International Left-handers day

International Left-Handers Day Takes place annually on the 13th of August, to promote awareness of the inconveniences faced by left-handers and increase public awareness of the advantages and disadvantages of being left handed in a predominantly right-handed world and to celebrate Left-handers’ creativity, adaptability and sporting prowess. It was founded by the Left-Handers Club in 1992, with the club itself having been founded in 1990. It celebrates their uniqueness and differences. Left-handed people make up approximatelyseven to ten percent of the world’s population. Hundreds of millions of left-handed people in today’s society have to adapt to use right handed tools and objects. The firs Left-handers Day took place on August 13, 1997.( I myself am left handed and i used to find whenever i drew something with a pencil, i used to end up smudging what I had already drawn GRRRRR!)

Right-handedness is most common. Right-handed people are more skillful with their right hands when performing tasks. Studies suggest that 88–92% of the world population is right-handed. Left-handedness is far less common than right-handedness. Left-handed people are more skillful with their left hands when performing tasks. Studies suggest that approximately 10% of the world population is left-handed. ambidexterity (the ability to use both hands )occurs in about a 1% of the population and is quite rare, although it can be learned. A truly ambidextrous person is able to do any task equally well with either hand. Those who learn it still tend to favor their originally dominant hand.
Ambilevous or ambisinister people demonstrate awkwardness with both hands. Ambisinistrous motor skills or a low level of dexterity can be the result of a debilitating physical condition or injury.

There are several theories of how handedness develops in individual humans. Occurrences during prenatal development may be important; researchers studied fetuses in utero and determined that handedness in the womb was a very accurate predictor of handedness after birth. In a 2013 study, 39% of infants (6 to 14 months) and 97% of toddlers (18 to 24 months) demonstrated a hand preference.One common theory, as to how hand preference affects the hemispheres, is the brain hemisphere division of labor. Since speaking and handiwork require fine motor skills, its presumption is that it would be more efficient to have one brain hemisphere do both, rather than having it divided up. Since in most people, the left side of the brain controls speaking, right-handedness predominates. This theory also predicts that left-handed people have a reversed brain division of labor.

Verbal processing in right-handed individuals takes place mostly in the left hemisphere, whereas visuospatial processing is mostly done in the opposite hemisphere. Left-handed individuals have a heterogeneous brain organization in which their brain hemisphere is either organized in the same way as right-handers (but with the hemispheres reversed) or even such that both hemispheres are used for verbal processing. When the average is taken across all types of left-handedness, it shows that left-handers are less lateralized. Left handedness can also be inherited. To date, two theoretical single gene models have been proposed to explain the patterns of inheritance of handedness, by Marian Annett of the University of Leicester and by Professor Chris McManus of UCL. However evidence from linkage and genome-wide association studies suggests that genetic variance in hand preference cannot be explained by a single genetic locus and that it is polygenic and at least 40 loci contribute to determining this trait.

Genome-wide association studies have been carried out to measure of relative hand skill these found that genes involved in the determination of left/right asymmetry in the body play a key role in determining hand preference. This suggest that the same mechanisms that determine left/right asymmetry in the body (e.g. Nodal signaling and ciliogenesis) also play a role in the development of brain asymmetry (hand preference is an indication of of brain asymmetry for motor function). Studies also indicate that genetic factors explain 25% of the variance in handedness, while environmental factors explain the remaining 75%. Asymmetric methylation of CpG sites is also thought to plays a key role in gene expression asymmetries. studies also indicate that individuals who have had in-utero exposure to diethylstilbestrol (a synthetic estrogen-based fertility drug) were more likely to be left-handed. Diethylstilbestrol animal studies “suggest that estrogen affects the developing brain, including the part that governs sexual behavior and right and left dominance”. There is evidence that the position of the fetus in the final trimester and a baby’s subsequent birth position can also affect hand preference.  About two-thirds of fetuses present with their left occiput (back of the head) present at birth grew up to be left handed. This partly explains why prematurity results in a decrease in right-handedness. asymmetric prenatal positioning can also create asymmetric stimulation of the vestibular system, which is involved in the development of hand preference. Every major disorder in which patients show reduced right-handedness is associated with either vestibular abnormalities or delay, and asymmetry of the vestibular cortex is strongly correlated with hand preference. Some suggest that ultrasound may affect the brains of unborn children, causing higher rates of left-handedness in children whose mothers received ultrasounds during pregnancy, although research does not corroborate this. Some scientific papers suggested the life expectancy of left-handed people was nine years less than that of right-handed people, although these findings were quickly discredited.

