Examine individual changes

'{{Redirect|Leftie|the political term|Left-wing politics}} {{Redirect|Southpaw}} {{POV|date=August 2010}} [[File:Linkshaender 01.jpg|thumb|275px|A person writing "Linkshänder" (German for ''left-hander'') with the left hand.]] '''Left-handedness''' is the preference for the left hand over the right for everyday activities such as [[Penmanship|writing]]. Seven to ten percent of the adult population is left-handed.{{Citation needed|date=March 2010}} ==Causes of left-handedness== {{Main|Handedness}} * Hand orientation is developed in fetuses, most commonly determined by observing which hand is predominantly held close to the mouth.<ref>Hopkins, B., Lems, W., Janssen, B. & Butterworth, G. (1987) Postural and motor asymmetries in newlyborns. Human Neurobiology 6:153–56</ref> *In 2007, researchers discovered that specific [[alleles]] of at least one of three [[single-nucleotide polymorphism]]s upstream of the already known [[LRRTM1]] gene, were linked to left-handedness.<ref>[http://www.nature.com/mp/journal/v12/n12/abs/4002053a.html Francks et al. Molecular Psychiatry (2007) 12:1129-1139]</ref><ref>Gene for left-handedness is found, http://news.bbc.co.uk/2/hi/health/6923577.stm, BBC, 31 July 2007</ref> *Vanishing Twin Theory: This theory postulates that left-handed individuals were originally part of an identical twin pair, with the right-handed twin fetus failing to develop early in development. The theory has however been debunked by Australian researchers.<ref>[http://www.abc.net.au/science/news/health/HealthRepublish_505182.htm Vanishing twin theory debunked]</ref> *Long-term impairment of the right hand: People with long-term impairment of the right hand are more likely to become left-handed, even after their right hand heals.{{Citation needed|date=September 2007}} Such long-term impairment is defined as eight months or more. *[[Testosterone]]: Exposure to higher rates of testosterone before birth can lead to a left-handed child.<ref>Watkins M (1995). [http://www.hcs.harvard.edu/~husn/BRAIN/vol2/left.html Creation of the Sinister: Biological Contributions to Left-handedness] Accessed May 2007.</ref> This is the Geschwind theory, named after the neurologist who proposed it, [[Norman Geschwind]]. It suggests that variations in levels of testosterone during pregnancy shape the development of the fetal brain. Testosterone suppresses the growth of the left [[cerebral hemisphere]] and so more neurons migrate to the right hemisphere{{Citation needed|date=January 2010}}. The highly developed right hemisphere is now better suited to function as the center of language and handedness. The fetus is more likely to become left-handed, since the right hemisphere controls the left half of the body. The theory goes on to tie the exposure to higher levels of testosterone and the resultant right-hemisphere dominance to [[auto-immune disorder]]s, [[learning disorder]]s, [[dyslexia]], and [[stuttering]], as well as increased [[Spatial Visualization Ability|spatial ability]]. ==Social stigma and repression of left-handedness== [[Image:lefthandersday.jpg|thumb|right|Left Handers' Day, August 13, 2002]] === Negative associations of left-handedness in language === {{Off-topic|relative direction|date=December 2009}} There are many colloquial terms used to refer to a left-handed person, e.g. "southpaw" or "goofy" (USA). Some are just slang or jargon words, while other references may be offensive or demeaning, either in context or in origin (e.g. the British "cack-handed").[http://www.thefreedictionary.com/cack-handed] In more technical contexts, 'sinistral' may be used in place of 'left-handed' and 'sinistrality' in place of 'left-handedness'. Both of these technical terms derive from ''sinestra'', a Latin word meaning 'left'.<ref>[http://www.yourdictionary.com/wotd/wotd.pl?word=sinistral "Sinistral"] - YourDictionary.com definition. Accessed June 2006.