# Bias against left-handed people
Bias against left-handed people is the sustained pattern of stigma, suppression, and practical disadvantage directed at the roughly one in ten humans whose preferred hand is the left. A large meta-analysis concluded that 10.6% of the world's population is left-handed, with cultural pressure against left-hand use moderating that prevalence across regions.[1](https://pubmed.ncbi.nlm.nih.gov/32237881/) The bias has religious, linguistic, medical, and educational dimensions, and it has eased unevenly: attitudes liberalized across [Western culture](https://www.edgepedia.org/western-culture) in the twentieth century while remaining restrictive in much of the world.[2](https://www.sciencedirect.com/science/article/pii/S0160932713000045)
| Key fact | Detail |
|---|---|
| Prevalence | 10.6% of the world's population is left-handed, per a global meta-analysis; the same evolutionary mechanisms are argued to maintain a roughly 1:10 ratio, with cultural pressure moderating the magnitude.[1](https://pubmed.ncbi.nlm.nih.gov/32237881/) |
| Symbolic roots | "Sinister" literally means left; in the Middle Ages a left-hander risked accusation of witchcraft, and the Devil was considered a southpaw.[3](https://time.com/3978951/lefties-history/) |
| Pseudoscientific claims | Cesare Lombroso linked left-handedness to criminality; later claims tied it to obstetric brain damage and to dying seven years earlier, all of which research has undermined.[4](https://pubmed.ncbi.nlm.nih.gov/22757625/) • [5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7058267/) |
| Forced switching | Mass public education institutionalized right-hand training in the 19th and early 20th centuries; in Canadian residential schools the ban on left-handedness was strictly and harshly enforced.[6](https://lefthanded.io/history-of-left-handedness/) • [7](https://www.barondeschauer.com/uploads/8/4/7/5/84752080/trc-survivors_speak_out--2015.pdf) |
| Global reach | For an estimated two-thirds of the world's population, including China, India, and much of the Islamic world, being born left-handed exposes a person to discrimination and stigma.[2](https://www.sciencedirect.com/science/article/pii/S0160932713000045) |
| Practical bias | The "right-sided world hypothesis" holds that the physical environment favors the right-handed majority; most powered tools in workshops are available in a right-handed format only.[8](https://www.sciencedirect.com/science/article/pii/S0278262605001351) • [9](https://left-in.org/wp-content/uploads/2024/04/Handedness-in-Education-Discussion-Paper-FINAL.pdf) |
| Reversal | As pressure eased, measured left-handedness rose: French data showed a clear generation effect in left-hand writing during the second half of the twentieth century.[10](https://pmc.ncbi.nlm.nih.gov/articles/PMC2666081/) |
## Symbolism and religious stigma
The bias long predates science. Chris McManus, professor of psychology at [University College London](https://www.edgepedia.org/university-college-london) who has researched lateralisation for over four decades, traces the myths to the symbolism of asymmetry, in which 'right' is universally seen as 'good' and 'left' as 'bad'.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7058267/) The anthropologist Robert Hertz's 1909 study *La prééminence de la main droite* analyzed this as a dual symbolic classification in which the right was sacred and the left profane.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7058267/) *TIME* reported that in the Middle Ages the left-hander "lived in danger of being accused of practicing witchcraft," that "the Devil himself was considered a southpaw," and that evil spirits were "always conjured up by left-handed gestures."[3](https://time.com/3978951/lefties-history/) The English word "sinister" preserves the association, since it means "on or toward the left hand."[11](https://citeseerx.ist.psu.edu/document?doi=bda490f71f285d36f726949cae0f4d1eec79e14c&repid=rep1&type=pdf)
The dominant current, in McManus's phrase, was a "sustained and transcultural abhorrence of left-handedness" that persisted across societies.[2](https://www.sciencedirect.com/science/article/pii/S0160932713000045)
## Pseudoscience and medical myth
**Criminality and pathology.** In 1903 the criminologist [Cesare Lombroso](https://www.edgepedia.org/cesare-lombroso) made unsubstantiated claims that left-handedness was associated with criminality, and such claims encouraged 19th-century efforts to force left-handed children to write right-handed.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7058267/) Hertz challenged Lombroso, insisting that the predominance of right-handedness, whatever its biological substrate, was ultimately a cultural artifact.[4](https://pubmed.ncbi.nlm.nih.gov/22757625/) The debate's terms persist: left-handedness continues to be portrayed, in the framing first elaborated by Lombroso and Hertz, either as a cause of learning disabilities or as a key to creativity and talent.[4](https://pubmed.ncbi.nlm.nih.gov/22757625/)
**The pathology theory of the 1970s.