Why Are More People Right-Handed Than Left-Handed?

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.

Comments

  1. Anonymous says

    I’m left handed but is it true that lefties die sooner than righties?

  2. Anonymous says

    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

  3. anonymous says

    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

  4. anonymous says

    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

  5. Megan says

    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.

  6. Steve Carpenter says

    Liz, both my parents have brown hair and yet I have red hair. Using your logic, hair colour is not passed on genetically.

  7. Byrn says

    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.

  8. Elizabeth Gillmann says

    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.

  9. Elise Dosch says

    hey were any of born left handed or did you learn to be left handed cause i was born left handed! its fun being unique.

  10. need help says

    Well i`m right handed and my one brother is right,my other brother left, my dad left,my mom left. I want to learn to be both right and left but its harder for a righty because facts tell that left handed people can use both hands easier than a right hander all i have to learn is how to be left handed also i want to learn how to do almost everything with left also alongside right. Please give me some advice or help.

  11. ML says

    My two older sisters and I are all left-handed. Only know of 2 distant relatives who are also left-handed. My middle sister can’t use right-handed scissors, and I can’t use left-handed scissors. I’m mostly leftie in all other ways however.

    I knew, growing up, that being left-handed was somewhat rare, however, I didn’t realize until recently that 3 leftie siblings was really unusual. Has anyone heard of similar family stories?

  12. G says

    Me my brother and sister are both lefthanded but my mum and dad are righthanded

  13. UNICORN-FREAK says

    Well its funny, my friend teddy(disguise name cuz theres a whole lota weirdos out there) has an asian mom with brown eyes and a white dad with blue eyes(so sorry to be rude if you are somehow offended) teddy has blue eyes but her little brother and sister twins have hazel eyes with i think some green in the middle.and my other friend licorice(disguise name again) looks seemly black(sorry if youre offended) but her parent are viet and dont have a trace of black looks in them.ive never studied genetics but i no that 1 out of a million a viet couple would have a black child

  14. Elise Dosch says

    Hello again does anybody live in Fort Mill South Carolina that is left handed?

  15. matt says

    The facts and they are more like statistics then facts, are that approximatley 5 righties per leftie, or 1 of 6 people is a leftie. That is the only thing you can really draw out of everything they said. It is only a statistic. Nothing more nothing less. What they go on to do, which is anybody’s right to do is to postulate a theory .. that is all they can do .. their theory our ancestors in the cavemen days had a harder time staying alive while they were left handed. It was harder but not impossible and so some have obviously survived and hence we still have a population that is still 1/6 lefties or about 16% of the population.

  16. Tom Fisher says

    Of all the left and right handed people I have met, left handed people are definitely cleverer than their right handed counterparts.

  17. Matt says

    The “sword-and-shield” hypothesis was debunked decades ago. In studies of countries with high rates of violence and murder, left handedness is actually more common, presumably because a left-handed person can catch someone off guard if the victim is used to fighting only right-handed people.

    The prevailing hypothesis today is that it was in the “meningitis belt” of Africa, early in human history. Meningitis is disproportionately more lethal in right-brained individuals (and thus more commonly left-handed people).

    Stats on handedness are also skewed because social stigma causes many natural left-handed people to use their right hands.

  18. Richard says

    Im right handed but many of my friends are left handed. But studies show that left handed people die nine year earlier than a right handed person. Justin bieber barack Obama and bill gates are left handed. Bill gate made right handed mouse because their is more tight handed people. I still used my left hand to twist caps open and open doors. Be glad that you got two hands rather than one!

  19. dee cee says

    I am a biologist, or was one when I graduated 30 years ago. Left or right handedness does have, off the top of my head, a genetic component. Not saying that there are not other factors during fetal development that are also significant.
    But now with wikipedia and google, everyone can know what I know in 10 minutes or less.

    For instance: “A large study of twins from 25,732 families by Medland et al. (2006) has indicated that the heritability of handedness is 24%.[14] This leaves about three quarters of the effect to be explained by environmental factors.”

    And: “Previc, after reviewing a large number of studies, found evidence that the position of the fetus the final trimester and a baby’s subsequent birth position can affect handedness.”

    Also interesting, left handed college grads make 10 to 15% more than right handed grads. Left handed people are about one and a half times more likely to die in a fatal accident and have two times the chance for a stressful delivery. Which brings us back to the postulate that there is a cause and effect going on in fetal development.

Leave a Reply

Your email address will not be published. Required fields are marked *