# Why are the majority of people right-handed? **URL:** \ **Category:** Factual Questions\ **Created:** [March 13, 2016, 8:04am UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848 "2016-03-13T08:04:07Z")\ **Posts on this page:** 18\ **Page:** 2
**Author:** ![Surreal](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@Surreal](https://boards.straightdope.com/u/Surreal)\ **Post date:** [March 14, 2016, 3:07pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/21 "2016-03-14T15:07:33Z")
Not being right-handed seems to be a risk factor for a huge array of disorders: > **[Publications](https://ccf.fiu.edu/research/publications/)** > [@](#): > > An examination of the literature (more than 46,000 articles—PubMed search, June 2012) shows that “non-right-handedness” is associated with a host of psychological traits (e.g., a**utism, Attention Deficit-Hyperactivity Disorder (ADHD) developmental coordination disorder, schizophrenia and bipolar disorders, Down’s syndrome, dyslexia, learning disabilities, stuttering, and sexual partner preferences**) and medical conditions (e.g., **congenital adrenal hyperplasia, arthritis and ulcers, recovery from brain damage, stature, and early menarche** ). ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [March 14, 2016, 3:41pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/22 "2016-03-14T15:41:40Z")
> [@Try2B\_Comprehensive](#): > > Ultimately I bet it comes down to [molecular chirality](http://www.rowland.harvard.edu/rjf/fischer/background.php). Somehow. Well, then you’d have to explain why most parrots are lefties (really, they are). Apparently having a dominant hand is advantageous in some manner, and it may be that _which_ side was normally dominant was a matter of chance in a distant ancestor, and that handedness has been passed down to us. ---
**Author:** ![Charlie\_Wayne](https://avatars.discourse-cdn.com/v4/letter/c/4bbf92/32.png) [@Charlie\_Wayne](https://boards.straightdope.com/u/Charlie_Wayne)\ **Post date:** [March 14, 2016, 6:15pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/23 "2016-03-14T18:15:26Z")
> [@Broomstick](#): > > Well, then you’d have to explain why most parrots are lefties (really, they are). > > Apparently having a dominant hand is advantageous in some manner, and it may be that _which_ side was normally dominant was a matter of chance in a distant ancestor, and that handedness has been passed down to us. Hello Broomstick, 🙂 How can you tell that parrots are left-handed? Do you mean that they always stand on one foot and eat by picking up food with the other foot? I’m not sure which foot you would call “dominant”. But that’s very interesting. I had a parrot for ten years and I never noticed that she always ate food I gave her by holding it with the same foot. She hated the store-bought bird food and would make a huge ruckus unless I fed her by hand. She always insisted on eating only the same food that I ate. But I never minded. I loved to feed her by hand. Her favorite food was pizza. Believe it or not. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [March 14, 2016, 7:33pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/24 "2016-03-14T19:33:27Z")
> [@Charlie\_Wayne](#): > > How can you tell that parrots are left-handed? Do you mean that they always stand on one foot and eat by picking up food with the other foot? I’m not sure which foot you would call “dominant”. Not _always_ but according to my (admittedly not exhaustive) research [most parrots prefer picking up/holding/manipulating things with one foot over the other.](http://www.reuters.com/article/us-parrots-hands-idUSTRE71277420110203) My conures have both definitely favored their left foot for this. The three cockatiels I’ve had don’t seem to pick up/hold/etc. much of anything and if they had a preference I’ve never been able to figure it out. The lovebirds were less inclined to use their feet as hands than the conures but all three seemed to favor the left when they did such things. Informal browsing turns this up as a frequent observation, that parrots tend to be left-dominant. It’s not as strong as in humans, but it does show up statistically. > [@](#): > > But that’s very interesting. I had a parrot for ten years and I never noticed that she always ate food I gave her by holding it with the same foot. Not all parrots have a dominant foot, and even those that do tend not to be as preferential as humans. I should probably point out that avian brains are structured very differently than mammalian brains, and that might well account for some of the differences here. Which is why I speculate that handedness might have have an advantage, but _which_ hand is preferred