Old thread and quite exciting. I was just wondering why, if the arrows are used as potential proof of contact between European technology and native american, couldn´t this exchange have happened in Siberia? For example if there are two accepted migrations into America with two groups of basically similar tribes, was that just chance or couldn´t they have just stayed in contact with the Siberians updating the Americans on technology? What is the arrow technique was developed in the Americas and went through Siberia into Europe.
Isn´t it possible that the second wave of immigration into America was simply invited in and guided? Perhaps hard to prove, but why would the Bering straits have to be a one way street. I think it is funny that people get precious over this subject, the world after all is a globe. An Irish Monk got near to Cananda in a canoe, it can´t have been that hard or completely unknown of. I can understand those who did know about a way didn´t spread it about, maps have always been preciously guarded, but to think the Americas couldn´t have been discovered multiple times by different people is more ridiculous in my opinion. When I grew I thought it was likely that someone else had found America before Columbus, but it was impossible to say it. Now we are told an Icelandic European "discovered" it first. It seems the further forward in time we go the further back we see.
Of course, we shouldn´t forget multiple people invent things (or re-discover them) at the same time all the time. The TV, the telephone, the radio, oddly there is usually a few people who come up with similar ideas in different locations somewhat independently. Probably because the same issues are arising in their lives. That there is technology regression also shouldn´t be surprising, most Cro Magnons could probably navigate by the stars, I doubt many Europeans could do this on a dark night. The Chinese regressed in technology quite markedly after their massive boon where it is even suspected a Chinese admiral "discovered" America.