Of population that is left handed: Study Reveals Why Lefties Are Rare
Study Reveals Why Lefties Are Rare
Scientists have long wondered why left-handed people are a rarity. Stories about being slapped on the wrist for being a lefty aside, there must be some deeper, evolutionary reason, scientists figure. A new study suggests lefties are rare because of the balance between cooperation and competition in human evolution. The findings come thanks to some data from the sports world.
Representing only 10 percent of the general human population, left-handers have been viewed with suspicion and persecuted across history. The word “sinister” even derives from “left or left-hand.”
Researchers at Northwestern University now report that a high degree of cooperation, not something odd or sinister, plays a key role in the rarity of left-handedness.
They developed a mathematical model that shows the low percentage of lefties is a result of the balance between cooperation and competition in human evolution.
Professor Daniel M. Abrams and graduate student Mark J. Panaggio—both right-handers—are the first to use real-world data (from competitive sports) to test and confirm the hypothesis that social behavior is related to population-level handedness.
The results are published this week in the Journal of the Royal Society Interface.
“The more social the animal—where cooperation is highly valued—the more the general population will trend toward one side,” says Abrams, an assistant professor of engineering sciences and applied mathematics at the McCormick School of Engineering and Applied Science.
“The most important factor for an efficient society is a high degree of cooperation. In humans, this has resulted in a right-handed majority.”
If societies were entirely cooperative everyone would be same-handed, Abrams said. But if competition were more important, one could expect the population to be 50-50. The new model can predict accurately the percentage of left-handers in a group—humans, parrots, baseball players, golfers—based on the degrees of cooperation and competition in the social interaction.
The model helps to explain our right-handed world now and historically: the 90-10 right-handed to left-handed ratio has remained the same for more than 5,000 years. It also explains the dominance of left-handed athletes in many sports where competition can drive the number of lefties up to a disproportionate level.
Cooperation favors same-handedness—for sharing the same tools, for example. Physical competition, on the other hand, favors the unusual. In a fight, a left-hander would have the advantage in a right-handed world.
Abrams and Panaggio turned to the world of sports for data to support their balance of cooperation and competition theory. Their model accurately predicted the number of elite left-handed athletes in baseball, boxing, hockey, fencing, and table tennis—more than 50 percent among top baseball players and well above 10 percent (the general population rate) for the other sports.
On the other hand, the number of successful left-handed PGA golfers is very low, only 4 percent. The model also accurately predicted this.
“The accuracy of our model’s predictions when applied to sports data supports the idea that we are seeing the same effect in human society,” Abrams says.
Handedness, the preference for using one hand over the other, is partially genetic and partially environmental. Identical twins, who share exactly the same genes, don’t always share the same handedness.
“As computers and simulation become more widespread in science, it remains important to create understandable mathematical models of the phenomena that interest us, such as the left-handed minority,” Abrams says.
“By discarding unnecessary elements, these simple models can give us insight into the most important aspects of a problem, sometimes even shedding light on things seemingly outside the domain of math.”
The James S. McDonnell Foundation supported this research.
Scientific Theories for Some People Are Left-Handed
- Tuesday August 13 is International Lefthanders Day.
- About 10% of the population is left-handed.
- There have been several theories over the years about why some people favor their left hand.
- A study published last year found that right- or left-handedness may have nothing to do with the brain — instead, it could be determined by gene activity in the spinal cord while you are in the womb.
- Visit Business Insider’s homepage for more stories.
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Left-handed people haven’t always been treated well throughout history. They’ve been persecuted for their disposition, being been labeled as evil — or even as witches — despite making up about 10% of the population. In fact, the word “sinister” comes from “left” or “left hand.”
There have been a few theories over the decades about why some people are left-handed, including an outdated idea that it has something to do with mothers who are stressed while pregnant.
It’s down to the spinal cord — not the brain
Research since the 1980s has found that our preference for our left or right hand is most likely determined before we are born — ultrasound screenings suggest as early as the eighth week of pregnancy. From the 13th week in the womb, babies tend to suck either their right or their left thumb.
It was previously thought that the genetic differences between the left and right hemispheres of the brain determine whether someone is left- or right-handed. But a study published last year in the journal eLife found that the answer could lie in the spinal cord.
The research — by Sebastian Ocklenburg, Judith Schmitz, and Onur Gunturkun from Ruhr University Bochum, along with other colleagues from the Netherlands and South Africa — found that gene activity in the spinal cord was asymmetrical in the womb and could be what causes a person to be left- or right-handed.
Arm and hand movements start in the brain, in an area called the motor cortex, which sends a signal to the spinal cord that’s translated into a motion. The researchers found that while the fetus is growing in the womb, up until about 15 weeks, the motor cortex and the spinal cord are not yet connected, but right- or left-handedness has already been determined.
In other words, the fetus can already start movements and chooses a favorite hand before the brain starts controlling the body.
To study this, the researchers analyzed gene expression in the spinal cord in the eighth through the 12th week of pregnancy. They found significant differences in the left and right segments of the spinal cord that control arm and leg movement.
They concluded that the asymmetrical nature of the spinal cord could be down to something called epigenetics, or how organisms are affected by changes in their gene expression rather than in the genes themselves. These changes are often brought about by environmental influences and can affect how a baby grows.
These gene-expression differences could affect the right and left parts of the spinal cord differently, resulting in lefties and righties.
So why are lefties so rare?
Scientists have long tried to answer this.
In 2012, researchers at Northwestern University developed a mathematical model to show that the percentage of left-handed people was a result of human evolution — specifically, a balance of cooperation and competition.
In other words, they thought that, though the basis for right- or left-handedness may be genetic, there could be a social factor that explains why the ratio is so high.
“The more social the animal — where cooperation is highly valued — the more the general population will trend toward one side,” Daniel Abrams, an assistant professor at the McCormick School of Engineering and Applied Science who helped develop the model, told LiveScience.
“The most important factor for an efficient society is a high degree of cooperation,” he added. “In humans, this has resulted in a right-handed majority.”
In other words, we may have, for some reason, evolved to favor right-handedness, so anyone deviating from this may have been conditioned to use that hand primarily despite their genetic predisposition.
In fact, Judith Schmitz, one of the authors of the new study, told Business Insider that twin studies have shown the contribution of genetics for handedness is about 25%.
The new study couldn’t explain the majority of right-handedness, but Schmitz explained how bird research can show how genetics and environment can be the cause.