</ref> Left hand shakes are a sign of disrespect – however the left hand shake is the standard in the international [[Scouting]] movement. In [[Hebrew language|Hebrew]], as well as in other ancient [[Semitic language|Semitic]] and [[Mesopotamian]] languages, the term "left" was a symbol of power or custody.<ref>Jeffries Hamilton. Social Justice and Deuteronomy: the Case of Deuteronomy 15. (Atlanta: Scholar's Press, 1992) p. 145.</ref> The left hand symbolized the power to shame society, and was used as a metaphor for misfortune, [[natural evil]], or punishment from the gods. This metaphor survived ancient culture and was integrated into mainstream [[Christianity]] by early [[Catholic]] [[theologians]] as [[Ambrose of Milan]]<ref>Ambrose of Milan: political letters and speeches / translated with an introduction and notes by J.H.W.G. Liebeschuetz, (Liverpool, England: Liverpool University Press, 2005).</ref> to modern [[Protestant]] [[theologians]] such as [[Karl Barth]]<ref>Rosemary Radford Ruether, The Left Hand of God in the Theology of Karl Barth--Karl Barth as a Mythopoeic Theologian. (The Journal of Religious Thought: 1968-69).</ref> to attribute [[natural evil]] to [[God]] in explaining God's [[omnipotence]] over the [[universe]]. Meanings gradually developed from use of these terms in the ancient languages. In many European languages, "right" is not only a synonym for correctness, but also stands for authority and justice: [[German language|German]] ''recht'', [[French language|French]] ''droit'', [[Spanish language|Spanish]] ''derecho'', [[Portuguese language|Portuguese]] ''direito''; in most [[Slavic language]]s the root ''prav'' is used in words carrying meanings of correctness or justice. The right hand has also historically been associated with skill: the [[Latin language|Latin]] word for right-handed is ''dexter'', as in dexterity; indeed, the Spanish term ''diestro'' and the [[Italian language|Italian]]'s ''destro'', mean both "right-handed" and "skillful". In Irish, "deas" means "right side" and "nice". "Ciotóg" is the left hand and is related to "ciotach" meaning "awkward"<ref>[http://archives.tcm.ie/thekingdom/2003/07/24/story10018.asp "My Left Foot",] ''The Kingdom'', 24 July 2003. Accessed June 2006.</ref>; in French, "gauche" means "left" and is also a synonym of "maladroit", meaning "clumsy". Same for the Italian "maldestro" (literally "bad right" or "not right" with the term ''right'' here used as opposed to ''left'' and not to ''wrong'') and the Dutch word "links". In German the word "link" means that someone is back-stabbing, or a liar. Meanwhile, the English word ''sinister'' comes from the Latin word ''sinestra'', which originally meant "left" but took on meanings of "evil" or "unlucky" by the [[Classical Latin]] era. Alternatively, ''sinister'' comes from the Latin word ''sinus'' meaning "pocket": a traditional Roman [[toga]] had only one pocket, located on the left side. The contemporary [[Italian language|Italian]] word ''sinistra'' has both meanings of sinister and left (the masculine adjective for sinister being ''sinistro''). The Spanish ''siniestra'' has both, too, although the 'left' meaning is less common and is usually expressed by ''izquierda,''<ref>[http://etimologias.dechile.net/?izquierda Etimología de izquierda], deChile.com. Accessed June 2006. (Spanish)</ref> a [[Basque (language)|Basque]] word that made its way into [[Portuguese Language|Portuguese]] too. In Portuguese, the most common word for left-handed person, ''canhoto'', was once used to identify the devil, and ''canhestro'', a related word, means "clumsy" (''sinistro'' means only "sinister"). Furthermore, in English, the expression "To have two left feet" refers to clumsiness in the domains of football or dancing. The left side is often associated with awkwardness and clumsiness. The English expression "having two left feet", the Polish expression "mieć dwie lewe ręce", the Dutch expression "''twee linkerhanden hebben''", the Spanish