It'd be nice to think that IQ is not a big determining factor for how successful and happy we are in life.
But not so, several studies will say.
One study by the University of Delaware found that contrary to popular belief, the higher your IQ, the more likely you are socially smart.
Another study, this time Swedish, has drawn a link between lower IQ scores and suicidal feelings, hypothesising that lower IQs mean poorer problem solving abilities, and thus a diminished ability in dealing with stress in difficult situations.
And while genetics make up an estimated 40 to 80 per cent of a person's IQ, there are a number of factors that determine how smart you are, or how dumb you get.
Most people would readily agree that getting a knock to the head would knock some points off their IQ as well, but what if you were told that your daily junk food habit is not only making you fat, it's making you stupid?
And that those people who spend hours and hours holding long, pointless meetings are not only lacking in EQ, they are probably lacking in IQ as well?
Compiled by cracked.com, here are some of the reasons why some people are dumber than they should be:
Long meetings not only waste your time, they are a brain drain
Here's a reason to give your boss on why long meetings should be abolished - they make everybody involved dumber.
"You may joke about how committee meetings make you feel brain dead, but our findings suggest that they may make you act brain dead as well," said Read Montague, director of the Human Neuroimaging Laboratory and the Computational Psychiatry Unit at the Virginia Tech Carilion Research Institute.
His study found that people perform less well on IQ tests directly after spending time in small social groups than they did when they were alone.
And if their performance was publicly revealed and ranked among their peers, they performed even worse.
It is theorised that this is as being in the presence of someone whom you think is smarter than you triggers debilitative cognitive responses by making us act stupid because we feel stupid.
Brain scans revealed that just being reminded of how the rest of group were scoring lit up parts of the brain responsible for fear, anxiety and emotional response.
Being around the fairer sex
How about this? Just being around a beautiful woman, or even mentioning her name, can make men more stupid.
In 2009, a study demonstrated that after a short interaction with an attractive woman, men displayed poorer performance in mental tasks. The more beautiful the woman, the stronger the effect.
That's not all. A more recent study showed that even the mere anticipation of interacting with a woman is enough to impair the cognitive abilities of men.
Researcher Sanne Nauts and her team from Radboud University Nijmegen in the Netherlands had participants take part in a cognitively demanding test.
During the test, they were told that a person with either a male or female name would be watching them through a webcam.
The participants knew nothing of the invisible "watcher", other than his or her sex. But just knowing an invisible woman was watching them was enough to severely impact their performance.
In another experiment, the researchers decided to tell the participants that they would be watched by a woman before they took the test.
In reality, the participants never took the test, but took another cognitive test to measure their current level of mental function. Researchers found that just the anticipation of being watched by a woman was enough to make the men score terribly.
Interesting enough, both studies found that this effect only applies to men. Women apparently are not made dumber by interacting with men.
Jetlag gives you permanent brain damage
Jet setting around the world may sound glamorous, but what if the cost is your brain cells?
A study conducted to investigate the effect of flying on Indian male and female flight attendants (FAs) found that a whopping 67.47 per cent of FAs who fly more than 10 years suffer from memory loss.
The paper, published in 2007, found that stress, loss of memory and headaches appeared to share the same etiology such as hypoxia (the deprivation of adequate oxygen supply to body parts), jetlag and irregular sleep.
Another study, this time conducted at the University of California, Berkeley, found that hamsters subjected to extreme, chronic jetlag had about half the normal rate of new neuron birth in a part of the brain, by as much as 50 per cent.
These animals, when later tested in learning and memory, performed poorer than the control group hamsters.
It wasn't that the hamsters were sleep deprived. The two groups of hamsters slept the same total number of hours, but one group had their hours screwed up by sleeping at times completely unrelated to their external environment.
The most frightening point is.. it is permanent.
Or at least a long term problem. The learning and memory problems remained even after the hamsters were put back on a 28 days back-to-normal schedule.
Getting spanked by your mom
Mothers beware: Sparing the rod may spoil the child, but spank your children and you risk giving them long-term developmental damage.
According to research done by the University of New Hampshire, children who are spanked have lower IQs worldwide.
