When one thinks of the implications of being a righty or a lefty, writing comes to mind pretty quick.
Did you ever consider eye dominance? When you take a picture, you bring the camera towards one eye so you can truly see what you want to photograph.
So not only do we have a dominant hand; we also have a dominant eye.
What about the ear then? Is there a difference between hearing and listening? If 40% of us prefer listening with the left ear while 30% of us prefer taking pictures with our left eye, only 10% of us write with the left hand. Why would you think that is?
There was a time where being left-handed was considered an inherent default.
So where does it come from that we are lefties or righties?
We know that chimps choose a dominant hand for tasks that require fine motor skills. That being said, that dominant hand seems interchangeable for chimps.
In Neanderthals, things were already a bit different. They were intelligent yet clumsy. They would use their teeth to masticate meat while, with one hand; they would use a knife to cut the meat. We find that 10% of Neanderthals were lefties.
We also know by now that being a righty or a leftie is genetic to a certain extent. There could be up to 40 genes that play a role. We have not yet identified the ones that are necessarily involved.
Psychologist Chris McManus from the University College London stipulates that lefties brains are organized in a more variable way than righties brains. He believes that lefties are more talented yet they would be lacking in some specific areas.
Others do not share his opinion. Dorothy Bishop is a developmental neuropsychology professor from Oxford University and she indicates that we sometimes make associations between handedness and certain characteristics yet there are no real cause to effect phenomenon here.
All the while, Peter Hepper, from Queen University, in Belfast studied the behavior of fetuses and found that 9 out of 10 of them preferred sucking on their right thumb.
Glen Doman and Carl Delacato (founders of the IAHP) as of 1955 were developing a pyramid of motor development. They stipulate that, at stage 6 of 7, a child of 5 years old works on developing hemispheric balance. Based on that accomplishment, by stage 7, at age 6, he develops a dominance where, as this dominance develops optimally, dominant hand, eye, ear and foot would be on the same side.
It is my experience in Posturology and in Functional Neurology that we achieve our best results when we balance the brain towards cortical dominance.