Anybody, but especially scientists, who assume that the Prehistorical era(s) were static and lacked adventurers / explorers is a fool. The concept of seeking greener fields just over that hill probably originated with Ogg&Ugg.
There is a Smithsonian Scientist who postulates that the Clovis Arrowhead may have been a copy of similar arrowheads being used in Ice Age France and brought to the New World by nomadic hunters of seals and the like moving along the ice sheets.
To assume that there have not been individual and small group influences is a fallacy BUT it is Columbus who made the New World a lasting reality as his discovery was the PERMANENT ONE!
Here ya go.
Dennis Sanford is a good guy.