The IQs of children aged two to four who were not spanked were as much as five points higher four years later than the IQs of those who were spanked.
"How often parents spanked made a difference. The more spanking, the slower the development of the child's mental ability. But even small amounts of spanking made a difference," said Straus Paschall, senior research scientist at the Pacific Institute for Research and Evaluation.
One reason as to why hitting a child may knock off IQ points is that corporal punishment is extremely stressful, and can cause post-traumatic stress symptoms, such as the child being fearful that terrible things are about to happen and being easily startled.
This makes children more aggressive and antisocial, and can cause cognitive impairment and developmental difficulties.
Being fat makes you mentally slow
It may be a controversial point to make, but science says that being obese not only makes you physically unattractive, it also makes you dull in the attic.
A study has found that children three years old and younger who stuff themselves with foods high in fats, sugars and processed foods grow up to have a lower IQ, while those who eat a healthy diet end up as smarter adults.
This is as the brain is believed to be growing at its fastest rate during the first three years of life, and depriving the brain of proper nutrients at this crucial period may have serious ramifications later on in life.
Eating junk food is not only linked to duller minds in childhood. Other studies have found that diet in adulthood also affects mental performance in later years.
A study, published in a 2003 issue of the International Journal of Obesity, found that obesity works independently, as well as hand in hand with other risk factors, to cause a decline in thinking ability, especially for memory and learning.
Those with a "body mass index" of 30 or more performed significantly worse in tests of mental ability, the Boston study found.
It was suggested that obesity may damage brain function by making it harder for blood to reach the brain.
Other studies have speculated that the reduced cognitive abilities of obese people might be due to their resistance to sugar (caused by prolonged exposure to excessive sugar), which affects the health of brain cells.
Living in a bustling city
If you are living in Singapore, you are by definition living in a city - and it's likely to be screwing up your brain.
Researchers from the University of Michigan found that just being in an urban environment can impair our basic mental processes.
After spending just a few minutes in a crowded city street, your memory capabilities are affected and the mind suffers from a drop in self-control.
In a series of psychological tests, subjects who walked through a city ended up in a worse mood and scored poorly in attention and working memory tests.
The reason is simple: A city, with a concentration of activity in a small area, is a brain drain. The mind has to pay attention to so much stimuli and irrelevant things that what results is an overload on the brain's processing power.
This is in contrast to looking at nature and wide areas of greenery, which has been proven to be beneficial to the brain. One study has demonstrated, for example, that hospital patients recover more quickly when greenery is visible from their hospital windows.
Are you the older or younger sibling?
Are you the older or younger sibling?
If you have an older sibling, chances are your older brother or sister is smarter than you.
Several studies have found that firstborn children score higher on IQ tests than their younger siblings - a fact backed-up by history, where most Nobel Prize winners and US presidents are firstborns.
However, as a consolation, the effect seems to be slight - a study found that the average difference in IQ was just three points higher in an eldest child than in the second.
Researchers believe this effect is due to family dynamics, and not biological factors. A firstborn is likely to have had more alone time with his or her parents, and those extra months or years of undivided attention can translate into IQ results.
But all is not lost if you are a secondborn. Older siblings tend to exhibit more dutiful and cautious behaviour than their siblings, while younger siblings often develop other skills, like social charm, inventiveness and confidence.
Breastfeeding can increase a child's IQ by 3 to 8 points
Yes, breastfeeding is tied to kids' brain power.
In a 2011 study from the UK, kids who were breastfed as babies had higher scores on tests of vocabulary and reasoning at age five than those who weren't breastfed.
"There are essential fatty acids in breast milk which are good for cell development and brain development in particular," said Amanda Sacker, one of the authors of the new study from the Institute for Social and Economic Research at the University of Essex.
She added that there also could be differences in hormones and growth factors which are lacking in formula. A third possibility is that the act of cuddling during breastfeeding sessions may be translating to better smarts in the future.
This adds on the the host of benefits science has found in favour of breastfeeding, including lower infection risks, stronger lungs and less asthma.
The World Health Organisation (WHO) recommends that mothers exclusively breast feed their babies for the first six months of their lives, and continue to do so until at least two years of age.
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