"And the world's ugliest dog is... Wild Thang!" The crowd roars. A tiny creature is held aloft for all to see. The spectators at the Marin-Sonoma County Fair in California could not be happier with their champion.

Wild Thang is an eight-year-old PekingeseA toy dog breed originating from China. They were once favoured as companions by the Chinese Imperial court. with fuzzy fur and a long, flopping tongue. As a puppy he contracted a virus which nearly killed him. His teeth never developed and his right leg has permanent damage. 

The competition organisers insist that the contest is not cruel, but rather about "having fun with some wonderful characters and showing the world that these dogs are really beautiful". Many of the entrants are rescued from the street, and Wild Thang has helped to raise money to rescue seven Pekingese from Ukraine.

So why exactly is Wild Thang, with his frizzy hair and flopping tongue, considered ugly? It all comes down to a lack of symmetry, say some scientists. 

For a long time, facial symmetry has been held up as a reliable indicator of physical attractiveness. Experts call it the "Evolutionary Advantage Theory"; examples of asymmetry suggest that an individual has issues that have affected their development, from mutationsChanges to the structure of genes. and injuries to stress, malnourishmentWhen someone does not have the nutrients they need in their food. or disease.¹

In short, without even thinking about it, we associate symmetry with good genes and physical health, and these are traits we might want to pass on to our children. 

The symmetry theory has taken off in popular culture. On social media, filters such as "Inverted", "Twins" or "Mirror" promise to show people how symmetrical - and thus beautiful - they really are. 

Years earlier, journalist Haley Nahman tried out a physical contraption called the "True Mirror" in her office. It promised to let users "see how you really are". Her co-workers were "horrified". "Everyone was convinced they looked crooked and absurd, a collection of PicassoPablo Picasso (1881-1973) is regarded as the greatest artist of the 20th Century. Three of his paintings have sold for more than 0 million (82m).-like features that no-one else could corroborateSupport a statement or theory. It comes from a Latin verb meaning to strengthen.."

Today, some scientists remain unconvinced by the symmetry theory. In real life, perfect symmetry can be boring, even unnerving. "If you create a perfect symmetrical face in the lab, those faces have very low beauty ratings," says UCLAUniversity of California, Los Angeles. psychology professor Dahlia W Zaidel.² "We never look at perfectly symmetrical faces, never from the minute we are born." 

In fact, throughout history, people have added imperfections in order to appear more attractive. In 18th Century Mexico, "chiqueadores" made from tortoiseshell were added to the forehead, while in Europe, what started off as covers for smallpoxA disease estimated to have killed 300 million people in the 20th Century. scars soon became a fad among the aristocracy. 

Later, the real beauty marks of models such as Marilyn Monroe and Cindy Crawford popularised facial flaws in Hollywood. Today, "fake freckles" are a TikTok trend. 

The desire for the real, not just the divine, does not only exist in the beauty industry. Musicians will sometimes leave flaws in their songs. Interior designers know that people often find wonky objects more charming. In Japan, the aesthetic wabi-sabi finds beauty in imperfection. The practice of kintsugi involves mending broken crockery with gold. The object's flaws are not hidden. Instead, they are highlighted. 

Is it more attractive to be imperfect?

Yes: Human beings are by nature imperfect. It is these imperfections that make us organic and real. Somebody who was 100% perfect in all ways would simply be unnerving.

No: We are drawn to symmetry and perfection as a sign of good health. There are some traits that almost everyone finds attractive.

Or... The old saying goes: "Beauty is in the eye of the beholder." And it is true. What is considered "perfect" or "imperfect" has varied wildly throughout history. There is no one single example of a truly attractive person.