Humans can't get enough corn -- it's 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.
Which makes it all the more surprising that corn basically shouldn’t be edible at all.
Of course, it's a completely legit human food now,
but, to get there, corn has had to come a long way.
There are a whole host of reasons why corn never should have been
one of the plants we domesticated for food,
much less one of the top ten staple crops on our plates.
So, this is the unlikely story of an unassuming grass
that became one of the heavy hitters of the human diet.
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The evolution of corn, also called maize in some parts of the world,
is sort of 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.
Those kernels were puny, tough, and literally indigestible, so the people who
encountered teosinte wouldn’t have bothered with the kernels at all.
Because it’s an annual grass that looks exactly nothing like modern corn,
for a very long time scientists were flummoxed
about where teosinte fit in corn’s family tree, and if it did at all.
The debates over corn’s true ancestry became so contentious
that it became known as the corn wars.
And that battle raged for nearly half a century, until additional genetic evidence
showed once and for all that teosinte alone was the ancestor of modern corn.
And thus, a corn truce was called, and there was peace in the land.
Huzzah!
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.
The Mesoamerican people would either chew on the stalks or juice them
to ferment the sweet liquid into alcohol, because that’s also a thing
humans like to do with plants that contain sugary liquids.
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.
Each teosinte kernel is covered in a rock hard shell called glume
that renders it basically inedible to humans.
The glume on the kernels of teosinte keeps the seed intact as it travels through
an animal's digestive system or overwinters on the ground for months.
Very useful for the plant, but not whoever's trying to eat it.
Ancient cultivators most likely began selecting seeds of teosinte
with the softest glume.
These days, the glume is the part of the corn on the cob
that gets stuck between your teeth.
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.
All these changes show us that corn as we know it today would never have existed
if people hadn’t started tinkering with it.
In fact, modern corn is completely unable to reproduce without human help
because it doesn't have a mechanism for dispersing its seeds.
So, 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 the nutrients
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.
See, nixtamalization solved a lot of the nutritional problems
with corn that we mentioned.
It increases the dietary fiber, calcium, and the bioavailability of iron in the grain,
meaning how much of it you can actually absorb.
But most importantly, it also increases the bioavailability of niacin,
also called 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.
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Thanks for watching!
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