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“In chicken and pigeons, a genetic factor determines the position in the egg before hatch — the embryo is curled such that the right eye is turned to the semi-translucent eggshell, while the left eye is covered by the embryo’s own body,” she said.
“Thus, the right eye is stimulated by light before hatch, whereas the left one is mostly light deprived. This combination of genetic and environmental factors (light) induces a visual asymmetry — pigeons and chicken are better in visual discrimination, categorization, and memorization of visual patterns with their right eye than with their left eye. If chicken or pigeon eggs are incubated in darkness, the development of this asymmetry is prevented.”
Why exactly people are left-handed is still a bit of a mystery — partly because left-handed people are often excluded from scientific research, experts say — and it’s hard to predict whether a child will be left or right-handed once they are born.
One thing we do know, though, is that the neurological differences between left- and right-handed people are small, and supposed behavioral or psychological distinctions have largely been debunked.
Left handers day: How many people are left handed and why are more people right handed?
Today is a day to celebrate the lefty (Picture: Getty)
Today, 13 August, is Left-Handers Day, which is apparently an opportunity ‘to tell your family and friends how proud you are of being left-handed, and also raise awareness of the everyday issues that lefties face’.
That is according to the Left Handers Club, who started the special day in 1992 and point out that we ‘live in a world designed for right-handers.’
This is true, because the vast majority of human beings are right handed, making the left handed products much more difficult to come by.
So how many people are left handed and why is it that the trait is so unusual?
How many people are left handed?
The estimated percentage of left handed people across the globe is 8-15%, with most figures studies suggesting it is 10-12%.
Taking the average of 11%, this would mean that 836,000,000 people are left handed across the globe, out of a population of 7.6 billion.
It has also been shown in a 2008 study that a left handed person is 23% more likely to be male than female.
Today is a day to celebrate lefties (Picture: Getty)
Why are so many more people right handed than left handed?
There is no definitive answer to this question, but the most accepted theory relates to which side of the brain controls the right hand.
According to Jason Goldman for the BBC, the right side of the body is largely controlled by the left hemisphere on the brain, the same side of the brain that deals with language.
It was about 1.5 million years ago that evidence of right handed dominance became clear through tools found in Kenya, whereas there was little or no evidence that there was a preference before that.
It is from that time on that language is believed to have developed in humans and with the left hemisphere processing the linguistic skills, right handedness may well have occurred as a side effect.
This is called the Homo loquens hypothesis.
So why are some people left handed?
It appears that some people’s brains are organised differently to the majority, although this is not necessarily a negative thing.
‘Left-handers are much more variable in the way that their brains are organised,’ explained psychologist Chris McManus, from University College London, to the BBC.
A certain amount of mystery surrounds left handedness (Picture: Getty Images/PhotoAlto)
‘My personal hunch is that left-handers are both more talented, and suffer deficits. If you are left-handed you might find yourself with a slightly unusual way your brain is organised and suddenly that gives you skills that other people don’t have.’
Dorothy Bishop is Professor of Developmental Neuropsychology at the University of Oxford, looks at it differently: ‘I myself am left-handed and I always wondered why I was different from other people.
‘There’s been all sorts of claims over the years linking left-handedness with disabilities like dyslexia and autism. On the other hand, there have been positive attributes – it’s claimed that architects and musicians are more likely to be left-handed.’
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Why are more people right-handed?
M.K. Holder is an affiliated scientist in the Center for the Integrative Study of Animal Behavior at Indiana University. She replies:
In the 160 years in which “handedness” has been studied we have learned quite a lot, but we still cannot precisely describe what
causes humans preferentially to use one hand over the other, or why human populations are biased toward right-hand use rather
than left-hand use.
Scientists disagree over what percentage of human populations are “right-handed” or “left-handed” because there is no standard, empirical definition for measuring “handedness”; our criteria vary, and are based on various theoretical explanations because we are still trying to understand the mechanisms involved. But I can describe in general terms what we do know.
Most humans (say 70 percent to 95 percent) are right-handed, a minority (say 5 percent to 30 percent) are left-handed, and an indeterminate number of people are probably best described as ambidextrous. This appears to be universally true for all human
populations anywhere in the world. There is evidence for genetic influence for handedness; however, it is non-Mendelian and
geneticists cannot agree on the exact process. There is evidence that handedness can be influenced (and changed) by social and cultural mechanisms. For instance, teachers have been known to force children to switch from using their left hand to using their right hand for writing. Also, some more restrictive societies show less left-handedness in their populations than other more permissive societies.
Some researchers argue there is evidence for cases of “pathological” left-handedness related to brain trauma during birth. And many researchers trace the cause of handedness back to pre-natal, interuterine developmental processes, back to the time when the fetal brain is first developing distinct cerebral hemispheres. In the 1860s the French surgeon Paul Broca noted a relationship between right-handedness and left-hemispheric brain specialization for language abilities. But the hand-brain association is neither a simple, nor reliable, correlation. Studies conducted in the 1970s showed that most left-handers have the same left-hemispheric brain specialization for language typical of all humans–only a portion of left-handers have different patterns of language specialization.
So the bottom line is, we have a good general idea of the causes of right-handedness in human populations, but we have yet to work out the precise details, including why the direction is right instead of left.
Do other primates show a similar tendency to favor one hand over the other?
The second question (do non-human primates show handedness) is currently a controversial one. It is important to note the
difference between an individual animal being left- or right-handed, and most of the animals in an entire population being either
left- or right-handed. It is not unusual for individual animals to show a preferential use of one hand over the other, to develop an
individual hand preference. But there is no consensus among researchers that any non-human species shows the same species-level handedness found in humans.
There are a few researchers who argue for this, but most of these work with animals in laboratory or captive settings, performing
manual tasks that are very different from how animals use their hands in the wild.
In addition to studying handedness in humans, I have also studied hand usage in mountain gorillas (in Rwanda) as well as chimpanzees, red colobus monkeys, redtail monkeys and grey-cheeked mangabeys (in Uganda). My own research shows that individual monkeys and apes often develop individual preferences (both left and right) for manual tasks, but I have found no evidence for population-level handedness, as seen in humans.
Answer originally posted August 18, 1997.
Largest Study to Date Asks How Many People Are Left-handed
From Leonardo da Vinci to Oprah Winfrey, and from Napoleon Bonaparte to Jimi Hendrix the talents of left-handers have been celebrated across the generations.
However, the prevalence of people who favour their left hand over their right has always been a rough estimate – until now.
