I throw and write using my right hand

[eigenguy]

I throw and write using my right hand, but for things that I do with both hands like swing a baseball bat or hold a knife and fork when cutting food I do as a lefty. Does anyone know what this might mean? I couldn't find anything on the net about this. Thanks.

 

[Monique]

Actually, I saw that researchers have done a whole-genome scan to search for genes that possibly could be involved in handedness. It just went by my eyes though, I'd have to look it up again and see if they actually found interesting regions on the genome..

 

[pragyan]

Is handedness ONLY Genetic? Or is it possible for a person- say right handed, which is considered to be the default, to practice writing with the left hand AND succeed WITHOUT developing any side- syndromes... like left handed ppl who practice being right handed, are known to develop speech problems like stamering.

Besides, these kid of traits are likely to be multigenic sincethe coordination of many components- neurons involved in vision, hearing, voluntary muscle movements and motor neuron activity are going to be involved.


Howz life otherwise?

 

[Monique]

I think there is definitely something genetic or developmental that forces people to become left/right handed. How about in India, Pragyan? Is it a cultural phenomenon that eating may only be done with the right hand? In families where this is a rule, children still prefer to do all other activities, such a writing, with the left hand.

 

[Monique]

Here is the article:
http://www.nature.com/cgi-taf/DynaPage.taf?file=/ejhg/journal/v11/n10/abs/5201048a.html&dynoptions=doi1066569636

We have performed a genome scan using 25 nuclear families consisting of right-handed parents with at least two left-handed children. Handedness was assessed as a qualitative trait using a laterality quotient. Laterality quotients indicate the direction of handedness, which is hand preference for performing unimanual tasks. Both parametric and nonparametric linkage analyses were applied. The parametric analysis using the single-locus genetic model of Klar resulted in four different regions with LOD scores higher than 1. The region on chromosome 10q26 gave a suggestive LOD score of 2.02 at a recombination fraction of 0.05. Nonparametric analysis gave an NPL score for this region of 2.16. However, further fine mapping of the region on chromosome 10q26 failed to obtain a higher LOD score. These results suggest that handedness is a human quantitative trait locus and that the proposed non-Mendelian monogenic models are incorrect.

I cannot get the the full article, so I cannot really comment on what they found. The published in Nature, I would guess they have got something to say.. but they say they found a lod score just above 2 (suggestive linkage) but couldn't increase the signal by finemapping (false positive?).

 

[eigenguy]

Originally posted by Monique
I think there is definitely something genetic or developmental that forces people to become left/right handed.

Born lefties will become righties if forced early enough etc.

 

[Sonny Crockett]

Originally posted by eigenguy
Born lefties will become righties if forced early enough etc.

I am mainly left-handed. Some things I was "forced" into doing right-handed were sports-related, like golf. There were no left-handed clubs in our family so I had to learn with right-handed clubs. I also never had a baseball glove for my right hand until it was too late. I was already converted. I bat left-handed though because there is no equipment difference.

It is written that Pythagoras was the one who started the whole "left=bad" thing. It may have started before him, but he was definitely crazy enough to have started it. Anyone read his "ipse dixits"? One of them was: When beginning a journey, always start with your right foot. Another: Under no circumstances should you eat your dog. Pretty weird. Anyway, now I am just rambling. Sorry. In latin left means "sinister" (I think. That is what I was taught).

 

[Monique]

Yes, left is sinister, right dexter.

 

[pragyan]

... and "dexter" has a laboratory!

...sorry 'bout that- couldn't resist cracking it!

In India, left is... or was somehow considered inauspicious if not "sinister"! So children who were left handed were forced to do things ( not limited by the polarity of the equipment in use) using only the right hand.

I think early western culture will also show the same kind of trend.

But a majority of people are right handed. Right? If so, then does right handedness provide any , however tiny, evolutionary advantage over left haqndedness? And maybe left handed ness is not harmful so it hasn't been selected against... but since most ppl use their "rights" , I wonder if it is beneficial in anyway...

 

[hypnagogue]

I really doubt there is some evolutionary advantage in being right handed vs left handed, in itself. If anything, one could maybe claim that right handedness vs left handedness arises as a side effect of some deeper difference in brain organization, and that there is something evolutionarily advantageous about the deeper brain organization of a right hander.

I'm more inclined to think that the prevelance of right handed people is more of an arbitrary result brought about by culture, however. For instance, I can't really vouch for the validity of this, but I have heard that in older times (in the middle east I believe) the right hand was desiganted as the 'clean' hand and therefore handling food with the dirty left hand was a grave offense punishable by, er, forceful removal of the left hand from the perpetrator's body. That would certainly count as a cultural pressure against left handers, if it's true.

