child hands
Children with symmetrical hands react faster in mental tests, study shows.Tania Cataldo/Flickr

Children who have symmetrical hands are more intelligent than those without, a study has suggested. Published in the journal Developmental Psychology, scientists found that children with balanced physical proportions of their hands were able to react faster in mental tests.

This was also found to be true after accounting for age and gender differences. The researchers, from the Universities of Edinburgh and Glasgow, looked at 856 children aged between four and 15.

Hand symmetry was recorded with a digital scanner, while the reaction times were measured in a computer-based test. Findings showed a link between symmetry and mental performance.

Researchers believe bodily symmetry could be a sign of biological fitness. Previously, scientists had found a connection between body symmetry and mental performance in old age – men with more symmetrical faces were less likely to experience cognitive slow-down in later life. Similarly, it has long been known symmetrical faces are linked with attractiveness.

Speaking about the latest study, Ian Deary, director of the Centre for Cognitive Ageing and Cognitive Epidemiology, said: "The connection between physical symmetry and reaction times could be an important clue to health and well-being over a person's life course. This finding can shed light on how the mind and the body develop together from childhood to older age."

David Hope, from the Centre for Medical Education, added: "This finding links cognitive ability and health very early in the life course – even before school age physical actions are connected with a person's body then reflected in mental function."