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Left-Handedness The right side of the brain controls the motor skills of the left side of the body, and vice versa. So perhaps, differences in the two halves of the brain may account for right- and left-handedness. There’s a genetic component and being a southpaw condition does tend to run in families, but not as much as intelligence or height. With identical twins one can be right-handed and the other left-handed; so, they are not completely identical after all. In 2017, researchers at universities in the Netherlands and South Africa put forward the explanation that handedness is determined in the womb by asymmetrical genetic activity in the spinal cord. These theories about the origin of handedness don't alter the reality that lefties have difficulties in a right-handed world. Bias Against Southpaws The words themselves show prejudice. The Latin roots for right and left are dexter and sinister. Dexter gives us dextrous, meaning nimble, skilled, agile, etc. Sinister means, evil, dark, wrong etc. In the Middle Ages, left-handed people were often persecuted for being in league with the devil. The Spanish Inquisitors saw left-handedness as evidence of witchcraft and deviance from Catholic orthodoxy. Even after the Age of Reason supposedly civilized us, left-handed children were brutalized in school. Their left hands were tied behind them in their chairs to force them to write right-handed. If both hands were free, anyone spotted writing left-handedly got a sharp whack across the knuckles with a ruler. The influential 19th century physician Cesare Lambroso claimed to be able to spot criminal tendencies in the faces of people. He also put it about that lefties carried the mark of criminality. As recently as the middle of the 20th century, the “eminent American psychoanalyst Abram Blau was still suggesting that left-handedness was merely due to perversity and the result of emotional negativism, on a par with a child’s obstinate refusal to eat everything on its plate. As adults, Blau asserted, left-handers became stubborn, rebellious, rigid and (for some reason) obsessed with cleanliness (rightleftrightwrong.com).” And, according to a 2013 article in the Smithsonian magazine “For 2/3 of the world’s population, being born left handed is still met with distrust and stigma.” Myths About Lefties There’s a quote floating about the Internet attributed to the Irish novelist Maggie O’Farrell that “Two and a half thousand left-handed people are killed every year using things made for right-handed people.” However, it’s impossible to track down a credible source for that statistic. There’s another oft-quoted number that pulls us up short: “Left-handed people, on average, die nine years earlier than righties.” This information comes from two American psychologists, Diane Halpern and Stanley Coren. The statement was published in prestigious journals such as The New England Journal of Medicine and Nature. But, Chris McManus, professor of psychology and medical education at UniversityCollege, London challenges the claim. “If this were true,” he told the BBC, “it would be the largest single predictor we had of life expectancy - it would be like smoking 120 cigarettes a day plus doing a number of other dangerous things simultaneously. It really is highly implausible that an epidemiologist wouldn’t have spotted it previously.” Certainly, left-handed people find can openers, scissors, writing in binders, and other things difficult – but, hardly fatal. Lefties in Sport Left-handed athletes have an advantage over right-handed ones in many sports. Rik Smits is a linguist who wrote the 2010 book, The Puzzle of Left-Handedness. He points out that lefties train against righties nine times out of ten, but righties train against lefties only once out of ten times. That means that right-handed athletes are “… forced to engage in an asymmetrical battle for which they’re poorly prepared, against an opponent who’s a dab hand at dealing with this type of asymmetry …” In field hockey, left-handed players are allowed to take part but they must use a stick made for right-handers. Left-handed ice hockey players can use left-handed sticks. But, here’s an interesting puzzler courtesy of The New York Times: “According to sales figures from stick