In the biggest ever global study of handedness researchers from across Europe, led by the National and Kapodistrian University of Athens and in the UK by the University of St Andrews, have concluded that 10.6% of the world’s population are left handed.
Details of the study of more than two million people by researchers at the National and Kapodistrian University of Athens, University of Oxford, University of Bristol, Ruhr University Bochum and St Andrews are published in Psychological Bulletin today (Thursday 2 April 2020).
Frequency of left-handedness has shaped and underpinned different fields of research, from cognitive neuroscience to human evolution. While hundreds of empirical studies have assessed handedness, there has never been a large-scale, comprehensive review of the prevalence of handedness and the factors which moderate it.
For the study researchers examined five meta-analyses involving 2,396,170 individuals on hand preference for different manual tasks. They showed that left-handedness prevalence lies between 9.34% using the most stringent criterion of left-handedness, to 18.1% using the most lenient criterion of non-right-handedness, with the best overall estimate being 10.6%.
Typically handedness is measured by which hand is used to write with. However, for this study researchers allowed for the fact that about 9% of people use different hands for different tasks which further improved the accuracy for their findings.
Understanding handedness contributes to our understanding of human evolution. For example, it has been claimed that right-handedness, along with the capacity to make and use tools, to use language, and to show functional and anatomical cerebral specialisation, are characteristics specific to humans, and that they are intimately tied together in the divergent evolution of man from apes.
The lead UK author of the study, Dr Silvia Paracchini, of the School of Medicine at St Andrews, said: “This study will provide a useful reference for different areas of handedness research. In addition to providing reliable figures, the study highlights variability across studies depending on the different criteria used to measure handedness. While we intuitively classify handedness as a left/right category, these data show that the proportion of people using different hands for different tasks is almost as big as the proportion of the left-handers.”
Reference: Papadatou-Pastou, M., Ntolka, E., Schmitz, J., Martin, M., Munafò, M. R., Ocklenburg, S., & Paracchini, S. (2020). Human handedness: A meta-analysis. Psychological Bulletin. https://doi.org/10.1037/bul0000229
This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source.
Opinion: The world needs to be more left-handed
Living in a right-handed society as a left-handed person has become a physical burden. It’s time to stop instilling myths and discriminatory ideals against left-handed people.
Ten percent of the population is left-handed, however, our modern world is still targeted towards right-handedness. Ultimately, lefties are forced to adapt. In order to be accommodating to all, the world needs to modernize by recognizing left-handed people instead of forcing them to fit into a mold made for the other 90%.
Being a lefty, I’ve been forced to live in a right-handed world since childhood, and I’ve been asking questions no one has had the answer to since.
Why are microwave buttons and oven knobs usually only on the right side?
Why is there never a desk comfortable for me to sit in but my classmates all have arm support?
Why are pens at the bank always attached on the right side?
Why do I always have to struggle with notebooks, scissors, vegetable peelers not working?
In order for the world to continue to modernize, these issues need solutions and some solutions are simple.
More work should be done to increase fairness between lefties and righties instead of resorting to forcing left-handed children to be righties.
Put oven knobs along the bottom of the stove instead of on the right side so that all stoves can have knobs in a neutral place.
If a standard class contains 25-30 students, and about 10% of the world population is left-handed, then every classroom should contain at least two desks reserved for left-handed students.
Left-handed students should be allowed to use pens instead of pencils as their primary writing tool in school because pencil smears when the left-hand passes over the writing which can make notes blurry.
Every classroom should have at least one pair of lefty scissors.
The world needs to be more accommodating to left-handed people, in the same way it’s accommodating to any other group of people who are different.
According to 2015 census data, less than 1% of the world population is blind, yet tactile paving is used all over the country to protect those who are blind and have impaired vision.
According to the World Health Organization, as of 2018, over 5% of the world population is deaf or hard of hearing, but all modern TVs are built with support for closed captioning.
About 10% of the world population is left-handed but accommodations for them are still lacking.
Society has modernized in other ways. Accommodations for people with Dyslexia or ADHD now exist, when previously they weren’t available.
Similar accommodations for lefties have yet to be made. If I want to purchase a pair of scissors or a vegetable peeler that will work for me, I have to go to a special store to seek that out. The world hasn’t put enough work into making the lives of lefties easier.
I don’t think it’s fair to compare being left-handed with living with a disability, however, it’s important to recognize the world makes accommodations for different functioning bodies, often with the exception of left-handed people. Accommodations for all circumstances relating to a large portion of the affected communities should be available.
Instead, the world pressures lefties to change by either forcing a child to write with their right hand or hoping they learn to become ambidextrous.
One could argue that you’re doing your child a favor by stopping them from using their left hand before it becomes a habit. If they learn to be right-handed early, there’s no need to learn how to adapt to the right-handed world. There is evidence that proves there are no long-term consequences of switching handedness, however, this idea goes against the concept of uniqueness parents also encourage.
Forcing a child to use their non-dominant hand teaches them being left-handed is not something they should celebrate and is therefore bad. This outdated idea does not represent what American culture stands for, the acceptance of others who are different from ourselves.
Forcing anyone into anything that is unnatural to them is immoral, so why does American society still consider it reasonable for parents and teachers to force children to write with their other hand?
Perhaps it comes from a place of misunderstanding.
Several left-handed myths originated in the ‘60s and ’70s from Michael Barsley’s books on left-handedness.
A report covering the last half-century of handedness research for sage Journals, an independent publishing company, said popular books about left-handedness spread misinformation. Chris McManus said, “Michael Barsley’s popular books on left-handedness, with their myriad successors in books, newspapers and on the Internet, promulgated a series of endlessly repeated half-truths and myths.”
These false truths spread to the masses increasing unintentional discrimination against lefties. Myths that left-handed people die-younger, have poor health and superstitions that the left side of the body is related to evil, contributed to why parents throughout history forced their children to write with their right hand.
Children in school would be beaten for something they could not control. Jesse Robinson, a 21-year-old, left-handed SRJC student shared that for him, being left-handed has always been an advantage because he plays baseball. Robinson’s mom, who’s also left-handed, hasn’t been so lucky.
“Her teacher would smack her hand with the metal side of a ruler because she wrote with her left hand. My mom is now ambidextrous due to her experiences in elementary school,” Robinson said.
Historically, it has not been uncommon for teachers to slap left-handed student’s hands with rulers until they learned to use their right hand. Abusing people for something they cannot help is frowned upon by society, but yet people still do.
