This and other articles from Dave are available at www.BehaviourSolutions.com.  This article is written from a UK perspective and statistics relate to the UK. 

Over 500 million people worldwide are left handed. Being left handed as recently as the 1900s meant problems for a pupil in school. Often children were forced to write right-handed and often had their left hand tied to the chair to stop them using it. As recently as 1950s when I was in Primary School I was forced to eat lunch as a right-handed person would. Things were even worse at the turn of the century between the 19th and 20th centuries left-handedness was beaten out of children. There was a severe discrimination against left-handers. Many words used to describe left-handedness have alternative negative meanings – awkward, clumsy, sly and sinister. 

In the 1970s a piece of research was conducted which reinforced the view that pupils were ‘discouraged’ from being left-handed earlier in the century. For example only 3% of 55-64 year olds were left-handed and this had increased to 11% of 15-24 year olds. In fact in the past 100 years the proportion of left-handers has gone up 400%. 

About 12% of men and 8% of women are left-handed. Males are therefore 50% more likely to be left-handed than women. Left-handedness is more common in men because of the exposure of the foetus to excess testosterone which suppresses the development of the left brain and causes neurons to migrate to the right hemisphere of the brain. The male foetus is more susceptible to the influence of testosterone. This results in the right area developing as a centre for language and the area of the dominant hand (right side of the brain results in left hand dominance). In right-handed people the left side of the brain controls language and speech but in left-handed people the opposite is true. There is also a link between left- handedness and having an increased chance of having language problems, dyslexia, stuttering and childhood autism. 

There is a genetic link to left-handedness and a gene has been discovered that increases the chances of being left-handed. It is known as LRRTM1. This genetic connection is reinforced by the fact that if one twin is born left-handed, there is a 76% chance that the other twin will also be left-handed. Older women are also more likely to have left-handed children and now that women are having babies later in life could also be a reason for an increase in the number of left-handers. 

Up to 30% of children are arriving at Primary School not knowing if they are left or right-handed. This is because many children do not go through a crawling phase as a result of parental fears of leaving babies on their fronts because of cot deaths. This is a key phase in helping babies develop their co-ordination and understand their dominant hand. Often the children are wrongly diagnosed at 5 with development problems when in fact they do not know their dominant hand. 

The hair whorl from the crown on the top of the head (where your hair spirals from) can give an indication on whether a person is left-handed. In 95% of right-handers, hair tends to grow from the whorl in a clockwise direction. Left-handers and ambidextrous can coil either clockwise or anti-clockwise. 

Many students who are left-handed need help to navigate what is a right-handed world. Some problems are:

  • When writing in ink, left-handers tend to smudge their writing as their hand follows the pen.
  • When using scissors the edges on the blades are shaped for right-handed use.
  • Using computer mice – these are set up for right-handed use.
  • Book spines get in the way of a left-hander writing.
  • Musical instruments are made for right-handers – guitar, wind instruments (trumpets etc) keyboards.
  • Cameras are orientated for right-handers.
  • Equipment in technology – irons, saws, knives, tin openers, power tools are made for right-handed use.
  • Sports equipment such as golf clubs are made for right-handers.