manufacturers, a majority of Canadian hockey players shoot left-handed, and a majority of American players shoot right-handed. No reason is known for this disparity, which cuts across all age groups and has persisted for decades.” How about soccer? Only, about half the people who are left-handed are also left-foot dominant. So, when such a rarity tries out for a soccer team she or he will immediately be put on the left wing and get way more playing time than all the righties. A skilled left-foot dominant player will have professional coaches fighting for their services. There’s big money to be had. Two of the greatest soccer players ever, Diego Maradona and Lionel Messi are lefties. According to LiveScience about a quarter of all professional baseball players are left-handed. Washington University aerospace engineer David Peters has analyzed why this is the case. A left-handed hitter is already a couple of paces closer to first base than a right-hander and the momentum of his swing will help the start of his run. Over a season of 162 games that slight edge makes a difference. Similarly, with left-handed pitchers. As he goes into his wind-up he faces first base so it’s a little bit easier to pick off a runner who is trying to steal second base. Left-handed players have a few other smaller advantages over right-handers, which is why they are disproportionately represented on major league teams. “The right half of the brain controls the left half of the body. This means that only left-handed people are in their right mind.” Anonymous Adaptations for Lefties Many products are on the market to help left-handed people – scissors, can openers, three-ring binders, and the like. Measuring tapes for southpaws have the scale running from right to left. Refrigerator doors can have hinges mounted on the left side to make it easier for lefties to open. Even boomerangs can be made with the wing profile reversed so it will get lift if spinning clockwise. But, how about the Indian motorcycle? From 1901 to 1953, the Massachusetts company turned out machines with the throttle on the left handlebar. Police forces in the United States started buying Indian motorcycles in large numbers. Why? Because cops could operate the throttle with their left hand leaving their right hand free for shooting a gun. Yes, the world of the left-handed can sometimes be a strange one. Bonus Factoids In 2007, Christopher Ruebeck and colleagues published a study in Laterality magazine that showed a “significant wage effect for left-handed men with high levels of education.” That effect was that southpaws earn 15 percent more than righties. A 2005 French study found a strong connection between left-handedness and aggression in primitive societies: “… the frequency of left-handers is strongly and positively correlated with the rate of homicides across traditional societies. It ranges from three percent in the most pacifistic societies, to 27 percent in the most violent and warlike.” The theory is that lefties have a physical advantage over righties by throwing the totally unexpected left hook. According to the BBC program Quite Interesting “After a double hand transplant, right-handed patients can become left-handed.” At some early point in his career, every young factory worker is sent to the stores by the seasoned veterans to fetch a left-handed hammer, bucket, or screwdriver. Sending for tartan paint is another favourite gag. Sources - “History of Handedness - Recent History.” Luke Mastin, rightleftrightwrong.com, 2012. - “Two-Thirds of the World Still Hates Lefties.” Rose Eveleth, Smithsonian, May 17, 2013. - “Do Left-Handed People Really Die Young?” Hannah Barnes, BBC News, September 7, 2013. - “It’s Not Political, but More Canadians Are Lefties.” Jeff Z. Kleinfeb, New York Times, February 15, 2010. - “The Puzzle of Left-Handedness.” Rik Smits, Reaktion Books Ltd., 2010. - “20 Little-Known Facts About Being Left-Handed.” Amanda Macmillan, Health.com, November 23, 2015. - “Handedness, Homicide and Negative Frequency-Dependent Selection.” Charlotte Faurie and Michel Raymond, Royal Society Publishing, January 7, 2005. - “Handedness and Earnings. Christopher Rueback et al, Laterality, February 5, 2007. Questions & Answers Comments I found your article very interesting and informative, Rupert. I always knew that left-handed people were at a disadvantage with using right-handed tools, but I never knew that athletes actually had an advantage since they train against right-handed people more often than the other way around. I also found it interestng that boomerangs are designed for right-handed throwing. I never thought of that before. You gave lots of interesting facts and you sure did a lot of research for this! It was definitely worth reading. I love the quote by Anonymous, so funny. It's amazing to me that, in a double hand transplant, a right handed person may become left handed. Best article I've read on left-handedness.
