Christians, If God made Adam and Eve perfect?

Then why were the Neanderthals, Paleolithic, sapiens, ect. different from the humans of today? I mean these different species of humans had different sized skulls, shapes, postures, height ect. In my view these were not "perfect bodies." Sure some might say that they were in fact animals, but they used tools and buried their dead which means they were intelligent. Where did these species of humans come from? Did they actually come from Adam himself? I know that once Adam sinned humans stopped being perfect but how is it possible for humans that were descendants from Adam (who had a perfect body to begin with) begin to evolve into an imperfect body and then back to modern humans?