is claimed to be 38,000 years. The "Clovis First" argument required humans to arrive after the retreating ice age opened and "ice free corridor" and humans flooded in. However, there was no evidence of such a corridor, or occupancy and reaching the tip of South America by the known occupancy date required some pretty determined marching. Most agree there were four waves into the American and that the start date would be around 20,000 years ago, That's the time and immigrations required to explain the known languages and DNA variation among the Native Americans. There are theories about groups crossing the Atlantic and South Pacific. However they are controversial.