Our brains can estimate upper body strength for fighting just from facial pictures. The idea here is that our ancestors needed to know when to fight or back off. So we have this innate ability.
(Santa Barbara, Calif.) –– For our ancestors, misjudging the physical strength of a would-be opponent might have resulted in painful –– and potentially deadly –– defeat.
Now, a study conducted by a team of scientists at the University of California, Santa Barbara has found that a mechanism exists within the human brain that enables people to determine with uncanny accuracy the fighting ability of men around them by honing in on their upper body strength. What's more, that assessment can be made even when everything but the men's faces are obscured from view. A paper highlighting the researchers' findings appears in the current issue of the Proceedings of the Royal Society.
"Assessing fighting ability was important for our ancestors, and the characteristic that the mind implicitly equates with fighting ability is upper body strength," said Aaron Sell, a postdoctoral fellow at UCSB's Center for Evolutionary Psychology and the paper's lead author. "That's the component of strength that's most relevant to premodern combat. The visual assessment of fighting ability is almost perfectly correlated with the perception of strength, and both closely track actual upper body strength. What is a bit spooky is that upper body strength can even be read on a person's face.
Maybe facial muscles get built up along with upper chest and arm muscles? Or necks become thicker? Or testosterone levels determine average muscularity as well as extent of masculine features in faces such as thick bone above the eyes.
Some major names in evolutionary psychology (Cosmides and Tooby at UCSB) were involved in this work.
Sell conducted the study with Leda Cosmides, a professor of psychology and co-director of the Center for Evolutionary Psychology; John Tooby, a professor of anthropology and also co-director of the Center for Evolutionary Psychology; Michael Gurven, an associate professor of anthropology; and graduate students Daniel Sznycer and Christopher von Rueden.
Perception of fighting ability as guessed from facial pictures correlated with measured upper body weight lifting capacity.
When the photographs depicted men whose strength had been measured precisely on weight-lifting machines, the researchers found an almost perfect correlation between perceptions of fighting ability and perceptions of strength. "When you see that kind of correlation it's telling you you're measuring the same underlying variable," said Tooby.
They also found that perceptions of strength and fighting ability reflected the target's actual strength, as measured on weight-lifting machines at the gym. In other sections of the study, the researchers showed that this result extended far beyond the gym. Both men and women accurately judge men's strength, whether those men are drawn from a general campus population, a hunter-horticulturalist group in Bolivia, or a group of herder-horticulturalists living in the Argentinian Andes.
Imagine future humans whose upper body strength and facial features become basically disconnected from each other (that can already happen with steroid usage). Innate ability to generalize from facial features won't always work. But there's not an obvious genetic fix to do for future offspring since the current rules that our brain uses will still work for some people and any genetic change in how we analyze facial features will just change which humans we make the errors about. Maybe future humans will just remove that capability in their offspring.
Here's another research result that will some day guide prospective parents who want to select and modify embryos to guarantee the success of their kids. Our brains are wired up to find certain facial shapes as more trustworthy.
A pair of Princeton psychology researchers has developed a computer program that allows scientists to analyze better than ever before what it is about certain human faces that makes them look either trustworthy or fearsome. In doing so, they have also found that the program allows them to construct computer-generated faces that display the most trustworthy or dominant faces possible.
Such work could have implications for those who care what effect their faces may have upon a beholder, from salespeople to criminal defendants, the researchers said.
In a paper appearing in the online edition this week of the Proceedings of the National Academy of Sciences, Alexander Todorov, an assistant professor of psychology and public affairs at Princeton, and Nikolaas Oosterhof, a research specialist, continue an inquiry into the myriad messages conveyed by the human face. In 2005, Todorov's lab garnered international headlines with a study published in Science demonstrating that quick facial judgments can accurately predict real-world election results.
This opens up the possibility that Hollywood casting agents could use software to go through large numbers of photos to discover, for example, faces that would make for fearsome dictators or slashers or evil spies.
A U-shaped mouth and an almost surprised look to the eyes maximize feelings of trustworthiness. Eyebrowser close to the eyes project a dominant look.
From there, using a commercial software program that generates composites of human faces (based on laser scans of real subjects), the scientists asked another group of test subjects to look at 300 faces and rate them for trustworthiness, dominance and threat. Common features of both trustworthiness and dominance emerged. A trustworthy face, at its most extreme, has a U-shaped mouth and eyes that form an almost surprised look. An untrustworthy face, at its most extreme, is an angry one with the edges of the mouth curled down and eyebrows pointing down at the center. The least dominant face possible is one resembling a baby's with a larger distance between the eyes and the eyebrows than other faces. A threatening face can be obtained by averaging an untrustworthy and a dominant face.
With the ability to predict reactions to faces comes the ability to design faces to maximize desired reactions. Want to design a dominant and highly trusted face for a future leader?
Using the program and the ratings from subjects, the scientists could actually construct models of how faces vary on these social dimensions. Once those models were established, the scientists could exaggerate faces along these dimensions, show them to other test subjects to confirm that they were eliciting the predicted emotional response, and find out what facial features are critical for different social judgments.
Within 20 years if not sooner offspring genetic engineering will be used to choose appearances of offspring. Imagine the possibilities. Ambitious parents who want their kids to become CEOs and high elected officials will select embryos that will grow up to to become adults with facial appearances and body shapes that maximize their potential to dominate and control others.
Are faces that elicit feelings of trust really more trustworthy? Why would our genes that cause that reaction have been selected for unless that reaction was justified?
