What boggles me is why similar sites have been found throughout the world. It is actually pretty rare that two completely disassociated groups discover the same process at roughly the same time and use it for roughly the same purpose. Normally ideas are spread through contact with the originating culture. In fact, I do not know of a single breakthrough technology, which this surely would have to be considering the time period, that was spontaneously discovered in separated areas at the same time. Hell, even the rediscovery of technology normally takes several centuries.

I remember about twenty years ago some guy touting an environmental technology, and he had mentioned that his technology was similar to that used by the ancient Egyptians to build the pyramids. Seemed pretty wild speculation back then. 
> 
> Having said that I could never really believe the huge blocks being hauled into place. Bags of sand etc and vessels of water - now we are talking.-
You should see the size of the blocks of stone in Cuzco and Saysaxihuman (Sp?) in Peru. Not only enormous, but set in place to resist earthquakes!