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I remember in elementary school being amused by the idea of handedness so I decided to practice writing with my left hand as well. I'm not great at it but even to this day I can write legibly with my left hand from that little bit of practice as a child.

Anyone can get much better at using their non-dominant hand (if they have one) with just a bit of practice. The effect is much much stronger when you do so as a child.

I’m left handed and never understood left handed mice at all. I write with my left and swing and kick left handed, but all gaming stuff has always been the same way anyone else does. I’m pretty sure up down left right switching to wasd is a function of that setup being more comfortable with the mouse to the right of the keyboard, correct?

For this sort of motor skill, it’s definitely learned. For stringed instruments, for example, it’s the left hand which has the more finely managed manipulation than the right (it’s interesting to note that only guitar-family instruments are commonly made in left-handed versions, although some of that may come down to logistics of string ensembles where having one left-handed violin in the violin section would cause a bit of chaos with colliding bows that is less of an issue with guitar ensembles where there are fewer musicians and they’re less tightly packed in the performance space). Likewise, the fingering on woodwind instruments doesn’t really favor one hand over the other. In contrast, brass instruments are decidedly right-handed (I suppose one might be able to manage a trumpet left-handed, but I’ve never tried. I don’t think other brass instruments could be fingered with the left hand at all.

Something super simple and revealing is try pressing on the brakes with your left foot.

The original paper is titled "Bipedalism and brain expansion explain human handedness". It doesn't seek to explain why we have a right-handed preference specifically (vs left-handed), but rather why humans have such a strong handedness preference compared to ancestors who had only a mild right-handed preference.

IOW, why handed vs ambidextrous, not so much why left-handed vs right-handed.

> My theory is if any child wants help with fine motor control the help is provided by a left hand to a left hand.

Neither of my parents were left handed, and yet, here I am; despite attempts otherwise I might add.

Oddly enough, a lot of my "nerd friends" are left handed, and I'm also left handed. /shrug

without reading .. my immediate guess is that one hand is needed for maintaining upright balance, while the other hand grasps something important ?

I overused my right hand with computers - mouse + many keyboard keys like arrows, enter, backspace, etc

so I switched to a left-handed mouse. I cursed for about a week, then sometimes fumbled, and then it just worked.

Now years later, if I use a right-handed mouse to do say a first-person-shooter, I overcorrect like I'm drunk on wildly pitching ship.

left-hand is dialed in and precise.

I think some of this stuff is learned and not innate.

but yeah, goofy-foot on skateboard feels... just wrong.

I think this is probably related to which eye is more dominant for you. I've never skateboarded, but if I imagine myself doing it, it would also be facing left. And it's because my right eye is dominant and I would like that to be facing forward.

I'm goofy footed as well - skate boarding with my left foot forward is like trying to throw a ball with my left hand. I also found that if I was rollerblading or ice-skating, turning to my left (counter clockwise) with a foot-over-foot action I can do super easy, but turning turning clockwise I always struggled with.

Me too, but on a snowboard. (I suppose I'd be the same on a skateboard) My second time snowboarding was quite a few years after my first, and I just could not get the hang of it, wondering how I was faring so much worse than before. It took me all day to remember I was "goofy", and once I switched it was much better.

I'm right-handed, but I snowboard goofy. Coincidence (or not?) my left leg is dominant. I can kick a ball just fine with my left foot, but when I try to kick with my right foot I feel like I'm going to capsize. When I'm riding a bike and I have to stop, my right foot goes down. When I start again I use my left leg to muscle the crank through the first revolution or two.

Do you hold a baseball bat lefty too?

I skate/surf goofy (or used to... haven't done much of either lately :P) and prefer to hold a baseball bat or a golf club lefty, despite being right-handed. And I have an immediate family member who's left-handed but bats righty!

I think skate stance is much more evenly distributed (closer to 50/50) than handedness (about 10% left).

What does "face left" mean? Left foot front? That's regular.

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To drain pasta or noodles quickly, I put it in a colander, hold it above my kitchen sink, and swirl it around in quick circles. I realized about a month ago my circles are always counterclockwise, and very efficient, but that I can't keep a clockwise spin going for more than a few cycles before messing up. Since then I keep trying to spin my pasta clockwise (such are the small excitements and adventures of my wfh life), starting with very slow movements, but I just can't do it. There's something weird about this motor skill specifically that eludes me. I'm left-handed but my right-handed writing is reasonable and I play piano with matched abilities in both hands. Maybe one day, with enough practice, my pasta will go clockwise.

