Corn and the remaining highly durable cobs are known to be far, far older. And as those are maize as well, means that popcorn is likely as old as the oldest corn fossils known.

Domestication by 10K yrs. ago. Existing as a species likely 20K years or more. It's NOT all about humans, but about where Teosinta came from and how old that very likely goes back, too. Corn likely originated 10K's of years before we humans came to North Am.