Category: Intelligence

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).

The more of the foods they consumed, the higher their IQs.

A diet low in sugars, fats and processed foods consumed at a young age may increase your intelligence, research finds.

Children under 3-years-old fed diets that are packed full of nutrients and vitamins have higher IQs.

The more healthily they eat, the higher their IQ.

The study followed the wellbeing and health of 14,000 children born between 1991 and 1992 in the UK.

What they ate was tracked up to the age of 8, when they were given an intelligence test.

The results showed that children who ate a health-conscious diet including more salad, rice, pasta, fish and fruit had higher IQs at age 8.

Those consuming more junk food high in fats and sugars had lower IQs.

The study’s authors conclude that:

“…a poor diet associated with high fat, sugar and processed food content in early childhood may be associated with small reductions in IQ in later childhood, while a healthy diet, associated with high intakes of nutrient rich foods described at about the time of IQ assessment may be associated with small increases in IQ.”

There was little effect on IQ from what children ate between ages 4 and 7.

The authors say:

“This suggests that any cognitive/behavioural effects relating to eating habits in early childhood may well persist into later childhood, despite any subsequent changes (including improvements) to dietary intake.

It is possible that good nutrition during this period [under 3 years-old] may encourage optimal brain growth.”

The study was published in the Journal of Epidemiology and Community Health (Northstone et al., 2011).

The foods boosts fluid intelligence, which is the speed at which the brain works.

Eating organic food is linked to a higher IQ, a study finds.

School-age children who ate more organic food had higher scores on tests of fluid intelligence and working memory.

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.

Working memory, meanwhile, is vital to holding pieces of visual, verbal or other information in your mind while you manipulate them.

Better working memory has been linked to improved learning, attention and other vital outcomes.

The higher levels of nutrients in organic foods may account for the boost to IQ, said Dr Jordi Júlvez, study co-author:

“Healthy diets, including organic diets, are richer than fast food diets in nutrients necessary for the brain, such as fatty acids, vitamins and antioxidants, which together may enhance cognitive function in childhood.”

In contrast, eating fast food, being exposed to tobacco smoke and house crowding were all linked to lower scores on tests of fluid intelligence.

Children’s brains are sensitive

The results come from over one thousand children aged 6 to 11-years-old in six different European countries, including the UK and Spain.

The research examined 87 factors that the unborn child might be exposed to along with another 122 factors that could affect them during childhood.

The brain is still developing in childhood, so it is particularly sensitive to toxicity.

Low levels of toxicity that may have little affect on the adult brain can still influence children’s brains.

Dr Jordi Júlvez, study co-author, explained the main predictors of higher IQ:

“In our study, we found better scores in fluid intelligence and working memory with higher organic food intake and lower fast food intake.”

As for the predictors of lower IQ, Professor Martine Vrijheid, study co-author, said:

“We observed that several prenatal environmental pollutants (indoor air pollution and tobacco smoke) and lifestyle habits during childhood (diet, sleep and family social capital) were associated with behavioral problems in children.”

The study is notable because of its comprehensive approach to a huge range of variables, said Professor Vrijheid:

“One of the strengths of this study on cognition and the earlier study on behavioral problems is that we systematically analyzed a much wider range of exposure biomarkers in blood and urine to determine the internal levels in the model and that we analyzed both prenatal and childhood exposure variables.”

→ Other dietary changes linked to high IQ include nuts, a diet low in sugars, fats and processed foods, fruits and vegetables,

The study was published in the journal Environment International (de Bont et al., 2021).