About one person in ten is left-handed. The best current estimate, from a 2020 analysis of studies covering almost 2.4 million people, puts the figure at 10.6%, rising to around 18% if you count everyone who is not strongly right-handed. Left-handedness runs in families but is only partly genetic, and it is not a sign of being "right-brained", more creative or more likely to get ill.
Lefties have attracted myths for centuries, and lists of "amazing facts" about them still circulate widely online. Some of those facts hold up, some are half-true, and a few seem to have no source at all. Below we go through 23 popular claims, keeping each of the original illustrations, and say plainly what the evidence supports. Where a figure cannot be traced to a real study, we say so.
A quick note on how handedness is measured: researchers usually ask which hand people use for a set of tasks such as writing, throwing, using scissors or a toothbrush. Depending on how strict the definition is, the share of left-handers changes noticeably, which is one reason so many different percentages float around. Mixed-handedness, where people use different hands for different tasks, turns out to be almost as common as true left-handedness.
How many people are left-handed?
1. Claim: only 5 to 10% of people are lefties
This is a little low. The 2020 meta-analysis published in Psychological Bulletin, led by researchers in Athens with colleagues at St Andrews, Oxford, Bristol and Bochum, found that about 10.6% of people are left-handed. Under the strictest definition the figure was 9.3%, and under the loosest it was 18.1%. Men are somewhat more likely than women to be left-handed.
14. Claim: there are about 30 million left-handed Americans
That is a reasonable ballpark. With roughly one in ten people left-handed and a US population of over 330 million, the true number is probably somewhat above 30 million. Worldwide, the same share works out at several hundred million left-handers.
10. Claim: mothers over 40 are 128% more likely to have a left-handed baby
We could not trace the 128% figure to a published study, so treat it as unverified. Researchers have looked at many prenatal factors, and some studies link left-handedness with lower birth weight, birth complications and certain hormone exposures in the womb. Heritability is modest: twin studies suggest genes explain only about a quarter of the variation in handedness.
Brain, body and health claims
3. Claim: lefties mainly use the right side of the brain
This is mostly a myth. Each side of the brain controls movement on the opposite side of the body, so the right hemisphere does steer the left hand. But about 70% of left-handers process language in the left hemisphere, just as most right-handers do, although their brains tend to be a little less lopsided. The popular idea of "right-brained" creative people and "left-brained" logical people is not supported by neuroscience.
2. Claim: lefties are three times as likely to become alcoholics
Some studies have reported a link between left- or mixed-handedness and alcohol problems, but there is no solid evidence for a threefold risk. Associations like this tend to be small and inconsistent between studies. Alcohol problems have many causes, and handedness is not a meaningful predictor for any individual.
4. Claim: left-handers reach puberty four to five months later
This claim appears in many lists, but we could not find a reliable study behind it. Puberty timing depends mainly on genetics, nutrition and body weight. Until a clear source turns up, it is best treated as unconfirmed trivia.
15. Claim: lefties get more allergies and asthma
This idea goes back to a 1980s theory by the neurologist Norman Geschwind, who proposed that left-handedness and immune disorders might share a cause in the developing brain. Later research produced mixed results, and no strong link with allergies or asthma has been established. If you have allergy symptoms, talk to a doctor; your writing hand is not the explanation.
19. Claim: left-handed people are more likely to have insomnia
Evidence here is thin. A few small studies have looked at handedness and sleep patterns, but there is no established finding that lefties suffer more insomnia. Poor sleep is common in everyone, and persistent problems are worth discussing with a doctor.
22. Claim: lefties see better underwater
We found no research supporting this, and it appears to be pure internet folklore. Underwater vision depends on the eye's ability to focus without air in front of the cornea, which has nothing to do with handedness. The Marco Polo meme above is about the swimming-pool game, not science.
23. Claim: left-handers get angry faster
Tennis great John McEnroe is indeed left-handed and famous for his on-court outbursts, but one hot-tempered champion proves nothing. Some personality studies have reported small differences between left- and right-handers in traits such as anxiety or shyness, not anger. The joke works; the "fact" does not.
Sport, skills and money
5. Claim: lefties excel at baseball, tennis, swimming and boxing
For sports where you face an opponent directly, this is largely true. Around 40% of seeded tennis players have been left-handed, about half of top fencers are, and in Major League Baseball in 2012 roughly 39% of hitters and 28% of pitchers were lefties. Left-handers are also over-represented and more successful in boxing and mixed martial arts. Spain's Feliciano López, pictured above, built a long career around a left-handed serve.
The usual explanation is surprise: opponents rarely practise against left-handers, so their angles and spins feel unfamiliar. Rafael Nadal is a famous case, a natural right-hander for most daily tasks who plays tennis left-handed. In swimming, where there is no opponent to surprise, there is no clear left-handed advantage.
12. Claim: lefties are better at maths and architecture
The evidence is weak. A large review found an average IQ difference between left- and right-handers of about 1.5 points, which is negligible. Left-handers are said to be over-represented in some groups, such as the high-IQ society Mensa, but there is no rule that they are better at maths or design. The picture above shows St. Louis's Gateway Arch, an architectural landmark rather than evidence of a left-handed talent.
16. Claim: lefties adapt more easily to using their right hand
There is something to this. Living in a world built for right-handers, many lefties learn to use right-handed scissors, computer mice, tools and instruments, so they are more often mixed-handed. That everyday practice can make it easier to switch hands after an injury, though it varies a lot from person to person.
7. Claim: left-handed graduates earn 26% more
The research is mixed. A 2006 US study found no overall earnings difference, though left-handers who went to college earned roughly 10 to 15% more, and press coverage quoted bigger figures for some subgroups. A 2014 study by the Harvard economist Joshua Goodman, published by the National Bureau of Economic Research, found the opposite: on average, left-handers earned 10 to 12% less over their lifetimes.