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Foto: Hina/FaH LJEVORUKE osobe, kojima se zbog te osobine pripisuju mnoge specifičnosti, ali i zbog čega se susreću s brojnim poteškoćama u svijetu prilagođenom za dešnjake, danas obilježavaju svoj dan. Međunarodni dan ljevorukih osoba ustanovljen je u Sjedinjenim Američkim Državama 1976., a tim se danom želi promovirati svijest o poteškoćama s kojima se susreću te o njihovim prednostima i nedostacima. Pretpostavlja se da ljevoruki čine oko 12 do 15 posto svjetskog stanovništva, a prema procjenama stručnjaka, u posljednjih sto godina broj ljudi koji više koriste lijevu ruku povećan je skoro za četiri puta. Ljevaci češće genijalci, ali imaju i veću šansu da postanu alkoholičari Prema američkom časopisu Scientific American 15 posto ljudi na svijetu je ljevoruko, te ima duplo više ljevorukih muškaraca nego žena, navodi se u statistici o ljevorukima na internet stranici lefthandersday.com. Ljevaci su češće genijalci nego dešnjaci, čak 20 posto MENSA-inih članova prema njihovim statistikama su ljevaci. Na stranici navode i da je jedna studija pokazala da su, od onih koji su samo pohađali fakultet, ljevaci u prosjeku 15 posto bogatiji od dešnjaka te 26 posto bogatiji kao akademski građani, ali i da ljevaci imaju triput veću šansu od dešnjaka da postanu alkoholičari. Ako su oba roditelja ljevoruka, postoji 50 posto šanse da i njihova djeca budu, dok je kod roditelja dešnjaka ta šansa dva posto. Statistika je pokazala i da su, što je starija trudnica, veće šansa da će roditi ljevaka. Ljevaci obično ulaze u pubertet četiri do pet mjeseci kasnije od dešnjaka, a prema jednoj studiji, životni vijek ljevaka devet je godina kraći od dešnjaka. Preferencija prema određenoj ruci određuje se još u prenatalnom razdoblju, a njezin ključni temelj je genetski. Sklonost jednoj ruci očituje se već u ranom djetinjstvu, kod većine djece prije pete godine života. Čak 90 posto beba u trbuhu sisa palac ruke koja će mu biti primarna. Taj postotak odgovara i postotku ljevorukih ljudi u populaciji. Također je zanimljivo kako su bebe koje su u sklopu istraživanja postavljali na trbuh okretanjem glave pokazale što će biti. One koje su kasnije postali ljevaci glavu su okretali na lijevu stranu ili na obje strane podjednako. Ljevoruki ljudi - individualisti, kreativni, intuitivni Zapravo je među ljevacima vrlo mali broj isključivih ljevaka. Više je onih koji su naučili koristiti i svoju desnu ruku podjednako spretno kao i lijevu, što im omogućava posebna građa i fiziologija mozga. U dešnjaka su mozgovne polutke asimetrično razvijene, tj. razvijenija je lijeva polovica mozga koja kontrolira desnu stranu tijela dešnjaka. Kod ljevaka ne postoji obrnuti slučaj. Mozgovne polutke su jednako razvijene, ali ljevaci imaju znatno više živčanih vlakana u mozgu od dešnjaka i upravo su ta vlakna bitna za brži prijenos informacija između mozgovnih polutki. Tu počiva i uzrok bolje snalažljivosti ljevaka u prostoru, bolje percepcije treće dimenzije i, što je upravo značajno za ljevake, boljih rezultata u logici i matematici. Ljevoruki ljudi su individualisti, kreativni, intuitivni, razmišljaju strateški, imaju neobično dobru glazbenu memoriju, osjećaj za proporcije, pa su zato veoma zastupljeni u umjetnosti i arhitekturi. Mnoge slavne osobe bile su ljevaci: Leonardo da Vinci, Michelangelo, Raphael, Albert Einstein, Napoléon Bonaparte, Fidel Castro, Henry Ford, Kurt Cobain, Jimi Hendrix, Ringo Starr, Greta Garbo, Marilyn Monroe. Od živućih ljevorukih poznati su Paul McCartney, George Michael, Robert DeNiro, Angelina Jolie, Phil Collins. Tri od pet posljednjih američkih predsjednika bili su ljevaci - Obama, Clinton i Bush stariji.