>>17186And the probability of any one act of intercourse causing pregnancy is very low because there are about three days of fertility each month, yeah, I understand.
But I think it was probably more obvious in cultures where sexual congress was more restrained and fertility higher. The phallic nature of symbols of fertility throughout the ancient world corroborate that, I think.
On the other hand, when everyone's having sex all the time, and doing it for years upon years before any pregnancy, the evidence is buried thoroughly.