Why have we evolved to have a dominant arm?

[Nagel]

Does anyone have an answer to this question? Surely having both arms equally able would give an evolutionary advantage and so be selected for. So why have we evolved to be right or left handed when it would be far more useful to be fully ambidextrous?

[chem1st]

Pens and swords.

 

Perhaps the keyboard will change this somewhat, but with the porn on the net perhaps not

[Nagel]

Sword use would be one skill where you would get a very important evolutionary advantage from being ambidextrous as they were absolutely a matter of life or death.

[shane39]

Sword use would be one skill where you would get a very important evolutionary advantage from being ambidextrous as they were absolutely a matter of life or death.

 

Your question is probably as baffling as to why the left side of the brain controls the right side of the body,and visa-versa.

[Nagel]

Your question is probably as baffling as to why the left side of the brain controls the right side of the body,and visa-versa.

 

Yes baffling, but these are the most interesting sorts of questions. None of these things will have happened with no reason as evolution doesn't work like that.

[*_ash_*]

Yes baffling, but these are the most interesting sorts of questions. None of these things will have happened with no reason as evolution doesn't work like that.

 

I agree. I think it's an interesting question.

 

auto has provided the first theory - I'm interested to read more.

[HarmOKnee]

One theory is that it is because the left side of the brain is used for language, so hand signals which came before language tended to be done with the right hand.

 

Hmm, how did the right hand know that the left side of the brain was for language if language hadn't been invented?

[Rupert_Baehr]

One theory is that it is because the left side of the brain is used for language, so hand signals which came before language tended to be done with the right hand.

 

Yahoo Answers ads a codicil to that: "...subsequent research had found that while 95% of right handed people did indeed process language in the left hemisphere, so did 70% of left handed people - and half of the rest used both hemispheres."

 

I'm left-handed for most things, but there are a few things I can't do left-handed. I hold a knife and fork like a right-handed person would do (and I find it difficult to do that the left-handed way) but I hold a spoon with my left hand.

 

When I learnt to play a guitar (albeit not very well) I couldn't do that left-handed.

 

I'm also 'left eyed'. When I fire a weapon (pistol, rifle or even a bow and arrow) I use my left eye to sight. - I can't use my right eye. (If I try to shoot right-handed, the shots/arrows will probably go out of the range high left.)

 

Some aircraft are flown using the left hand, some the right - that never presented a problem. Similarly, I (like everybody else) work the tiller on a boat with whichever hand is nearest.

 

When I first went to school, the Infants' class teacher tried to persuade me to write with my right hand. - She gave up (fortunately.) I heard somebody say (Old wive's tale?) "If you try to make a left-handed child write with his right hand, he will start to stutter." I've no idea whether there is any evidence to support that argument, but I wonder whether it might have something to do with the 'language' side of the brain?

[MrSmith]

Does anyone have an answer to this question? Surely having both arms equally able would give an evolutionary advantage and so be selected for. So why have we evolved to be right or left handed when it would be far more useful to be fully ambidextrous?

 

I haven't, I'm ambidextrous but the down side is I am also dyslexic, it is normal for one side of the brain to dominate but usually in dyslexic's neither side is dominant which gives you the ability to use both legs, arms, hands equally. The down side is that because you never develop a preference it tends to take longer to learn many things.

Someone that can kick a ball equally well with both feet won’t usually be able to kick it as well as someone with a dominant foot. Because I can write equally well with both hands my writing isn’t as good as someone with a dominate hand.

One of the first signs to look out for in a child is if they keep swapping hands when painting and playing, they could be dyslexic.

[skinz]

I agree. I think it's an interesting question.

 

auto has provided the first theory - I'm interested to read more.

 

Ditto..one of the most interesting questions to date.

 

I haven't, I'm ambidextrous but the down side is I am also dyslexic, it is normal for one side of the brain to dominate but usually in dyslexic's neither side is dominant which gives you the ability to use both legs, arms, hands equally. The down side is that because you never develop a preference it tends to take longer to learn many things.

Someone that can kick a ball equally well with both feet won’t usually be able to kick it as well as someone with a dominant foot. Because I can write equally well with both hands my writing isn’t as good as someone with a dominate hand.

One of the first signs to look out for in a child is if they keep swapping hands when painting and playing, they could be dyslexic.

 

An interesting prognosis/theory Mr Smith.

 

The whole question could be argued in reverse. When a child is born is it's limbs not equal? Therefore it's safe to assume using the same logic that rather than one organ becoming more dominant one organ is actually dumbing down.