Physical abuse of lefties may not be as prevalent in the modern-day U.S. but still, not enough is being done to ensure lefties are treated as equals.
The first step is recognizing the problem, from there, change can be made.
Here’s How Many People Are Left-Handed
From scissors to desks to baseball mitts, there are constant reminders that the world just isn’t designed for left-handed people. While being a lefty can make a person feel left out, southpaws aren’t as unique as you might think.
Approximately 10 percent of the population is thought to be left-handed. That means there could be upwards of 700 million total lefties around the globe. In fact, being a lefty is significantly more common than having blue eyes, red hair, or identifying as a member of the LGBT community.
So, what causes someone to be left-handed in the first place? A DNA quirk? An inherited trait? A curse? The short answer is that scientists simply aren’t sure why some people are singled out to be southpaws. However, while science hasn’t pinpointed a specific gene that causes people to be left-handed, there may be some significance to this feature. In fact, during a 2015 presentation to London’s Royal Society, Dr. Silvia Paracchini, a human geneticist from the University of St. Andrews, revealed that there are differences in the brains of left- and right-handed individuals.
Left-handed individuals have significantly more nerve fibers in their corpus callosum, which divides the brain’s left and right hemispheres. A lefty has about 11 percent more nerve fibers in this strip of the brain than a righty. As such, leftys’ brains share information between hemispheres at an elevated pace.
So, while you may never write comfortably in a spiral-bound notebook or find using a manual can opener easy, at least you’ve got plenty of brainpower that can help you find solutions to those lefty conundrums. And when you want to know more about the hows and whys of the world, the 50 Awesome Facts About Everything might just surprise you yet.
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90,000 How do scientists explain left-handedness and whether left-handers differ from right-handers
About 10 percent of the world’s population is left-handed. Approximately 780 million people.
Such a ratio of right-handers and left-handers exists, apparently, throughout the history of mankind. For example, 90 percent of the studied Homo habilis (man of skill), who lived 1.8 million years ago, are right-handed, 10 percent are left-handed. Scientists make such conclusions by studying ancient instruments and skeletons.
Why do some people become left-handed? Or are they born? There is no exact answer to these questions yet.
Causes of left-handedness
On the one hand, this is genetics. In 2019, scientists identified four DNA markers that are associated with left-handedness. True, it is believed that genes are only 25 percent responsible for the dominant human hand.
Another 75 percent appears to be a variety of environmental factors. What country were you born in. Was it at this time customary to retrain left-handers so that they became right-handed? How much did you weigh at birth and did you breastfeed?After all, whether you are a man or a woman – according to statistics, men are slightly more prone to being left-handed.
There are scientists who explain the phenomenon of left-handers by the course of evolution. In 2012, the United States developed a mathematical model according to which the high number of right-handers in relation to left-handers is due to the fact that people prefer to cooperate with each other, rather than compete. From an evolutionary perspective, the ratio of right-handers to left-handers helps humans survive.
For example, in order to use the same tools and share them among themselves, it is better for people to have the same dominant hand.According to the same mathematical model, if people did not compete with each other at all, evolution would leave left-handers behind – but it was precisely because of competition that this did not happen.
Lefties vs. Right-handers
There are studies that show that left-handers prefer not only the left hand, but in general – the left side. And right-handers – right.
During one such experiment, left-handers and right-handers were told the story of two animals – good and bad. After that, the animals had to be drawn on paper in two frames.Left-handers put a good animal in the left frame, and right-handers – in the right.
Amusing facts like this end the difference between people with different dominant hands. This feature has nothing to do with the behavior or success of a person, says child psychologist Alexei Pokryshkin.
“Sometimes a child’s left-handedness [manifests itself] along with other features. For example, with dyslexia. But it’s dyslexia, not left-handedness. These are different things,” Pokryshkin explains. “There are no differences between left-handed and right-handed people.”
The psychologist claims that left-handed people, especially in childhood, need only help to adjust to the right-handed world.
“Since I live in a world where there is a large concentration of right-handers, I have adapted to this,” says neurosurgeon Alexander Levov, left-hander. It is more convenient for me when the nurse stands on the left side and puts the instruments in my left hand. The nurses who work with me know which instrument to put in which hand.All instruments are adapted to some extent. “
At the same time, it has developed so culturally and historically that many negative associations are associated with left-handers. In some languages, the words “left” and “left-handed” (including Russian) have negative connotations. In Islam, traditionally the left hand is considered unclean, although this varies.
“I was interested, for example, whether it is possible to eat from the left hand. I cannot retrain,” says Guzel Bakhshieva, a leading specialist in the control department in a construction company, left-handed and Muslim.- The teacher in the mosque told me that this is now a different attitude and they are now looking at it differently. There is no longer a negative connotation. The Quran simply does not say anything about the left hand. This, apparently, from the life of the prophet. Maybe he did more with his right hand. And people made such conclusions. “
Officially or unofficially, left-handers were retrained not only in the USSR. Until now, this is done, for example, in China and Japan. At the same time, it is not always possible to completely retrain left-handed children.
“The teachers at the school told me to start writing with my right hand,” says neurosurgeon Levov.- When I had to write, I put the pen in my left hand. Accordingly, the hand was tied so that it was not on the desk or it was impossible to put a pen in it. There were certain stereotypes in teaching that required such brutal parenting methods. After being retrained, I became ambidextrous. I write with my right hand. And I do the rest with my left. “
Being left-handed: inconvenience or advantage
Retraining children is easier than adapting to the needs of left-handers. A British job site in 2015 conducted a survey of working people.The authors concluded that 12 percent of the kingdom’s workforce is left-handed (that’s 4.5 million). Of these, 20 percent have difficulties in the workplace (852 thousand people). Their workplace or the equipment they work with is right-handed.
It’s not always easy for lefties to be musicians. One of the greatest guitarists, Jimi Hendrix, was left-handed. He used regular guitars, but turned them over to the other side and pulled the strings in the right order.
The piano is not easy to play either.
“When playing the piano, the main part always goes to the right hand, and the left hand seems to accompany. And it was very difficult for me, because I looked at the notes and played with my left hand what was for the right hand,” says designer Yulia Makogon. – It all ended with the fact that I had to leave the game, because it was very difficult for me. It was such a straightforward difficulty that I faced. ”
In many cases, left-handed military personnel have to learn to hold a weapon in their right hand.If the shells fly out from the right, they can injure a left-handed shooter. Some types of weapons can be modified: special reflectors are installed on it.
