International Left handers Day 13 August 2014

International Left handers Day

August 13 is designated International Lefthanders Day by Lefthanders International. It was first observed on the 13th of August, 1976. As the name suggests, it is meant to promote awareness of the inconveniences facing left-handers in a predominantly right-handed world. It celebrates their uniqueness and differences, who are from seven to ten percent of the world's population. Thousands of left-handed people in today's society have to adapt to use right handed tools and objects.

There’s also a more serious side to the day, which spreads awareness about the special needs of left-handed kids. Also, left-handers are far more likely to develop schizophrenia than right-handers, for reasons not well understood.


While it had been observed on Aug. 13 of each year by many left handers since 1976, Left-handers Day was declared by the Left-Hander's Day Club on August 13, 1996. It was made to annually celebrate certain people's sinistrality and raise awareness of the advantages and disadvantages of being left-handed.



Mothers who give birth over the age of 40 are 128 percent more likely to have a child with left-handedness than a woman who has a baby in her 20s.

Lefties have been traced back to the caveman days. Archaeologists believe that some cave paintings were created by a left- handed artist.

There are phrases in English, which suggest left-handedness is negative. A “left-handed complement” is an insult. A “left-handed marriage” is not at all a marriage but an adulterous sexual relationship.

Lefties are more likely to be geniuses. 

Throughout history, being left-handed was seen as various things, like: a bad habit, rebellion, criminality, the mark of the devil, a sign of neurosis, or even a trait marking creativity and musical ability.
Left-handedness runs in the family, the British royal family namely. The Queen Mother, Queen Elizabeth II, Prince Charles, and Prince William are or were all lefties.

Lefties are more likely to loathe spiral notebooks. 

Here are some other famous lefties: President Barak Obama, Oprah, Angelina Jolie, Julia Roberts, Justin Bieber, Sarah Jessica Parker, Bruce Willis, Scarlett Johansson, Jon Stewart, Lady Gaga and Tina Fey. 

It’s not sure what makes a person become a lefty. Some scientists say it could be more testosterone in utero; others say it could be the hand babies prefer to have in their mouths.

The Boston Strangler, Jack the Ripper and Osama Bin Laden were all lefties.

Among Eskimos, every lefty is a potential sorcerer.

Some researchers believe lefties are better at handling stimuli, which means they’re naturally better at video games.

Some scholars say lefties are the last unorganized minority in society because they don’t have a collective power or real sense of common identity.

In Scotland, if a person is a unlucky it is said he or she was “baptized by a left-handed priest.”

Lefties tend to be more susceptible to negative emotions like depression and anger because they engage in the right side of their brains more aggressively.

Some scholars say lefties generally die nine years earlier than righties.

Nearly 30 million people in the U.S. are left-handed.

There are many artistic representations that show Satan as being left-handed.




Left-handers have been the subject of curiosity, stigma and even fear over the centuries. Researchers now, however, are recognizing the scientific importance of understanding why people use one hand or the other to write, eat or toss a ball.

Handedness, as the dominance of one hand over the other is called, provides a window into the way our brains are wired, experts say. And it may help shed light on disorders related to brain development, like dyslexia, schizophrenia and attention deficit hyperactivity disorder, or ADHD, which are more common in left-handed people.

Modern lefty lore says left-handers are smarter, more creative and have an advantage over righties. But is it true? WSJ's Christina Tsuei looks into the science of lefties.

Other recent research suggests that mixed-handedness—using different hands for daily tasks and not having a dominant one—may be even more strongly linked than left-handedness to ADHD and possibly other conditions.

About 10% of people are left-handed, according to expert estimates. Another 1% of the population is mixed-handed. What causes people not to favor their right hand is only partly due to genetics—even identical twins, who have 100% of the same genes, don't always share handedness.

More important, researchers say, are environmental factors—especially stress—in the womb. Babies born to older mothers or at a lower birth weight are more likely to be lefties, for example. And mothers who were exposed to unusually high levels of stress during pregnancy are more likely to give birth to a left-handed child. A review of research, published in 2009 in the journal Neuropsychologia, estimated that about 25% of the variability in handedness is due to genetics.

On average there is no significant difference in IQ between righties and lefties, studies show, belying popular perceptions. There is some evidence that lefties are better at divergent thinking, or starting from existing knowledge to develop new concepts, which is considered an element of creativity. And left-handed people have salaries that on average are about 10% lower than righties, according to recent research performed at Harvard University that analyzed large income data bases, although findings of some earlier studies were mixed.
Left-handed people make up about 10% of the population, while 1% of the population appear not to be dominant with either hand, known as mixed-handed.

