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“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
History,CuriositiesSEP 24, 2025

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society

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Americans might have been a whole lot more intelligent had it not been for lead-based gasoline. Lead was first added to gasoline in 1923, apparently to keep our car engines 'healthy.' But the move came at the expense of our own well-being.
Leaded gas was banned in 1996. But a 2022 study revealed that exposure to car exhaust from leaded gas during childhood stole a collective 824 million IQ points from more than 170 million Americans alive today. To put it into perspective, that's about half the population of the United States. But we should also remember that the U.S. was not the only country to use lead in gas. And some countries still did so right up until 2021.
If this is the first time you're hearing about this, it might be because the lead-gasoline era was one of the most downplayed, damaging events in history. It left a lasting impact on society, the effects of which are still being felt today.
Someone recently asked, "Which historical event induced more damage to society than people realize?" and the answers came pouring in faster than a car's tank being filled with gasoline... From leaders who wiped out millions of people, to Chernobyl's contribution to climate change, netizens dug deep to draw attention to the incidents and eras that they believe need to be shamed.
Bored Panda has put together a list of the best answers for you to scroll through while you contemplate how different the world might have been today. We also unpack the findings of the leaded-gasoline research paper a bit more. You can read that info between the images.

#1

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
I would say the arrival of Tatcher/Reagan in power. They managed to lower the tax rate for the wealthiest individuals from 70% to 30%, with the biggest nonsense ever proposed in economics, the trickle-down theory.

It was supposed to boost the economy, but in reality it only made the state and its citizens poorer, widening inequalities like never before. In fact, there is a consensus among economists, which is rare, that trickle-down economics does not work.

But now we find ourselves with a society where the tax burden was shifted from the richest to the middle class, which has been stagnating ever since. The rich are getting richer, the middle class is being strangled, and the poor are getting poorer.

Forty years later, we are still suffering from this s****y model.
97points

Millions of people around the world put fuel or gas in their cars' tanks without giving it too much thought. But up until 1996, in America, gasoline contained lead...

According to health experts, there is no safe level of lead exposure at any point in life. That's because lead is neurotoxic and can erode brain cells after it enters the body.

“Lead is able to reach the bloodstream once it’s inhaled as dust, or ingested, or consumed in water,” says Aaron Reuben, a PhD candidate in clinical psychology at Duke University. “In the bloodstream, it's able to pass into the brain through the blood-brain barrier, which is quite good at keeping a lot of toxicants and pathogens out of the brain, but not all of them.”

Reuben adds that one major way lead can get into people's bloodstreams is through automotive exhaust. This means that anyone born before 1996, when leaded gas for cars was banned, was exposed to "concerningly high" levels of lead.

#2

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The historical event that did more damage to society than anything that came before it was the re- election of orange donny. i fear that the US will not recover from what he has already done and it isn’t over. well, it isn’t over unless he has a heart attack and drops dead tomorrow. and it is those warm and fuzzy thoughts that keep me going.
90points

#3

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
Mitch McConnell refusing to allow Obama's supreme court nominee get a hearing a full year before Obama's term ended. This was the start of the end of the Republic.
81points

Reuben was among a group of researchers who investigated the effects of leaded gasoline on Americans. Their paper, titled “Half of the US Population Exposed to Adverse Lead Levels in Early Childhood,” was published in 2022 in the journal Proceedings of the National Academy of Sciences.

The team used publicly available data on U.S. childhood blood-lead levels, leaded-gas use, and population statistics to determine their findings. "From this data, they estimated lead’s a*****t on our intelligence by calculating IQ points lost from leaded gas exposure as a proxy for its harmful impact on public health," explains the Duke University site, adding the researchers were "stunned" by the results.

“I frankly was shocked. And when I look at the numbers, I'm still shocked even though I'm prepared for it," said co-author of the study Michael McFarland, a professor of sociology at Florida State University.

#4

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The exportation of radicalized evangelical Christianity from the USA to Africa.

It turned dozens of countries aggressively homophobic that weren’t that way before, and it’s also the leading cause of people being persecuted for alleged witchcraft… in 2025.

It was an American preacher, Scott Lively, who was the main sponsor of Uganda’s infamous “K**l the Gays” bill.
67points

#5

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
Invention of social media, specifically Facebook. It was weaponized and single handedly swung an election in Trump's favor. And now, we're here during the sunsetting of democracy in the U.S.

Social media continues to be a weapon for strategic political disinformation and fueling division, not just in the U.S. but also Ukraine post-2014 and several other countries.
53points

#6

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
Citizens United. This ruling guaranteed we would be where we are today. Owned by oligarchs, with laws bought by the highest bidder. Two separate systems of Justice, and no checks and balances for those in power. Foreign agents running rampant. Zero accountability...
51points

The researchers noted that as of 2015, more than half of the U.S. population (over 170 million Americans) had "clinically concerning" levels of lead in their blood when they were children.

