Research and Survey on Left Hander

Left-handed writing is a mirror image to that of the right-hander, making the teaching process confusing for the right-handed teacher of a left-handed student. The result is that left-handed students often learn to write with their hand curled around the pen so that it can meet the paper at the same angle as the right-hander,inhibiting the left hand from writing freely. Once this habit is formed, it is difficult to break. This curling of the hand results in the heel of the palm being placed behind the writing, forcing the writer to lift it off the paper and making the grip even more awkward. In addition, constantly lifting and replacing the hand over fresh ink often causes smudging, causing problems for many left-handed students, especially in exam situations. When the left hand is held correctly, it is below the writing, as is typical for right-handers.

Hand orientation is developed in fetuses, most commonly determined by observing which hand is predominantly held close to the mouth. In 2007, researchers discovered that specific alleles of at least one of thr e single-nucleotide polymorphisms upstream of the already known LRRTM1 gene, were linked to left-handedness.

Another theory states that exposure to higher rates of testosterone before birth can lead to a left-handed child. This is the Geschwind theory, named after the neurologist who proposed it, Norman Geschwind. It suggests that variations in levels of testosterone during pregnancy shape the development of the fetal brain. Testosterone suppresses the growth of the left cerebral hemisphere and so more neurons migrate to the right hemisphere. The highly developed right hemisphere is now better suited to function as the center of language and handedness. The fetus is more likely to become left-handed, since the right hemisphere controls the left half of the body. The theory goes on to tie the exposure to higher levels of testosterone and the resultant right-hemisphere dominance to auto-immune disorders, learning disorders, dyslexia, and stuttering, as well as increased spatial ability.

A left-handed individual may be known as a southpaw, particularly in a sports context. It is widely accepted that the term originated in the United States, in the game of baseball. Ballparks are often designed so that batters are facing east, so that the afternoon or evening sun does not shine in their eyes. This means that left-handed pitchers are throwing with their south-side arm. The Oxford English Dictionary lists a non-baseball citation for "south paw", meaning a punch with the left hand, as early as 1848, just three years after the first organized baseball game.

In baseball, due to the direction in which curveballs and sliders break, it is generally accepted that the pitcher has an advantage when his handedness is the same as the batter's, and the batter has an advantage when they are opposite. For this reason, many baseball teams include a left-handed specialist pitcher, who is brought into the game specifically to pitch to dangerous left-handed batters in crucial situations.

In boxing, someone who boxes left-handed is frequently referred to as southpaw. The term is also used to refer to a stance in which the boxer places the right foot in front of the left, so it is possible for a right-handed boxer to box with a southpaw stance. Most boxers, southpaw or otherwise, tend to train with sparring partners who adopt an orthodox stance which gives southpaws an advantage. Manny Pacquiao is an example of a southpaw (although he writes with his right hand). In the popular boxing film series Rocky, the main character Rocky Balboa is a 'southpaw'. Southpaw is also a term in professional wrestling, often giving them the advantage.

In 2006, researchers at Lafayette College and Johns Hopkins University in a study found that right-handed men are 15 percent poorer than left-handed men for those who attended college, and 26 percent poorer if they graduated. The wage difference remains unexplained, and appears to apply to women.