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15 Things We Now Know About Intelligence

by Staff Writers

From ways of measuring it to knowing what it really means, there are a lot of myths and misunderstandings about intelligence. After decades of research (or perhaps centuries, if you count pre-Scientific Revolution work), we still don’t know everything there is to know about intelligence, but in many areas we’re getting a whole lot closer to having a complete understanding. Here, we chronicle some of the more recent findings in intelligence research, some of which confirm things we’ve long known about our mental abilities along with a few findings that are still hotly contested by both scientists and laymen alike.

  1. Intelligence is a more accurate predictor of future success than socioeconomic background.

    Recent studies have shown that being from an economically disadvantaged background and lacking social connections may not hurt you as much when it comes to education and future success, provided you’ve got a high IQ, that is. Professor Yoav Ganzach at Tel Aviv University directly pitted socioeconomic status against intelligence, finding that intelligence was a better predictor of future success than money or status. While children of wealthier families often start higher on the totem pole at work, those who were more intelligent moved more quickly through the ranks and enjoyed better long-term pay prospects.

  2. Staying in school keeps IQ from slipping.

    Staying in school has some big benefits when it comes to IQ. Education itself can have an impact on raising IQ, but the greatest effect of education on intelligence isn’t about raising it but maintaining it. Students who drop out show marked drops in IQ that tend to grow each additional month they’re away from school. This factor has been explored in a wide range of studies. In a large-scale Swedish study, researchers found that for each year of high school not completed, young men lost 1.8 IQ points. Others have shown a marked decline in IQ scores over the summer months when children are away from school.

  3. Your birthday can influence your IQ.

    Your birthday doesn’t change your genetic propensity for having a higher or lower IQ, but it can have an effect on the environmental factors that impact intelligence. One of those is the first age at which children enter school, with those who are born later in the year likely to wait another full year before entering. When these students come of age, they will have been in school a full year less than their peers. How does this impact intelligence? Research has shown that there is a correlation between each year of school completed and IQ, with a gain of around 3.5 points for every year, resulting in students who are born late in the year having lower IQ scores as a group.

  4. Intelligence isn’t static.

    The IQ you were born with won’t necessarily be the same as that you die with. While genetics plays a large role in determining intelligence, factors like education, job type, and even leisure activities can impact how intelligence changes as you age. Other forms of intelligence, like emotional intelligence, are even more dynamic and can be the result of a variety of experiences throughout life or even impacted by one’s own emotional state.

  5. Diet influences IQ.

    When it comes to intelligence, the saying that you are what you eat couldn’t be more true. The structure and health of your brain is impacted significantly by what you eat, so it should be no surprise that IQ is as well. A study of more than 7,000 children found that a poor diet (rich in sugars, fats, and processed foods) in childhood led to a lower IQ later in life and that eating a healthy diet (rich in vegetables, fish, and healthy grains) resulted in a higher IQ. Another study of New York City schoolchildren found that by removing preservatives, colorings, dyes, and artificial flavoring from the school menu resulted in a 14% rise in IQ scores.

  6. Genetics has a powerful influence over IQ.

    Researchers are increasingly leaning toward nature as being the primary determinant in our intelligence levels rather than nurture. This is based on a variety of factors but can include the efficiency of the connections in the brain, quality of the myelin sheaths around the axons in the brain (myelin acts like an insulator for electrical impulses in the body), the volume and location of gray matter in the cerebral cortex, the volume of sub-cortical gray matter, and the speediness of white matter tracts. These factors are highly heritable and can have a marked impact on intelligence, exerting an influence that only grows as an individual ages.

  7. IQ scores can make you more confident, or less so.

    For some, a high IQ score may help them push to live up to their potential, make them more confident in their abilities, and motivate them to great success. Unfortunately, studies have shown that it can also have the opposite effect when scores aren’t so good. Some recipients of low or average scores simply give up, believing that their IQ has doomed them to a life of mediocrity so there’s no sense in even trying to be smart or achieve more than they believe their IQ affords them. The reality? IQ can play a role in success in life, but a wide range of other factors separate from general intelligence, like emotional intelligence, street smarts, and luck, also play a role. Those on the low end of the spectrum can wind up fabulously successful and those on the high end can just as easily wind up destitute.

  8. Breastfed babies do have a marginally higher IQ.

    There is a lot of controversy surrounding whether or not mothers should breastfeed, with one of the key arguments for the practice being that babies that are breastfed have higher IQs. Whichever side you fall on, the reality is that there is a small increase in IQ in babies that are breastfed, usually between three and eight IQ points by age 3. It’s unclear what causes this but some researchers think it’s due to a combination of immune factors and high levels of omega-3 fatty acids in the mother’s milk, though new studies suggest it could be related to the occurrence of a particular gene.