expression "''tener dos pies izquierdos''", the German expression "''zwei linke Hände haben''", the Bulgarian expression "''dve levi ratse''", the French expression "''avoir deux mains gauches''" and the Czech expression "''Mít obě ruce levé''" ("to have two left hands") all mean being clumsy. Moreover, the German idiom "''mit dem linken Fuß aufgestanden sein''", the Spanish expression "''levantarse con el pie izquierdo''" and the french one "''s'être levé du pied gauche''" (literally, to have gotten up with the left foot) means to have a bad day and do everything wrong or unsuccessfully (like "to get out of the wrong side of the bed" in English). In ancient China, the left has been the "bad" side. The adjective "left" ([[Chinese character]]: {{lang|zh|{{linktext|左}}}}, [[Mandarin Chinese|Mandarin]]: zuǒ) means "improper" or "out of accord". For instance, the phrase "left path" ({{lang|zh|{{linktext|左|道}}}}, Mandarin: zuǒdao) stands for illegal or immoral means. The character for "left", {{lang|zh|{{linktext|左}}}} depicts a left hand attending to work. In contrast, the character for "right", {{lang|zh|{{linktext|右}}}} (Mandarin: yòu) depicts a right hand in relation to the mouth, suggesting the act of eating. Contrast this pattern with the [[Muslim]] example below. At the same time, in modern Chinese conscience the left is firmly held as the dominant and "male" side, epitomized in the formula "man-left, woman-right". In [[Welsh language|Welsh]], the word ''chwith'' means left, but can also mean strange, awkward, or wrong. The phrase ''tu chwith allan'' (left side out) refers to an object being inside-out.<ref>{{cite web |url=http://www.aber.ac.uk/~gpcwww/pdf/GPC0018-03.pdf |title=Geiriadur Prifysgol Cymru |page=1735 |accessdate=2008-07-28|format=PDF}}</ref> In some Spanish-speaking countries, to do something ''por izquierda'' means to engage in corrupt conduct or employ illegitimate means; whereas ''por derecha'' or ''a derechas'' means to do it the right (legitimate) way.<ref>[http://forum.wordreference.com/showthread.php?t=1295427]</ref> In [[Dutch language|Dutch]], "twee linkerhanden hebben" (having two left hands) means that one is clumsy or is a very poor handyman. The English equivalent of the phrase is "being all thumbs". In [[Finnish language|Finnish]], the word ''oikea'' means both ''right'' (okay, correct) and ''right'' (the opposite of left). In [[Estonian language|Estonian]], the word ''pahem'' stands for both ''left'' and ''worse'' and the word ''parem'' stands for both ''right'' and ''better''. In [[Hungarian language|Hungarian]], the word for ''right'' is ''jobb'' which also means ''better''. The word for ''left'' is ''bal'', and is used in expressions such as ''kétbalkezes'' ("having two left hands"), ''balszerencse'' (bad luck), ''bal lábbal kel fel'' ("get up (from bed) with the left leg", an omen that predicts a bad day coming up). In [[Swedish language|Swedish]], ''vänster'' means left. The term ''vänsterprassel'' means infidelity, adultery; cheating. From this term the verb ''vänstra'' (lit. "lefting") is derived. In [[Ireland]] left handedness is called a "ciotógach" (kyut-OH-goch) which is the [[Irish language]] term for left-handed. It is frequently used amongst Irish people, e.g. "she gave him a slap of the ciotógach after he insulted her at the bar" the word ciotógach is not derogatory and is held with affection amongst left-handed people. In [[Polish language|Polish]], the word "lewy" means: left (opposite of right), and colloquial "illegal" (opposite of legal). Also the phrase "Mieć dwie lewe ręce", like in [[Dutch language|Dutch]], means "to have two left hands", it describes clumsy people. The [[Scots language|Scots]] term for left-handedness is ''corrie fistit''. The term can be used to convey clumsiness. In some parts of the English-speaking world 'cack-handed' is slang for left-handed (it is also used to mean clumsy). The origin of this term is disputed, but some suggest it is derived from the Latin ''cacare'', in reference to the habit of performing ablutions with the left hand, leaving the right hand 'clean'.