Has anybody any idea why we aren´t? You would think that being ambidexter would give one an evolutionary advantage. Like in primitive warfare for instance, you could smack your enemy´s skull (or defend yourself against someone trying to smack yours) with both your left and right hand.
And then there´s another argument: being right or lefthanded is more specific. Why would evolution (or god) create a feature in humans, that is very specific, but yet, serves no purpose?

who isn't?
I can shoot right, or left handed.
I write left, throw right.

I don't really see an evolutionary advantage to being ambidextrous for all skills though

Evolution and god are entitled to mess up. Maybe we cleaned ourselves with one hand and ate with another? Maybe in our more ape-like days one hand was stuck to a tree all the time?

I save thinking time by not wondering which hand to use for certain one handed tasks.

Someone messed up my food supply millions of years ago... and NOW look what it did to me!

Yeah, ofcourse i meant:'why aren´t MOST people ambidexter?'

left-hemisphere dominance? (it controls the right hand and vice versa)

When you specialize your brain to be ambidexter it will mean that parts of your brain in each brain half will be used for a very specific body movement. It can be advantageous to have a more specialized part of a certain brain half where all power is diverted to a certain task without having to deal with body movements.

Another idea is that if you use both hands for something it might overall cost more energy (brain wise and/or body wise).


Kind regards,

The Traveler

That makes sense. I never looked at it that way.

It could also maybe explain why i often feel the tendency to cross my legs when i´m doing complex things like typing: to relax the part of my brain that isn´t involved in that particular activity. A sort of subcounscious efficiency mechanism.

And benzyme: you´re wasting your energy man

Handedness is not an all or nothing phenomenon; rather, theres a spectrum ranging from strong R handedness- weak R handedness- ambidexterity- weak L handedness- strong L handedness.

Its important to note that some L handers are taught to write with their R hand and one can often get an inkling of this discrepancy by:

1.observing the posture of the R hand when the alleged R hander writes; often they hold the pen which is a mirror-image of the way the L hander holds it and this is clearly different to the 'natural' R handers posture when writing;

2.Asking which hand they throw a ball with, stir coffee/tea, flip a coin or hold a knife;

3.Asking about a family history of L handedness or ambidexterity.This is important because cerebral hemispheric dominance for language is strongly determined by heredity. Handedness and cerebral dominance for speech are closely allied.

Approximately 90% of people are considered definitely R handed;of this 90%, 99% are strongly L hemisphere dominant for language.Damage here will therefore cause aphasia/dysphasia ie speech problems.The L hander doesnt show the same pattern.About 40% of L handers tend to be R hemisphere dominant for speech, with the remaining 60% being L hemisphere dominant for speech.The degree of dominance is also not as strong as found in R handers and about 80% of L handers have significant language function in both hemispheres.

As a result of this, damage to either hemisphere in the L hander will cause speech problems in 80% of cases but the degree of dysfunction will be less than that resulting from L hemisphere damage in a R hander.

Knowing the cerebral dominance for language is important to know as the risk of hemisphere surgery and its effect on language has profound implications when considering surgery.

One can establish hemispheric dominance by injecting one carotid artery with Sodium Amytal at angiography and observing the effect on speech production and comprehension.

Neurology is effing great, IMO.

A lot of researchers seem to agree that our dominant right-handedness is a byproduct of left brain dominance. If so, the question of polytrip becomes "Why do we mostly show left brain dominance?" and that's some fascinating stuff.

Non human primates don't even come close to the degree of brain lateralization in humans, so it might have to do with the development of language, particularly vocal language, and evidence suggests that appeared quite late in evolution.

Some ideas go like this - 1) Bipedalism releasing the hands, 2) Use of hands in communication, and 3) Vocal communication emerging as another step in the evolution of communication.

But how does lateralization fit here?

One speculation that I like, and agree with IME, is that left/right hemispheres show somehow different ways to process information. Left hemisphere seems to be efficient in fast, serial processing and right hemisphere in parallel processing. Kind of analytical vs. holistic.

If we follow this, maybe language (essentially serial) is more likely to develop the left hemisphere and increase its influence.

But you could try to refute this by suggesting that this hypothetical serial-processing of the left human brain might be an adaptation to the development of vocal language, and not the reason behind lateralization... so it looks like an egg-chicken situation.

One interesting take on this topic (and at least universecannon knows it here) is in Left in the Dark. The book is a nice read, and among other things proposes that lateralization is a not-so-optimal brain function, derived from a change of diet in the evolution of hominids.

I bat right handed, I play hockey left handed..I can golf right or left handed. I write with my right hand..I surf, snowboard and skateboad regular(left foot leading)..

I once met someone who snowboarded goofy(right foot foreward) but could only skateboard regular. Weird.

when i was a child i broke my right arm, as a result i had to do all my homework and such with my left hand.
as a result, i ended up having better writing, and felt more comfortable writing with my left hand then my right.

after the cast was removed i was (as far as writing goes) ambidextrous for a good while, but as i did everything with my healed right arm it slowly dominated again, and now i cannot write with my left hand at all (again).

also when studying percussion i trained my left hand a lot harder than my right hand (as it was both slower and hard to keep time with) as a result, as far as drumming goes, i am basically ambidextrous, in fact excelling at some things with my left hand.

based on these experiences, it is my belief that which hand dominates is largely based on how you train yourself to use your body.
just like how people who lose their arms become extremely dexterous with their feet and legs.

i write with my right hand and do nearly everything else with my left.

1 handed task - lefty

2 handed tasks - righty

*goes back in time slaps kindergarden teacher who says right hand is the one that we 'write' with.


Seriously kids.

i practice juggling and play guitar to improve my ambidexterity, but i also consciously try and do things with my right hand (which is definitely my "off" hand, and was before i injured my right shoulder/elbow/wrist making it harder to use) because I firmly believe that trying to exert awareness and control directly over your nervous system is...just good for ya.

I was completely ambidextrous until I broke my left arm when I was in elementary school, now I can no longer write or throw with my left hand, but most everything else I can do still

To agree with Shadowman-x, juggling does help improve ambidexterity.

Another note which I find interesting, I have discovered that I can crack a bullwhip (mine's an 8 foot) much easier with my left arm, than my with my right, surprisingly enough my dad has the same phenomenon, yet he never broke either of his arms.

I am a serial abuser of my hands, mostly the right one, and have had several brushes with repetitive stress issues. As a result I've divided up my daily tasks far more equitably between hands. Tablet, right hand; mouse, left. Precise detail painting, right hand; looser stuff, left. The right hand is obviously far more trained but the left one is perfectly good and has fewer bad habits- the loose painting work I do lefty tends to have less stylized and more fundamental brushwork, which for me is a good thing.

Right handedness is something many of us are born with but that the world around us reinforces continually, starting with those first grade teachers. Most tools and equipment are optimized for right handed use. Because of this, lefties have more accidents- not because they are clumsy but because their tools are.

On a side note, almost all chickens are born right handed. So a simplistic brain function explanation makes perfect sense.

i try to assign tasks that ill complete with my left hand to increase my functionality of it.

in high school i tried doing my math homework with only my left hand, needless to say it made the problems much harder...