Lefties experience difficulties in everyday life. Many things are designed for right-handed people – regular scissors do not cut if held in the left hand. Can openers – do not open cans. It is even difficult to write – in those languages where it is done from left to right, everything written is erased by hand.
“I tried a lot of pens. I needed to understand that the pen would not leak and stain, so that nothing would get dirty for me,” says Yulia Makogon.- My hand was always in the pen. Straight soiled. I wrote and walked with my hand. And when it was required to sign something very important or to draw up something, I just got used to putting a sheet under my arm. And everything came out somehow neatly for me. In principle, it did not create any difficulties. At first, yes. And then already how fantasy works. And how you can adapt. “
Of course, with languages written from right to left, the opposite is true.
“Arabic is written from right to left.And the right-hander finds himself in my position when writing in Arabic. It is not very convenient to write in Arabic with the right hand. And it was very easy for me to master the Arabic script, “says Bakhshieva.
The advantage of left-handers is often manifested in martial arts: boxing, karate, fencing.
“I was engaged in martial arts at the same time. And it was completely unexpected for my opponents that I was left-handed,” says Bakhshieva. “When your opponent does not know that you are left-handed, he loses. Because I have a left-handed leader.Basically, right-handed people use their left hand as a defense. And I could work well with my left. “
Student Denis Khaustov, who is engaged in boxing, says: “At the competitions I stood in the right-hander for the first 10 seconds, and then abruptly switched to the left-hander. I had about 30 seconds of surprise. It helped me to earn more points.”
90,000 Left-handed DNA found. Their brains are different from right-handers
- James Gallagher
- BBC Science & Health Correspondent
Photo Credit, Getty Images
Scientists have discovered the first genetic codes. embedded in DNA molecules that are associated with people’s tendency to use their left hand predominantly.
These codes are also included in the structure and functioning of the brain (especially in the areas responsible for a person’s language skills).
Researchers at the University of Oxford believe that left-handed people may have better verbal communication skills.
What does the new data say?
About one in ten people in the world are left-handed.
Studies carried out on twins have revealed that DNA is inherited from parents and plays a role in a person’s preference for a particular hand.
Photo author, Getty Images
Former US President Barack Obama is left-handed
A team of researchers turned to the data of the British Biobank, the repositories of which contain complete information about the DNA (genetic code sequence) of 400 thousand people.
38 thousand of them were left-handed.
Scientists had to compare a huge amount of genetic data from left-handers and right-handers to find the DNA regions that determine the tendency to use the left hand.
A study published in the journal Brain identifies four such key areas.
“This is the first time we have learned that the tendency to use the left or right hand is genetically determined,” one of the research team members, Professor Gwenall Duo, told the BBC.
How does it work?
Changes were found in the sequence of genes responsible for the formation of the inner part of the body’s cells (cytoskeleton, a cell framework located in the cytoplasm of a cell).
The same changes affecting the cytoskeleton of snails lead to the fact that in some of them the shells are twisted counterclockwise, that is, in fact, they are left-handed snails.
Photo author, University of Nottingham
Jeremy with one of his right-handed offspring
Scanning data samples from participants in the British Biobank showed that the cytoskeleton changes the structure of the white matter in the brain.
“For the first time, we were able to establish in relation to a person that differences in the cytoskeleton associated with the dominance of one or another hand are visible in the structure of the brain,” said Professor Duo, who is herself left-handed.
In left-handed study participants, the left and right hemispheres of the brain were better connected and more coordinated in the areas of language proficiency.
Scientists have suggested that left-handed people may have better developed verbal skills, although there is no direct evidence for this theory yet.
According to the results of the study, left-handers have a higher risk of developing schizophrenia and less of Parkinson’s disease than right-handers.
Will our perceptions of lefties change?
Being left-handed is not easy.“In many cultures, the left-handed person is considered an evil person or a failure, and this is reflected in the language,” explains the author of the report, surgeon who performs hand surgery, Professor Dominique Furniss.
In French, the word “gauche” can mean both “left” and “awkward”. In English, the word “right” means “right” and “one who is right”.
In many European languages, the word “law” is not only synonymous with correctness, but is also used as “power” and “justice”, in most Slavic languages the root of “rights” is used in words that carry the meanings of correctness and justice.
“Our research shows that being left-handed is all about having a certain brain structure, it has nothing to do with luck or anger,” adds Furniss.
“This trait is due to genetic variation that we have identified.”
So this is the end of the story?
This is still a long way off.
The best theory is that the dominance of this or that hand is 25% due to genetics, and 75% due to the environment and everything that is not related to genetics.
The study was able to identify only 1% of this genetic trait in left-handers, and only among the inhabitants of Britain.
Much more research needs to be done to see the full picture of a person’s genetic predisposition to using the left hand.
What is the difference between the brain and behavior of right-handers and left-handers
Why left-handers and right-handers cannot be treated in the same way, how the leading hand decides for us who to vote for in the elections, how to change the idea of good and bad with a glove in 12 minutes, is it good to be ambidextrous – these and other questions are answered by the Science Department of Newspapers …Ru “.
Pens, scissors, cars, computer mice … All these things are designed for 85% of humanity – right-handers. In recent years, scientists have begun to pay attention to left-handers as completely different, differently thinking and living individuals. Scientists have found out whether you are left-handed or right-handed not only with which hand you write, but also how you see the world and how you interact with it.
The hand votes for reason
Researchers from the University of Chicago claim that, while performing habitual actions, people subconsciously choose the side that is more convenient and comfortable for them – and that is the side of the working hand.This means that if a right-handed person sees two people who are equally attractive to him in a bar, he will instinctively get to know the person standing on the right side. A person will behave in the same way in the store: not seeing any special differences between the two products, left-handers choose the left-handed product, and right-handers choose the right one.
13 September 13:59
Why do right-handers and left-handers think so differently? The study’s lead author, Daniel Casasanto, suggested that the concept that people choose “good” and “bad” depends in part on which hand they use more often.He says that people can act much more freely with the dominant hand, therefore they unconsciously associate good things with it.
If this fact seems quite logical, then the following observation of scientists was quite unexpected for them. It turned out that this behavior carries over to the selection of candidates on the ballot papers during voting:
The likelihood that right-handers will choose a candidate whose last name is written on the right side of the page is 15% higher than in the case of left-handers.
This means that if a person has not completely decided on his political preferences and expects to think, already being in the voting booth, chance may well play a cruel joke with him.
