It goes without saying that men who are physical stronger tend to be more aggressive, and women who are physically more attractive are outgoing. But why is this? And to what extent do our looks really affect our personality?

A new study, published in the journal Evolution and Human Behavior, investigated this question and discovered it’s not entirely a result of looks; instead, it comes down to gender and behaviour.

The team of scientists from the University of Gottingen examined two independent groups of participants from Germany and the UK. All participants were imaged using a 3D body scanner, and had their grip and upper body strength measured to determine their strength and physique.

The researchers found that they could not confirm a clear connection between attractiveness and extraversion in women.

“Although women who consider themselves attractive are actually more likely to be sociable and less shy, it could be their positive self-image that is the reason for this,” said the study’s lead author, Christoph von Borell.

In order to determine whether their outward behaviour was actually a result of their appearance alone, the researchers chose a study design in which physical attractiveness was assessed by other people.

“When we did this, the connection can no longer be observed,” explained von Borell.

When it came to men, the study showed that more muscular men were indeed more extraverted and considered aggressive behaviour to be more useful.

In many other behaviours, however, the results showed no clear connection with the men’s appearance.