may be due to random chance in an ancestor. Humans might have had that ancestor as a righty, birds like parrots might have had a lefty in that position. Most mammals (again, informal research) _don’t_ show a preference for one hand over another. The great apes (chimps, gorillas, orangutans) show some tendency towards a dominant hand, but _which_ hand seems a bit random and there are plenty who don’t show handedness. Chimps and gorillas _might_ be slightly more inclined to be right handed, and orangutans slightly more likely left handed but the evidence is weak at best from what I’ve seen. It might be (note all the qualifications indicating speculation here - it’s all over what I’ve found on the subject) that preferring one hand over the other makes you a better toolmaker/user, in which case the strong tendency to favor one hand makes a lot of sense in humans, but doesn’t account for being right handed so frequently as opposed to left. It might account for handedness in parrot species that frequently grasp/manipulate objects, in that specializing with one leg for grasping a perch/supporting the body and the other for finer manipulations also makes sense, for similar reasons as humans, but again _which_ hand is preferred is not accounted for. Crows _also_ show a preference in such matters - let’s get more formal and call it “lateralization” which gets away from “hands” and towards “whatever the critter manipulate with or favors”. New Caledonian crows are _also_ tool users and makers and _also_ show a lateralization preference - [with most being righties!](http://www.nature.com/news/2004/040322/full/news040322-6.html) At least when they’re making tools. Here’s a bit more on [handedness in animals](http://news.nationalgeographic.com/news/2001/12/1212_TVcrow.html) So… apparently lateralization appears in species that make/use tools and might have something to do with brain organization. _Which_ side is favored seems a bit of a crap shoot, but the more a species makes and uses tools the more likely the majority will favor one side or another. Bottom line: it appears to be connected to tool making and use, and since humans are so specialized in that role it makes some sense we’d have strong lateralization. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [March 14, 2016, 9:32pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/25 "2016-03-14T21:32:53Z")
> [@Chronos](#): > > Why have a dominant hand at all? Because it’s more useful to have one hand that you’re really good at than two hands that you’re sort of good at, which you’d have if you practiced with both equally. > > Why do most humans have the same dominant hand? At a guess, it’s because we’re tool-users, and it’s advantageous for everyone to be able to use the same tools. > > Why is it not all of us? Being the opposite handedness from normal can be an advantage in direct physical competition, because you’ll react differently than your opponent expects. This used to be an advantage in swordfighting, and is still an advantage in baseball pitching. Apparently, a ratio of about 9 to 1 is the sweet spot where these two benefits balance out. > > Why is the common dominant hand specifically the right one? That’s just happenstance. With a slightly different evolutionary path, it could have been the left just as easily. That’s probably the likely explanation. We learn a lot of tasks (motor skills) by repetitive training until it becomes instinctive. By using the same hand every time, we learn the task faster and get better at it, until it just “feels right”. One explanation I recall reading (obviously someone being somewhat sarcastic) was that left-handedness was the brain development compensating for oxygen starvation and brain damage during birth. 🙂 ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [March 14, 2016, 9:35pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/26 "2016-03-14T21:35:38Z")
> [@Broomstick](#): > > Crows _also_ show a preference in such matters - let’s get more formal and call it “lateralization” which gets away from “hands” and towards “whatever the critter manipulate with or favors”. New Caledonian crows are _also_ tool users and makers and _also_ show a lateralization preference - [with most being righties!](http://www.nature.com/news/2004/040322/full/news040322-6.html) At least when they’re making tools. Here’s a bit more on [handedness in animals](http://news.nationalgeographic.com/news/2001/12/1212_TVcrow.html) Nature? NatGeo!? Okay that’s it, turn in your Dope card (you got one, right?). [Here’s a credible cite](http://www.straightdope.com/columns/read/990/is-there-such-a-thing-as-a-left-handed-cat). 😛 ---
