I think a lot of superstitions come from the difficulty of telling the difference between something happening at the same time or one after the other, and there been a true correlation. That is why we have scientists after all. But science is expensive, both in time and materials, a hunter gatherer would be unlikely to have the free time to test repeatedly if say scaring a pregnant woman would harm the baby. That and the power of gossip and language and you have the makings of a myth.

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