Footprints in Mexican volcanic ash dated to 1.3 million years ago, which is just another way of saying they were either made by aliens or almost all existing anthropology can be thrown right out the window.
Once you start to realize that the Earth itself may be far older than previously thought, all sorts of things are possible.
Read that book mentioned above by Dalrymple. Was a real eye opener for me. Basically most paleogeologists say one thing in public and another behind closed doors. The reality is, nobody is certain just how old this planet actually is.