**Author:** ![Fear\_the\_Turtle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_the_turtle/32/2926_2.png) [@Fear\_the\_Turtle](https://boards.straightdope.com/u/Fear_the_Turtle)\ **Post date:** [March 14, 2016, 9:44pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/27 "2016-03-14T21:44:03Z")
Anyone want to hazard a guess as to why I’m right handed but left footed? From my earliest memories, it always felt more natural to kick a ball with my left foot. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [March 14, 2016, 10:24pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/28 "2016-03-14T22:24:27Z")
> [@md2000](#): > > One explanation I recall reading (obviously someone being somewhat sarcastic) was that left-handedness was the brain development compensating for oxygen starvation and brain damage during birth. 🙂 While left-handedness _can_ be a compensation for damage (people who lose their arm or are paralyzed by a stroke can learn to use the non-dominant hand for tasks that used to be done by the now missing or useless hand) it’s not always. There are developmental situations where all the internal organs are a mirror image of the usual arrangement, and such people are, not surprisingly, frequently left-handed. That’s not damage, that’s a reversal of some early signal in the embryo. If a lefty’s brain is arranged more as a righty’s that might be a case of damage compensation, but if the lefty’s brain is a mirror image of the typical righty’s I’d suspect it’s a developmental reversal of some sort (not everything has to be reversed. Pre-birth development can be complicated). We can actually make such determinations in a living brain. When my mother (a lefty) had a stroke they did imaging that showed her brain organization was mirror to the typical righty’s (which was fortunate, because if it wasn’t the stroke would have been far more damaging than it was). The doc’s said it was important to know these things when planning for rehab. They also said that you occasionally find a righty with a “mirror” brain, that is, their brain is a mirror image of a typical righty, which means in _that_ case being right-handed might be a case of pre-birth damage compensation in someone who should have been a lefty! ---
**Author:** ![ratatoskK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ratatoskk/32/2987_2.png) [@ratatoskK](https://boards.straightdope.com/u/ratatoskK)\ **Post date:** [March 14, 2016, 11:16pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/29 "2016-03-14T23:16:09Z")
Read [Right Hand, Left Hand: The Origins of Asymmetry in Brains, Bodies, Atoms and Cultures.](http://www.amazon.com/Right-Hand-Left-Asymmetry-Cultures/dp/0674016130/ref=sr_1_1?ie=UTF8&qid=1457997274&sr=8-1&keywords=right+hand+left+hand)It has all you need to know… ---
**Author:** ![j666](https://avatars.discourse-cdn.com/v4/letter/j/9de0a6/32.png) [@j666](https://boards.straightdope.com/u/j666)\ **Post date:** [March 15, 2016, 1:46am UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/30 "2016-03-15T01:46:57Z")
> [@Surreal](#): > > Not being right-handed seems to be a risk factor for a huge array of disorders: > > [Publications | FIU Center for Children and Families](http://ccf.fiu.edu/research/publications/articles-2010-present/michel_nelson_babik_campbell_marcinowski_2013.pdf) Prefering to have a sexual partner is a disorder? > [@Fear\_the\_Turtle](#): > > Anyone want to hazard a guess as to why I’m right handed but left footed? From my earliest memories, it always felt more natural to kick a ball with my left foot. But if you write in the sand with your toe, which foot do you use? No, really. I catch and throw equally well (which is to say not very) with both hands, iron only with my right hand (even with irons with the cord in the center), sew and saw only with my left, cut with the left but stir with the right, cut in with my left hand and paint with my right, brush my teeth with the left but lather and loofah preferentially with the right … But by foot or by hand, I alway write with my left. Maybe you balance better on the right leg. [And most of my dogs have been right pawed] ---
**Author:** ![Try2B\_Comprehensive](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/try2b_comprehensive/32/65_2.png) [@Try2B\_Comprehensive](https://boards.straightdope.com/u/Try2B_Comprehensive)\ **Post date:** [March 15, 2016, 2:41am UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/31 "2016-03-15T02:41:23Z")
[Some crabs](http://i.kinja-img.com/gawker-media/image/upload/s--tIYT19D0--/18lq6i8eiv200jpg.jpg) are obviously handed… ---