Historically Left-handed people as a group have historically produced an above-average quota of high achievers. left-handers’ brains are structured differently (in a way that increases their range of abilities) and the genes that determine left-handedness also govern development of the language centers of the brain This allows them to process language, spatial relations and emotions in more diverse and potentially creative ways, Many left-handers are also gifted in music and math. The development of hand preference in toddlers (18-24months) also correlates with language abilities. Lower-birth-weight and complications at birth are positively correlated with left-handness and A variety of neuropsychiatric and developmental disorders like autism spectrum disorders, depression, bipolar disorder, anxiety disorders, schizophrenia, and alcoholism has been associated with left-handed people. many people with cerebral palsy are also left-handed. Research suggests that there is also an increased risk of suffering bone fractures, developing Breast Cancer, heart disease, Parkinson’s Disease or multiple sclerosis in left-handed women. However, left-handers enjoy an advantage in fighting and sports and many left-handers take part in Interactive sports such as table tennis, badminton, cricket, and tennis. In fencing, about half the participants are left-handed.

In cricket, a bowler’s left-handedness can give them an advantage because a left-handed bowler challenges A right-handed batsman more than a right-handed bowler does, because the angle of a bowler’s delivery to an opposite-handed batsman is much more penetrating than that of a bowler to a same-handed batsman  While In baseball, a right-handed pitcher’s curve ball will break away from a right-handed batter and towards a left-handed batter and left-handed batters have a slight advantage over right-handed batters when facing right-handed pitchers. Left-handed batters have a slightly shorter run from the batter’s box to first base than right-handers. This gives left-handers a slight advantage in beating throws to first base on infield ground balls. Defensively in baseball, left-handedness is considered an advantage for first basemen because they are better suited to fielding balls hit in the gap between first and second base, and because they do not have to pivot their body around before throwing the ball to another infielder. A left-handed catcher would have a potentially more dangerous time tagging out a baserunner trying to score.In four wall handball, typical strategy is to play along the left wall forcing the opponent to use their left hand to counter the attack. In water polo the centre forward position has an advantage in turning to shoot on net when rotating the reverse direction. Ice hockey typically uses a strategy in which a defence pairing includes one left-handed and one right-handed defender. However in most sports hand preference has little or no advantage. Golf and miniature golf feature occasional situations when obstacles on one side of the ball but not the other interfere with the stance or swing of a right- or left-handed player. Paraphilias (atypical sexual interests) have also been linked to higher rates of left-handedness.

Many tools and procedures are designed to facilitate use by right-handed people, often without even realizing difficulties placed on the left-handed. During the Industrial Revolution, workers needed to operate complex machinery that was almost certainly designed with right-handers in mind. This would have made left-handers more visible and at the same time appear less capable and more clumsy. Children were taught to write with a dip pen. While a right-hander could smoothly drag the pen across paper from left to right, a dip pen could not easily be pushed across by the left hand without digging into the paper and making blots and stains.even today Thousands of left-handed people  have to adapt to use right handed tools and objects.

Left-handed people have been considered unlucky or even malicious for their difference by the right-handed majority. In many European languages, including English, the word for the direction “right” also means “correct” or “proper”. Throughout history, being left-handed was considered negative. The Latin adjective sinister means “left” as well as “unlucky”, and this double meaning survives in European derivatives of Latin, including the English word “sinister”. There are many negative connotations associated with the phrase “left-handed”: clumsy, awkward, unlucky, insincere, sinister, malicious, and so on. A “left-handed compliment” is also considered one that is unflattering or dismissive in meaning. In French, gauche means both “left” and “awkward” or “clumsy”, while droit(e) (cognate to English direct and related to “adroit”) means both “right” and “straight”, as well as “law” and the legal sense of “right”. The name “Dexter” derives from the Latin for “right”, as does the word “dexterity” meaning manual skill.  Black magic is sometimes referred to as the “left-hand path”. In Taiwan and China, left-handed people are strongly encouraged to switch to being right-handed, or at least switch to writing with the right hand. Due to the importance of stroke order, developed for the comfortable use of right-handed people. It is more difficult to write legible Chinese characters with the left hand than it is to write Latin letters because it can cause smudging if the outward side of the hand is allowed to drag across the writing, writing in the Latin alphabet might possibly be less feasible with the left hand than the right under certain circumstances. Conversely, right-to-left alphabets, such as the Arabic and Hebrew, Are easier to write with the left hand in general.

 

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s