History, language and prejudice
8. Claim: left-handedness was once seen as a vice, a devil's mark or a sign of deviance
This one is true, and the history is not funny. For generations, left-handed children in many countries, including the Soviet Union, were forced to write with their right hand, and in some places, such as parts of Uganda, they were beaten or had their left hand tied. Britain's King George VI was made to write right-handed as a child. Left-handedness was at various times linked to sin, rebellion, criminality and sexual "deviance", all claims that have no basis. The Simpsons' "Leftorium" shop, shown above, is a gentler modern joke about how poorly the world serves lefties.
9. Claim: "left" comes from an Anglo-Saxon word meaning broken or weak
Close. Etymological dictionaries trace "left" to Old English lyft or left, glossed as weak, clumsy or foolish; it survives in the Old English word lyftādl, meaning palsy or paralysis. "Broken" is a stretch. Many languages also use the word for "right" to mean correct, as English does, and Latin sinister originally meant simply "left".
20. Claim: 13 August is International Left-Handers Day
True. The day is marked every year on 13 August and was launched in 1992 by the UK-based Left-Handers Club, founded two years earlier. It is used to raise awareness of the everyday difficulties lefties face, from smudged ink to awkward can openers.
Famous left-handers, real and doubtful
6. Claim: four of seven recent US presidents were left-handed
Broadly true for the period when this list was written. Gerald Ford, George H. W. Bush, Bill Clinton and Barack Obama are widely reported as left-handed, and Ronald Reagan is often counted too, as a natural lefty said to have been taught to write with his right hand. Obama, pictured signing a document with his left hand, made the trait highly visible.
13. Claim: one in four Apollo astronauts was left-handed
We could not verify this, and NASA has not published handedness data for its Apollo crews. Twenty-four men flew to the Moon on Apollo missions, so the claim would mean about six lefties, but no reliable list exists. Treat it as unconfirmed.
18. Claim: the Queen Mother, Elizabeth II, Charles and William are lefties
Partly true at best. King George VI, father of Elizabeth II, was naturally left-handed, and Prince William is widely reported to be a lefty. Evidence for the Queen Mother, Queen Elizabeth II and King Charles III is much weaker, and reports conflict. Royal handedness lists online often repeat each other without a source.
21. Claim: the Boston Strangler, Osama bin Laden and Jack the Ripper were left-handed
Only one part of this is reasonably solid: the FBI's wanted notice for Osama bin Laden described him as left-handed. Jack the Ripper was never identified, so his handedness cannot be known, and doctors in 1888 disagreed about it. We found no reliable source for the Boston Strangler. Above all, handedness says nothing about whether someone is likely to commit a crime, an old prejudice that the list unfortunately echoes.
Animals and keyboard trivia
11. Claim: cats, rats and mice split evenly between left and right paws
Partly true. Many animals show individual paw preferences, but across a whole species the split is often close to even, unlike humans, about 90% of whom are right-handed. In domestic cats, dogs and horses, studies have found a sex difference: females more often favour the right paw or limb, males the left.
17. Claim: the longest words typed with only the left hand are "sweaterdresses" and "tesseradecades"
On a standard QWERTY keyboard, both 14-letter words can indeed be typed using only keys on the left side. The better-known example is "stewardesses", at 12 letters. It is a fun reminder that the QWERTY layout gives the left hand a surprising share of English typing.
What the evidence really says about lefties
Strip away the trivia and a clear picture remains. Left-handedness is common, partly inherited, and mostly harmless. It brings a real advantage in face-to-face sports and has a long, painful history of prejudice. Many of the health, personality and intelligence claims attached to it are weak, exaggerated or untraceable.
If you are a lefty, the most useful things are practical: left-handed scissors and tools, a pen that does not smudge, and teachers who let children write with the hand that comes naturally. If you are a parent, there is no reason to try to change a child's handedness, and good reason not to.
Sources: University of St Andrews, 2 April 2020: World's biggest study of left-handedness; Wikipedia: Handedness (prevalence, sport, health, income and history); Wiktionary: left (etymology); original list by Aunty Acid via Idealist4ever; McEnroe photograph © Susan Mullane.
i doubt there were hundreds or thousands of studies to confirm most of this. obviously, whether or not a particular person is left-handed doesn't need much proof
ReplyDeleteI doubt your doubt because studies bare confirm anything. They are the results of financial strivings.
DeleteCommon sense is barely paricipating when studies are spoken of and as I just said, Studies tend to result in the way the financiers want them to result.
it has logical explanation. Using your left hand activates the muscles on the right side of your body and using your right hand activates the muscles on the left side of your body. RIght side is creative and left side is analitic. The greats do it as good with both. It's something you can teach yourself to do. 90% are right handed today because the society decided this. You can control analitical humans easier than creative humans.
DeleteNotice how President Obama holds his hand when he writes. That's because teachers insist that the paper slant to the right when learning to write so we lefties had no choice but to bunch up our hands.
ReplyDeleteWhat about "stewardesses"?
ReplyDeleteI've been hearing that people being more "right-brained" or "left-brained" is a myth- one source I remember was a person who studied the correlation between language & neurology on a word origin podcast, 'The Allusionist'
ReplyDeleteit has logical explanation. Using your left hand activates the muscles on the right side of your body and using your right hand activates the muscles on the left side of your body. RIght side is creative and left side is analitic. The greats do it as good with both. It's something you can teach yourself to do. 90% are right handed today because the society decided this. You can control analitical humans easier than creative humans.
Delete