The old adage may have it that we shouldn't judge a book by its cover, but ever since Aristotle first wrote about the art of physiognomy, people have thought it possible to deduce character traits from someone's facial features.
Though now dismissed as pseudoscience, there​ may still be a kernel of truth in the idea that someone's face can shape their destiny - a Princeton University study showed it takes us a 10th of a second to size up the cut of a stranger's jib and, rightly or wrongly, we react to them accordingly.
Hence, recent studies suggest that those with ​what we perceive to be ​dominant faces (fuller jaws and thicker brows) are more likely to make CEO, that juries are more inclined to believe baby-faced men are not guilty of certain crimes, and that politicians with competent-looking faces (higher cheekbones and angular jaws) have a greater chance of being elected.

"It's all about perception, not actual behaviour, and of course much of this may be a self-fulfilling prophecy: that people who look competent are often given better jobs and then become more competent at them," explains Dr Lisa DeBruine, who runs the Face Research Lab in the Institute of Neuroscience and Psychology at the University of Glasgow, and studies how - and why - people respond differently to different face shapes.Now, a new UK series is using cutting edge science to play with our prejudices and explore how the physical make-up of our faces can give away our inner secrets, affect our career prospects - and ​could ​even sway the US electorate.
"Research shows there are 13 main attributes people are most likely to spontaneously judge about a face: aggressiveness, attractiveness, compassion, confidence, dominance, emotional stability, intelligence, meanness, responsibility, sociability, trustworthiness, happiness, and weirdness.
"But the way we perceive someone basically all boils down to how dominant or trustworthy we think they look. We automatically read facial cues to try to assess a person's desire to do us harm or good versus their ability to do so."

Dr DeBruine says Donald Trump tries to make himself appear more dominant by making his face more aggressive and masculine. Photo / AP

Dr DeBruine maintains that (whatever those scientifically shaky "how to tell your personality from your face-shape" quizzes might have you believe) the width between a person's eyes or the shape of their chin won't actually tell you anything about their personality. But that doesn't stop our subconscious making snap judgements.
"Social conditioning plays a huge part in what we gauge from looking at someone, when all we have to go on is what we can immediately see," explains Dr DeBruine. "So for most people, a competent-looking face looks trustworthy and dominant, but not too dominant. And we tend to associate competent faces with the kinds of people who are in charge in our society.
"But because men still tend to be at the top in the majority of industries, we also associate these attributes with masculinity. So as men naturally tend to have wider faces, fuller jaws, thicker brows which are closer to their eyes, and slightly lower hairlines than women, all these attributes are also associated with dominance.
"Meanwhile, women's eyes tend to be a bit rounder, and wider eyes tend to come across as more trustworthy."
So in order to appear dominant and competent, a politician seeking office - whether male or female - should ideally possess wide eyes, a strong jawline, a thick brow bone and a broad face? Delightful.
On Your Face Says It All Dr DeBruine explores how the physical makeup of a politician's face can have a huge effect on how well they play with voters, even though it may bear no reflection of their abilities.
Though she won't be drawn on specific facial features of leading political figures, she explains that competent-looking faces are less round, have less distance between eyes and eyebrows, have higher cheekbones and more angular jaws, and in general are more mature looking and attractive.
According to Dr DeBruine, the kind of face which undecided voters are drawn to partly depends on how under threat they feel at the time of voting. "In the case of general elections, people have tended to go for different kinds of leaders depending on whether the election was held during peacetime or wartime," she explains.
"During wartime, people are looking for a dominant leader. Facial width is the simplest measure of how people perceive dominance, so a politician with a wider, more masculine face might be more successful than one with a narrow, more feminine face."
These stereotypes are currently being played out on the world stage, as Donald Trump seeks to convince the American people that the country is under attack and needs to be made great again.

Wider eyes tend to come across as more trustworthy, something Clinton will need to work on at the final debate tomorrow. Photo / AP

"At the moment, it behoves Donald Trump to convince everyone that we are living through a time of war to exacerbate the idea that this is a wartime decision," explains DeBruine. "And he does that not just through his rhetoric but by narrowing his eyes and thereby accentuating his brow bone, and pursing his lips which makes him look more aggressive."
So what does this mean for Hillary Clinton: caught, like so many women in politics, in a catch 22 whereby she has to be seen to look dominant and competent, without eschewing her femininity.
After the first televised debate at the end of September, Clinton was accused of having what was dubbed 'Resting Hillary Face', for her tendency to let her disdain for her opponent shine through on her face rather than in her speeches.
A play on the term Resting B*tch Face, which is applied to any woman who fails to look sunny and amenable 24/7, it is also, Dr DeBruine explains, a label which tends only to be applied to women, whom society expect to appear warm and open.
Clinton can't win. Too stern, and she's seen as bossy and grumpy; too smiley and she's false or weak. In the last debate she was even deemed part-automaton for failing to flinch when a fly landed on her face. "PROOF! She's a robot!" screamed the Internet.
"The trouble is, for women, looking more masculine also makes you look older, and age is not on Hillary's side in this election," says Dr DeBruine. "She has to look competent but not unfeminine because we judge people very harshly for being gender non-conforming.
"One thing she does do is to open her eyes wider at certain points when she is talking because it makes her seem more trustworthy."
In the third and final presidential debate before next month's election on October 19th, Clinton will no doubt once again come under scrutiny for what the chairman of the Republican National Committee described as her "angry and defensive" face.
"Truly," Dr DeBruine says, "the self control this woman must have is phenomenal."

Tom Hiddleston is apparently unlikely to be the next Bond for the simple reason that his face is too feminine compared to previous Bonds. Photo / AP

Though reluctant to make any kind of prediction as to which way the election might swing, one thing DeBruine can tell me with absolute certainty, however, is that Tom Hiddleston will not be playing 007 anytime soon.
"If you merge the faces of all seven former James Bonds, you can see that they all have startlingly similar facial makeup. Bond has always been super masculine, with a typically dominant face shape.
"Tom Hiddleston has a much more feminine face, so science just wouldn't allow it to be him," she jokes.
"My money's on Idris Elba."