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Scientists Explain Why Some People Are Left-Handed

Scientists Explain Why Some People Are Left-Handed

One tenth of the human population is left-handed, with some countries having more left-handed people than others. Less-developed countries appear to have a more even mix of left- and right-handed people, whereas advanced countries such as Japan have less than one tenth of their population as left-handed. But why are some people left-handed? Is it all to do with the country you are born in? Is it genetics, nature or nurture? Which things about lefties are myths and which are facts?

Can Left-Handedness Be Predicted?

Some say left-handedness can be predicted by the position of the child in the womb, but there are many times when this prediction model breaks down. In fact, the predictive model used is only marginally better than guessing, which suggests the position in the womb is only a possible indicator or stimulating factor and is not actually a predominant factor in what makes a person left- or right-handed.

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Is It Genetic?

Just like the position in the womb, there are some people that make convincing arguments that show genetics may be an influencer, but it is not a determining factor or a reliably predictive factor (just like the position in the womb). This has been proven by the fact that identical twins with identical DNA may be right- or left-handed. Even with triplets, there may be one or two that are left-handed and the other one or two that are right handed — which throws out most arguments that being left-handed is genetic.

There are some that say the left- or right-handedness of your parents is an influencing factor, with two right-handed parents only having left-handed children 10% of the time. However, if two right-handed parents give up their baby at birth and hand it off to a left-handed couple, then the child is only 10% likely to be right-handed, which proves genetics has nothing to do with it.

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People Used To Be Left- And Right-Handed In Equal Portions

We appear to have had left-handed people for generations. In fact, there is a varied amount of evidence that suggests that left-handed people have been around for over 500,000 years — but that is not really the issue. What is the issue is that these days, being left-handed is a negative thing, but in the past it was normal. Furthermore, before being right-handed was considered ideal, people were an even mix of right- and left-handed.

Swords And The Left-Hand Side Of The Road

Back in the days when horses were a main mode of transportation, people traveled on the left side of a road. That meant that when people passed them on horses, they would be on their right hand side. It becomes common practice to fight with your sword in your right hand because that is where the most likely attack would come from. People learned to hold their shield with their left hand and their sword with their right hand so that they may fight as they pass each other. People also saluted with their right hand for a similar reason, because it helped to expose their face (if they were wearing head amour), and showed that their right hand was free of weapons. Children were encouraged to be right-handed so that they may hold their sword with their right hand.

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The Pen Is Mightier Than The Sword

When people became more advanced and learn to write on paper, they discovered that writing with their right hand was easier than writing with their left. Writing with their left hand would cover what was being written and would smudge the ink on the page. Ergo, children were encouraged to be right-handed so that they may learn more easily and write without hindrance.

The Mouse Is In The House

Even computers are built for right-handed people. It is common for the mouse to be on the right side of the keyboard and for the index finger of the right hand to click the left mouse button as opposed to the middle finger of the left hand. Keyboards are also set up with number pads on the right instead of the left, which favors right-handed people once again.

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Children Copy Their Parents

The idea that many children must be born right-handed is a myth. The reason so many children become right-handed is that they watch their parents and copy them. They see their parents doing things whilst predominantly using their right hand and so they copy them. For example, if a child picks up a spoon with the same hand as his or her parent, then the child may copy the finger placement on the spoon. This cannot be done if the child picks up the spoon with the other hand because the position of the fingers and the palm of the hand would be all wrong and the child would struggle to copy the parent. 

So, next time you are left wondering why a child seems to prefer the left or right hand, try taking a look at the adults around them.

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Last Updated on June 6, 2019

Science Says Silence Is Much More Important To Our Brains Than We Think

Science Says Silence Is Much More Important To Our Brains Than We Think

In 2011, the Finnish Tourist Board ran a campaign that used silence as a marketing ‘product’. They sought to entice people to visit Finland and experience the beauty of this silent land. They released a series of photographs of single figures in the nature and used the slogan “Silence, Please”. A tag line was added by Simon Anholt, an international country branding consultant, “No talking, but action.”

Eva Kiviranta the manager of the social media for VisitFinland.com said: “We decided, instead of saying that it’s really empty and really quiet and nobody is talking about anything here, let’s embrace it and make it a good thing”.

