Category: Intelligence

It is linked to higher IQ and being 30% less likely to suffer major depression.

People who are intelligent are 30 percent more likely to be short-sighted, research finds.

Intelligent people are also 30 percent less likely to suffer from major depression.

The findings are part of a study looking at the genetic underpinnings of intelligence.

The results come from 300,486 people aged 16 to 102 who had their DNA analysed.

The researchers found 148 different genetic locations were linked to cognitive ability.

Smarter people are also likely to have better mental health, a lower risk of cancer and greater longevity.

In fact, intelligent people are 17 percent more likely to live longer.

Dr Gail Davies, the study’s first author, said:

“This study, the largest genetic study of cognitive function, has identified many genetic differences that contribute to the heritability of thinking skills.

The discovery of shared genetic effects on health outcomes and brain structure provides a foundation for exploring the mechanisms by which these differences influence thinking skills throughout a lifetime.”

The search for connections between genes and intelligence has proved difficult.

Professor Ian Deary, who led the study, explained:

“Less than a decade ago we were searching for genes related to intelligence with about 3,000 participants, and we found almost nothing.

Now with 100 times that number of participants, and with more than 200 scientists working together, we have discovered almost 150 genetic regions that are related to how clever people are.

[…]

One thing we know from these results is that good thinking skills are a part of good health overall.”

The study was published in the journal Nature Communications (Davies et al., 2018).

IQ peaks and stops increasing at around 20 years of age and then is mostly fixed for life.

IQ peaks at around 20-years-old and later effort will not improve it much beyond this point, research finds.

The complexity of people’s jobs, higher education, socialising and reading all probably have little effect on peak cognitive ability.

Naturally, these activities have many other benefits, but little influence on intelligence.

However, education is particularly important at an early age when the brain is still developing.

By early adulthood, though, most people’s IQ has settled down.

When IQ is fixed

IQ can increase by as much as 20 points in only four years across the early to late teens, research finds (Ramsden et al., 2011).

During this time young people’s IQ shifts dramatically both up and down.

For the study, 33 adolescents were followed over four years.

Ms Sue Ramsden, the study’s first author, explained the results:

“We found a considerable amount of change in how our subjects performed on the IQ tests in 2008 compared to four years earlier.

Some subjects performed markedly better but some performed considerably worse.

We found a clear correlation between this change in performance and changes in the structure of their brains and so can say with some certainty that these changes in IQ are real.”

Can IQ be increased after this peak?

However, while some studies have suggested that cognitive activities in later life can improve IQ, Professor William S. Kremen, author of one study on the subject, thinks otherwise:

“The findings suggest that the impact of education, occupational complexity and engagement in cognitive activities on later life cognitive function likely reflects reverse causation.

In other words, they are largely downstream effects of young adult intellectual capacity.”

The study included 1,009 men now in their 50s and 60s whose IQ was assessed when they were around 20-years-old.

They were given tests of abstract reasoning, verbal fluency and memory, among with other cognitive measures.

The results showed that most of the difference between the men’s IQs in mid-life was explained by the difference between them at around 20-years-old.

In comparison, the complexity of the job they had, the intellectual activities they engaged in, and their education in the meantime hardly had any effect on their peak IQ.

Brain scans also showed that IQ at age 20 was associated with the surface area of the cerebral cortex.

The cerebral cortex is the brain’s gray matter, the part that performs the higher functions of thinking, perceiving and language.

Most of the benefits of education for peak IQ likely happen before young adulthood, said Professor Kremen:

“Our findings suggest we should look at this from a lifespan perspective.

Enhancing cognitive reserve and reducing later life cognitive decline may really need to begin with more access to quality childhood and adolescent education.”

Maybe IQ does not stop increasing

Not everyone agrees, though, that IQ is fixed, since there is increasing evidence of brain plasticity at later ages.

Perhaps IQ and can peak later and higher?

Professor Cathy Price, who co-authored the study with Ms Sue Ramsden, said:

“The question is, if our brain structure can change throughout our adult lives, can our IQ also change?

My guess is yes.

There is plenty of evidence to suggest that our brains can adapt and their structure changes, even in adulthood.”

The study was published in the journal PNAS (Kremen et al., 2019).

The strongest personality feature of high fluid intelligence.

Being willing to entertain new, unconventional ideas is the strongest personality trait linked to high fluid intelligence, research finds.

Preferring variety and new activities over routine and sameness is also linked to high intelligence, the same survey found.

People with high intelligence are more likely to enjoy philosophical arguments, brain teasers, new problems and eccentric or uncommon activities.

Fluid intelligence refers to the speed at which the brain works.

It is like the raw power of an engine or the speed at which a computer can process information.

In contrast, crystalised intelligence roughly refers to general knowledge.

The study’s authors write that fluid intelligence was…

“…correlated with Actions and Ideas.

[…]

Ideas refers to intellectual curiosity.

This trait is seen as an active pursuit of intellectual interests, and as a willingness to consider new, perhaps unconventional ideas.

High scorers on this scale enjoy philosophical arguments and brain teasers.”

Both actions and ideas are components or ‘sub-factors’ of the personality factor of openness to experience, which is strongly linked to intelligence.

Sub-factors of openness that were not strongly linked to intelligence included ‘fantasy’, ‘feelings’ and ‘values’, suggesting these do not tell us anything about a person’s intelligence.

The findings come from a survey of 2,658 employees at 10 different British companies.

All completed tests of intelligence and personality.

