Archaeologists found 4,000-year-old popcorn kernels in a New Mexico cave that could still pop.

The discovery occurred during an expedition led by Herbert Dick and Earle Smith at Bat Cave in Catron County, New Mexico. Using radiocarbon dating, scientists determined the oldest corn samples were approximately 4,000 years old. The cave's unique microclimate provided a low-humidity environment that prevented the kernels from rotting or losing their internal moisture balance.Popcorn is a specific variety of maize known as Zea mays everta. It is the only type of corn that pops because its kernels possess an unusually thick hull. This hull allows internal pressure to build as the small amount of water inside the starchy center turns into steam. When the pressure reaches about 135 pounds per square inch, the hull ruptures and the starch expands into a white foam.The Bat Cave samples ranged from the size of a penny to about 2 inches long. These findings provided the first archaeological evidence that popcorn was one of the earliest forms of corn consumed by humans in North America. Later studies by the Botanical Museum of Harvard University confirmed that these ancient grains were structurally identical to modern popcorn varieties. This suggests that the genetic traits for popping have been selectively bred and maintained by indigenous farmers for millennia.