Being left-handed is only partially genetic.

For reasons not clearly understood, handedness depends mainly on how a baby's brain develops while in the womb.

On average there is no difference in intelligence between right-and left-handed people. But lefties do better on an element of creativity known as divergent thinking.

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Six of the last 12 U.S. presidents, including Barack Obama and George H. W. Bush, have been lefties.



Left-handed people earn on average 10% lower salaries than righties, according to a recent study. Findings of some earlier studies on income have been mixed.

Despite popular misperceptions, lefties aren't more accident prone than right-handed people and don't tend to die at a younger age.

Left-handedness has been linked to increased risk of certain neurodevelopmental disorders like schizophrenia and ADHD. Mixed-handedness is even more strongly associated with ADHD.

Most people's brains have a dominant side. More symmetrical brains of mixed-handed people may explain the link to some neural disorders.


Left-handedness appears to be associated with a greater risk for a number of psychiatric and developmental disorders. While lefties make up about 10% of the overall population, about 20% of people with schizophrenia are lefties, for example. Links between left-handedness and dyslexia, ADHD and some mood disorders have also been reported in research studies.

The reasons for this aren't clear. Scientists speculate it could be related to a concept known as brain lateralization. The brain has two halves. Each performs primarily separate, specialized functions, such as language processing, which mainly takes place in the left hemisphere. There is lots of communication between the hemispheres.

Typically in right-handers, the brain's left side is dominant. But this tendency doesn't hold up with lefties, as scientists previously believed. Some 70% of lefties rely on the left hemisphere for their language centers, a key brain function, says Metten Somers, a psychiatrist and researcher who studies brain lateralization at Utrecht University Medical Center in the Netherlands. This doesn't appear to present problems, scientists say.

The other 30% of lefties appear to exhibit either a right-dominant or distributed pattern, Dr. Somers says. They may be more prone to impaired learning or functioning, and at greater risk for brain disorders, he says.

Hemisphere dominance is typical and more efficient. Symmetry, in which neither side is dominant, is believed linked to disorders, researchers say. People with schizophrenia, for instance, exhibit more symmetrical activation of their brain hemispheres than those without the disorder, studies show.

In a 2008 study, Alina Rodriguez, a psychology professor at Mid Sweden University in Östersund who studies handedness, brain development and ADHD, found that left- or mixed-handedness in children was linked to a greater risk of difficulty with language as well as ADHD symptoms. In another study published last year in Pediatrics, involving nearly 8,000 Finnish children, Dr. Rodriguez found that mixed-handedness rather than left-handedness was linked to ADHD symptoms.

And knowing that a child was mixed-handed and had ADHD symptoms at age 8 helped predict much more accurately than just knowing they had symptoms at that age whether the child would continue to have symptoms at age 16. (What happens when people are forced to switch from writing with their dominant hand to the other isn't well known, experts say.)


One reason that not more is known about lefties is that many studies of how the brain works prohibit left-handers from participating because their brain wiring is known to be different, says Robin Nusslock, a psychology professor at Northwestern University in Evanston, Ill., who uses neuroimaging to study mood disorders.

Research that suggests that there is a link between favoring the left hand and an increased risk of bipolar disorder and ADHD, among other conditions. Emily Nelson has details on Lunch Break.

A potential pathway between prenatal stress and brain wiring could be cortisol, the body's main stress hormone, which can interfere with brain development, says Carsten Obel, a professor at the public-health department at Aarhus University in Denmark who has conducted research on the prenatal environment and risk of disease. Cortisol is able to pass over the placenta barrier to influence the baby.

Lefties have an advantage in sports such as tennis, fencing and baseball, when up against a righthanded competitor, but not in noninteractive sports such as gymnastics. Agence France Presse/Getty Images

Several studies show that stressful life events, such as the death of a loved one or job loss, during pregnancy increase the risk of having non-right-handed children. In one study of 834 Danish mothers and their 3-year-old children, Dr. Obel and his colleagues found that mothers who reported multiple stressful events during their third trimester of pregnancy and experienced distress were more than three times as likely to have a mixed-handed child, 17% compared with 5%, according to the 2003 paper published in Developmental Medicine & Child Neurology.

