system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do archaeologists differentiate between a widespread cultural tradition and an isolated incident?

This is kind of hard to put into words. What I'm asking is, how would an archaeologist be able to tell if what they've just found is evidence of a massive cultural phenomenon or just a weird and singular thing? 

Like, if someone dug up an ancient carving that they hadn't seen before, would they assume that it had some sort of religious or cultural purpose immediately? Or would they just think "the guy that made this must've been really into carving"? Do they just always assume the latter until they see the carving pop up in different areas, or do they go towards the former more often without explicit backup evidence?
gpt
Short answer: they guess.  It’s an educated guess, based on evidence left behind and knowledge about the culture, but it is a guess.

It’s not always right, either.  There are some hilarious cases of mistakes coming to light.   

One famous example a couple of centuries ago, archaeologists found a peculiar, triangular object made of metal in a home they were excavating.   It was ornately carved and had two holes bored into it.

They came up with all kinds of theories to explain this beautiful piece.   Eventually they settled on it being a means of worshiping one of the local deities - that the holes were a means of whirling the thing around so that light could shine through it.

Eventually, the local people could stand it no longer and informed the foreign archaeologists that the object was, in fact, an iron.   They still used identical irons, and the holes were for the handle, which was missing.   And the ornate carvings?   Well, the woman who had once owned that iron had clearly wanted it to be pretty.   She’d likely spent a lot of time in its company, after all.

This is a rather extreme example of guessing incorrectly, but it does make the point nicely.   Archaeologists do their best, but they are human.