Pluto and the modern day understanding of Neanderthals are probably Top 5 learning corrections in my lifetime.

One thing that i think should be considered in human archaeology is the narratives/stories/myths from different cultures featuring "different sorts of people". Many were handed down orally from the misty past before being written down and hence may contain some truths to them.

We are often quick to dismiss them as mere fanciful story-telling of primitive cultures but i am not so sure.