Another large study followed 1,700 Swedish mothers and children until the kids were 5 years old. It found that mothers with depressive symptoms or who underwent stressful life events while pregnant were more likely to have left- or mixed-handed children. The work was published by Dr. Rodriguez and her colleagues in 2008 in the Journal of Child Psychology and Psychiatry.

Experts suggest that left- and mixed-handedness could be used as a risk factor for possible psychiatric or developmental conditions, along with behavioral difficulties, such as having a hard time in school. The presence of such risk factors could prompt early evaluation for those conditions, they say.



The Health Risks of Being Left-Handed

Lefties Face Chance Of ADHD, Other Disorders; Brain Wiring Holds Clues


Left-handers have been the subject of curiosity, stigma and even fear over the centuries. Researchers now, however, are recognizing the scientific importance of understanding why people use one hand or the other to write, eat or toss a ball.

Handedness, as the dominance of one hand over the other is called, provides a window into the way our brains are wired, experts say. And it may help shed light on disorders related to brain development, like dyslexia, schizophrenia and attention deficit hyperactivity disorder, or ADHD, which are more common in left-handed people.

Modern lefty lore says left-handers are smarter, more creative and have an advantage over righties. But is it true? WSJ's Christina Tsuei looks into the science of lefties.

Other recent research suggests that mixed-handedness—using different hands for daily tasks and not having a dominant one—may be even more strongly linked than left-handedness to ADHD and possibly other conditions.

About 10% of people are left-handed, according to expert estimates. Another 1% of the population is mixed-handed. What causes people not to favor their right hand is only partly due to genetics—even identical twins, who have 100% of the same genes, don't always share handedness.

More important, researchers say, are environmental factors—especially stress—in the womb. Babies born to older mothers or at a lower birth weight are more likely to be lefties, for example. And mothers who were exposed to unusually high levels of stress during pregnancy are more likely to give birth to a left-handed child. A review of research, published in 2009 in the journal Neuropsychologia, estimated that about 25% of the variability in handedness is due to genetics.

On average there is no significant difference in IQ between righties and lefties, studies show, belying popular perceptions. There is some evidence that lefties are better at divergent thinking, or starting from existing knowledge to develop new concepts, which is considered an element of creativity. And left-handed people have salaries that on average are about 10% lower than righties, according to recent research performed at Harvard University that analyzed large income data bases, although findings of some earlier studies were mixed.



One reason that not more is known about lefties is that many studies of how the brain works prohibit left-handers from participating because their brain wiring is known to be different, says Robin Nusslock, a psychology professor at Northwestern University in Evanston, Ill., who uses neuroimaging to study mood disorders.

Research that suggests that there is a link between favoring the left hand and an increased risk of bipolar disorder and ADHD, among other conditions. Emily Nelson has details on Lunch Break.


A potential pathway between prenatal stress and brain wiring could be cortisol, the body's main stress hormone, which can interfere with brain development, says Carsten Obel, a professor at the public-health department at Aarhus University in Denmark who has conducted research on the prenatal environment and risk of disease. Cortisol is able to pass over the placenta barrier to influence the baby.

Lefties have an advantage in sports such as tennis, fencing and baseball, when up against a righthanded competitor, but not in noninteractive sports such as gymnastics. Agence France Presse/Getty Images

Several studies show that stressful life events, such as the death of a loved one or job loss, during pregnancy increase the risk of having non-right-handed children. In one study of 834 Danish mothers and their 3-year-old children, Dr. Obel and his colleagues found that mothers who reported multiple stressful events during their third trimester of pregnancy and experienced distress were more than three times as likely to have a mixed-handed child, 17% compared with 5%, according to the 2003 paper published in Developmental Medicine & Child Neurology.




Why Are Some People Left-Handed?

Being a righty or a lefty could be linked to variations in a network of genes that influence right or left asymmetries in the body and brain





President Barack Obama is left-handed, as well as at least six former presidents.

For the left-handed people of the world, life isn’t easy. Throughout much of history, massive stigmas attached to left-handedness meant they were singled out as everything from unclean to witches. In Medieval times, writing with your left-hand was a surefire way to be accused of being possessed by the devil; after all, the devil himself was thought to be a lefty. The world has gotten progressively more accepting of left-handed folk, but there are still some undeniable bummers associated with a left-handed proclivity: desks and spiral notebooks pose a constant battle, scissors are all but impossible to use and–according to some studies–life-expectancy might be lower than for right-handed people.

