Do Left-handed People Develop Differently in the Womb?

Published September 7th, 2019 - 05:46 GMT
(Shutterstock/ File Photo)
(Shutterstock/ File Photo)
Highlights
Four genetic regions have been discovered which may cause left-handedness .

Four genetic regions have been discovered which may cause left-handedness, and they could also be the reason lefties have superior language skills. 

The study of left-handed folk failed to identify any precise 'left-handed genes' but was able to narrow it down within the human genome to certain areas. 

Researchers then found that left-handedness may be a byproduct of how the brain develops in the womb as well as the body's microtubules. 

These form the cells cytoskeleton, the internal scaffolding that does most of the heavy lifting within human cells. 

Dr Akira Wiberg, a Medical Research Council fellow at the University of Oxford, who carried out the analyses, said: 'We discovered that, in left-handed participants, the language areas of the left and right sides of the brain communicate with each other in a more coordinated way.

'This raises the intriguing possibility for future research that left-handers might have an advantage when it comes to performing verbal tasks, but it must be remembered that these differences were only seen as averages over very large numbers of people and not all left-handers will be similar.'

Around one in ten people are left-handed with genes responsible for a quarter of cases, according to previous studies.

Dr Wiberg said: 'Around 90 per cent of people are right-handed, and this has been the case for at least 10,000 years.

'Many researchers have studied the biological basis of handedness, but using large datasets from UK Biobank has allowed us to shed considerably more light on the processes leading to left-handedness.'

The findings were based on an analysis of the genes of 400,000 participants from the UK Biobank, including 38,332 who were left-handed.

Professor Dominic Furniss, joint senior author on the study, said: 'Throughout history, left-handedness has been considered unlucky, or even malicious.

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'Indeed, this is reflected in the words for left and right in many languages. For example, in English "right" also means correct or proper; in French 'gauche' means both left and clumsy.

'Here we have demonstrated that left-handedness is a consequence of the developmental biology of the brain, in part driven by the complex interplay of many genes.

'It is part of the rich tapestry of what makes us human.'

The exact genes that cause left-handedness are not known but the new study, published in the journal Brain, linked four genetic traits or 'regions' with it.

Three were linked with proteins that are in turn linked with tiny structures similar to bones within cells, known as microtubules.

These tiny molecules form part of the 'scaffolding' inside cells, or the cytoskeleton, which guides how cells are constructed as well as what they do.

The researchers found having the left-handed genetic traits affected the cytoskeletons in an area of the brain that joins regions that deal with language.

Professor Gwenaëlle Douaud, said: 'Many animals show left-right asymmetry in their development, such as snail shells coiling to the left or right, and this is driven by genes for cell scaffolding, what we call the 'cytoskeleton'.

'For the first time in humans, we have been able to establish that these handedness-associated cytoskeletal differences are actually visible in the brain.

'We know from other animals, such as snails and frogs, that these effects are caused by very early genetically-guided events, so this raises the tantalising possibility that the hallmarks of the future development of handedness start appearing in the brain in the womb.' 

This article has been adapted from its original source.


© Associated Newspapers Ltd.

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