Some years ago I read a book whose thesis was that not only were our ancestors cannibals, it was the very fact of their diet which especially included eating brains that was the cause of the quantum leap in our own brain development and evolution of the species into homo sapiens.
I can’t remember the name of the book or the author, but I can’t seem to forget the idea behind it. It’s a no-brainer.
Probably the second Indiana Jones movie made a deep impression on him.