Some statistics would be of help in this discussion. Does anyone know what the distributions of right handers vs left handers are like internationally? Do some cultures have higher proportions of right handers than others, or is the distribution more or less uniform across all cultures?

 

[pragyan]

Hmmm... that maybe true. There are a lot many features that exist because of no particular reason and because they are not harmful- beczuse they have NOT been selected AGAINST and NOT because they have been selected FOR.
I don't have any data- will try and get hold of it. In the meanwhile, looking at monique's articlemay help.

 

[Monique]

My Hindu friend grew up in a family where food was to be eaten with the auspicious right hand, not that he liked it since he is a lefty. That makes me think that there is definitely an underlying biological reason for left/right handedness.

 

[hypnagogue]

Originally posted by Monique
My Hindu friend grew up in a family where food was to be eaten with the auspicious right hand, not that he liked it since he is a lefty. That makes me think that there is definitely an underlying biological reason for left/right handedness.

If anything, this only seems to support the idea that right/left handedness is largely determined by cultural factors. Just because the right hand is seen as being auspicious doesn't mean that there's really something to it.

 

[iansmith]

Originally posted by hypnagogue
If anything, this only seems to support the idea that right/left handedness is largely determined by cultural factors. Just because the right hand is seen as being auspicious doesn't mean that there's really something to it.

If think there migth some genetic factor into handness. From my own experiemence, my brother is a lefty. When my brother would eat (when he was a year old), my mom you put a spoon in his rigth hand and my brother would transfert the ustensil from his rigth to the left. My brother would never eat or do anything with his rigth. According to my mom account, for me it would not matter which hand I used. Now, I'm rigth handed but i can used my left with very few problem.

 

[hypnagogue]

Originally posted by iansmith
If think there migth some genetic factor into handness. From my own experiemence, my brother is a lefty. When my brother would eat (when he was a year old), my mom you put a spoon in his rigth hand and my brother would transfert the ustensil from his rigth to the left. My brother would never eat or do anything with his rigth. According to my mom account, for me it would not matter which hand I used. Now, I'm rigth handed but i can used my left with very few problem.

I'm not denying that handedness has a genetic basis. I'm just questioning why we see the predominance of right handers-- and I'm just skeptical that the predominance is indicative of an evolutionary advantage. Instead of any classical evolutionary pressures favoring righies over lefties, I propose that the pressures favoring righties over lefties may have been mainly culturally enforced.

 

[Monique]

Originally posted by hypnagogue
If anything, this only seems to support the idea that right/left handedness is largely determined by cultural factors. Just because the right hand is seen as being auspicious doesn't mean that there's really something to it.

You misunderstood, even though the left hand is regarded as being auspicious, he is still a lefty, going against cultural norm (ofcourse still eating with the right hand, but prefering the left).

 

[iansmith]

Maybe the handness is a simple example of a Mendellian genetics where rigth is the dominant trait whereas the left is a recessive trait. Using basic calculation we end with 75% of the population that are rigth handed and 25% of the being left ended.

Social pressure will skew the data but a born lefty still give is genes to his progeny.

 

[hypnagogue]

Originally posted by Monique
You misunderstood, even though the left hand is regarded as being auspicious, he is still a lefty, going against cultural norm (ofcourse still eating with the right hand, but prefering the left).

No I understood... I'm not saying social pressures determine your handedness for you. Just that the main 'advantage' of being right handed historically has been a function of social norms and circumstances, rather than having actual survival value.

 

[Kerrie]

i believe handedness is genetic...my 3 year old son is a total leftie, and i was a leftie until age 7 myself (not sure why i switched according to my mother)...i also believe that handedness determines how one approaches problem solving in life as lefties defintiely think different then the majority right-handedness world but come to the same "conclusions"...they also have to adapt due to how doors, cars, etc are all set up for right handers...

 

[Mattius_]

I Write, eat with left; throw with right.

I do think that left handed people approach problems differently then right handed people. But as kerrie said, both right and left come to the same conclusion.

One statistic i do know to be valid is the fact that left handed people on average live 7 years less...

I would guess stress... but it could be an accumulation of things.

 

[Janus]

Originally posted by Mattius_
I Write, eat with left; throw with right.

I'm simular in that I do everything right handed, except when I put pencil to paper. When I write or draw, I use my left hand.