I would think right-handedness is largely reinforced through learning gross motor skills as an infant. If you always use your right, your brain optimises for that.

I wonder whether something simple like being allowed to select and use an object with either hand rather than having it offered to your right hand retains ambidextrous by the time handedness became fixed in the brain around age 4-6.

Here's my five minute lunchtime hypothesis: it's because the heart is on the left. As human behavior demanded increasing precision from the hands, being a little farther from the heartbeat was a slight advantage.

I remember reading that there is evidence that Neanderthals tended to be left handed. Someone else might be able to confirm/debunk this.

As a lefty I never had any problems adapting to a right hand mouse and actually find the keyboard to be better suited as a "left hand" activity and would have a hard time switching it up.

I have switched between left and right mouse every few years when I was younger, just to see what works best for me. I could adapt to both, even though I can only write and draw with my left hand. I have settled with left-hand mouse because I feel like I can be a bit more precise for graphical works and shooters.

With the trackpad on my Laptop, I switch quite frequently and haven’t yet noticed any difference in precision. The movement is very different than mouse or pen control though and comes more from individual/multiple fingers instead of the whole hand or arm, so I guess that explains it.

I mouse right-handed because it’s convenient, but I still naturally default to doing any novel task left-handed. It’s not a matter of fine motor skills, you can learn to do anything with either hand if you decide to, it’s just an unconscious preference.

With modern controllers the main joystick/thumbstick is on the left side. People are using both hands for fine control in different circumstances.

I used right all the time. Got RSI. Now I use left at work all day, and right at home when gaming.

At work, I don't use a left handed mouse. Just those cheaper but common symmetrical ones. And I don't bother changing handedness. I just pick up the mouse and put it to the left of the keyboard.

shrug It works.

I’m a leftie from a 50% leftie family. Apparently I showed my left handedness as a baby when grasping for things and hardly used my right hand. My mother was also a leftie, but in her generation she was forced to write with her right hand. The net result being she could write equally well with both hands. When I learnt this I tried to copy it.

The introduction of this article makes reference to a couple of papers (e.g. https://doi.org/10.1038/s41598-017-16827-y ) that handedness is observable in utero but cautions small sample sizes for these studies.

Left-to-right writing systems are optimized for right-hand use. Two examples:

* if you're left-handed, your hand smudges over the ink before it dries. There are various contortions that some left-handed people do (hover the hand or wrap it around from above) - right handed ones don't need any of that.

* stroke patterns, as usually learnt in school, result in pushing away if left handed, vs drawing to, if you're right handed. This results in less ideal strokes, and if you're working with a sharp pencil/pen on a sensitive paper, this can tear the paper. If you're working with a felt-tip pen, the line width/pressure suffers as well.

That said, if you really make an effort, you can have a pretty decent handwriting if you're left handed. And if you are forced to use right hand when learning handwriting, you can still have a pretty decent handwriting.

I'm not familiar with details of chinese handwriting (what's easier/better if you're left vs right handed), wouldn't be surprise the constraints are similar.

So I guess your remark about messy handwriting is related to the strict standards for the students (which includes expectation they must write with right hand).

Due to a broken right-hand, I had to write with my left for 3 months and noticed that our alphabet is made for right-handedness. That's why I agree with your take that writing with the left hand is basically unnatural. But since typing is more important than writing nowadays (or am I in a bubble?), I don't think students should be guided to write with their right hand.

Seems probable that's simply because it isn't tolerated as a choice.

Though the best evidence to refute "There are no left-handed in China" is that it didn't take long to find a left handed Chinese baseball player

https://en.wikipedia.org/wiki/Chen_Hao_(baseball)

In many parts of Asia they will 'correct' children who are using their left hands.

That's only meaningful if the messiness of the handwriting correlates significantly with the handedness.

(and none out of thousands seems statistically unlikely: China has lower numbers of reported left-handers, but it's 3% vs 10%)

My father was left handed like me and he got in trouble from teachers.

It's possible that Chinese will one day obtain individuality and freedom and they can write left handed. That would kill the one last advantage the West has.

In my own personal and subjective experience, the correlation between left handed people I know and "edginess"-level is almost 1.

I am inclined to believe this is a learned trait rather than an innate one (excluding the obvious reasons why one would be left-handed only).

One of many articles out there debunking the pop-psych mythology around brain lateralization: https://themindcompany.com/blog/left-brain-right-brain-myth

Interestingly, playing left-handed in "field" hockey is actually illegal for safety reasons and left-handed sticks don't exist.