<ref>[http://www.worldwidewords.org/qa/qa-cac1.htm world wide words]</ref> However, other source suggest that it is derived from the Old Norse word ''keikr'', meaning "bent backwards" <ref>[http://www.merriam-webster.com/dictionary/cack%20handed "Cack-handed"] - Merriam Webster Dictionary definition.</ref> Australians frequently use "cacky-handed". A less common Australian slang word for a left-handed individual is the term ''Molly-Dooker'', whose origins cannot be ascertained for certain.<ref>Quinion, Michael (2003). [http://www.worldwidewords.org/qa/qa-mol2.htm ''World Wide Words: Mollydooker'']. Retrieved on 31 October 2008.</ref> Amongst [[Muslim]]s, and in some societies including [[Nepal]] and [[India]], it is customary to use the left hand for cleaning oneself with water after defecating. The right hand is commonly known in contradistinction from the left, as the hand used for eating.<ref>Muhammad Saed Abdul-Rahman (2007). [http://books.google.com/books?id=ZfMjhRAkn_kC ''Islam: Questions and Answers - Manners (Part 1)''] Published by MSA Publication Ltd, London. {{OCLC|58477120}} ISBN 1-86179-336-7.</ref> Even the word "[[ambidexterity]]" reflects the [[bias]]. Its intended meaning is, "skillful on both sides". However, since it keeps the [[Latin]] root "dexter", which means "right", it ends up conveying the idea of being "right-handed at both sides". This bias is also apparent in the lesser-known [[antonym]] "ambisinistrous", which means "clumsy on both sides" and derives from the Latin root "sinister", which means "left".<ref>[http://www.yourdictionary.com/wotd/wotd.pl?word=ambisinistrous "Ambisinistrous"] - YourDictionary.com definition, November 28, 2003.</ref> === Positive connotations === [[File:Inca lloque yupanqui.jpg|thumb|right|120px|[[Lloque Yupanqui]], the third [[Sapa Inca]], whose name means "the glorified lefthander"]] Among [[Inca civilization|Incas]] left-handers were called (and now are called among the indigenous peoples of the [[Andes]]) ''lloq'e'' ({{lang-qu|lluq'i}}) which has positive value. Peoples of the Andes consider that left-handers possess special spiritual abilities, including [[magic (paranormal)|magic]] and [[healing]]. Third [[Sapa Inca]] - Lloque Yupanqui — was the left-hander, his name in transfer with Quechua means «the glorified lefthander». In tantras Buddhist, the left hand represents the wisdom. {{clr}} ===Accessibility of implements and skills=== [[Image:2scissors-clean.jpg|thumb|left-handed (left) and right-handed (right) scissors]] [[Image:Japanese knife blade types.png|thumb|Kitchen knives: (1) symmetrical, (2) right-handed, (3) left-handed]] Right-handed tools can be difficult or uncomfortable to use for people who are left-handed. For example, [[Scissors#.27Handed.27_scissors|(right-handed) scissors]], a very common tool, are arranged so that the line being cut along can be seen by a right-handed user, but is obscured to a left-handed user. Furthermore, the handles are often molded in a way that is difficult for a left-hander to hold, and extensive use in such cases can lead to varying levels of discomfort. Most importantly, the scissoring or shearing action - how the blades work together (how they are attached at the pivot) - operates correctly for a right-hander, but a left-hander will tend to force the blades apart rather than shearing the target substance.