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Why is almost everyone right-handed? A new study connects it to bipedalism

ox.ac.uk

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Re: Why is almost everyone right-handed? A new study connects it to bipedalism

#41

Post by Hotdogsteve »

jvanderbot wrote: post #34
SoftTalker wrote: post #32

Earlier quoted context omitted.

When was that? I know it used to happen, but I haven't heard of or seen that in my lifetime, I'm nearly 60.

Probably because it didn't happen to you, or kindergarteners don't know better and just play along. I only remember it because I was a little shit and got into a big fight about it. It would have been late 80s.

An elementary school teacher of mine had this happen to her (this was in the early '90s, so her experience I'm guessing would have been in the late '60s).

One day she wrote her name twice on the whiteboard and asked us to identify the difference between the two; visually they were identical, but she wrote one with her left hand and one with her right. She said as a kid she was made to use her right hand when she started showing signs of left-hand dominance.

Re: Why is almost everyone right-handed? A new study connects it to bipedalism

#42

Post by yawpitch »

stackghost wrote: post #25
yawpitch wrote: post #22

Earlier quoted context omitted.

Here’s my multiple years of anatomy classes response: the heart isn’t on the left. The aorta is, sure, but the vena cava is on the right. Also people with situs inversus (essentially all organs flipped laterally from “normal”) aren’t obviously more prone to left-handedness.

>Here’s my multiple years of anatomy classes response: the heart isn’t on the left. Why is the left lung smaller, then?

The heart is asymmetrical, but it’s in roughly the center of the chest. The left auricle and ventricle are larger muscles because they’re pumping through the descending aorta to the extremities, that’s the systemic circulatory branch, the plumbing for which is also largely to the right, while the right are pumping into the lungs alone as part of the pulmonary circulatory branch. The left lung (right on those with situs inversus) has two lobes and basically accommodates the extra muscle mass on its side of the heart, but if you really want to kill someone you stab them through the sternum, kind of dead center, not where they hold their hand when performing patriotism.

Re: Why is almost everyone right-handed? A new study connects it to bipedalism

#43

Post by rolph »

SoftTalker wrote: post #32
jvanderbot wrote: post #27

Earlier quoted context omitted.

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.

When was that? I know it used to happen, but I haven't heard of or seen that in my lifetime, I'm nearly 60.

it happened to me, and when my parents found out they flipped out.

i found out about my parents reaction like everyone else,, suddenly there was a bunch of screaming profanity and acoustic violence coming from the principals office

Re: Why is almost everyone right-handed? A new study connects it to bipedalism

#44

Post by rybosworld »

yawpitch wrote: post #22
scythe wrote: post #16

Earlier quoted context omitted.

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.

Here’s my multiple years of anatomy classes response: the heart isn’t on the left. The aorta is, sure, but the vena cava is on the right. Also people with situs inversus (essentially all organs flipped laterally from “normal”) aren’t obviously more prone to left-handedness.

Not disagreeing that handedness is probably unrelated to heart position.

But why would situs inversus somehow be tied to this at all? If there's a gene that favors right-handedness, it's not like it would somehow "choose" left-handedness because the individual has their internal organs flipped.

Re: Why is almost everyone right-handed? A new study connects it to bipedalism

#45

Post by nephihaha »

liquidise wrote: post #33
NickC25 wrote: post #14

What does it say for mixed-handed folks like myself (different skillsets per hand - in other words, throw and write with different hands)? What about cross-dominance (different body parts differ on dominant side - in other words, a right-handed person being left-foot dominant)? 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 i…

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

"Left-footed and right-handed"

Same as Mickey Dolenz who drummed for the Monkees. Very unusual combination.

Re: Why is almost everyone right-handed? A new study connects it to bipedalism

#46

Post by nephihaha »

Freak_NL wrote: post #10

So why are us southpaws a rarity? The article and the linked research paper both point to bipedalism and bigger brains as the cause, and the paper vaguely seems to hint at selective pressures leading to the right hand getting favoured by the majority of the population, but why? The question from the headline is excellent, if only it was actually answered.

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

Re: Why is almost everyone right-handed? A new study connects it to bipedalism

#47

Post by xattt »

gherkinnn wrote: post #23
scythe wrote: post #16

Earlier quoted context omitted.

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.

Wikipedia on Situs Inversus (visceral organs are mirrored, heart on the right, liver on left) [0], mentions mixed results regarding handedness. There would be a load of other confounding factors here and I know nothing about medicine. 0 - https://en.wikipedia.org/wiki/Situs_inversus

Childhood handedness development within the brain became independent of organ positioning, after positioning had become established.

Re: Why is almost everyone right-handed? A new study connects it to bipedalism

#48

Post by rybosworld »

yawpitch wrote: post #18
hypnodrones wrote: post #15

I would be interested in studies into impact of left hemisphere importantce on the right hand usage, possibly the more sophisticated and "logical" usage of our hands pressured it as well.

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

It's true that the creative vs. logical side of the brain is mostly a myth.

But the hemispheres absolutely DO specialize in very predictable ways. Core language faculties are almost always handled by the left hemisphere, for instance.

Face processing is almost universally handled by the right hemisphere.

We know these things from people who have suffered an injury to one of their hemispheres. A person with damage to the right hemisphere has a chance of not being able to recognize faces, but that's almost never seen in an injury that exclusively effects the left-hemisphere.

Re: Why is almost everyone right-handed? A new study connects it to bipedalism

#49

Post by stackghost »

yawpitch wrote: post #42
stackghost wrote: post #25

Earlier quoted context omitted.

>Here’s my multiple years of anatomy classes response: the heart isn’t on the left. Why is the left lung smaller, then?

The heart is asymmetrical, but it’s in roughly the center of the chest. The left auricle and ventricle are larger muscles because they’re pumping through the descending aorta to the extremities, that’s the systemic circulatory branch, the plumbing for which is also largely to the right, while the right are pumping into the lungs alone as part of the pulmonary circulatory branch. The left lung (right on those with sit…

>if you really want to kill someone you stab them through the sternum, kind of dead center, not where they hold their hand when performing patriotism.

Noted, thanks.

Re: Why is almost everyone right-handed? A new study connects it to bipedalism

#50

Post by booleandilemma »

scythe wrote: post #16
Freak_NL wrote: post #10

So why are us southpaws a rarity? The article and the linked research paper both point to bipedalism and bigger brains as the cause, and the paper vaguely seems to hint at selective pressures leading to the right hand getting favoured by the majority of the population, but why? The question from the headline is excellent, if only it was actually answered.

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 wonder why you're getting downvoted? Even if it turns out you're completely wrong it's still an interesting point and something I never even considered before.
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