** Paul Satz's 1972 concept of pathological left-handedness was a valid model for a small subset of cases, but Paul Bakan and colleagues extrapolated it into influential claims that left-handedness resulted primarily from pathological factors, with obstetric trauma causing minimal brain damage.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7058267/) The data were almost entirely indirect. McManus tested the claim against the 1958 National Child Development Study, which recorded midwife-documented birth details for 11,000 births and professionally assessed handedness at ages 7 and 11; left-handedness showed minimal or probably no relationship to birth trauma.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7058267/) Dorothy Bishop's later studies of motor control suggested that at most about one in 20 left-handers may have a pathological aetiology.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7058267/)
**Other myths.** McManus lists among the field's false ideas the claims that left-handers die seven years earlier than right-handers and the "brainedness" notion that left-handers are more right-brained; a 2017 survey found 64% of the general public still agreed that some people are "left-brained" and others "right-brained."[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7058267/) The Geschwind-Behan-Galaburda theory, which linked left-handedness to auto-immune disease via fetal testosterone, was found in meta-analysis to have extremely weak support, and direct measurements later showed no relation between fetal testosterone and handedness.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7058267/)
## Forced conversion in schools
The institutional form of the bias ran through education. Through mass public schooling, the 19th and early 20th centuries made right-hand training an institutional practice; whole cohorts of left-handed pupils were compelled to write with their right hands, yielding grown-ups who kept right-hand dominance for formal tasks while staying left-handed within.[6](https://lefthanded.io/history-of-left-handedness/) In Canada and Europe it was common for schools to force left-handed children to learn to write with their right hands; at Canadian residential schools, the ban on left-handedness was strictly and harshly enforced, with teachers forcing students to switch hands.[7](https://www.barondeschauer.com/uploads/8/4/7/5/84752080/trc-survivors_speak_out--2015.pdf) Lower historical rates of left-handedness are attributed predominantly to children being encouraged to write with the right hand in school, and the percentage of left-handed children has risen in recent years as that freedom increased.[12](https://adc.bmj.com/content/archdischild/109/Suppl_1/A221.1.full.pdf)
The change is measurable. Dellatolas and colleagues observed an increase in left-hand use for writing in France across generations, showing that educational attitudes changed significantly during the second half of the twentieth century.[10](https://pmc.ncbi.nlm.nih.gov/articles/PMC2666081/) *TIME* noted that some observers attributed the recent run of left-handed US presidents partly to teachers only recently stopping conversion efforts.[3](https://time.com/3978951/lefties-history/)
## Contemporary stigma across cultures
The bias remains geographically uneven. The study of China concluded that attitudes and practices toward left-handers respond to historical and cultural pressures, and that for two-thirds of the world's population, adding India and much of the Islamic world to China, being born left-handed exposes one to discrimination and stigma.[2](https://www.sciencedirect.com/science/article/pii/S0160932713000045) In Malawi, greeting somebody with the left hand is culturally offensive, and socio-cultural biases against left-hand preference include religious beliefs and social mores.[8](https://www.sciencedirect.com/science/article/pii/S0278262605001351) A stigmatization scale developed for the [Middle East and North Africa](https://www.edgepedia.org/middle-east-and-north-africa) region documents societal pressures on left-handed individuals, especially in Arab and Muslim cultures.[13](https://nchr.elsevierpure.com/en/publications/development-of-the-left-handedness-stigmatization-scale-for-the-m/) By contrast, a Serbian study of medical students' social stereotypes found that social tolerance toward left-handed people is commonly accepted in the twenty-first century, though not universally.[14](https://www.tandfonline.com/doi/abs/10.1080/1357650X.2012.755993) A study of beliefs about the left-handed personality in Western samples found the prevailing stereotype was not negative, arguing against the status of left-handers as a stigmatised group in modern Western culture.[15](https://doi.org/10.1080/1357650x.2011.631546)