What makes humanity’s bias against lefties all the more unfair is that left-handed people are born that way. In fact, scientists have speculated for years that a single gene could control a left-right preference in humans. Unfortunately, they just couldn’t pinpoint exactly where the gene might lie.

Now, in a paper published today in PLOS Genetics a group of researchers have identified a network of genes that relate to handedness in humans. What’s more, they’ve linked this preference to the development of asymmetry in the body and the brain.

In previous studies, the researchers observed that patients with dyslexia exhibited a correlation between the gene PCSK6 and handedness. Because every gene has two copies (known as alleles), every gene has two chances for mutation; what the researches found was that dyslexic patients with more variance in PCSK6–meaning that one or both of their PSCK6 alleles had mutated–were more likely to be right-handed.

The research team found this especially interesting, because they knew that PCSK6 was a gene directly associated with the development of left-right asymmetry in the body. They weren’t sure why this would present itself only in dyslexic patients, as dyslexia and handedness are not related. So the team expanded the study to include more than 2,600 people who don’t have dyslexia.

The study found that PCSK6 didn’t work alone in affecting handedness in the general population. Other genes, also responsible for creating left-right asymmetry in the body, were strongly associated with handedness. Like PCSK6, the effect that these genes have on handedness depends on how many mutations the alleles undergo. Each gene has the potential for mutation–the more mutations a person has in any one direction (toward right handedness or left handedness) the more likely they are to use that hand as their dominant hand, or so the researchers speculate.

The hypothesis is a logical response to a key question: If handedness is genetic and if right-handedness is such a dominant trait, why hasn’t left-handedness been forced out of the genetic pool? In reality, the research suggests that handedness could be more subtle than simple “dominant” or “recessive” traits–a whole host of genes might play significant roles.

What’s especially exciting is that these genes all relate to the development of left-right asymmetry in the body and brain, creating a strong case for correlation between the development of this symmetry and the development of handedness. Disrupting any of these genes could lead to serious physical asymmetry, like situs inversus, a condition where the body’s organs are reversed (heart on the right side of the body, for example). In mice, the disruption of PCSK6 resulted in serious abnormal positioning of organs in their bodies.

If physical asymmetry is related to handedness, then people with situs inversus should favor one hand more often than what you’d find in the general population. Studies show that this isn’t the case–individuals with this condition mirror the general population’s split in handedness–leading the researchers to postulate that while these genes certainly influence handedness, there might be other mechanisms in the body that compensate for handedness in the event of major physiological asymmetries.

Other animals, such as polar bears or chimpanzees, also have handedness–chimpanzees have been known to prefer one hand to the other when using tools or looking for food, but the split within a population hangs around 50/50. Humans are the only species that show a truly distinct bias toward one hand or the other: a 90/10 right/left split throughout the population.

One predominant hypothesis for this bias relates to another distinct human trait: language ability. Language ability is split between the different hemispheres of the brain, much like handedness, which suggests that handedness became compartmentalized along with language ability, For most, the parts of the brain that govern language are are present in the left-side of the brain–these people tend to be right-handed. The few that have language skills focused in the right side of the brain tend to be left-handed.

However, William Brandler, a PhD student at Oxford University and the paper’s lead author, isn’t convinced that this theory holds much stock, as correlations between language and handedness in research aren’t well established. Brandler is more interested in learning how the permutations and combinations of genetic mutations play into humans’ likelihood to be right-handed. “Through understanding the genetics of handedness, we might be able to understand how it evolved,” he says. “Once we have the full picture of all the genes involved, and how they interact with other genes, we might be able to understand how and why there is such a bias.”

And he’s confident that even if environmental factors (like the continued hatred of lefties by two-thirds of the world) place pressure on handedness, any baseline bias still boils down to genetics. “People think it’s just an environmental thing, but you’ve got to think, why is there that initial bias in the first place, and why do you see that bias across all societies? Why aren’t there societies where you see a bias to the left?” Brandler asks. “There is a genetic component to handedness, hundreds of different genetic variants, and each one might push you one way or the other, and it’s the type of variance, along with the environment you’re in and the pressures acting on you, which affect your handedness.”

But until a larger population can be tested–hundreds of thousands, by Brandler’s estimates–a full genetic map of what controls handedness and why our population isn’t evenly split between righties and lefties can’t be determined. “It’s going to take a bit of time before these materialize—but it will happen,” Brandler says. “There’s been a whole revolution in genetics such that, in a few years time, we’re really going to start to understand the genetic basis of complex traits.”