<ref>[http://www.dailymotion.com/video/xqbrm_left-handed-scissors-and-cutting_school Lefthanded scissors explained] (dailymotion.com video)</ref> Left-handed [[scissors]] require inverting both the handles and the blades if the left-handed user is to fully see the progress of the cut. Right-handed scissors place the thumb's blade on the left side, while left-handed scissors have this on the right side. This ensures the left hand's motion draws the blades together while cutting, ensuring a cleaner cut. Input devices for computers can present obstacles for the left-handed when optimized for the right. Some computer installations have the [[Mouse (computing)|computer mouse]] placed on the right side of the keyboard and unable to be reposition to the left. The mouse itself is also sometimes shaped to fit the right hand better. Most operating systems allow a user to reverse the functionality of mouse buttons to accommodate left-handed use. [[Trackball]]s and [[trackpads]] are often shaped for right-handed use. Even with the ability to change the functionality of buttons, these devices may be difficult for left-handed use. While European-style [[kitchen knife|kitchen knives]] are symmetrical, [[Japanese kitchen knives]] have the cutting edge ground [[asymmetric]]ally, with ratios ranging from 70-30 for the average chef's knife, to 90-10 for professional [[sushi]] chef knives; left-handed models are rare, and usually must be specially ordered or custom made.<ref>[http://www.nytimes.com/2006/09/23/business/23pursuits.html?_r=1&oref=slogin "How to Succeed at Knife-Sharpening Without Losing a Thumb"] ''[[New York Times]]'', September 23, 2006. Accessed September 23, 2006.</ref> Left-handed adaptations have even bridged the world of music. Left-handed guitars are manufactured as an alternative to using a flipped around right-handed guitar. There have even been inverted pianos where the deepest notes correspond to the rightmost keys instead of the leftmost.<ref>[http://www.lefthandedpiano.co.uk/about.html The First Left-Handed Piano]</ref> Inverted [[trumpet]]s are made, too. Although the trumpet's valves are normally designed to be operated with the right hand, the prevailing belief is that left-handed trumpeters aren't at a significant disadvantage. The [[horn (instrument)|French horn]], for example, is played with the left hand, yet most horn players are right-handed. Left-handed golf clubs were one of the earlier, and well-accepted, manifestations of a special version of an implement; the most notable left-handed-playing participant being [[Phil Mickelson]] (he is naturally right-handed). Other items which could prove to be inconvenient for left-handers include train-station [[turnstile]]s, [[can opener]]s, circular saws, potato [[peeler]]s, [[corkscrew]]s, [[ruler]]s, number keys on [[Keyboard (computing)|keyboard]]s, [[watch]]es, [[chequebook]]s, spiral [[notebook]]s, [[boomerang]]s, [[measuring cup]]s and [[pencil sharpener]]s. {{gallery|lines=3 |File:Left handed keypad.png|Left handed keypad |File:Shadowing gretsch, left handed.jpg|Girl playing guitar left-handed |File:Montre senestre.JPG|A reverse-style watch has hands that move counter-clockwise. |File:Trackman marble wheel.JPG|A right-handed trackball is difficult to use with the left hand }} ====Handwriting==== [[File:Barack Obama signs at his desk2.jpg|thumb|The current [[President of the United States]], [[Barack Obama]], is left-handed]] Left-handed people who speak [[Arabic]], [[Persian language|Persian]], [[Urdu]], [[Hebrew]] or any other right-to-left script do not have the same difficulties with writing. The right-to-left nature of these languages prevents left-handers from running their hand on the ink as happens with left to right languages. However, because these alphabets were developed for right-handed people{{Citation needed|date=August 2010}}, the characters are still often more easily matched to a right-handed profile. Left-handed people also have an advantage in learning 19th-Century [[copperplate script|copperplate]] hands, which control line-width by pressure on the point. === In sports === [[File:John Danks.jpg|thumb|Pitcher [[John Danks]] throwing left-handed]] [[File:McEnroe John.jpg|thumb|[[John McEnroe]] plays left-handed]] A left-handed individual may be known as a '''southpaw''', particularly in a [[sports]] context. It is widely accepted that the term originated in the [[United States]], in the game of [[baseball]].