  9. Less intelligent people may be more inclined toward prejudice.

    The world can be a scary and confusing place, even to those who have the intelligence to understand the often complex factors that keep it running. To those without those abilities, it is undoubtedly an even more uncertain place. In a highly controversial new study, a team of Canadian researchers has found a link between intelligence and prejudice, showing that those with lower IQs are often more likely to develop prejudiced beliefs and to be more conservative in their views. This resistance to change and oversimplification of the world around them may be an attempt to create structure and order and make the world easier to comprehend, researchers believe. Not everyone is buying it though, and more research on the topic can be expected in future years.

  10. Not all intelligence ages the same.

    Intelligence may change throughout your life. One of the key factors? Genetics. Your genes play a big role in how your brain ages and thus how your IQ ages, too. Of course, genes aren’t the only factor at play, as education, activity, and other environmental factors can help to raise or lower IQ regardless of age. A Scottish study that spanned over 80 years found that cognition changes with age, and that for some people, these changes are more rapid. For the most part, childhood intelligence was found to correlate with intelligence in old age, but the relationship was far from perfect, being influenced by genetics as well as environmental factors.

  11. Intelligence is correlated with more drinking, less sex.

    Research has demonstrated some somewhat strange connections between intelligence, drinking, and intercourse. Two long-term studies, one in the UK and one in the U.S., found that more intelligent children grew up to drink more and more heavily as adults than less intelligent children. The reasons aren’t quite clear, and scientists have come up with a variety of reasons why this could be the case. Yet while the smart kids might grow up to be serious boozers, they’re much less likely than their peers to engage in sex as teens. Among students with IQs of 110 and above, 70.3% were virgins, while among those with slightly below average IQ (70 to 90) only 50.2% were virgins. An adolescent with an IQ of 100 was found to be one and a half to five times more likely to have had intercourse than a teen with a score of 120 or 130. Unsurprisingly, these results continue into college, with students at elite schools much less likely to have had sex than their peers at large.

  12. Those with higher IQ tend to worry more

    Odd as it might seem, those with higher levels of intelligence tend to be worrywarts more than their less intelligence counterparts. New research suggests that intelligence may have co-evolved with worry in humans. Why? Because worry may cause individuals to avoid dangerous situations, even those with a low risk, resulting in higher levels of survival, making it just as positive of a trait to have as higher intelligence. Other studies have found that worry isn’t absent from those with low IQ, however, with those individuals tending to worry more, possibly because they struggle to achieve success in life.

  13. You can make yourself smarter but only if you believe you can.

    If you believe that your intelligence is set from birth, then for you, it will be, research from Michigan State University suggests. Intelligence is malleable only to the degree that individuals believe it is, though genetic limits also play a role. Students participating in the study were asked to make split-second decisions and recordings were taken anytime a mistake was made. Those who believed that intelligence could change were much more likely to try to fix a mistake or to learn from it. These growth-minded individuals performed much better on subsequent tests, showing that sometimes ability really is all in the mind. Other studies have found that intelligence can be raised through better nutrition, education, and even exercise.

  14. Men and women demonstrate equal intelligence.

    While much has been made of differing spatial and linguistic abilities in men and women, overall there is very little, if any, difference between women and men in terms of average general intelligence. This may go without saying today, but in past years it was a hotly debated topic, with many scientists believing that the smaller brain size and delicate temperament (so they said) made women intellectual inferiors. The only difference between male and female intelligence that can be substantiated? Intelligence in women seems to be tied to the frontal lobe and Broca’s area, while in men the frontal and parietal lobes are the seat of IQ.

  15. There’s more than one way to be smart.

    Intelligence isn’t as simple as an IQ test might lead you to believe. In fact, some believe that IQ tests are highly unreliable ways to measure any type of intelligence, and they’ve been hotly contested since they were first put into use. Regardless of this fact, there is more to intelligence than just the narrow spectrum of mental abilities that are measurable by IQ tests. Many researchers now subscribe to the idea that there are multiple intelligences, seven to be precise, including linguistic, logical-mathematical, musical, bodily-kinesthetic, spatial, interpersonal, and intrapersonal. No matter which definition of intelligence you subscribe to, one thing is clear: the complexities of the human mind are hard to pin down in any one theory, and it may be years before we have any definitive ways to measure all aspects of human intelligence, not just how we score on tests.