**Author:** ![DorkVader](https://avatars.discourse-cdn.com/v4/letter/d/73ab20/32.png) [@DorkVader](https://boards.straightdope.com/u/DorkVader)\ **Post date:** [March 17, 2016, 12:30am UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/32 "2016-03-17T00:30:14Z")
> [@thelurkinghorror](#): > > Do they provide left-handed rifles in the military or do you just deal with brass ejecting in front of your face? Being cross-dominant is obnoxious sometimes. pssst, I know it isn’t really germane to the main discussion, but, they will provide you with a[deflector](https://www.google.com/search?q=m4+carbine+brass+deflector&biw=1455&bih=692&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiiktaFusbLAhXDwYMKHTWSCmsQsAQIIg#imgrc=8011hY9UXDBUrM%3A) or [catcher](https://www.google.com/search?q=m4+carbine+brass+deflector&biw=1455&bih=692&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiiktaFusbLAhXDwYMKHTWSCmsQsAQIIg#imgrc=u6Y91wwYer_x1M%3A) if you bug your platoon sgt and/or supply sgt long enough and fill out the paperwork enough times, at least in the US army anyway. ---
**Author:** ![MacLir](https://avatars.discourse-cdn.com/v4/letter/m/9e8a1a/32.png) [@MacLir](https://boards.straightdope.com/u/MacLir)\ **Post date:** [March 17, 2016, 2:33pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/33 "2016-03-17T14:33:10Z")
Allegedly, when I was a baby I showed a left preference, but was trained to be right-handed to fit in with the majority. Subtly not forcefully, and from the very beginning. Some of the alleged physical indicators (finger length, etc.) support this. :dubious: Possibly as a result, I tend to have less of a hand preference than most people I’ve met. I eat “British style” when it has a lot of cutting or if my right arm is restricted, “American style” when it involves a lot of scooping, and never consciously think about which one. I “mouse” with my left, but use a right-hand mouse - to me mousing is an inherently left-handed activity (leaves your right free for the keyboard, and you can have the main QWERTY keyboard aligned with your monitor more easily.) :rolleyes: I’ve noticed I have a tendency to use my left for activities with a higher probability of hand injury - without conscious thought of it. Basically, things with a high degree of fine motor skills go to my right hand, medium levels have a habitual right tendency but can be done either way, and low skill activities are whichever hand is easiest. ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [March 17, 2016, 8:28pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/34 "2016-03-17T20:28:25Z")
> [@Broomstick](#): > > So… apparently lateralization appears in species that make/use tools and might have something to do with brain organization. _Which_ side is favored seems a bit of a crap shoot, but the more a species makes and uses tools the more likely the majority will favor one side or another. > > Bottom line: it appears to be connected to tool making and use, and since humans are so specialized in that role it makes some sense we’d have strong lateralization. Although there are some exceptions - grey whales are mostly right-handed -flippered -mouthed, we know this from [imaging their feeding dives](http://onlinelibrary.wiley.com/doi/10.1111/j.1748-7692.2006.00006.x/full) and observing the relative wear on the right-versus-left sides of their heads. Much handedness may indeed be related to tool-use, but other forms of manipulation of the environment may be important to the exceptions. ---
**Author:** ![Surreal](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@Surreal](https://boards.straightdope.com/u/Surreal)\ **Post date:** [March 17, 2016, 10:03pm UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/35 "2016-03-17T22:03:18Z")
> [@j666](#): > > Prefering to have a sexual partner is a disorder? It depends: > **[Are Left-Handed People More Pedophilic Than Right-Handed People?](https://boards.straightdope.com/sdmb/showthread.php?t=491944)** > > Is it true that left-handed people are significantly more inclined to be pedophiles than right-handed people? If so, why does this correlation exist? Does this tendency hold for just the act of becoming aroused, or is there an association between... ---
**Author:** ![j666](https://avatars.discourse-cdn.com/v4/letter/j/9de0a6/32.png) [@j666](https://boards.straightdope.com/u/j666)\ **Post date:** [March 18, 2016, 2:03am UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/36 "2016-03-18T02:03:44Z")
> [@Surreal](#): > > It depends: > > [Are Left-Handed People More Pedophilic Than Right-Handed People? - Factual Questions - Straight Dope Message Board](http://boards.straightdope.com/sdmb/showthread.php?t=491944) I know I don’t want to read that thread. ---
