Life Science What makes a left-hander? Aussie research brings the answer a step closer

What makes a left-hander? Aussie research brings the answer a step closer

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It used to be seen as a trait of the devil and smacked out of young learners – but left-handedness has gradually edged into vogue, picking up an association with creative and cool people.

It even got a sub-plot in The Simpsons courtesy of Ned Flanders.

Researchers are still puzzling, however, over just why some people are left-handed (plus the even more rare ambidextrous).

Turns out, it might be more environmentally driven than we first thought.

An Australian study analysed the data from more than 1.7 million people, in the largest study of its kind.

The team, from QIMR Berghofer Medical Research Institute and the University of Queensland, identified 48 genetic variants that have the ability to influence a person’s dominant hand. Previously, only five had been identified.

Royal family portrait
The Queen’s father was believed to have been left-handed, and there’s some theories there is an over-representation of left-handers in the Royal Family. Photo: AAP

Of those 48, 41 had a part to play in deciding if a person was left-handed, co-senior author Sarah Medland said. A further seven were linked to ambidexterity.

An individual’s hand preference is first shown during gestation – even as embryos we can begin to show a dominant hand.

David Evans, joint-senior author from the University of Queensland, said the data analysis showed genetics only account for a fraction of variation in handedness – it was much more environmental factors that came into play.

“This percentage was similar for ambidexterity, meaning factors such as injuring a hand or training by playing sport or musical instruments are likely to have a strong role in a person’s ability to use both hands equally well,” Professor Evans said.

Homer’s neighbour Ned Flanders is a left-hander and opens the Leftorium, in The Simpsons.

So while there’s still no definite ruling on just why some of us favour our left over our right – and there may never be – the research still helps builds the bigger picture of human biology.

“There is an enduring fascination with why some people are left- or right-handed or both, understanding why some people are left-handed and others right-handed is also an important research question because handedness can influence brain structure and the way different functions are located within the brain,” Professor Medland explained.

The research was published in Nature Human Behaviour on Tuesday.

The left and right of it all

The prevalence of left-handedness varies across the world – from 3.5 per cent in China to more than 13 per cent in the Netherlands.

Australia sits with about 10 per cent of the population.

Infographic: The Countries With The Most Left-Handed People | Statista

In many parts of the world there’s still some bias against left-handers – the left hand can be considered dirty (it’s usually the one that gets the job of ah, wiping, whereas the right hand is for eating, shaking hands, that sort of thing).

Discrimination against lefties can go all the way back to King George VI of England, who was forced to write with his right hand – as was the norm at the time – but was often papped using his left hand for other activities that one usually favours their dominant for.

At its worst, bias against the left-handers went as far as linking them to the devil himself. Or at least, sin in general.