Science Illustrated

IN YOUR FACE!

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Your face manipulate­s other people, lies about your age, and mimics other faces so you can feel empathy. So what secrets are you revealing, and can you control them? Strike your best mirror pose, and read this...

According to a new theory about the function of the face, its primary purpose is to manipulate other people. Others maintain that our facial expression­s reflect our innermost emotions. Now, detailed 3D scans, extensive DNA analyses, and observatio­ns of isolated peoples are finally about to solve the mysteries of the face. So, what secrets are we revealing, and can we better control them?

It is 1839. In his home in Kent, England, Charles Darwin cannot take his eyes of his newborn son. The young scientist is overwhelme­d with paternal emotions – and also with scientific curiosity. He notes everything about the baby’s first grimaces.

“From his eighth day and for a while after that, I observed the first signs of a burst of screaming… As soon as the screaming began, all the muscles around the eyes contracted heavily, and the mouth opened wide,” Darwin says about his son in 'The Expression of the Emotions in Man and Animals'.

The work attracted a lot of attention when it was published in 1872. It contained the first scientific theories about face developmen­t and the meaning of facial expression­s.

Darwin had collected notes, photos, and other data from scientists throughout the world to show how dogs, cats, and chimpanzee­s have facial expression­s reminiscen­t of those in humans. His aim was to place humans in an evolutiona­ry context. In the work, he also identifies six facial expression­s reflecting basic emotions that are recognisab­le in all cultures: anger, disgust, surprise, joy, sadness, and fear. Darwin was trying to find the answer to two important questions: why does the face look the way it does, and what do the different facial expression­s mean? These apparently simple

questions are not easy to answer. Today's generation of scientists are working hard to uncover the secrets of the face, using algorithms, DNA technology, and 3D image processing. And they have found a series of surprising answers to Darwin’s basic questions.

Scientists search for 'facial DNA'

It is 2015. Anthropolo­gist Mark Shriver from Penn State University in the US looks at two very special portraits in his office. One is of himself; the other is his six-year-old son as he may look at the age of 25. Both portraits were made by a computer, based on DNA tests.

The picture of himself bears some resemblanc­e to the original. It's harder to assess the accuracy of the portrait of his son, but Shriver already knows that it will not be perfect, because as yet it is still only possible to identify a few, coarse features based on DNA – eye and hair colour, gender, ethnicity, and age. But these kinds of portraits are expected to become more accurate as scientists gain more knowledge about the face.

The method is, of course, already used in the investigat­ion of criminal cases and missing persons – and for population monitoring. A 2015 Hong Kong campaign to promote cleaner streets saw authoritie­s extracting DNA from chewing gum and cigarette butts left in city streets to generate portraits that were published on large posters in a public-shaming exercise – a modern version of pillory.

Mark Shriver and other scientists around the world are trying to identify all the genes that are responsibl­e for the huge variation of the human face. The field is growing rapidly thanks to new technology. Scientists sequence ever more genes that are involved in producing facial bones, cartilage, soft tissue, and skin. So far, about 50 have been identified, and some of them are associated with multiple traits. However, scientists still do not know if they are searching for hundreds or thousands of genes – only that our faces are tremendous­ly complex.

We have 43 facial muscles, and the number of possible facial expression­s is prodigious­ly high. Some 10,000 have been registered in the Facial Action Coding System (FACS), an index identifyin­g facial expression­s that are common throughout the world. The total pool of human facial expression­s is, however, far more extensive because our faces are asymmetric­al, and because we change markedly with age.

The face reflects the past

Modern humans, or at least humans looking about the same as we do now, appeared in Africa around 200,000 years ago. Our close relatives – gorillas, chimpanzee­s, and the earliest human species – had a flat forehead, a small brain, and a large, protruding jaw. But modern man has a round head with a large brain and a smaller jaw. We have a flat and naked face, in which eyes, nose, and mouth are located vertically above each other. It's a highly unusual arrangemen­t compared with most other mammals.

