Speaking of fermentation… My contention is that ethanol was discovered by a bold and probably fool-hearty paleo ancestor who dipped his cupped hand into an abandoned honey tree to taste the stagnant liquid pooled inside. Soon enough our ancestors learned how to make the stuff just by leaving watered down honey sitting out exposed to fresh air. Maybe by accident and maybe by “I wonder what would happen if…”
Fermentation of wild grapes probably followed not long afterwards. But beer! Now that’s a different matter. Making beer is more complex than letting honey and grape/fruit juice sit out exposed to the air. Maybe some enterprising housewife (and I suspect it was a woman who made the discovery - the Sumerian goddess of beer was Anana) decided to sprout barley as a way to make the hard grains more chewable, rather than just grind them and add water to make a paste or soup. Probably by accident some of the sprouted barley got left in a pot or cup of water for a few days and began to ferment. Later someone discovered that if you roasted the sprouted barley just enough to burn off the green sprouts, it tasted even better!
Until Louis Pasteur discovered yeast in the 19th century, no one had any idea of how ethanol existed. How it got into mead, wine or beer. It was just magic. Of course, when you depend upon wild yeasts floating around on currents of air to innoculate your nascent brew, you face a big risk that something else floating around will get to it first. That something else was usually vinegar bacteria. Although it might sometimes be a deadly bacterium instead. So there were casualties, to be sure.
Yes, vinegar has been around as long as making ethanol. I suppose sooner or later someone would decide to drink the ‘batch that went bad’. Nothing all that bad happened as a result and so you just drank it so it didn’t go to waste.
That’s my story.