Paying service to the human lip-Dr Karl Kruszelnicki

 They can seal tight, suck, blow, whistle, hold and kiss. With hundreds of muscles and multiple layers of cells, the human lip serves a much greater role than we give them credit for, as Dr Karl Kruszelnicki explains.

If you follow social media, especially of the Kardashian kind, you will surely have seen human lips of unbelievable shapes and sizes. You might even have become a little confused as to what makes up the ideal lip—just one more thing to worry about.

Luckily, plastic surgeons have done a study to let us know what’s hot, and what’s not.

In most animals, the lips are fairly unimportant. They’re often just a few folds of tissue hanging around the outside of the jaws.

Turtles and birds have given up on lips altogether—their lips have evolved into hard beaks of keratin. But in mammals, the trend has gone the other way, and lips have become very important.

Mammalian mouth curtains

Our human lips have about a dozen muscles attached to them, so they can perform complex actions. We can create huge numbers of different sounds, as well as whistle and even play musical instruments.

Human lips are soft and highly mobile body parts. Baby lips are sensitive tactile organs—which is why the littlies are forever shoving things in their mouths.

Adult lips can be good for kissing. And besides being an erogenous zone, the actual shape and size of the lips is linked to attractiveness.

On the practical front, lips hold food inside your mouth. They can shut so tightly that solids, liquids or gases can be kept either in or out.

Being able to wrap your lips strongly around something lets an adult suck up a gluggy thickshake, and lets a baby breastfeed.

The skin on most of your face has up to 16 separate layers of cells. But the skin on your lips is much thinner—with only three to five layers of cells. This thinness allows the red blood cells to give the lips their glamorous red tinge.

But lips do miss out on hair and sweat glands. That means they miss out on the normal protective layers of body oils and sweat. And because they dry out more quickly, you can get chapped lips.

A plastic surgeon repairs lips after an injury. And it won’t surprise you to know that surgeons can also pump up the volume of uninjured lips.

There are several different popular cosmetic procedures to boost the size of the lips. They include temporary injectable fillers such as hyaluronic acid, as well as longer term fillers such as structural fat from other parts of your body, and even soft synthetic implants.

But even after centuries of lip surgery, you might be surprised to know that the aesthetic proportions of the lips and their effect on facial attractiveness are still poorly defined.

Luscious lips

This is why several surgeons from the Department of Otolaryngology-Head and Neck Surgery at the University of California in Irvine carried out a survey. They wanted to know what would be the most attractive lip dimensions for white women.

In the first part of this survey, the surgeons started with images of 20 white women, aged 18 to 25 years.

They then used Photoshop-type-technology to make the lips appear bigger or smaller. Some 150 people ranked the faces as being more or less attractive.

It turned out they thought that the most attractive lips were about 50 per cent bigger than what most women actually had.

In the second part of this survey, the surgeons again manipulated the lips with software.

But this time they varied the relative sizes of the upper and lower lips. Overall, the judges liked them best if the lower lip was twice the height of the upper lip.

It’s hard to get that particular pumped up look with just a touch of lippy—if you want your lips to be fully on-trend, get out your duckface and go the full Kardashian.