Popcorn is a truly ancient snack. Archaeologists have uncovered popcorn kernels that are 4,000 years old. They were so well-preserved, they could still pop.
Dolores Piperno, a paleobotanist with the Smithsonian's Tropical Research Insitute, says corn, and specifically popcorn, helped lay the foundations for the Aztec empire.
"When you have a very highly productive crop like corn, that makes the rise of high civilizations possible," she says.
Piperno grows the wild, great-grandaddy of modern corn — a weird grain called teosinte. It has just a few kernels on each stalk, and they're too hard to eat or to grind into flour. But teosinte has a special property that almost makes up for these shortcomings: It can pop.
"All early corns were popcorns," Piperno says. "They were around for millennia before these other forms of corn."
After a couple of thousand years, the Mesoamericans managed to cultivate varieties of corn that were good for flour, but they still ate popcorn. The Aztec language even has a word for the sound of many kernels popping at once — totopoca.
After the Spanish invaded, popcorn spread around the world, and soon people began to figure out how popcorn actually works.
It turns out that rock-hard kernel — the thing that makes teosinte and popcorn impossible to eat raw — is the key.
"It acts as a pressure cooker," says David Jackson, a food scientist at the University of Nebraska. He says the durable kernel keeps water and starch sealed inside. When a kernel is heated, the starch liquefies and the pressure builds until the seed coat breaks.
"The pressure cooker essentially fails, and it explodes outward into a popped kernel," Jackson says.
The liquefied starch froths outward, cooling and solidifying in a fraction of a second. If you look at a popped kernel under the microscope, you can actually see the bubbles that were formed by the expanding steam. That's why popcorn is so light and fluffy — it's made of bubbles.
There's something to think about next time you're stuck watching a bad movie.
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Transcript
DAVID GREENE, HOST:
It's Oscar time, which means I'm thinking about going to the movies. A trip to the movies, though, not cheap these days. Twelve-dollar tickets, four to $5 for a soda or a box of candy. And a large-popcorn can run you upwards of 10 bucks. Turns out, while you're munching on that overpriced All-American popped finger food, you're actually snacking on a truly ancient treat. Archeologists have uncovered popcorn kernels that are 4,000 years old. And they're so well preserved, they could still pop.
NPR's Adam Cole explores the history and the science of his favorite movie snack.
ADAM COLE, BYLINE: Dolores Piperno studies the foundation of empires. And by that she means corn.
DOLORES PIPERNO: When you have a very highly productive crop like corn, that makes the rise of high civilizations possible.
COLE: Piperno works at the Smithsonian's Tropical Research Institute in Panama, cultivating corn's wild ancestor - a weird grain called teosinte. It has just a few kernels on each stalk, and they're too rock hard to eat or to grind into flour.
PIPERNO: It'd be hard to make a tortilla out of it.
COLE: But Piperno says teosinte has one property that might make up for the whole no-tortillas thing.
(SOUNDBITE OF POPPING CORN)
PIPERNO: All early corns were popcorns. They were around for millennia before these other forms of corn.
COLE: After a couple thousand years, the Mesoamericans managed to cultivate varieties of corn that were good for flour, but they still ate popcorn. The Aztec language even has a word for the sound of many kernels popping at once: totopoca.
After the Spanish invaded, popcorn spread around the world. And soon, people began to figure out how popcorn actually works. It turns out that rock-hard kernel - the thing that makes teosinte and popcorn impossible to eat raw - is the key.
DAVID JACKSON: It acts as a pressure cooker.
COLE: That's David Jackson, a food scientist at the University of Nebraska. He says the durable kernel keeps water and starch sealed inside. When a kernel is heated, the starch liquefies. The pressure builds and then totopoca.
(SOUNDBITE OF POPPING CORN)
JACKSON: The pressure cooker essentially fails and it explodes outward into a popped kernel.
COLE: The seed coat breaks and the liquefied starch froths outward, cooling and solidifying in a fraction of a second. If you look at a popped kernel under a microscope, you can actually see the bubbles that were formed by the expanding steam. That's why popcorn is so light and fluffy, it's made of bubbles - and there's something to think about next time you're stuck watching a bad movie.
(SOUNDBITE OF POPPING CORN)
COLE: Adam Cole, NPR News. Transcript provided by NPR, Copyright NPR.
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