<ref>[http://www.fightbeat.com/article_detail.php?AT=57 Southpaws: Doing It Right the Wrong Way] (fightbeat.com) Accessed August 2006.</ref> [[Ballpark]]s are often designed so that batters are facing east, so that the afternoon or evening sun does not shine in their eyes.<ref>[http://mlb.mlb.com/mlb/downloads/y2008/official_rules/01_objectives_of_the_game.pdf Rules of Major League Baseball, Section 1.04]</ref> This means that left-handed [[pitchers]] are throwing with their south-side arm.<ref>Olmert, Michael (1996). ''Milton's Teeth and Ovid's Umbrella: Curiouser & Curiouser Adventures in History'', p.108. Simon & Schuster, New York. ISBN 0-684-80164-7.</ref> The [[Oxford English Dictionary]] lists a non-baseball citation for "south paw", meaning a punch with the left hand, as early as 1848,<ref>Morris, Evan (1995). [http://www.word-detective.com/093098.html Word detective research]. Accessed June 2006.</ref> just three years after the first organized baseball game, with the note "(orig. U.S., in Baseball)."<ref>Oxford English Dictionary Online, accessed May 2009</ref> In [[baseball]], due to the direction in which [[curveball]]s and [[slider]]s break, it is generally accepted that the pitcher has an advantage when his handedness is the same as the batter's, and the batter has an advantage when they are opposite. For this reason, many baseball teams include a [[left-handed specialist]] pitcher, who is brought into the game specifically to pitch to dangerous left-handed batters in crucial situations. In [[boxing]], someone who boxes left-handed is frequently referred to as southpaw. The term is also used to refer to a stance in which the boxer places the right foot in front of the left, so it is possible for a right-handed boxer to box with a southpaw stance. Most boxers, southpaw or otherwise, tend to train with sparring partners who adopt an orthodox stance which gives southpaws an advantage. [[Manny Pacquiao]] is an example of a southpaw (although he writes with his right hand). In the popular boxing film series [[Rocky]], the main character [[Rocky Balboa]] is a 'southpaw'. Southpaw is also a term in professional wrestling, often giving them the advantage. [[Fencing]] weapons feature left- and right-handed grips, and a left-handed fencer's stance is opposite that of a right-handed opponent. Left-handed fencers have an advantage over right-handed opponents because the line of defence favors their sword arm. In [[tennis]], southpaws hold the racket in their left hand. Because of this, their grip of the handle is supposedly adjusted in a slightly different style from right-handed players. Some world champion left-handed tennis players include [[Jimmy Connors]], [[Guillermo Vilas]], [[John McEnroe]], [[Martina Navratilova]], [[Marcelo Ríos]], and [[Rafael Nadal]]. Several contemporary console video games have an option to reconfigure the control scheme of the controller to make it more accessible to left-handed gamers. {{clr}} ====Firearms==== [[File:Rem700 action lefthand standard right.jpg|left|thumb|Standard length of left-handed [[Remington 700]] rifle]] [[File:SQT trainees doing CQB drills.jpg|thumb|right|A [[United States Navy SEALs|US Navy SEALs]] left-handed shooter]] The vast majority of [[firearm]]s are designed for right-handed shooters, with the operating handle, magazine release, and/or safety mechanisms set up for manipulation by the right hand, and fired cartridge cases ejected to the right. Also, scopes and sights may be mounted in such a way as to require the shooter to place the rifle against the right shoulder. A left-handed shooter must either purchase a left-handed or ambidextrous firearm (which are manufactured in smaller numbers and are generally more expensive and/or harder to obtain), shoot a right-handed gun left-handed (which presents certain difficulties, such as the controls being improperly