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The mystery of why left-handers are so much rarer (2016)

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Re: The mystery of why left-handers are so much rarer (2016)

#231

Post by defrost »

Al-Khwarizmi wrote: post #222
_whiteCaps_ wrote: post #103

Earlier quoted context omitted.

I thought that scissors were made to be right handed, and you need a 'reversed' pair for left handed people. Or is that a scam?

It's not a scam. My son is left-handed and his left-handed scissors don't work for me, while my right-handed scissors don't work for him. I have never understood why, though. In my mind, if you rotate the scissors 180 degrees, they should become the other kind (assuming the handles are symmetric, not those ergonomic asymmetric ones, I mean). And I just don't see why not no matter how hard I think. I'm not a dumb pers…

There's more to a good pair of scissors (eg: Dressmakers scissors) than you may have considered.

Left and Right handed versions are asymmetric mirror images of each other than cannot be rotated to match.

Consider:

* Smaller top loop for thumb.

* Larger bottom loop for fingers.

* Loops have width and are bevelled; wider where the thumb first enters, narrower on the side the thumb comes out, these are shaped for comfort and control.

* The action of moving a thumb and fingers "up and down" has a slight twisting action to it that is factored into how the anvil and cutting blades of the scissors are arranged so that the left twist causes the blades to run tight against each other when left handed and mirrored for the right twist of the right hand.

Re: The mystery of why left-handers are so much rarer (2016)

#232

Post by puzzledobserver »

Al-Khwarizmi wrote: post #222
_whiteCaps_ wrote: post #103

Earlier quoted context omitted.

I thought that scissors were made to be right handed, and you need a 'reversed' pair for left handed people. Or is that a scam?

It's not a scam. My son is left-handed and his left-handed scissors don't work for me, while my right-handed scissors don't work for him. I have never understood why, though. In my mind, if you rotate the scissors 180 degrees, they should become the other kind (assuming the handles are symmetric, not those ergonomic asymmetric ones, I mean). And I just don't see why not no matter how hard I think. I'm not a dumb pers…

I'm right-handed, and usually use scissors with my right hand. When I try using them with my left hand, two things happen: First, they doesn't sit right in my palm, because of the way they are sculpted. Beyond this, and more importantly, they are no longer as effective in cutting things.

Here's my understanding of why this is. When holding the scissors with your hands, in addition to the up-and-down force you exert on the blade with your fingers, you also exert a small side-to-side force with your fingers. With my right handed scissors in my right hand, this force pushes to the outside on the upper handle and to the inside on the lower handle. This force also makes the scissors feel more comfortable.

On the other side of the fulcrum, though, the upper handle controls the lower blade and the lower handle controls the upper blade. Here, the lateral forces end up drawing the blades closer together, giving a tighter pair of edges between which shearing forces are applied. This makes the cutting action more effective than if lateral forces were absent.

In my left hand, the (outside at the top and inside at the bottom) lateral forces end up pushing the blades further apart on the other side of the fulcrum. This reduces the shear force and makes the cutting action less effective.

To compensate for this while operating the scissors with your left hand, you would need to adopt a weird style: Consciously pull to the inside with your thumb, and to the outside with your remaining fingers. You'll notice that the scissors are now much more effective than before. It is also a deeply uncomfortable grip.

The issue is that scissors are (surprisingly) chiral sculptures. In the case of regular right-handed scissors, when viewed edge down, the handle closer to the viewer passes through the left of the fulcrum. I have never used a pair of left-handed scissors, but I would presume that for them, the closer handle passes through the right side of the fulcrum.

Re: The mystery of why left-handers are so much rarer (2016)

#233

Post by kendoka111 »

obfuscator wrote: post #230

So many left-handers here that feel disadvantaged in our right-handed society. If you ever want to do one thing where you feel you left-handedness gives you an advantage, pick up Kendo (the Japanese swordfighting). You have to wield your sword like everybody else but the aiming is done with your left while the right just provides the power for the stroke (the katana is a two-handed weapon). Since you are not supposed…

This is completely wrong btw.

No power ever comes from the right.

That is why there are warm up exercises using katate (single left hand warm up) to loosen and focus on your left.

It makes no sense for power to come from the right as fumikomi (the leaping motion at the time of the strike) is done using your left hips and legs.

