Did someone dare you to eat an acorn when you were a kid? Yeah? Me, too. And I'm sure you spat it out in disgust, as well. It might have been your first strong experience of astringency, the quality in food that makes you pucker and your tongue feel fuzzy with near-electric bitterness. Astringency likely has a lot to do with why acorns have fallen out of favor as a food for humans. That hasn't always been the case. Many cultures have utilized acorns throughout the ages, including some of the first people to inhabit California. Even today, circular depressions can be found in the rocks there, evidence of acorn processing.