## The right-sided world
Beyond attitudes, left-handers face a built environment designed for the other hand. The "right-sided world hypothesis" of Porac and Coren holds that the physical environment favors the right-handed majority.[8](https://www.sciencedirect.com/science/article/pii/S0278262605001351) In secondary school woodworking and metalworking classes, most powered tools are available in a right-handed format only, requiring extreme care for left-handed students.[9](https://left-in.org/wp-content/uploads/2024/04/Handedness-in-Education-Discussion-Paper-FINAL.pdf) Scissors are a standard example: left-handed scissors exist because ordinary scissors are shaped for right-hand use, and even products marketed as suitable for left-handers are sometimes simply right-handed scissors that are comfortable when held in the left hand.[16](https://journals.mmupress.com/index.php/ijoras/article/view/630) • [17](https://www.education.gov.au/system/files/consultations/Leftys%20Left%20Handed%20Products%20and%20Resources.pdf) Commercial response came late: the London shop Anything Left-Handed, Ltd., opened in the late 1960s by William Gruby after a dinner party of complaining left-handed guests, stocked left-handed versions of kitchen hardware, irons, dressmakers' scissors, and cricket bats.[3](https://time.com/3978951/lefties-history/)
## Why the minority persists
The bias interacts with the biology it misreads. Left-handedness is not simply a mirrored brain: 97% of right-handers have their motor speech area located exclusively in the left hemisphere, but only 60% of left-handers do, with 30% bihemispheric and 10% right-localized.[18](https://pmc.ncbi.nlm.nih.gov/articles/PMC3258574/) The roughly 1:10 ratio is argued to be maintained by evolutionary mechanisms that apply across regions, with cultural pressure moderating only the magnitude of prevalence.[1](https://pubmed.ncbi.nlm.nih.gov/32237881/) One measurable consequence of the minority's distinctiveness is in antagonistic sports: left-handers make up about 15% of the top 100 male professional tennis players over 1985 to 2016, above their share of the male population.[19](https://arxiv.org/abs/2412.20360) [Understanding](https://www.edgepedia.org/understanding) handedness properly, McManus argues, would also mean understanding cerebral lateralisation properly, with implications for human evolution and pathology; the symbolic power of right and left, which fueled the bias, also fueled a century of neuromythology that research is still correcting.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7058267/)
## References
1. [Human handedness: A meta-analysis, Psychological Bulletin (2020)](https://pubmed.ncbi.nlm.nih.gov/32237881/)
2. [Why are there (almost) no left-handers in China?, ScienceDirect](https://www.sciencedirect.com/science/article/pii/S0160932713000045)
3. [How Lefties First Gained Acceptance, TIME](https://time.com/3978951/lefties-history/)
4. [Deficit or creativity: Cesare Lombroso, Robert Hertz, and the meanings of left-handedness, PubMed](https://pubmed.ncbi.nlm.nih.gov/22757625/)
5. [Chris McManus (2019). Half a century of handedness research, Brain and Neuroscience Advances](https://pmc.ncbi.nlm.nih.gov/articles/PMC7058267/)
6. [History of Left-Handedness: A Timeline From Ancient Rome to Today](https://lefthanded.io/history-of-left-handedness/)
7. [TRC Survivors Speak Out (2015)](https://www.barondeschauer.com/uploads/8/4/7/5/84752080/trc-survivors_speak_out--2015.pdf)
8. [Cultural and environmental pressure against left-hand preference in urban and semi-urban Malawi, ScienceDirect](https://www.sciencedirect.com/science/article/pii/S0278262605001351)
9. [Tools and Equipment, Left-in Handedness in Education Discussion Paper](https://left-in.org/wp-content/uploads/2024/04/Handedness-in-Education-Discussion-Paper-FINAL.pdf)
10. [Why are some people left-handed? An evolutionary perspective, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC2666081/)
11. [Including Handedness in Group Diversity Research and Practice](https://citeseerx.ist.psu.edu/document?doi=bda490f71f285d36f726949cae0f4d1eec79e14c&repid=rep1&type=pdf)
12. [Right-handedness has predominated in humans, Archives of Disease in Childhood](https://adc.bmj.com/content/archdischild/109/Suppl_1/A221.1.full.pdf)
13. [Development of the Left-Handedness Stigmatization Scale for the MENA region (LHSS-MENA)](https://nchr.elsevierpure.com/en/publications/development-of-the-left-handedness-stigmatization-scale-for-the-m/)
14. [Social stereotyping of left-handers in Serbia, Laterality](https://www.tandfonline.com/doi/abs/10.1080/1357650X.2012.755993)
15. [A sinister plot? Facts, beliefs, and stereotypes about the left-handed personality, Laterality](https://doi.org/10.1080/1357650x.2011.631546)
16. [Review on Accessibility of Scissors for the Left-handed and Ambidextrous, IJORAS](https://journals.mmupress.com/index.php/ijoras/article/view/630)
17. [Classroom tools to assist left-handed students, Australian Department of Education](https://www.education.gov.au/system/files/consultations/Leftys%20Left%20Handed%20Products%20and%20Resources.pdf)
18. [Understanding Left-Handedness, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC3258574/)
19. [Left-handed representation in top 100 male professional tennis players, arXiv](https://arxiv.org/abs/2412.20360)
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