So which features might hint at belligerence? Sell suspects the brow ridge and jaw, two structures that are shaped by testosterone in puberty. (High testosterone has been linked with masculine looks as well as with aggression.) Other scientists propose a different measure: the width-to-height ratio of the face, as measured from cheek to cheek and lip to brow. Last year, a team of Canadian psychologists showed that men with wider faces (think Ernie) score higher in lab tests of aggression than slender-faced men (think Bert). They also found that wide-faced hockey players rack up more penalty minutes. Now, two studies in Psychological Science—one from August and another forthcoming—reinforce the notion that stout-faced men appear tougher and are more likely to behave in aggressive and untrustworthy ways.
The idea is not far from what William Sheldon proposed in the 1940s. Certain excitable meat-headed mesomorphs, he wrote, were prone to "muscular unreasonableness" and could be "as destructively dangerous in a human setting as a great gray owl in a colony of Snowshoe rabbits." (These, of course, were the Great Gray Owls.) Sheldon suggested not only that mesomorphic men were prone to aggression but that they were more likely to be criminals. So, was he right?
The psychologist Robert Deaner recently went through the database of mug shots of the Michigan Department of Corrections and measured the facial width-to-height ratios of 688 white convicted criminals. He classified each inmate as either violent or nonviolent based on FBI standards and compared their faces with their crimes. There was no difference in the average width-to-height ratio of violent vs. nonviolent offenders, he says. However, Deaner did find that prisoners' faces were significantly wider than a population of undergraduates. Curiously, pro hockey players had even wider faces than the prisoners. His conclusion: "Face width does not predict violent crime. … [W]e believe the cliché, 'never judge a book by its cover' remains sound advice."
We seem to have a strong tendency to ignore that advice. A number of studies have demonstrated that most people hold similar stereotypes about what criminals look like and believe that "the face fits the crime." This can play out in court: The psychologist Leslie Zebrowitz has shown that "mature-faced" defendants are more likely to be found guilty of certain kinds of crimes. And when baby-faced defendants are found guilty, they tend to get more lenient sentences. She calls this form of discrimination "face-ism" and argues that defendants shouldn't be required to show their faces in court. But if it is proved that the male face does indeed reveal "honest" signals about aggressiveness, jurors might deserve access to that information. (Then, too, defense attorneys might want to adopt a novel legal strategy: the meathead defense. "My client can't be blamed for his actions because he suffers from high testosterone. Just look at his face!")
To be clear, no one is saying cops should start rounding up meatheads. But it wouldn't be unprecedented in the annals of physiognomy; Earnest Hooton, an avowed eugenicist, proposed permanent lockup for people of poor genetic stock. A major aim of William Sheldon's work was to identify for eugenic elimination that which he termed "PPPP": poor protoplasm, poorly put-together.
Today's physiognomists share none of these racist attitudes. But racial issues inevitably emerge from the science. For example, if there are racial differences in upper body strength, then Aaron Sell's theory predicts there might be racial differences in aggression. (Jon Entine, author of Taboo: Why Black Athletes Dominate Sports and Why We're Afraid To Talk About It, claims that what evidence there is on the topic suggests that Eurasian whites have the strongest upper bodies.)
Bias may also seep into the lab. Study participants may be responding to subtle racial cues, for example, when a psychologist asks them which of two faces looks more "dominant." This kind of feature-based discrimination does occur: A 2004 study (PDF) showed that people with more Afrocentric facial features receive harsher prison sentences— even when the individuals are white. In this respect, racism and face-ism are one and the same.
Physiognomy faces other tough questions. For example: How do we know that tough-looking dudes don't act tough simply because society treats them like thugs? How do we know that a penchant for aggression doesn't also incline men to pump iron, which alters their bodies and their faces? In any event, even if it is proved that manly-faced men tend to be naughty by nature, a policy of facial profiling won't guarantee our safety. India's baby-faced killer—and the many baby-faced killers who have come before him—would seem to prove the point.