10 million years ago, our gene for the enzyme that helps us process alcohol (alcohol dehydrogenase) underwent a mutation that left it 40x more effective. Before that, even small quantities of alcohol would be poisonous to humans. Of course, the farming of grain and the brewing that coincided with it wouldn’t develop until roughly 10,000 years ago, but in the intervening time this mutation allowed humans to consume (and get tipsy off of) rotten fruit. (From Entangled Life)
Yeast is the fungus we have to thank for alcohol and all the comedy, tragedy, and human culture it’s given rise to.