located for them or hot shell cases being ejected towards their body, especially their eyes or down their collar or right sleeve), or learn to shoot right-handed (which may be less comfortable or "natural" for them). A related issue is [[ocular dominance]], due to which left-handed people may wish to shoot right-handed, and vice versa. Some modern firearms are ambidextrous (e.g. the [[FN P90]] and [[Heckler & Koch P7]]), or can be converted between right- and left-handed operation (e.g. the [[Heckler & Koch G36]] and [[Steyr AUG]]). [[Bullpup]] rifles are particularly problematic for left-handers unless they can be reconfigured, since empty shells would be ejected straight into the shooter's face and cheek potentially causing injury. The British [[SA80|LA-85 Assault Rifle]] must be fired right-handed, placing left-handed soldiers at a disadvantage; this policy does however mean that any soldier can pick up and immediately fire a fallen comrade's gun without checking its configuration and potentially needing to convert it. In contrast the [[Steyr AUG]] is of a modular design, and the ejection port and extractor can be switched/replaced to suit the handedness of the soldier operating it. The [[M16 rifle|M-16]] and its variants have a fixed ejection port, but being a conventional (i.e. not bullpup) design the ejection port is forward of the operator and hence able to be fired either handed. Circa 1980, with the introduction of the M16A2 version, a case deflector was incorporated adjacent to the ejector port to direct discarded shells in a more forward direction, making the rifle even more left hand operator friendly. The deflector is not always effective, however, as the ejected shell still stands a chance of hitting the left-handed shooter's cheek, especially in windy conditions. [[Lever action]] and [[pump action]] firearms present fewer difficulties for left-handers than [[bolt action]] weapons do. Many weapons with adjustable sights allow for left-handed use, but a right eye dominant shooter is necessary to adjust. In fact, most weapons adjust well enough that a weapon will not eject shells into a left-hander's eye. ====Cameras==== One of the few cameras ever produced for left-handers was the half-frame [[Yashica]] Samurai. Cameras predominantly have the hand grip, shutter release, film wind lever and commonly used selection buttons, switches and dials controlled by the right hand, lens controls (where present) tend to be accessible by either hand. When a left-handed person uses a right-handed camera the hand control can be less steady and hence produce camera shake leading to poorer pictures at low shutter speeds {{Citation needed|date=July 2010}}. == Correlations with left-handedness == ===Left-handedness and intelligence=== In his book ''Right-Hand, Left-Hand'',<ref>[http://www.righthandlefthand.com/ Right-Hand, Left-Hand official website] Accessed June 2006.</ref> Chris McManus of [[University College London]] argues that the proportion of left-handers is increasing and left-handed people as a group have historically produced an above-average quota of high achievers. He says that left-handers' brains are structured differently in a way that increases their range of abilities, and the genes that determine left-handedness also govern development of the language centres of the brain. In a 2006 U.S. study, researchers from [[Lafayette College]] and [[Johns Hopkins University]] concluded that there was no scientifically significant correlation between handedness and earnings for the general population, but for college education people left-handers earned 10 to 15 percent more than their right-handed counterparts.<ref>"[http://www.slate.com/id/2147842 Sinister and Rich: The evidence that lefties earn more]", by Joel Waldfogel. Appeared in ''[[Slate (magazine)|Slate]]'' on August 16, 2006.