Treat left-handers differently
The authors of the study did not stop at simply recording the characteristics of people’s behavior – they found that the differences between right-handers and left-handers extend to the brain. For right-handers, the centers responsible for creativity and a sense of happiness are located in the left hemisphere, for left-handers – vice versa.This means that therapies targeting specific areas of the brain can have the opposite effect on a person, depending on their dominant hand.
“Scientists have long believed that the centers responsible for happiness and anger are located in the left hemisphere,” says one of the study’s authors, Dr. Daniel Casasanto.-
It turns out that this is true only for right-handers, and the organization of brain activity depends on which hand is the leading one. ”
Such discoveries are of great importance for the treatment of various mental disorders – for example, depression, which doctors are trying to relieve the patient of by increasing the activity of the left hemisphere. In fact, for left-handed people, such treatment can have the opposite effect, so therapy should be directed to the right hemisphere.
How to Throw the Glove to the Mind
As mentioned above, right-handers subconsciously associate good with the right side of space, and bad with the left, left-handed people – vice versa. To test whether this behavior can be changed, scientists from the Max Planck Institute for Psycholinguistics and the University of Pennsylvania conducted a series of unusual experiments. More information on this study can be found on on the pages of the journal Psychological Science.
Scientists have proven that even
A few minutes of left-handed work can change the right-hander’s beliefs that right is good and left is bad.
In the first experiment, people were asked to choose one of two products, one from two candidates for a job, and also to rate which of the two alien creatures depicted in the pictures was smarter than the other. Right-handers, as expected, were much more likely to choose right-handed objects, and left-handers – left-handed. Then the scientists tested how the right-handers thought about the good and the bad after they lost the ability to control the right hand: either due to some kind of injury, or when the actions of the leading hand were artificially limited (the subjects put on a ski glove).
It turned out that those who lost the ability to fully control the right hand considered the left “good” – just like the “natural” left-handers.The same pattern was found in healthy students who performed various motor tasks with the right hand in a bulky glove, requiring speed and dexterity.
After 12 minutes of such “clumsy” motor activity with the dominant hand, right-handers changed their judgments about the fact that the right is good and the left is bad.
Scientists say that people are used to thinking that their judgments are rational and their concepts are stable. But if wearing a glove for a few minutes can completely change people’s ordinary judgments about what is bad and what is good, then perhaps our minds are more susceptible to change than we previously thought?
Is it good to be ambidextrous?
There is an opinion among the people that the ideal and universal embodiment of human skills in relation to right- and left-handedness is ambidexterity – equal possession of the right and left hands.Scientists have destroyed this myth: it turns out that the owners of this amazing ability have much more difficult life than ordinary right-handers and left-handers.
Scientists assure that children with ambidexterity are much more likely to experience problems with languages, health, perform worse at school and are prone to attention deficit hyperactivity disorder (ADHD).
Researchers from Imperial College London and other European institutions suggest their findings may help teachers and healthcare professionals identify children who are most at risk of developing certain problems.This study was published in the journal Pediatrics .
Every hundredth child is ambidextrous. Researchers examined about 8,000 children, 87 of whom were ambidextrous, and found that between the ages of 7-8, children with both hands were twice as likely to have difficulty learning their native language and school performance as their right-handed peers. …
When these children reached the age of 15-16, ambidexters were again twice as likely to develop symptoms of attention deficit hyperactivity disorder.”Two-handed” adolescents, as at an earlier age, had more problems with the language than right-handers.
At the moment, scientists know little about what contributes to the formation of ambidexterity in children, but researchers suggest that this may be due to the work of the hemispheres, as in right-handers and left-handers. For a more detailed understanding of the problem, the researchers propose to deepen and continue further work. Scientists also emphasize that they only found an increased tendency towards certain disorders and problems in ambidextra – this does not mean that such problems arise in all ambidextra, without exception.
90,000 Your child is left-handed
Left-handed people – only 10% of the world’s population, and the whole world is adapted for the right-handed majority. Check out tips for parenting and educating children with a dominant left hand.
Being left-handed in the modern world is easier and easier than before, and to some extent even honorable. There are many geniuses of our time among left-handed people, sociological studies tell us that left-handers earn more money, and left-handers themselves are indeed often very talented and extraordinary personalities.
And what is the difference between right-handed children and left-handed children in terms of psychological development?
A left-handed child may have spatial confusion, as their spatial imagination is less developed. But, like all growing up kids, they want to know as much as possible. That is why left-handers often ask questions, fix their attention on the same film, fairy tale, fragment of the text. This does not make a left-handed child dumb. It’s just that the kid has to build logical chains in his head.It is more difficult for him to get to the bottom of the truth. And all because the left hemisphere is responsible for logic, which is less developed in left-handers.
The upbringing and education of children with a leading left hand also has its own characteristics.
Ten Tips for Parents,
to make it easier for them to understand their little geniuses
1. Remind your child which hand is right and which is left.
Lefty doesn’t understand well which hand is left and which is right.Buy a bright bracelet or watch for your child. You can make some kind of decoration with him. The hand with the bracelet is the left one. The child will quickly be able to navigate if there is such a reminder.
2. Do not emphasize that the child is left-handed.
Do not focus on the fact that the child is left-handed. The kid should not feel like a stranger among his peers. Parents should try to act as discreetly as possible to help their child cope with difficulties.For example, you can ask the teacher to seat the child on the left at the desk, so that the right hand of the neighbor does not interfere with him.
3. Teach your child to use both hands.
From a very young age, left-handed people should be taught to work with both hands. This does not mean that it is necessary to take away its leading role from the left hand. Playing with a ball, playing musical instruments, all those hobbies in which both hands are involved will help.
4. Don’t rush the little left-hander.
A left-handed child will always be slower than a right-handed child. It is useless to rush, shout, show your displeasure. This will not make a left-handed child any faster. He will start to get nervous, fuss, panic. As a result, the child will not be able to concentrate on homework.
5. Repeat and reinforce knowledge.
Experts have proved that systematization of knowledge is very important for left-handers. That is, if a right-handed child can skip some of the nuances, but master the topic of the lesson as a whole, then it is impossible for a left-handed child.Each new material should be learned in stages, with repetition and consolidation.
6. Create a left-handed study space.
Attention should be paid to the correct organization of the workplace. Lights and textbooks should be on the right side.
7. Teach your left-handed child according to the schemes and rules.
It is always more difficult for a left-handed child to analyze, so offer simple and understandable diagrams in the learning process.It is better to make the rules for solving problems schematic, or even draw up an elementary memo on the stages of the task.