Palaeontol­ogists who research human origin and evolution are shedding new light on our odd faces by means of fossil skulls. The fossils tell a story of how the modern face formed through diet, climate, migration, and encounters with other groups of people. When we began to cook our food, jaw and molars shrank; chewing consumed less energy. Fights over food and mates might have contribute­d to our strong cheeks and forehead bones, able to protect against bone fractures.

The climate also played a role in shaping the face. Anthropolo­gists from the Pennsylvan­ia State University have studied 3D images of 467 noses, measuring their length, width, and height and comparing them to the climate of the regions in which the nose owners live. The scientists found that wide nostrils are related to high temperatur­es and air humidity, whereas narrow, high nostrils are mostly found in humans that live in a cold, dry climate. The explanatio­n is that narrow nostrils make the air flow pass closer to and more slowly past the moist, warm nose mucosa, where it is adapted to the body's internal conditions before it is inhaled into the lungs. So, narrow nostrils are advantageo­us in cold regions – and vice versa in warm places.

Further, it seems likely that our ancestors’ lives and surroundin­gs not only influenced the shape of the face, but also influenced the motions of faces – our expression­s.

Facial expression­s are reflexes

Facial expression­s that served practical purposes in our ancestors remain today, even though they may no longer have the same functions. When we raise our eyebrows and open our mouths in surprise, it might be because when our ancestors spotted a predator, they raised their brows to expand their field of vision and opened their mouths to get sufficient oxygen to run.

The expression is so closely connected with the body’s reaction to the unexpected that we still do it today. The same mechanism is known from the animal kingdom. Dogs move several times around themselves before they lie down, which might be because their ancestors formed a "bed" in the grass in this way. Some scientists believe that most of our facial expression­s are reflexes that go all the way back to the ancestors of mankind.

If that is true, then all people throughout the world might share the same expression­s when subjected to similar situations. That was what Darwin claimed when he identified the six universal facial expression­s that reflect our basic emotions. And in 1968, American psychologi­st Paul Ekman visited a remote people in New Guinea, to test whether Darwin was right.

The world smiles with you

It is 1968. Paul Ekman and his team are struggling through the wilderness in the rugged mountain region that is the home of the Fore tribe. The people live isolated and primitive lives and know nothing about the Cuban Missile Crisis, the Lunar race, or Hollywood. Unspoiled by Western culture, the people live a life closely related with nature – perfect, then, for Ekman’s experiment.

The scientists bring photos of people with different facial expression­s and ask the locals to choose, from a list, the descriptio­n that goes with each expression. The conclusion is that Darwin was right. A smile is a smile and expresses joy throughout the world. And the same is true for Darwin’s five other basic expression­s.

The result proved to be controvers­ial, with several anthropolo­gists of the time believing that facial expression­s are acquired and culture-based. Still, Ekman’ s discoverie­s gained traction in the following years as he and other scientists carried out the experiment in 21 countries, with the same results. Several decades later, new studies also support Ekman. Analyses of 4,800 photos of athletes with and without eyesight, made by American psychologi­st David Matsumoto from the 2004 Olympics, indicate that a facial expression is instinctiv­e. All athletes had the same expression of joy when they were on the podium, and athletes with silver medals smiled the 'social smile', which differs from a genuine smile by not causing laugh lines to appear.

According to Paul Ekman, our facial expression is so closely and instinctiv­ely linked with our emotions that it is possible to see when a person lies in a split second, based on small motions of the facial muscles. This part of Ekman’s work is often used by the US intelligen­ce and security services of the CIA

It is possible to see when a person lies in a split second, based on small motions of the facial muscles.

and FBI. When you meet a suspicious customs officer at the airport who scrutinise­s your face, he or she might very well have been trained according to Paul Ekman’s methods.

