I generally don't view TV but I cought a program tonight about the ancient Mayans on the History Channel. I you get a chance, you might view this, very interesting.
I find it difficult to believe their calanders were as accurate as the program suggested. But if they were that accurate, perhaps civilization is older than we realize, or perhaps someone actually visited them.
Perhaps possible, but it's difficult to understand how they could understand the precessive wobble using the naked eye, a 26,000 year cycle. How could they possibly understand a 26,000 year cycle using the naked eye?