The right half of the brain controls the left side of the body, and the left side of the brain controls the right side of the body.
In most people, the left side of the brain is better developed, so the right hand is stronger and more controllable than the left hand. But sometimes, the right side of the brain is more developed; then the person is left-handed.
Less than one person in six is left-handed. No one is sure why so many more people are right-handed. It’s possible that the reasons go back to the days of the caveman.
A person who was born right-handed would fight with a weapon in his right hand and use his left hand to shield himself; a left-handed person would fight with his left hand and shield himself with his right hand.
A person who uses his left hand to shield himself protects his heart, which is on the left side of the body. So, many right-handed persons who were wounded would survive, while left-handed persons would suffer wounds around their heart and die.
Over the course of evolution, this higher survival rate among right-handed persons could have led to more persons being born right-handed.
Possibly Related Amazing Facts:
- What Decides Whether You Will Be Right-Handed or Left-Handed?
- What Does Ambidextrous Mean and Why Do Some People Write Left-Handed But Play Sports Right-Handed?
- Who gets injured more often right-handed people or southpaws?
- Why Are Left Handed People More Accident Prone and How Are Left Handers At a Bigger Risk of Accidental Death?
- What is worse a stroke, a heart attack, or a brain aneurysm?
14 Comments
This is interesting! I’m left-handed… this is an amazing website! It’ easy to read and understand but I’m Hungarian! Good work!
I’m left handed but is it true that lefties die sooner than righties?
On average,righties live nine years longer than left handed people.
Brain asymmetry goes beyond men or cavemen, to just about all animals. As it turns out, while the brain if forming, a protein called Nodal attracts neurons to it, and the more Nodal, the larger concentration of nerve endings will exist in this spot. However, Nodal only exists on the left side of the body (Part of the reason why your heart is on the left side of your body too, actually). A complete lack of Nodal will leave a chance that things will get messed up, with the possibility of your heart being on the wrong side of your body (Dextrocardia). With a slight lack of Nodal, small abnormalities, such as left handedness occur.
-g
this is so wierd im write with my left hand but i do everything else with my right? e.g throwing, kicking a ball and my right arm is stonger
im not sure if this is true or not but once i heard that some people who were left handed had a twin earlier on in pregnency but the twin on the right handside lost nurisment and died thats why there left handed ?
but i do find this other fact intresting
if this happens to left handed people or vice-versa, why ar people bothright and left handed? could it be that both the sides og the brain are equally ‘cotrolable’? please explan
This is just my opinion, but I don’t think it’s possible to be born using both hands. I guess it’s possible. For example, if you break your arm or something and the doctor says you have to wear a cast for 6 months, it is a possibility that you will have to learn how to write with your other hand. And a lot of left-handed people can do things with their right, since it’s the most common. That’s just my opinion. That, and 3 of my mom’s sisters were left-handed, and her dad was left-handed but had to avert to right-handedness back then? Get it? Some people are ambidextrous b/c they had to change their handedness in school. Also one of my aunts eats with her right hand, yet again, she’s left-handed. What I’m saying is, most people who are ambidextrous, chose to be that way. Well, a lot of them anyway.
Your logic on this is completely flawed. Studies have not come up with any conclusive evidence that handed-ness has any genetic component. Thus, your theory that more right-handed people survived in the caveman days and therefore were able to pass along their genes is bunk. Not because more of them survived, that could be true, but it would have nothing to do with the possible handed-ness of their offspring. Both of my parents are left-handed. I am the oldest of four children and ALL of us are right handed. If you knew anything about genetics, which based on your passage I suspect that you don’t, you would understand that if lefthanded-ness is an inheritable trait and it is recessive, then ALL of my siblings and I would be left-handed. Or, conversely, if lefthanded-ness is inheritable and is a dominant trait, and righthanded-ness is recessive, then two righthanded people could only pass on righthanded genes and my grandmother (who is righthanded) would have had to have an affair with the mail man and cheated on my grandfather (righthanded) to produce my lefthanded mother. In short, if a couple only possesses the recessive trait, then all the offspring will have the trait. That does not happen with handed-ness. It is NOT inherited. Do your research before you spend time posting an article. This was an assinine argument.
Liz, both my parents have brown hair and yet I have red hair. Using your logic, hair colour is not passed on genetically.
No…….red hair can be recessive to brown hair. Or, as someone else mentioned, incomplete dominance is possible. My aunt has blue eyes, both her parents have brown eyes. This is because blue is a recessive trait. However, she (my aunt) and her husband can only produce blue eyed children because they both have blue eyes (recessive) and only carry blue-eyed genes. Follow? Look up simple Mendelian genetics. And yes, I understand that it is more complex than simple dominant/recessive and there are other ways that alleles are expressed. However, with left-handedness being as rare as it is, if it had a genetic component, it would be nearly impossible for two lefties (who must possess VERY rare genes if this is a genetic trait) to have FOUR right handed children, as is the case in my family.
Liz, you’re presuming that handedness is influenced by a single gene loci, and that there are only two possible alleles (left and right). Most traits have been shown to be the result of gene complexes and multitudes of alleles, which makes uncovering the basis for them all that much harder. It’s going to take a lot more research to definitvely ‘prove’ that handedness has no genetic component.
And besides that, you’re forgeting that phenotypic expression can not only be dominant/recessive, it can also be co-dominant, semi-dominant, or incompletely dominant.
This is guess, not a fact.
Your logic on this is completely flawed. Studies have not come up with any conclusive evidence that handed-ness has any genetic component. Thus, your theory that more right-handed people survived in the caveman days and therefore were able to pass along their genes is bunk. Not because more of them survived, that could be true, but it would have nothing to do with the possible handed-ness of their offspring. Both of my parents are left-handed. I am the oldest of four children and ALL of us are right handed. If you knew anything about genetics, which based on your passage I suspect that you don’t, you would understand that if lefthanded-ness is an inheritable trait and it is recessive, then ALL of my siblings and I would be left-handed. Or, conversely, if lefthanded-ness is inheritable and is a dominant trait, and righthanded-ness is recessive, then two righthanded people could only pass on righthanded genes and my grandmother (who is righthanded) would have had to have an affair with the mail man and cheated on my grandfather (righthanded) to produce my lefthanded mother. In short, if a couple only possesses the recessive trait, then all the offspring will have the trait. That does not happen with handed-ness. It is NOT inherited. Do your research before you spend time posting an article. This was an assinine argument.