I can't help but feel that some combination of the Birthday paradox [0] and primates churning out stories [1] is going on here. [0] https://en.wikipedia.org/wiki/Birthday_problem [1] https://en.wikipedia.org/wiki/Infinite_monkey_theorem
Can you explain why this is related to the birthday paradox please? I don't get it, sorry! :)
Just like the odds of two people in a group having the same birthday is surprisingly low, so are the odds of different cultures coming up with the same story.
If you add a bit of selection bias, where you ignore all cultures that don't have a seven sisters story and ignore all the other myths that are not similar and you could end up with this unsurprising coincidence.