Humans can’t get enough of corn - it’s found in most items on grocery store shelves, from chips to breakfast cereals to beverages and even baby formula. Corn makes up around 20% of the nutrition for all humans, worldwide. This is surprising, considering that corn should not be edible at all. To become a staple food, corn had to come a long way.
The evolution of corn, also called maize in some parts of the world, is a rags-to-riches story of the food world. Nine thousand years ago, there was no corn as we know it. The closest thing was a grass called teosinte that grew in modern day southern Mexico. Teosinte produces cobs that are only about a sixth of the size of a modern ear of corn, with between 5 and 12 kernels per ear that break apart easily, as opposed to modern corn’s hundreds of kernels on a sturdy cob.
It’s likely that teosinte was first cultivated by humans around the Balsas River Valley of southern Mexico about 9,000 years ago. The teosinte plant’s stalks contain a sweet juice, kind of like sugar cane. And archaeologists think that the stalks were the only reason Mesoamericans even cultivated teosinte in the first place, and it had nothing to do with the kernels.
Genetic studies have provided evidence that corn came directly from teosinte, but it’s less clear how the focus of cultivating the plant changed from stalk to kernel. What we do know is that it likely took just a few genetic changes to transform the hard-shelled teosinte seeds into something that could nourish a civilization. Over time, the nomadic people who cultivated teosinte started selecting the characteristics of the plants they liked best. Eventually, they set their sights on making the kernels as tender and plentiful as possible.
Another big step in making corn out of teosinte involved boosting the starch content in the kernels. Corn is about 73% starch by weight, which is much higher than teosinte’s kernels, and it’s what makes corn a great source of fast calories. Scientists still don’t know a lot about the early cultivation of corn. They’re still investigating how corn developed multiple rows of kernels per ear, and that solid cob you can really grab onto, among other things. Modern corn is completely unable to reproduce without human help because it doesn’t have a mechanism for dispersing its seeds. This shows us that corn as we know it today would never have existed if people hadn’t started tinkering with it. Thanks to the painstaking work of these ancient agriculturalists, humanity got a new, hard-won cereal crop!
But even after corn’s human architects had created a starchy, delicious grain, more work was necessary to make it as nutritious as possible. Because, remember – corn was never the best candidate for food in the first place. To this day, corn is among the least nutritious staple crops. Although it contains many of the nutrients we need, many of them aren’t in a form that can be absorbed by the human body.
But the pre-Colombian people of Mesoamerica who cultivated corn also invented a process called nixtamalization, which turned corn into more than just a side dish, and allowed it to be the basis of millions of people’s diets. Nixtamalization involves cooking and then steeping the corn kernels in an alkaline solution of water and wood ash. After the cooking process, the kernels are washed multiple times to remove the outer shell of the kernels, as well as excess alkaline solution. The result is a slurry called nixtamal, which was ground into a soft dough that could be used to make things like tortillas and tamales.
And it turns out that treating it with calcium hydroxide wasn’t just making it taste better. It was unlocking nutrients that would save lives. Nixtamalization solved a lot of the nutritional problems with corn by increasing its dietary fiber, calcium, and the bioavailability of iron and niacin (vitamin B3). Niacin is a coenzyme, which means it’s necessary for the functions of other enzymes in the body. It’s instrumental in turning food into energy, making fats and cholesterol, and creating and repairing DNA, among other critical tasks.
When Europeans came to Mesoamerica, they began eating corn, and brought it back to Europe with them. But when it became widely eaten as a staple crop there, those growing and eating it skipped the nixtamalization part. As a result, they came down with a disease called pellagra, which is a nasty combo of diarrhea, skin rashes, mouth sores and dementia. And the culprit was a lack of niacin.
Now, to be clear, it’s perfectly fine to eat corn that hasn’t been nixtamalized. We do it all the time. I mean, who doesn’t love corn on the cob? Pellagra is only a concern if you aren’t getting your niacin from any other parts of your diet, like, say, if you’re only eating corn that wasn’t nixtamalized.
Which means, if the Mesoamericans who cultivated corn didn’t also invent nixtamalization, eating mostly corn would have made them sick, so it never could have become foundational to their diets. And in turn, it never would have become such a big part of ours. It was against all odds that corn became edible, and then plentiful, and then yummy and nutritious. In that order.
So, the next time you’re enjoying a taco, take a moment to think about the many coincidences that brought that corn tortilla to your plate in the first place. This video, and the fact that you may be feeling a craving for tortilla chips right now, was made possible thanks to our friends over at Patreon. Our patrons support the work we do on this channel, and in exchange, they get access to a bunch of perks. For example, access to our exclusive discord, bloopers from our video shoots, and our behind the scenes podcast. So, if that sounds like a good deal, you can head over to patreon.com/scishow to sign up, or just to learn more. Thanks for watching! [♪ OUTRO]