Finland may be on to something very big. You could be seeing the very beginnings of using silence as a selling point as silence may be becoming more and more attractive. As the world around becomes increasingly loud and cluttered you may find yourself seeking out the reprieve that silent places and silence have to offer. This may be a wise move as studies are showing that silence is much more important to your brains than you might think.

Regenerated brain cells may be just a matter of silence.

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     A 2013 study on mice published in the journal Brain, Structure and Function used differed types of noise and silence and monitored the effect the sound and silence had on the brains of the mice.[1] The silence was intended to be the control in the study but what they found was surprising. The scientists discovered that when the mice were exposed to two hours of silence per day they developed new cells in the hippocampus. The hippocampus is a region of the brain associated with memory, emotion and learning.

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    The growth of new cells in the brain does not necessarily translate to tangible health benefits. However, in this instance, researcher Imke Kirste says that the cells appeared to become functioning neurons.

    “We saw that silence is really helping the new generated cells to differentiate into neurons, and integrate into the system.”

    In this sense silence can quite literally grow your brain.

    The brain is actively internalizing and evaluating information during silence

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      A 2001 study defined a “default mode” of brain function that showed that even when the brain was “resting” it was perpetually active internalizing and evaluating information.

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      Follow-up research found that the default mode is also used during the process of self-reflection. In 2013, in Frontiers in Human Neuroscience, Joseph Moran et al. wrote, the brain’s default mode network “is observed most closely during the psychological task of reflecting on one’s personalities and characteristics (self-reflection), rather than during self-recognition, thinking of the self-concept, or thinking about self-esteem, for example.

      “When the brain rests it is able to integrate internal and external information into “a conscious workspace,” said Moran and colleagues.

      When you are not distracted by noise or goal-orientated tasks, there appears to be a quiet time that allows your conscious workspace to process things. During these periods of silence, your brain has the freedom it needs to discover its place in your internal and external world.

      The default mode helps you think about profound things in an imaginative way.

      As Herman Melville once wrote,[2]

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      “All profound things and emotions of things are preceded and attended by silence.”

      Silence relieves stress and tension.

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        It has been found that noise can have a pronounced physical effect on our brains resulting in elevated levels of stress hormones. The sound waves reach the brain as electrical signals via the ear. The body reacts to these signals even if it is sleeping. It is thought that the amygdalae (located in the temporal lobes of the brain) which is associated with memory formation and emotion is activated and this causes a release of stress hormones. If you live in a consistently noisy environment that you are likely to experience chronically elevated levels of stress hormones.

        A study that was published in 2002 in Psychological Science (Vol. 13, No. 9) examined the effects that the relocation of Munich’s airport had on children’s health and cognition. Gary W. Evans, a professor of human ecology at Cornell University notes that children who are exposed to noise develop a stress response that causes them to ignore the noise. What is of interest is that these children not only ignored harmful stimuli they also ignored stimuli that they should be paying attention to such as speech. 

        “This study is among the strongest, probably the most definitive proof that noise – even at levels that do not produce any hearing damage – causes stress and is harmful to humans,” Evans says.[3]

        Silence seems to have the opposite effect of the brain to noise. While noise may cause stress and tension silence releases tension in the brain and body. A study published in the journal Heart discovered that two minutes of silence can prove to be even more relaxing than listening to “relaxing” music. They based these findings of changes they noticed in blood pressure and blood circulation in the brain.[4]

        Silence replenishes our cognitive resources.

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          The effect that noise pollution can have on cognitive task performance has been extensively studied. It has been found that noise harms task performance at work and school. It can also be the cause of decreased motivation and an increase in error making.  The cognitive functions most strongly affected by noise are reading attention, memory and problem solving.

          Studies have also concluded that children exposed to households or classrooms near airplane flight paths, railways or highways have lower reading scores and are slower in their development of cognitive and language skills.

          But it is not all bad news. It is possible for the brain to restore its finite cognitive resources. According to the attention restoration theory when you are in an environment with lower levels of sensory input the brain can ‘recover’ some of its cognitive abilities. In silence the brain is able to let down its sensory guard and restore some of what has been ‘lost’ through excess noise.[5]

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          Summation

          Traveling to Finland may just well be on your list of things to do. There you may find the silence you need to help your brain. Or, if Finland is a bit out of reach for now, you could simply take a quiet walk in a peaceful place in your neighborhood. This might prove to do you and your brain a world of good.

          Featured photo credit: Angelina Litvin via unsplash.com

          Reference

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