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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 September 10, 2018

Overcoming The Pain Of A Breakup: 3 Suggestions Based On Science

Overcoming The Pain Of A Breakup: 3 Suggestions Based On Science

We thought that the expression ‘broken heart’ was just a metaphor, but science is telling us that it is not: breakups and rejections do cause physical pain. When a group of psychologists asked research participants to look at images of their ex-partners who broke up with them, researchers found that the same brain areas that are activated by physical pain are also activated by looking at images of ex-partners. Looking at images of our ex is a painful experience, literally.[1].

Given that the effect of rejections and breakups is the same as the effect of physical pain, scientists have speculated on whether the practices that reduce physical pain could be used to reduce the emotional pain that follows from breakups and rejections. In a study on whether painkillers reduce the emotional pain caused by a breakup, researchers found that painkillers did help. Individuals who took painkillers were better able to deal with their breakup. Tamar Cohen wrote that “A simple dose of paracetamol could help ease the pain of a broken heart.”[2]

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Just like painkillers can be used to ease the pain of a broken heart, other practices that ease physical pain can also be used to ease the pain of rejections and breakups. Three of these scientifically validated practices are presented in this article.

Looking at images of loved ones

While images of ex-partners stimulate the pain neuro-circuitry in our brain, images of loved ones activate a different circuitry. Looking at images of people who care about us increases the release of oxytocin in our body. Oxytocin, or the “cuddle hormone,” is the hormone that our body relies on to induce in us a soothing feeling of tranquility, even when we are under high stress and pain.

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In fact, oxytocin was found to have a crucial role as a mother is giving birth to her baby. Despite the extreme pain that a mother has to endure during delivery, the high level of oxytocin secreted by her body transforms pain into pleasure. Mariem Melainine notes that, “Oxytocin levels are usually at their peak during delivery, which promotes a sense of euphoria in the mother and helps her develop a stronger bond with her baby.”[3]

Whenever you feel tempted to look at images of your ex-partner, log into your Facebook page and start browsing images of your loved ones. As Eva Ritvo, M.D. notes, “Facebook fools our brain into believing that loved ones surround us, which historically was essential to our survival. The human brain, because it evolved thousands of years before photography, fails on many levels to recognize the difference between pictures and people”[4]

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Exercise

Endorphins are neurotransmitters that reduce our perception of pain. When our body is high on endorphins, painful sensations are kept outside of conscious awareness. It was found that exercise causes endorphins to be secreted in the brain and as a result produce a feeling of power, as psychologist Alex Korb noted in his book: “Exercise causes your brain to release endorphins, neurotransmitters that act on your neurons like opiates (such as morphine or Vicodin) by sending a neural signal to reduce pain and provide anxiety relief.”[5] By inhibiting pain from being transmitted to our brain, exercise acts as a powerful antidote to the pain caused by rejections and breakups.

Meditation

Jon Kabat Zinn, a doctor who pioneered the use of mindfulness meditation therapy for patients with chronic pain, has argued that it is not pain itself that is harmful to our mental health, rather, it is the way we react to pain. When we react to pain with irritation, frustration, and self-pity, more pain is generated, and we enter a never ending spiral of painful thoughts and sensations.

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In order to disrupt the domino effect caused by reacting to pain with pain, Kabat Zinn and other proponents of mindfulness meditation therapy have suggested reacting to pain through nonjudgmental contemplation and acceptance. By practicing meditation on a daily basis and getting used to the habit of paying attention to the sensations generated by our body (including the painful ones and by observing these sensations nonjudgmentally and with compassion) our brain develops the habit of reacting to pain with grace and patience.

When you find yourself thinking about a recent breakup or a recent rejection, close your eyes and pay attention to the sensations produced by your body. Take deep breaths and as you are feeling the sensations produced by your body, distance yourself from them, and observe them without judgment and with compassion. If your brain starts wandering and gets distracted, gently bring back your compassionate nonjudgmental attention to your body. Try to do this exercise for one minute and gradually increase its duration.

With consistent practice, nonjudgmental acceptance will become our default reaction to breakups, rejections, and other disappointments that we experience in life. Every rejection and every breakup teaches us great lessons about relationships and about ourselves.

Featured photo credit: condesign via pixabay.com

Reference

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