Angry men stand out in a crowd.
By comparing how quickly human facial expressions of different types are detected in a crowd of neutral faces, researchers have demonstrated that male angry faces are a priority for visual processing – particularly for male observers. The findings are reported by Mark Williams of the Massachusetts Institute of Technology and Jason Mattingley of the University of Melbourne, Australia, and appear in the June 6th issue of Current Biology.
In evolutionary terms, it makes sense that our attention is attracted by threat in the environment. It has long been hypothesized that facial expressions that signal potential threat, such as anger, may capture attention and therefore "stand out" in a crowd. In fact, there are specific brain regions that are dedicated to processing threatening facial expressions. Given the many differences between males and females, with males being larger and more physically aggressive than females, one might also suspect differences in the way in which threat is detected from individuals of different genders.
In the new work, Williams and Mattingley show that angry male faces are found more rapidly than angry female faces by both men and women. In addition, men find angry faces of both genders faster than women, whereas women find socially relevant expressions (for example, happy or sad) more rapidly. The work suggests that although males are biased toward detecting threatening faces, and females are more attuned to socially relevant expressions, both sexes prioritize the detection of angry male faces; in short, angry men get noticed. The advantage for detecting angry male faces is consistent with the notion that human perceptual processes have been shaped by evolutionary pressures arising from the social environment.
Angry males are a greater potential threat than angry females. So it makes sense that natural selection would favor a wiring of human brains that make them more easily recognized.
There's a security angle here: Secret Service and other professional bodyguard outfits that need to recognize angry male would-be assassins might do that job better with male agents. However, do assassins look and feel angry? Or are some feeling thrills at what they are about to do? If assassins express other kinds of emotions when preparing to kill then maybe women would be better at recognizing them.
What I wonder: Just how many distinct adaptations and abilities has natural selection wired into human brains? How many of those abilities are trade-offs with other abilities? For example, in the case above while males have an advantage recognizing angry faces females have an advantage in decoding the meaning of other facial expressions.
Also, once scientists identify which genetic variations make those abilities more or less pronounced which abilities will people choose to give their offspring? I think the question of how people will genetically engineer their offspring is one of the most important questions we face for the future.
The set of behaviors that are thought to be innate rather than learned continues to expand.
Vanderbilt researchers, writing this week in the Proceedings of the National Academy of Sciences Online Early Edition, report that they can elicit these complex behaviors by stimulating specific areas in the brain of a small nocturnal primate called the Galago or bush baby (Otolemur garnetti). Their results provide significant new support for the proposition that all primate brains, including our own, contain such a repertoire of innate complex behaviors.
"We have now seen this feature in the brain of an Old World monkey and New World prosimian. The fact that it appears in the brains of two such divergent primates suggests that this form of organization evolved very early in the development of primates. That, in turn, suggests that it is characteristic of all primate brains, including the human brain," says Jon Kaas, the head of the research group, Distinguished Professor of Psychology at Vanderbilt University and investigator at the Vanderbilt Kennedy Center for Research on Human Development.
"These results explain why certain behaviors – such as defensive and aggressive movements, smiling and grasping food – are so similar around the world. It is because the instructions for these movements are built-in and not learned," he adds.
Over the last 20 years, neuroscientists have identified an area called the primary motor cortex, which, when stimulated, triggers simple muscle movements. The fact that they were able to produce only motions by single muscles and other simple movements reinforced the idea that only simple movements were hard-wired into primate brain circuitry.
Then, last year Michael Graziano at Princeton University pointed out that previous stimulation experiments in the motor cortex – the area that controls bodily motions – had been done using very short electrical pulses that last less than a half-second. He further suggested that longer pulses might stimulate more complicated motions. Working with alert macaques, he and his colleagues found that applying such long-duration signals did in fact elicit several of these complex behaviors, much as they had predicted.
Kaas and his colleagues, research assistant professor Iwona Stepniewska and doctoral student Pei-Chun Fang, decided to follow the Princeton researchers' lead and try long-duration stimuli in the simpler brain of the Galago. When they did, they also found that this type of stimuli triggered complex behaviors. In fact, they were able to stimulate a larger number of complex movements than the Princeton group had reported, including aggressive facial patterns, defensive forelimb movements, and hand-to-mouth and reaching-and-grasping movements.
The Princeton researchers stimulated areas in the motor cortex. The Vanderbilt researchers found that they could also elicit these behaviors by stimulating a nearby area of the brain called the posterior parietal cortex. This area is heavily interconnected with the motor cortex and had previously been associated with transforming data from the eyes and other senses into a spatial map of the surrounding environment. The new findings reveal that this brain area also plays an important role in complex, innate behaviors.
If a behavior is innate then some day it will become genetically reprogrammable. The reprogramming will be easier to do in embryos than in fully developed humans. A lot of the genetic coding that controls behavior does so by controlling development. Just what choices people will make once they can control the genetic coding of their offspring is one of the most important questions of the 21st century.
Even before offspring genetic engineering becomes possible the discoveries of more genetic causes of human behavior is going to lead to massive rethinks in how we approach child rearing, teaching, criminal justice, decisions about reproduction, and many other aspects of human life. Should a person who is genetically prone to violence be seen as morally responsible for his actions? Is that a reason not to imprison him? Or will people put their own safety first (which is what I'm guessing) and demand that if a violent guy can't help himself should he be jailed for a longer period of time? Also, if he can be identified as violent while still in childhood should be he isolated before he first murders or rapes?