8. Review and reinforce school material at home.
The left-hander has the most problems in a regular school. A large number of children in the class does not always allow you to find an individual approach to the child. Parents should be prepared to re-explain most of the material at home.
9.Pay attention to the letter.
It is almost always difficult for a left-handed child to learn to write. The student may not finish writing a line, write in a mirror image. Problems also arise when copying, rewriting any text. When reading, left-handed children may start reading from the middle of a sentence. Therefore, special attention should be paid to developing the habit of reading and writing from left to right. Draw the child’s attention to what is the right way to do it. You can use pictures with plots, ordinary game cubes to help.
10. Use a bookmark when reading.
When teaching to read or just work with books, parents should use a bookmark or ruler. It is very difficult for a left-hander to follow the lines in the text and not get lost, not skip further.
90,000 According to the WHO, only 3 to 10% of the world’s population are left-handed (right-brain)
The modern world is created for people who do everything with their right hand.Writing and kitchen utensils, doors and locks, computer mice and
much more has been done for right-handed people. This Day is meant to attract attention
societies to the problems faced by left-handers in the right-handed world;
draw the attention of designers, manufacturers and sellers to the need
take into account the convenience of left-handed people when using various items; dispel
prejudices and superstitions that have surrounded lefties for centuries
in different cultures; encourage scientific research in the field of study
the phenomenon of left-handedness.
How to recognize a left-handed child and what undesirable consequences can
lead the retraining of the “wrong” child, says a neurologist,
Head of the Department of Rehabilitation “Goldfish” Kuzbass
Regional Children’s Clinical Hospital Olga Yegereva.
You can determine whether your child is right-handed or left-handed, no earlier than 2-4 years. What
the kid often takes a spoon with his hand, reaches for a toy – it means that it is a hand
– dominant.Let the child listen to the ticking clock, look, to
which ear will he bring them. And notice what kind of eye it will be
look into a kaleidoscope. Only a combination of all these tests will show a left-handed person.
your child or right-handed.
In no case should a child be retrained to be left-handed. Since this is an attempt
change the biological nature of the child. We can force learning to write
right hand, but we cannot change the dominant role of the right hemisphere
brain.Forced retraining can lead to the development of neuroses, violation
sleep, headaches and poor performance in school.
There are several reasons for the birth of left-handed children. The most common –
genetic predisposition. Since, left-handed people are dominated by the right
hemisphere, then, as a rule, it is inherited genetically from parents to
children, after a generation, or even after two generations. Left-handed parents
very often left-handed children are born.
The second significant reason is birth trauma or hypoxic damage to the left
hemisphere. The right hemisphere takes over its functions and thus
becomes dominant (leading).
Lefties are considered to be more creative and talented people. This one has
scientific justification. Since the right hemisphere of the brain, which controls
the left half of the body, is responsible for our emotions, intuition, humanitarian
possibilities.Right-brain people (left-handers) – people are vulnerable, deeply
By the way, choosing a hand for writing does not mean that a person is a true left-hander.
or a true right-hander. Since it often happens that a person writes with the right
hand, but for other household tasks: cutting vegetables, playing on
violin, using a spoon, etc. – a person uses his left hand more.
Lateralization is inherent in our brain (Lateralization of functions
brain (lat.lateralis “lateral, located to the side”) –
the process taking place in ontogenesis, through which various
mental functions are associated with the left or right hemispheres of the brain
brain). There is a functional separation into the right and left sides.
The activity of the right half of the body is controlled by the left hemisphere, and
vice versa. Thus, each person has not only a dominant
hand, but also a leg, ear, eye.
You can check whether a person is left-handed or right-handed at home by doing
some simple tests.First, you need to interlace your fingers: the finger
the leading hand is on top. Second, you need to applaud: presenter
the hand will also be on top. It is necessary to determine which leg is supporting, that will be
leading. The easiest way to determine the leading eye is by winking.
(blinks the non-dominant eye) and aim (aim with the dominant eye). How
the more among the leading organs are left-sided, the more likely it is that
the person is left-handed.
Famous left-handers – politicians and the military: Caesar and Napoleon, Alexander
Macedonian and Charlemagne, Churchill, Bismarck and Fidel Castro.Among
American presidents – Gerald Ford, Bill Clinton, George W. Bush
and Barack Obama. The left-handers were the artists Leonardo da Vinci, Michelangelo,
Auguste Rodin, Pablo Picasso, Peter Paul Rubens, Albrecht Durer, writers
Hans Christian Andersen, Franz Kafka, Lewis Carroll, musicians Nicolo
Paganini, Wolfgang Amadeus Mozart, Sergei Rachmaninoff, actor Charlie Chaplin,
scientists Albert Einstein, Isaac Newton and many others.
In order for right-handed people to feel how left-handed people live in modern
the world, the initiators of the International Day of Left-handers offer today
try to perform the usual actions with your left hand.90,003 90,000 Meta-analysis counted 10.6 percent of left-handers
Vrubel Mikhail Alexandrovich “The Artist’s Left Hand”
European scientists have conducted a large-scale meta-analysis of works on the leading hand of a person, and more accurately calculated the number of left-handers.The average for all the studies reviewed (almost 2.4 million participants) was 10.6 percent left-handed, although this figure, depending on work, ranged from 9.3 to 18.1 percent. The article was published in the journal Psychological Bulletin .
The human brain is divided into two parts: although they appear to be the same outwardly, they are functionally asymmetrical. For example, the areas of the frontal and temporal lobes of the left hemisphere are responsible for speech, but the corresponding areas of the right hemisphere are no longer.That is why people who have had a stroke in the left hemisphere have severe speech impairments (aphasia) compared to those who have suffered from a stroke in the right hemisphere.
Different hemispheres are also responsible for the right and left parts of our body: the right hemisphere is responsible for the movements of the left hand, and the left hemisphere for the movement of the right. Due to the fact that the brain is functionally asymmetric, the sides of the body also work asymmetrically – this is how right-handers and left-handers turn out (you can read more details about this in our material).
Right-handers in the world are the absolute majority (about 90 percent), but their assessment is inaccurate, largely due to the fact that different studies conducting the calculation use different methods. In addition, they rarely take into account the number of ambidextrous (those who can use both left and right hands to perform different tasks), and also focus on only one task – writing.
