Human Intelligence

Is bigger better when it comes to brains?
Answered by Charles W. Bryant and HowStuffWorks
  • Charles W. Bryant

    Charles W. Bryant

  • HowStuffWorks

    HowStuffWorks

  1. Charles W. Bryant Co-Host, Stuff You Should Know
    Depending on whom you ask, the brain's size has everything or nothing to do with the intelligence of an animal. Some scientists contend that a bigger brain means a smarter animal. As evidence, they might point out that humans have larger brains than our primate cousins. That additional brain tissue could be correlated with a higher capacity to perform mental tasks associated with intelligence, like thinking, deducing and, of course, remembering the things you've learned and deduced.

    There is some consistency in the animal kingdom between brain size and intelligence, but just because a rhinoceros has a larger brain than a lab rat doesn't mean it's more intelligent. It's simply a larger animal. Because of this reality, scientists have devised a brain-to-body-size ratio curve that allows them to account for overall size when measuring the brain and intelligence.

    Other scientists argue that the physical size of the brain isn't what's important, but that intelligence lies in the number and firing power of the neurons. Physicist Albert Einstein is one example often used to support this hypothesis, as his brain was average in volume and weight, but more densely packed with neurons.

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  2. Scientists are divided on whether a bigger brain makes a person more intelligent. Part of the problem is that not every study uses the same criteria to decide how big a person's brain actually is. Some measure the size of the skull cavity the brain fits into, while others use scans of the brain itself. But even when researchers are using the same measurements, they may not analyze them in the same way. One study may factor in the person's overall body size, and another may adjust for age, sex or other factors. Although not everyone agrees, some studies have drawn strong conclusions. Psychologist Michael McDaniel, for example, conducted a study in which he concluded that bigger brains do indeed make smarter people.

    There is proof that a man's brain is, on average, slightly bigger than a woman's, and at least one study of intelligence has given men a slight advantage over women, but does this mean that bigger is better when it comes to brains? Not necessarily. First of all, it is possible to argue with the method and findings of the intelligence test (and of intelligence tests in general), and second, overall brain size may not be a useful measure. Albert Einstein, one of the greatest minds in human history, had a merely average-sized brain. But some parts of Einstein's brain, such as the inferior parietal region (connected with mathematical thinking), were larger than usual. So the size of certain areas of the brain may be of more significance in gauging the potential for intelligence than the overall size of the brain as a whole. Even then, we don't know whether the enlargement of an area causes the intelligence, or if the opposite might be true, as brains develop over time: The more you use your brain (whatever its size), the better it works.

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