**Author:** ![Sleel](https://avatars.discourse-cdn.com/v4/letter/s/73ab20/32.png) [@Sleel](https://boards.straightdope.com/u/Sleel)\ **Post date:** [March 25, 2016, 8:38am UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/37 "2016-03-25T08:38:30Z")
[Previous thread](http://boards.straightdope.com/sdmb/showthread.php?t=696952) [My reply in that thread](http://boards.straightdope.com/sdmb/showpost.php?p=16493176&postcount=34): > [@](#): > > Handedness is one byproduct of brain lateralization. We still don’t really know why lateralization became prevalent, but it seems to confer some advantages for separate processing. One reason why lefties are supposed to be more creative is that they tend to have less strongly lateralized brains, so they come up with connections between disparate ideas more easily. High intelligence also seems to be lightly correlated with left-handedness. > > There’s a pretty good chunk of The Language Instinct and How the Mind Works, both by Steven Pinker, that discuss lateralization, particularly the connection with language. Those are probably the most approachable, yet scientific books I’ve read on the subject. > > Handedness is actually a continuum, with few people being totally right- or left-dominant. Some degree of mixed body dominance is common. You might have someone who is strongly right-handed, but strongly left-eyed and weakly left-footed, like a friend of mine I taught to shoot better. You should shoot based on eye dominance, not hand dominance; target acquisition and aiming are the most important things. It took some work to get him using his left hand, but his accuracy and speed went way up afterward. > > While there is no single “left handed” gene, there are some genetic factors; handedness can run in families. But environment seems to be a stronger selector. Stressful conditions at conception and birth have an effect on the prevalence of left-handedness. > > [http://boards.straightdope.com/sdmb/newreply.php?do=newreply&p=16490512](http://boards.straightdope.com/sdmb/newreply.php?do=newreply&p=16490512) > > > [@](#): > > > > I would also imagine this effect would become more pronounced when it came to weapons, for combat, for hunting. People who were more proficient would kill off their opponents and have an easier time feeding themselves. Thus, if there was some social order for being trained to use them right-handed, and there’s some genetic predisposition toward one or the other, those who would have had a bit more natural skill would start to win out and spread that genetic predisposition, even if it is slight. > > Actually, violence selects for [more lefties](http://www.ncbi.nlm.nih.gov/pubmed/9025310). In other words, the minority preference confers an advantage in combat. Either that, or left handed people are naturally more violent 🙂 > > (Full disclosure: I’m left handed. You got a problem with that?!) > > From some of my anthropology reading I remember that the Yanomami have something like 20% incidence of left-handedness. “Fierce” men, who go on more raids and are more willing to undergo inter-tribal duels, have more wives than men who show less aggression, and these men are more likely to be left handed. (In duels they beat each other over the head with really long wooden poles, deliberately receiving head wounds to show how tough they are; this is not dissimilar to [Heidelberg dueling](http://en.wikipedia.org/wiki/Dueling_scar)). On preview: **NOT** a reply to the left-handed pedophilia thread. I’m pretty sure I stayed away from that mess. ---
**Author:** ![paulmarkj](https://avatars.discourse-cdn.com/v4/letter/p/9e8a1a/32.png) [@paulmarkj](https://boards.straightdope.com/u/paulmarkj)\ **Post date:** [March 25, 2016, 9:33am UTC](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848/38 "2016-03-25T09:33:44Z")
> [@RivkahChaya](#): > > …people who have been looking at the phenomenon have noted that left-handers who write with a hook tend to have learning problems or motor skills problems, while people who write in a way the mirrors the way a right-handed person writes rarely have any problems… That is an old fashioned prejudice. The idea that left hand people are ‘awkward’ comes from the fact they have to use right handed objects. Many right-handed people don’t realise how difficult this is. Try these: 1. Ask people to write backwards. Left handers are much better then right handers for two reasons: first, they backward direction is (at last!) in their favour. Second, left handers are used to adapting, not copying, hand movements. 2. Give a righty a left-handed corkscrew and watch them struggle! [Previous page](https://boards.straightdope.com/t/why-are-the-majority-of-people-right-handed/748848.md?page=1)