Answer:
Historians are always finding new pieces of evidence to change interpretations
Step-by-step explanation:
If a historian were to find something on the Pyramids of Giza 10 years ago and made the assumption that "The Pyramids were built for people", a new piece of evidence recently found could change that, and see that "The Pyramids were built for gods"
(I don't know if this assumption about the Pyramids is true, I just thought of the first thing in mind)