What it means if your hands match

Researchers found a connection from an early age between bodily symmetry, physical health and mental performance. Photo / 123RF

Children with more symmetrical hands may be smarter than their un-even-handed peers, a study has suggested.

Researchers at Edinburgh University found that youngsters with balanced proportions on their left and right hands were able to react more quickly in mental tests. This was true even after accounting for age and gender differences.

Researchers say the findings suggest a connection from an early age between bodily symmetry, physical health and mental performance.

"The connection between physical symmetry and reaction times could be an important clue to health and wellbeing over a person's life course," said Prof Ian Deary, director of the Centre for Cognitive Ageing and Cognitive Epidemiology at the University of Edinburgh, who led the research project.

"This finding can shed light on how the mind and the body develop together from childhood to older age."

Previous studies have already shown a link between bodily symmetry and mental performance in old age, as men with more symmetrical faces are less likely to experience a decrease of brain power in later life. However, it is the first time that the effect has been seen in children.

The team looked at health data from 856 youngsters between the ages of four and 15 in Edinburgh and recorded hand symmetry using a digital scanner.

They then tested reaction times using a computer-based test where participants were asked to play at being a frog trying to catch flies as they appeared on the screen.

The researchers found that those who caught the flies the quickest had the most symmetrical hands.

Previous research has indicated that reaction times are an important indicator of health, and reaction times speed up significantly as children approach adulthood, only to slow down when approaching older age.

Dr David Hope, from the Centre for Medical Education at the University of Edinburgh, said: "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."

In 2011 the same group at Edinburgh found it was possible to learn about a person's childhood by looking at how symmetrical their face is. Using 15 different facial features, they found that people with asymmetric faces tended to have more deprived childhoods, and harder upbringings, than those with symmetrical faces.

Their findings suggest that early childhood experiences, such as nutrition, illness, exposure to cigarette smoke and pollution, leave their mark in people's facial features. Surprisingly, their facial features were not affected by their socioeconomic status in later life, which suggests that even those who escape deprivation can never get away from their past.

The link between facial symmetry and exposure to stress in early life might explain why many studies have found that people with symmetrical faces are considered to be the most attractive. Lop-sided facial features may unconsciously provide a signal that a person is less desirable as a mate due to the stress they experienced in early life, which could leave them vulnerable to disease and premature death.

The study was published in the journal Developmental Psychology.