According to researchers, men with symmetrical faces are less likely to lose their memory and intelligence in later life, indicating facial symmetry is beneficial for mental health. Men, who have regular features and higher levels of facial symmetry, are more likely to be in better mental shape at the end of their lives, compared to others who aren't so lucky.

Psychologists comparing reasoning and reaction time test scores with measurements of facial symmetry in 216-men and women, analysing the results of the 1932 Scottish Mental Survey, mapped the faces of subjects from photographs, found having faces with matching left and right sides, made them less prone to mental decline between the ages of 79 and 83. They said it could show a link between physical condition and mental decline.

The results showed facial symmetry affected the ageing of men's mental processes, however, the same did not hold true for women. Researchers suggest it could be because DNA has a different affect on ageing among women, or it could be that they live four years longer than men on average.

The findings published in the journal Evolution and Human Behaviour reveal, mental functions decline more rapidly in the last four years before death.

Study lead, Dr Lars Penke from the University of Edinburgh says, facial symmetry reflects stability in men, indicating fewer genetic and environmental disturbances, such as, diseases, toxins, malnutrition or genetic mutations during an individual's development.

Previous research has also already shown associations between facial symmetry and general health and perceived physical attractiveness, including suggesting cognitive decline to be an aspect of body-wide ageing, a link that indicates facial symmetry can be used as a marker that could predict this decline.