Same but i feel many sports are weird in that i’ve never been convinced that there’s a particularly natural right or left handedness to them.

Eg. For pool does the more dextrous hand need to push the cue or does it line up and guide the front of the cue? I can see tradeoffs each way and the front hand is certainly not just limp when playing.

Hockey is similar. The top or the bottom hand being the more dextrous probably has tradeoffs but I don’t see either grip as being more or less natural for handedness. I don’t play hockey but play golf and cricket which have similar grips and am similar there to you too.

Same which makes me very poor at sports. I write right-handed. For anything sports related (riding a board, throwing a ball, golf, batting, bowling, etc) I'm leftie. My dad is left-handed, mother is right-handed. I have wondered if I should've been a left-handed writer and was corrected either explicitly or just by the environment to write right-handed.

Same! I am specifically left handed for pool and cannot figure out how to play it right handed - absolutely zero coordination.

It happens. I can play hockey with either hand as dominant. Too bad that wasn't really a useful talent like being a switch hitter in baseball. I'm generally left handed, but play musical instruments almost exclusively right handed. I had a friend teach me drums. He was right handed and didn't even think to ask me about my handedness, or didn't want to move stuff around (lefties have to adapt to a right handed world...). It didn't feel awkward though. I don't know why I play guitar right handed. The prevailing theory in my family is that I "learned" by mirroring Kurt Cobain on the TV screen...

In order to present it as a mental illness there would have to be some kind of negative effect, wouldn't there? These differences you mention don't stand out as harmful or even disadvantageous.

You were probably a left-handed person who was taught to write/use tools with their right hand in kindergarten. I got this treatment too.

I'm sorta here too. I'm right handed, no external pressure to use one hand or the other in early age. Mother is a lefty, father is a righty. As a result I often used the computer mouse on either side as a kid, really wherever it was left by the last user.

Learned to shoot a bow as a kid but only learned as an adult I'm left eye dominant, and to take advantage would require re-learning the bow in my left hand(many many strikes on my arm sent be back to a righty). Shooting guns is a similar situation, but I'm a fairly good shot regardless. It definitely makes using sights weird.

I'm semi-ambidextrous too, with enough focus I can somewhat cleanly write with either hand, and I'm generally good with my hands in fine tasks, with only a minor preference to pick up a tool with my right hand.

I wonder how common this is. People seem surprised when I demonstrate my left handed writing.

> I've been told that it's effectively a mental illness if discovered during childhood (as is ambidexterity). Yet I can't help but think that it is not a mental illness, but rather something else.

https://en.wikipedia.org/wiki/Handedness#Types: “Mixed-handedness or cross-dominance is the change of hand preference between different tasks. This is about as widespread as left-handedness.”

⇒ about 20% of the population is not strictly right-handed. That’s not a majority, but I think the word to use for that is “normal”.

Left-footed and right-handed. I find my "handedness" follows where the activity is driven from (upper/lower body).

Soccer, snowboarding, batting, golfing: lefty

Writing, throwing, tennis, pool: righty

They don't discuss a "why", so much as present data on the "how" and "when". If this work is valid and reliable, then it will be up to later research to propose and test hypotheses as the why.

In a nutshell, the paper basically says that the lateralization that led to the predominance of right-handedness occurred around the time humans became bipedal and around the time of neuroanatomical expansion, possibly related to bipedalism.

In other words, before these two changes, we used all four limbs for locomotion and had no preference for either forelimb for grasping. Then one or two things happened and right-handedness predominated. It seems that that neuroanatomical expansion took over the areas of the brain that previously allowed our left hands to be as capable as our right hands.

I write "one or two things happened" because it wasn't clear to me from the paper whether the neuroanatomical expansion that led to lateralization was necessary to and part of bipedalism, i.e., caused by our locomotion bits taking over other parts of the brain to manage our balance, or whether it was merely coincident with it.

Interesting questions asked and answered, more research needed.

Actual study here: https://journals.plos.org/plosbiology/article?id=10.1371/jou...

My take is that when they added extra factors to the Bayesian model, the plot was such that humans were no longer outliers.

Whether or not that's scientifically rigorous, or even interesting, I leave to others to determine.

'Everyone' is treated as singular (aside from 'everyone are' sounding completely wrong).

Confidently incorrect.

No, grammatically "everyone" is an indefinite pronoun. a single collective unit.

Is that a British thing? Nobody in North America uses "everyone are"