Like an interest in ideas, being willing to try new activities was also linked to intelligence, the authors write:

“Actions refers to willingness to try different activities, and to a preference for novelty and variety over familiarity and routine.

Fluid intelligence involves things like reaction times, quick thinking, reasoning, seeing relationships and approaching new problems.

This means that individuals high on [fluid intelligence] have an innate ability to cope more efficiently with novel experiences, and to deal with intellectually stimulating tasks such as brain teasers, which would thus make it rewarding for them to pursuit such activities.

Similarly, individuals low on [fluid intelligence] may in time grow to avoid such activities, due to their low ability to handle them, which would thus make them less rewarding.”

The study was published in the journal Learning and Individual Differences (Moutafi et al., 2006).

Which hair colour is linked to higher intelligence?

The stereotype has it that blondes, while having more fun, are not as smart.

However, contrary to the stereotype, blonde women have slightly higher IQs than brunettes, a study finds.

However, the difference is so small as to be statistically insignificant.

Blonde men, meanwhile, have similar IQs to men with other hair colours.

So, blondes are not dumb — whether they are male or female.

The point might seem trivial, but the study’s author, Dr Jay Zagorsky, argues that stereotypes can have real-world implications:

“Research shows that stereotypes often have an impact on hiring, promotions and other social experiences.

This study provides compelling evidence that there shouldn’t be any discrimination against blondes based on their intelligence.”

The conclusions come from a survey of 10,878 white Americans asked about their natural hair colour (Hispanics and African Americans were excluded to eliminate bias).

The results showed the average IQ of blonde-haired women was 103.2, 102.7 for brown hair, 101.2 for red hair and 100.5 for black hair.

However, the differences were so small as to be unlikely to represent a real difference.

Dr Zagorsky said:

“I don’t think you can say with certainty that blondes are smarter than others, but you can definitely say they are not any dumber.”

A factor that could explain blondes having higher IQ is that they also had more books in their homes during childhood, Dr Zagorsky said:

“If blondes have any slight advantage, it may simply be that they were more likely to grow up in homes with more intellectual stimulation.”

While the research may reveal little difference, stereotypes are powerful, Dr Zagorsky writes:

“…humans use a person’s looks as a signal for the person’s personality or productivity.

For example, blonde women are often stereotyped as dumb or incompetent while redheads are seen as people with fiery tempers.

These stereotypes are reinforced in popular culture with the dumb blonde female being a staple of Hollywood movies such as Reese Witherspoon in the “Legally Blonde” series or even Marilyn Monroe in “Gentlemen Prefer Blondes.”

The study was published in the journal Economics Bulletin (Zagorsky, 2016).

Study of over 7,000 finds diet linked to IQ.

People fed a healthier diet from an early age have a higher IQ, research reveals.

Children who were breastfed and later given plenty of fruits, vegetables and other healthy foods had IQs up to two points higher at age 8.

Dr Lisa Smithers, the study’s first author, said:

“Diet supplies the nutrients needed for the development of brain tissues in the first two years of life, and the aim of this study was to look at what impact diet would have on children’s IQs.

We found that children who were breastfed at six months and had a healthy diet regularly including foods such as legumes, cheese, fruit and vegetables at 15 and 24 months, had an IQ up to two points higher by age eight.

The results come from a study of over 7,000 children whose eating habits were analysed at ages 6 months, 15 months and two years.

They were followed until age 8.

Set against the benefits of healthy eating, children fed junk food had lower IQs, Dr Smithers said:

“Those children who had a diet regularly involving biscuits, chocolate, sweets, soft drinks and chips in the first two years of life had IQs up to two points lower by age eight.

We also found some negative impact on IQ from ready-prepared baby foods given at six months, but some positive associations when given at 24 months.”

Eating well is particularly important in the formative years, said Dr Smithers:

“While the differences in IQ are not huge, this study provides some of the strongest evidence to date that dietary patterns from six to 24 months have a small but significant effect on IQ at eight years of age.

It is important that we consider the longer-term impact of the foods we feed our children.”

The study was published in the European Journal of Epidemiology (Smithers et al., 2012).

The quality that people with higher IQ tend to have.

Freedom from prejudice is a clear sign that someone has a high IQ, a study finds.

More intelligent people are less likely to be either homophobic or racist, the research found.

On top of this, more intelligent people are also more likely to be trusting of others and sensitive to other people’s needs.

The conclusions come from a couple of studies in which people were given IQ tests and asked questions that probed whether they were prejudiced.

In one survey of 15,874 people in the UK, participants were asked questions like:

• “I wouldn’t mind working with people from other races.”

Their answers to questions like this were compared with IQ tests they had been given as children.

The results showed that people with lower IQs tended to display more overt racism.

A second group of 254 people in the US were asked about their attitudes to homosexuals, as well as being given IQ tests.

Once again, the results showed that people with lower IQs were more likely to be prejudiced against gay people.

The researchers found that in both groups of people, those with lower IQs had lower contact with people from minorities — in this case, races other than their own and gay people.

The study’s authors conclude that:

“…we found that lower general intelligence (g) in childhood predicts greater racism in adulthood a predictive effect of poor abstract-reasoning skills on antihomosexual prejudice, a relation partially mediated by both authoritarianism and low levels of intergroup contact.

Our results suggest that cognitive abilities play a critical, albeit underappreciated, role in prejudice.”

Authoritarianism is a disregard for the feelings and wishes of others.

Unsurprisingly, this was also linked to prejudice.

→ Discover 22 more signs of intelligence.

The study was published in the journal Psychological Science (Hodson & Busseri, 2012).