Re: The mystery of why left-handers are so much rarer (2016)

#234

Post by vanderZwan »

obfuscator wrote: post #230

So many left-handers here that feel disadvantaged in our right-handed society. If you ever want to do one thing where you feel you left-handedness gives you an advantage, pick up Kendo (the Japanese swordfighting). You have to wield your sword like everybody else but the aiming is done with your left while the right just provides the power for the stroke (the katana is a two-handed weapon). Since you are not supposed…

Doesn't left-handedness give an advantage in most sword fighting and fencing sports? As demonstrated by the percentage of left-handed players at the top level is higher than the population average? I heard the same thing is true with boxing, presumably other martial arts, and tennis (and who knows what else).

The explanation I've heard is that in any sport, on average one would train more with right-handed opponents. So when facing a left-handed opponent you are significantly less experienced, which results in left-handedness having a slight advantage.

That is a bit different than what you describe (since you're not allowed to use your katana in a left-handed fashion), but still.

Re: The mystery of why left-handers are so much rarer (2016)

#235

Post by tslater2006 »

pram wrote: post #139

Just throwing in my left handed anecdote here: the bottom of my hand was always covered in pencil graphite when I was in school because your hand drags over what you've been writing from left -> right. Also ring binders were a pain in the ass (your hand is blocked at the left margin lol)

I struggled with this through highschool. Pencil and gel pens were the worst. I never learned to write with my paper tilted like some lefties. I write just like a mirror image of a right hander, which lead to a lot of smudging and having to rewrite papers etc

This change my sophomore year in English class when my teacher told me a trick! Place a sticky note on the side of your hand that rests on the paper. No more smudging!

Re: The mystery of why left-handers are so much rarer (2016)

#236

Post by JodieBenitez »

Teever wrote: post #177
talldatethrow wrote: post #150

Earlier quoted context omitted.

I'm also left handed and this was never an issue for me. You hold the pencil out from your fingers thus your hand is sitting slightly below the line that is being written, traveling over unused paper constantly. Only people that do that weird claw thing have that problem.

The trade off is that you have less visibility of the letters you just wrote, which can be annoying sometimes and lead to spelling mistakes.

Yes, that's why we did the "weird claw thing" aforementioned.

Anyway, no more handwriting these days...

Re: The mystery of why left-handers are so much rarer (2016)

#237

Post by woolion »

Last week I asked my Chinese painting prof if we could try calligraphy, and he said "no".

"Left-handedness is too much of a problem, movements would be too awkward with the brush.

- So what happens with the small percentage of natural left-handed in China?

- It's beat out of them. I still use chopsticks with my left hand, because it's tolerated, but writing is just unacceptable."

So yeah, it's a complete mystery.

Recently there were some interesting papers looking at laterality from a more general point of view (which is a bit touched on with the simian examples in the article).

Given that there are strong genetic factors involved, it's not surprising that with tools becoming more prevalent in complex societies there would be a human co-evolution.

Re: The mystery of why left-handers are so much rarer (2016)

#238

Post by withinboredom »

kendoka111 wrote: post #233
obfuscator wrote: post #230

So many left-handers here that feel disadvantaged in our right-handed society. If you ever want to do one thing where you feel you left-handedness gives you an advantage, pick up Kendo (the Japanese swordfighting). You have to wield your sword like everybody else but the aiming is done with your left while the right just provides the power for the stroke (the katana is a two-handed weapon). Since you are not supposed…

This is completely wrong btw. No power ever comes from the right. That is why there are warm up exercises using katate (single left hand warm up) to loosen and focus on your left. It makes no sense for power to come from the right as fumikomi (the leaping motion at the time of the strike) is done using your left hips and legs.

~~Uh, did you read the comment?~~

Ah, I think that is a typo, otherwise the whole comment doesn't make sense and my brain corrected it.

Re: The mystery of why left-handers are so much rarer (2016)

#240

Post by ivolimmen »

I am a 100% left and I can do most (except writing) with my right. Well I can do writing if I do it slow but it looks horrible. I have a group of friends that I know from 25 years ago and the weird thing is: all my friends are left as well. On of my friends also married a left handed partner, so the lefties are in the majority in my friends group.
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