</ref>. ===Left-handedness and politics=== {{See also|Handedness of Presidents of the United States}} Of the seven most recent U.S. Presidents, four have been left-handed, including [[Barack Obama]], while a fifth is said to have been [[ambidexterity|ambidextrous]]. [[Prime Minister of the United Kingdom|British Prime Minister]] [[David Cameron]] is also left-handed. [[President of Mexico|Mexican President]] [[Felipe Calderón]] is left-handed as well. == Gallery == {{Gallery |height=120|width=120|lines=4 |File:Larry Gardner baseball card.jpg|[[Larry Gardner]] baseball card, Larry batted left-handed. |File:Al Bridwell.jpg|[[Al Bridwell]] batted left-handed |File:Left handed epiphone dot.jpg|Close-up of a guitar made for a left-handed person |File:Trefoil-knot-left-handed.jpg|Left-handed [[trefoil]] knot |File:Timpani left hand.jpg|Left-handed grip on [[timpani]] |File:Arturo Lopez.JPG|[[Arturo López]], pitcher for the [[San Diego Padres]] throws left-handed |File:PhilMickelsonTPC18thTee.jpg|[[Phil Mickelson]], who plays golf left-handed, following through after hitting a tee shot. }} ==See also== {{col-begin}}{{col-break}} * [[Chirality (chemistry)]] * [[Chirality (mathematics)]] * [[Chirality (physics)]] * [[Cross-dominance]] * [[Geschwind–Galaburda hypothesis]] * [[Handedness]] * [[Handedness and sexual orientation]] * [[Handedness of Presidents of the United States]] {{nb10}} * [[Handedness and mathematical ability]] {{col-break}} * [[Laterality]] * [[LRRTM1]] * [[Right-handedness]] * [[Situs inversus]] * [[The Tale of Cross-eyed Lefty from Tula and the Steel Flea]] {{col-end}} ==Notes== {{Reflist|2}} ==External links== {{Wiktionary}} {{Commons category|Left-handedness}} *[http://leftysportsblog.com Lefty Sports Blog] - A Sports Blog with the focus on Left Handed Atheles *[http://www.sciencedaily.com/releases/2006/04/060414010532.htm Lefties Have The Advantage In Adversarial Situations], ScienceDaily, April 14, 2006. *[http://www.scq.ubc.ca/?p=74 Science Creative Quarterly's overview of some of the genetic underpinnings of left-handedness] *[http://www.cbc.ca/quirks/archives/05-06/jun10.html Quirks & Quarks June 10, 2006] (CBC radio documentary on left-handedness including interviews with four scientists holding different views on the determinants of handedness) *[http://www.commonties.com/blog/2006/09/13/i-was-a-rebel/ A left-handed senior citizen recalls the emotional torment he faced at a New York public school in the 1920s.] (Audio slideshow) *[http://www.indiana.edu/~primate/left.html Famous Left-Handers] *Woznicki, Katrina (2005). [http://www.medpagetoday.com/HematologyOncology/BreastCancer/1810 "Breast Cancer Risk Doubles for Southpaw Women"], MedPage Today, 26 September. * Hansard (1998) ‘[http://www.publications.parliament.uk/pa/cm199798/cmhansrd/vo980722/debtext/80722-15.htm Left-handed Children]’, Debate contribution by the Rt Hon. Mr. Peter Luff (MP for Mid-Worcestershire), House of Commons, 22 July. * A 1918 [[Popular Science]] Monthly article on left-handedness -- ''Is your Child Left-Handed? Why, according to psychological tests, left-handed people ought to remain so'', [[Popular Science]] monthly, December 1918, page 22, Scanned by Google Books: http://books.google.com/books?id=EikDAAAAMBAJ&pg=PA22 {{hand}} {{DEFAULTSORT:Left-Handedness}} [[Category:Handedness]] [[Category:Discrimination]] [[ar:أعسر]] [[bg:Левичар]] [[ca:Esquerrà]] [[cs:Leváctví]] [[co:Mancinu]] [[da:Venstrehåndet]] [[de:Linkshänder]] [[el:Αριστεροχειρία]] [[es:Zurdera]] [[eo:Maldekstramanulo]] [[eu:Ezkerti]] [[fa:چپ‌دستی]] [[fr:Gaucherie]] [[ko:왼손잡이]] [[id:Kidal]] [[is:Örvhentur maður]] [[it:Mancinismo]] [[he:שמאליות]] [[lv:Kreilība]] [[lt:Kairiarankystė]] [[hu:Balkezesség]] [[arz:اشول]] [[nl:Linkshandigheid]] [[ja:左利き]] [[no:Venstrehendthet]] [[pl:Leworęczność]] [[pt:Canhoto]] [[ru:Левша]] [[sco:Caurie-fistit]] [[scn:Mancusu]] [[simple:Left-handedness]] [[sk:Ľavák]] [[sl:Levoročnost]] [[sr:Леворукост]] [[fi:Vasenkätisyys]] [[sv:Vänsterhänthet]] [[uk:Шульга]] [[vi:Thuận tay trái]] [[diq:Çolaxiye]] [[zh:左利手]]'