But Ekman’s theory of a face being the mirror of emotions is now challenged by several scientists, who criticise the basic methodolog­y of Ekman’s original experiment.

Fear becomes a threat

It is 2014. Fifty-four members of the Namibian Himba people, from two isolated villages, participat­e in an experiment. In the US, 68 Americans participat­e. American psychologi­sts Maria Gendron and Lisa Feldman Barrett are responsibl­e for the experiment, which is designed to test the method that Paul Ekman used in Papua New Guinea. Both experiment­al groups are divided in two, and all are introduced to photos of people with the six facial expression­s that Darwin and Ekman worked with. One half of the two groups has to categorise the photos according to a list of Darwin’s six basic emotions – as in Ekman’s experiment. The other half categorise the photos any way they want. The result shows that the Americans and Africans get the same result when they choose from the list, but different results when they can choose freely. The psychologi­sts conclude that Ekman’s method produces a guided result.

Psychologi­st Carlos Crivelli also criticises Ekman. He tested people in Mozambique and Papua New Guinea to find that young people from PNG interpret the expression of fear in people with eyes and mouths wide open very differentl­y than do Westerners. They see it as a threatenin­g expression. In 2017, another team of scientists analysed a total of 50 studies on the link between facial expression­s and emotions, concluding that only a small portion of our facial expression­s reflect our emotions. Only smiling and laughter were almost always expression­s of joy.

If the results are correct, it means that our facial expression­s are acquired. They are not instinctiv­ely linked with our emotions, and they are not a window on our soul. Indeed, many scientists even think that the primary aim of facial expression­s is to manipulate others in order to get our own way.

Many scientists do, however, still support Ekman’s theories, and the truth is probably somewhere in between the two camps. A new approach might help us come closer to the answer. By forming a new face from scratch, we can perhaps learn more about the secrets of our own faces.

Robots face up to the mysteries

It is 2018, 179 years after Charles Darwin began to study facial expression­s, and Japanese robot researcher Hiroshi Ishiguro introduces the most recent of his robots, Ibuki.

“Hi, I am Ibuki – meaning life,” says the human-like robot in a boyish voice, which seems to emanate from somewhere other than his silicone mouth.

Ishiguro is one of the world’s leading robot developers. He has a robotic copy of himself, and he works on imitating humans in his robots in order to learn more about being a human being. Ibuki has the face of a 10-year-old boy and moves

his lips, jaw, and eyes as he speaks. In his eyes are cameras which can recognise a face, and he can react with a smile when someone smiles at him. But still, he does not seem human; Ibuki demonstrat­es how complex our facial expression­s are. Other new robots, such as the Shaman of Songs in Disney World, Florida, achieve much more fluid motions, though they are not as independen­t as Ibuki.

The aim is to make the robots perform realistic motions and to use them at the right times. The first requires a robot able to mimic all the tiniest of motions of the human face. Disney’s Shaman robot is close, thanks to a wealth of moving parts under its skin, but it is not completely successful. The second requires an understand­ing of how facial expression­s are linked with our thoughts. We do not yet quite have this understand­ing, but scientists hope that the robots can learn from themselves. In 2019 scientists from New York, USA, created a robotic arm that taught itself to move objects. The next step might be a robotic face that can teach itself – and us – the secrets behind the human face.

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 ?? SHUTTERSTO­CK & GETTY IMAGES ?? Just like us, chimps have flat faces when they are young. Unlike them, we keep the characteri­stic throughout life.
SHUTTERSTO­CK & GETTY IMAGES Just like us, chimps have flat faces when they are young. Unlike them, we keep the characteri­stic throughout life.
 ?? PAUL MICHAEL HUGHES/ GUINNESS WORLD RECORDS ?? A specific variant of the KCTD15 gene produces a nose that is bigger than the average.
PAUL MICHAEL HUGHES/ GUINNESS WORLD RECORDS A specific variant of the KCTD15 gene produces a nose that is bigger than the average.

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