I once heard an interesting definition of what an expert is:
"An expert is a person who is far away from home and gives advice"
"An expert is a person who is far away from home and gives advice"
Of course people can't be born experts and for every expert there must be a prior step in their personal growth when they were less expert. But that doesn't prevent people from using an imperfect heuristic for judging whether you can trust someone's expertise.
Classic example is the pyramid structures around the world. The fact that people found that it's easy to pile rocks that way in order to build tall stable structures doesn't mean that there was a single culture that span the entire globe.