Think, too of those delicacy coffee beans that are harvested only after the civet cat eats them and poops them back out. How desperate was that guy for his morning cup?
I read somewhere (I think it might have been that History of Salt book) that this is pretty much exactly what happened. People noticed that olives became palatable after they’d been sloshing around in sea water for a long time. It was no jump to simply start brining them in jugs after that.
Since I am currently reading Salt by Mark Kurlansky, I just looked in the index for olives.
It says:
It doesn’t say how they learned that, other than:
But immediately prior, it says:
From this I conclude they already knew how to salt food for preservation, and so tried it with olives.
I live near the olive capital of the US, and judging form the millions of trees I pass in groves regularly, they are not likely to survive in wetlands. So I doubt that a random olive just happened to fall in some natural salt water when there was already an active salting industry.