Trump's "Very, Very Large Brain" Comment Underscores Myth About Intelligence

Intelligence has a lot more to do with what's inside your brain than its size.

President Donald Trump has repeatedly dedicated moments of his presidency to informing the public about his intelligence. A few weeks before he took office, Trump announced he didn’t need daily intelligence briefings because “I’m, like, a smart person.” In January, he reminded everyone on Twitter that his “two greatest assets have been mental stability and being, like, really smart.” Now, he’s telling reporters about his “very, very large brain.” But contrary to longstanding claims, a bigger brain doesn’t mean a smarter man.

Speaking at a press conference in New York on Wednesday, Trump referenced an interview that Michael Pillsbury, the Hudson Institutes director for Chinese strategy, gave to Fox News last month. Pillsbury said that China respects Trump because he is “so smart.”

“If you look at Mr. Pillsburgy, the leading authority on China, he was on a good show — I won’t mention the name of the show — recently,” Trump said. “And he was saying that China has total respect for Donald Trump and for Donald Trump’s very, very large brain.”

There’s a lot to unpack here, but let’s focus on the claim of a “very, very large brain.” If the insinuation is that a large brain is something to respect because it’s a more intelligent one, that’s a claim that’s scientifically unsound. For centuries, researchers have attempted to prove an association between brain size and intelligence. While that connection was declared to be true in the 1800s, scientists are now in the process of dismantling the association.

That’s because there’s a lot more to intelligence than brain size. First of all, humans are not the species with the largest brains. The brains of African elephants weigh about 13 pounds and the brains of sperm whales are a whopping 22 pounds. The adult human brain only weighs about 3 pounds.

“There is no clear correlation between absolute or relative brain size and intelligence,” scientists from Germany’s Brain Research Institute explain in a 2016 paper. “Assuming that absolute brain size is decisive for intelligence, then whales or elephants should be more intelligent than humans, and horses more intelligent than chimpanzees, which definitely is not the case.”

These are models of human ancestor brain size compared to modern day humans.

Matt Wood, UChicago

But we are smarter than the lesser bamboo bat, for example, which has the smallest brain of all the mammals. And the difference in brain size between us and our ancient Australopithecus ancestors is often credited as physiological evidence of our intellectual evolution. Some studies have even found that large brained animals are better at problem-solving. Historically, scientists have also used men’s larger brain volumes to explain why they are smarter than women. We now know that the latter part is categorically untrue, so what’s going on?

There are a few factors that can explain this discrepancy. One is that studies designed to observe intelligence often compare people’s brain size to their IQ scores. However, it is now understood that IQ does not accurately measure intelligence, despite Trump’s claims that his own IQ means he is not a “moron.” While IQ tests can reasonably measure people’s abstract reasoning and memorization skills, researchers have found that the tests measure a person’s social class and motivation to do well more than their raw intelligence.

“We show that the strength of the positive association of brain volume and IQ has been overestimated in the literature,” a team of University of Vienna scientists write in a 2015 paper. “While it is tempting to interpret this association in the context of human cognitive evolution and species differences in brain size and cognitive ability, we show that it is not warranted to interpret brain size as an isomorphic proxy of human intelligence difference.”

Although differences in brain size may explain why we are more intelligent than another comparable animal, like our close relation the chimpanzee, there doesn’t appear to much difference in intelligence when brain sizes of individual humans are compared. What matters more is what’s going on in the brain. Neuroscientific studies have found that the structure of the human brain is more important than its size when it comes to intelligence.

A thicker cerebral cortex, for example, plays a key role in memory and cognition and is believed to correlate with a higher measurement of intelligence. The speed at which nerve impulses can travel and the number of neuronal connections in the brain are also believed to be linked to increased intelligence. Other scientists argue that it’s the amount of grey matter that is most important. In 2004, one group of researchers declared that the mass of neurons and cells was a major driver of human intellect, and it was that the amount of grey matter in different brain regions determined people’s patterns of abilities.

Intelligence is a multifaceted phenomenon that includes self-awareness, emotional knowledge, and problem-solving. It’s confusing and we don’t really get it yet. But what scientists do know is that a bigger brain doesn’t make one man smarter than another. After all, when scientists examined the brain of Albert Einstein they found that morphologically, the structure of his brain didn’t reflect his intellect.

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