"Leaded gasoline consumption rose rapidly in the early 1960s and peaked in the 1970s," Duke Today reported. "As a result, Reuben and his colleagues found that essentially everyone born during those two decades are all but guaranteed to have been exposed to pernicious levels of lead from car exhaust."

This means they're at higher risk for long-term health impairments like reduced brain size. They also have a greater likelihood of mental illness and an increased risk of cardiovascular disease in adulthood.

But it doesn't stop there...

#7

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The decision to allow children schooled at home to have accreditation as if they went to a public school with a controlled curriculum has done irreparable harm to the world and we'll be feeling the impact of it for generations.
44points

#8

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The leaded gasoline era. It literally lowered IQs worldwide.
40points

#9

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The No Child Left Behind policy. It’s lead to the dumbing down of our country and the lowering of standards for education.

On average, 79% of U.S. adults nationwide are literate in 2024. 21% of adults in the US are illiterate in 2024. 54% of adults have a literacy below a 6th-grade level (20% are below 5th-grade level). link.
36points

Childhood lead exposure may have blunted America’s cumulative IQ score by an estimated 824 million points – nearly three points per person on average, the researchers found.

They calculated that at its worst, people born in the mid-to-late 1960s may have lost up to six IQ points. "Children registering the highest levels of lead in their blood, eight times the current minimum level to initiate clinical concern, fared even worse, potentially losing more than seven IQ points on average," reports Duke Today.

And while dropping 3-6 IQ points might not seem like a lot, the experts warn these changes are "dramatic enough to potentially shift people with below-average cognitive ability (IQ score less than 85) to being classified as having an intellectual disability (IQ score below 70)."

#10

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The Treaty of Versailles (1919). I think it fueled further conflicts for much of the 20th century.
36points

#11

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The introduction of microplastics to our ecology.
It is said that the average American consumes as much microplastics in a week as there is in a credit card.
Every biome is littered with microplastics. They are in our rainclouds. In the deepest jungles. In the permafrost of both poles. Scientists have found microplastics in the brains of still-born children. It could be our world-ender if we don't stop.
33points

#12

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The introduction and monetization of the 24/7 news cycle.
33points

Many countries started adding lead to gasoline in the 1920s. While it improved vehicle efficiency and engine performance, it was proven to be a toxic pollutant, particularly for children. Despite knowing this, governments took a while to act.

Japan became the first country to ban leaded gasoline in cars completely in 1986. Three and a half decades later, in 2021, Algeria became the last country to ban it. And, if you think about it, that really wasn't too long ago.

#13

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
COVID. A whole generation of kids were locked indoors during their formative years, and academic performance is really starting to show it.
31points

#14

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The creation of smart phones and social media.
30points

#15

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
*The Oprah Winfrey Show*

The show and the media empire it eventually created became a creduluous, uncritical platform for some incredibly stupid and frequently dangerous people/ideas for FOUR F*****G DECADES, like an aircraft carrier that launched a million bastards.

I absolutely despise Oprah and everything she stands for; genuinely believe the modern world would be a better place if Oprah™️ (the media phenomenon, not the person) had never existed.
29points

“Millions of us are walking around with a history of lead exposure,” warns Reuben. “It's not like you got into a car accident and had a rotator cuff tear that heals, and then you’re fine. It appears to be an insult carried in the body in different ways that we're still trying to understand, but that can have implications for life."

#16

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
I only recently learned about the eruption of Mount Tambora in 1815. Apparently it caused the 'year without a summer,' leading to famine and all sorts of knock-on effects, but it’s not something people really talk about much.
29points

#17

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The 1918 Spanish Flu is one of the most underrated historical events in terms of damage to society. It k**led more people than World War I, wiping out entire communities, overwhelming healthcare systems, and leaving long-term scars on economies and families. What’s wild is how little attention it gets in schools or conversations compared to wars. It reshaped public health, medicine, and even politics in ways we’re still feeling today, but most people barely know the scale of its impact.
28points

#18

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
Vietnam war ig,a section of Vietnamese still deals with birth defects and other complications.
27points

#19

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The rule of Genghis Khan. Estimates differ, but his rule wiped out around 30-40 million people and entire cultures. Those that were left had their countries effectively set back a millennium. The death he caused also regenerated enough forest to allegedly cool the planet.
25points

#20

“It Lowered IQs Worldwide”: 30 Historical Events That Left Everlasting Scars On Society
The partition of India. The bloodshed and the permanent enmity between two countries.
24points
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