Expert: John Shea - 1/29/2008

Question
Can you give me your take on the initial migration into North and South America? I am mostly curious as to why the majority of ancient cities and monuments are in South America rather than in North America (i.e. Tiahuanaco, Chichen Itza, etc.) Do the existence of these cities go against the Bering Strait migration theory? Also, I have recently read a theory that the first settlers of the western hemisphere crossed the Pacific to South America from Polynesia. Is this theory supported by anthropologists? Thank you.

Answer
Dear Anthony
Early civilizations aren't really my main area of expertise, but I'll give this a try. It's probably a mistake to think about civilizations as some kind of inevitable outcome of human social evolution. Humans haven't needed civilization (writing, irrigation agriculture, cities, state-level polities) for most of our evolution.  Civilizations develop in areas where more simple forms of social organization are inadequate.  Perhaps the early appearance of civilizations in South America is just telling us that this is a tough place to be a hunter-gatherer.
The early appearance of civilizations in South America does not contradict the Bering Strait colonization theory.  None of these civilizations are even close to the youngest estimate for the first human dispersal into the New World across the Bering Strait.
There is some evidence from DNA variation among chickens, of all things, that suggests there may have been contacts between Polynesians and the western coast of South America within the last thousand years, but the oldest plausible dates for such contacts are much younger than the oldest complex societies in the Andes.
Cheers,
John Shea