That golf ball-size swelling is an enlarged thyroid gland, and it's usually caused by consuming too little of the crucial micronutrient iodine. Humans traditionally get their iodine from seafood, so goiter boomed in populations that lived far from coastal areas. I'm guessing that goiter must have traditionally been blamed on lack of exposure to ghost pirates, because Western medicine didn't discover the link between goiter and iodine until the 19th century. And it wasn't until the 1920s that a doctor called David Murray Cowie heard about how landlocked Switzerland had vitalized their neck modeling industry by adding sodium iodide to the nation's table salt. Cowie convinced some of America's biggest salt manufacturers to follow the Swiss plan and dose America's salt right up.

At the time, iodine fans were focused on preventing deficiency and wiping out those nasty neck lumps. But then, in what was the exact opposite of every science fiction plot ever, this newfangled chemical in our food came with an unexpected side effect ... it made people smarter. In areas where iodine deficiency was formerly the norm, iodizing table salt increased people's IQ an average of 15 points.

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Science tried to meddle with nature. They tried to improve mankind. And ... it worked out pretty well, I guess.

What If It Hadn't Happened?

Ask a big chunk of the rest of the world. Despite the fact that the ensmartening effects of iodine have been known for decades, one-third of the Earth's population still has low iodine levels: It's the biggest cause of preventable mental retardation on the planet.

And it's about as easily fixable a social problem as you could ask for: Spraying salt with iodine costs about $1 per ton, and keeping someone adequately iodined costs about five cents per person, per year. Still, after solid gains for a few decades, worldwide salt-tainting efforts have slowed in the last 10 years or so. It's probably because the cause just isn't very glamorous: Convincing salt factories to install chemical-spraying machines just doesn't have the same photogenic power as digging a well or building a school. Apparently, my own suggested slogan of "Let's raise the world's IQ so we can decrease YouTube comments by 25 percent in 2018" just doesn't have much of a ring to it.

We've also used a lot of lead. This heavy metal has been used in everything from cosmetics to water pipes for thousands of years, even though it's a potent neurotoxin that has been associated with bad health and insanity since Roman times. So it's lucky that if you look at the blood of present-day Americans, you'll find lead levels that are pretty darn low.

What If It Hadn't Happened?

To see how bad things could be, we only need to look back to the last century. In the 1920s, General Motors started adding a compound called tetraethyl lead, or TEL, to gasoline. TEL increased gasoline's octane rating: In scientific terms, it acted as a kind of magic unicorn dust that made cars and airplanes run better. The federal government decided it was OK with this stuff going into the nation's gas tanks, because a task force assembled by the surgeon general (and populated mostly by industry scientists) concluded that TEL was only a "minor" public health risk. Workers handling the newfangled gasoline did have a tendency to go violently insane, and one worker ended up in a psychiatric institution for 40 years before dying, but everyone decided that the workers probably would have done that anyway.

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"It's OK. I'm just happy that the president of General Motors could afford that golden monocle."

Along with lead paint, which got big in America in the 1800s, America's new lead-farting roadways transformed the country into neurotoxin heaven. By the mid-'70s, almost 90 percent of young children in the U.S. had blood-lead levels that are now considered toxic. Around this time, people finally started asking, "Wait, didn't even the Romans know this stuff was poison? You know, the guys who thought you could read the future by examining pigeon guts?" Lead paint was banned in 1978, and leaded gasoline was phased out soon after.

Much like iodine, however, getting rid of lead didn't just cure a few sick people here and there. It made us smarter. Along with the insanity and death and stuff, lead causes irreversible brain damage in exposed children. In fact, a lot of people attribute America's lowered crime rates of the last few decades at least partially to the decline of leadtopia, because presumably once IQ goes up a bit, criminals start figuring out smarter ways to make money.

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"Wait ... what if I just sell this gun?"

Luckily, if you live in America and are a human, you probably don't have to worry about hookworm-gut anytime soon. That's because back in 1910, hardcore philanthropist John Rockefeller decided that he hated the little parasitical bastards. "I mean, just listen to the name," Rockefeller said (I assume), stroking his gloriously thick mustache, "Hook ... worm. That's just gross."

Rockefeller's foundation threw millions of dollars into wiping out hookworm in America: They built thousands of outhouses to prevent soil contamination and ran education campaigns warning people about the horrors that lurked before they walked outside barefoot. And it worked: Within only five years, hookworm was almost completely eradicated in the U.S.

What If It Hadn't Happened?

Hookworms mostly hung around in the South, where the warmer climate was favorable to its evil plans. At the height of their reign of terror, 75 percent of adults in some Southern counties were carrying the parasites. That meant that these people were dealing with anemia, fatigue, and impaired brain function. Northerners nicknamed the parasite "the germ of laziness," which is a bit unfair: "Laziness" is watching a whole season of Supernatural: Cat Version (in which one side of every scene is taken up by a giant cat) because your cat sat down in front of the TV screen and you can't be bothered getting up to move it. The key issue here is that you don't want to move the cat, rather than being unable to move it, because you're infected with worms that suck your blood.

So, not surprisingly, the results of eliminating hookworm were incredible. School attendance and literacy went up, because half the kids were no longer lying on the ground in a state of hookworm stupor. In states with formerly high infection rates, incomes as a whole actually increased. It's almost as if a healthy population is good for the economy or something.

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"Look, I could fix your brain parasites, but then I would no longer be able to use you
as a living illustration of laziness when I'm insulting my son."

Unfortunately, hookworm is still big in other places that weren't fortunate enough to have been saved by gloriously mustached philanthropists. About 700 million people worldwide still carry the parasite, leading to higher infant morbidity and (presumably) a lot of Cat Supernatural marathons. So next time you're outside barefoot and step on a bee, just appreciate that it isn't a life-ruining vampire worm.

Things started to change around the turn of the 20th century. Urbanization and the rise of processed and store-bought food meant that hidden food grossness was a bigger problem than it had ever been. Members of the nation's women's clubs, presumably sick of finding whole human hands in their lettuce, spearheaded a "stop putting gross shit in our food" movement, and with the support of then-president Teddy Roosevelt, the Pure Food and Drug Act was passed in 1906. Things have gone downhill for hand-lettuce manufacturers ever since.

What If It Hadn't Happened?

Life used to include such adventures as candy dyed with lead and flavored with arsenic, and the use of tasty preservatives like formaldehyde and borax.

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"Dinner's ready. It's bat. Embalmed bat."

If that's not enough to terrify you, keep in mind that Roosevelt enthusiastically supported the movement in part because, while serving in the Spanish American War, he was forced to eat beef that smelled like an "embalmed dead body" and was rumored to have been chemically tainted. Whether the beef was actually embalmed was never proven, but Roosevelt described the meat served to troops as "nasty" and said he would sooner "eat his hat" than consume it. And when Teddy fucking Roosevelt starts getting scared of the food being served, you know it must have been pretty damn terrible.

C. Coville has a Twitter here and a Tumblr here, and you should visit them if you're a good person.