Marietta Papadatou-Pastou from the Kapodistrian National University of Athens and her colleagues decided to clarify the number of right-handers and left-handers in the world using a meta-analysis: the sample for all studies included 2,396,170 people over 16 years old with different educational levels and from different countries.The studies used different methodologies to test the dominant hand, but in general the authors of the meta-analysis focused on the preference of study participants to use one or the other hand.
The number of left-handers among all study participants ranged from 9.3 percent, if the criteria for selecting left-handers were the most stringent (that is, this is the number of left-handers who use their left hand for everything), to 18.1 percent (the number of left-handed people who use left hand to perform at least some tasks).The average left-handers across all studies were 10.6 percent and 10.4 percent, excluding studies that looked at the dominant hand preference of professional athletes.
The percentage of left-handers from study to study depended, on the one hand, on the study itself and the methodology chosen in it (as well as on the year of publication of the article), and on the other, on the age and background of the participants. This is understandable: the desire to reduce the number of left-handers is highly dependent on the cultural characteristics of each individual population, and it also changes over time.For example, in the USSR, before the adoption of the relevant prohibiting laws, left-handed children were forcibly retrained both in schools and at home.
In addition to the most accurate counting of left-handers to date, scientists point out the importance of the methodology used in such studies: in their opinion, the problem with counting left-handers in the world is that studies use different assessment formats, on the one hand, and on the other hand, important side variables such as cultural characteristics are not always taken into account.
Of course, the functional laterality of the limbs is not an exclusively human feature: the asymmetry of the nervous system that determines it is inherent in most living organisms (of course, we are talking about those organisms that have a nervous system at all). So, left-handed and right-handed, for example, are among the bees: they have an individual tendency to choose the right or left side during flight.
Stationery for left-handed people
Stationery for left-handers
Lefties face difficulties and annoying inconveniences every day when they use a regular pen for writing, office scissors or a ruler: ink smears while writing; when you need to draw a line on the paper with a ruler, you have to keep your hand in an uncomfortable position, and in order to cut a sheet of paper with scissors, you need to bend over to see the cutting line.
Our selection of stationery products are specially designed for left-handed people and are great for everyday left-handed use.
Left-handed pens can be roughly divided into 3 types:
1.with ergonomic grip section,
2.with quick-drying ink,
3.with curved nib …
At the same time, several types can and most often are combined in one handle.
I. Ergonomic grip section
The grip section of these handles has specially positioned indentations for comfortable grip on the left hand. There are also handles that have not only a grip section, but the entire body has an ergonomic shape, thanks to which the handle literally “lies” in the left hand. These pens are comfortable to hold in the left hand, and with their help, writing becomes easier, and the correct placement of the fingers has a positive effect on posture and posture while writing.
Ballpoint pens Stabilo Easyball, LeftRight, Smartball; Maped Visio Pen.
Rollerball Stabilo EasyOriginal
Gel pen Stabilo Easygel.
Lamy ABC pencils, Faber-Castell Scribolino.
Fountain pens should be singled out as a separate item. Feathers for left-handed people have special markings – LH or L (left-handed), usually the line thickness corresponds to the average (M – medium). Such pens differ from standard pens in a cut that takes into account the specifics of writing with the left hand: it is typical for left-handers to “push” the pen forward, while right-handers, on the contrary, “pull” it across the paper.
Examples : Lamy ABC, Lamy Safari, Herlitz My.Pen Urban, Pelikan Pelikano Junior and Faber-Castell Scribolino.
If your child is left-handed and is just learning to write, pay attention to the special KUM holders marked L, which tell your child how to hold a pencil or pen correctly. These holders slide on a regular straight pen and easily convert it into a left-handed writing instrument. KUM manufactures products for left-handers with the assistance of German psychologist Johanna Barbara Settle (left-handed), who is the author of many books and scientific papers on the upbringing and development of left-handed children known in Germany.
II. Quick-drying ink
This type of pens uses special ink (the grip section can be completely normal, universally right- and left-handed). This ink dries quickly after being applied to paper, and when you move your left hand to the right, the written text is not smudged, and the ink does not stain your hand. These pens are popular among both left-handers and right-handers, the choice of models is very diverse. They produce ballpoint pens, gel pens, rollerballs, pens with caps and with a button, with an ergonomic grip section, etc.Here are some of them.
Ball: Pilot BPS-GP, Pilot Super Grip, Pilot RexGrip.
Gel: Pilot Frixion, Pilot G-Tec-C4, Pilot P-500, Pilot G6 Alfagel, Pilot G2, Pentel HyperG, Pentel Energel, Uni-ball Signo 207.
Rollers: Troika, Pilot Vball Grip, Pilot Hi -tecpoint.
Hybrid (low viscosity ink): Zebra Surari, Pilot Metropolitan, Pilot Acroball, Uni-ball Jetstream.
III. Curved nib
Pens of this type are not widely used, but they are gradually gaining popularity.The heart of these pens is the curved nib, which provides good visibility of the working surface of the sheet as if “through” the writing instrument. If you take an ordinary straight pen and write with it with your left hand, the body of the pen will very accurately obscure the written inscription. And in the handle of type 3, the body is bent in the right place so as not to obstruct the view. Thanks to this shape, the left-handed person does not need to bend his arm and take an uncomfortable position while writing.
When writing, the nib of the pen is almost perpendicular to the paper.This is convenient in that it does not scratch the paper and does not cause the discomfort that can appear when the pen is tilted normally.
Examples : Ballpoint pens Flair Angular Pen, Yoropen.
Rulers, sharpeners and scissors for left-handers
When using ordinary scissors, the left-hander does not see the cut line, and it often happens that the paper cannot be cut, but only bent. Scissors for left-handers differ in the position of the blades: left over right (like a mirror image of scissors for right-handers).They do not bend or wrinkle the paper, and allow you to visually control the cutting line. Scissors are available for both children and adults, with ergonomic handles for a comfortable grip.
Examples: Kum Lefty; Maped Sensoft 3D, KID, Office, Optimum; Westcott and Westcott Easy Grip; Brunnen; Lefty Cullinan.
In rulers for left-handers, the scale is drawn from right to left, thanks to this, when the line is drawn with the left hand from zero, the natural position of the hand is maintained, and the drawn line is not smeared by the hand.
Examples: Kum Flexi Shatterproof; Brunnen; Koh-I-Noor; Maped Left.
The left-handed sharpener uses the same “mirror image” principle: the blade is set with the cutting edge so that the pencil sharpens counterclockwise. This allows left-handers to maintain a natural hand position and minimizes the risk of lead breakage during sharpening.