Resting Hunt Face

We can tell if a stranger is good at getting meat just by looking at a single face pic.

If you fancy yourself as a good judge of faces—especially when trying to decide who to hire, who to invest your money with, or who to vote for—you’re probably kidding yourself. We may feel confident in discerning important skills from among an infinite sea of mugs, but the empirical reality is humbling. With a few notable exceptions, such as assessing fighting ability from male faces, we’re demonstrably bad at judging ability from faces alone.

Just look at the corporate world. Studies show that the selection of CEOs, along with those eye-watering salaries that companies are willing to offer them, vary as a function of the candidate’s facial appearance. It’s a powerful unconscious bias. It’s also just plain ineffective, as these automatic face judgments fail to predict actual profit-driven performance. That our species is so prone to making such costly errors, using faces to make rapid-fire but erroneous inferences about competence, is something of an evolutionary puzzle.

According to a team of researchers led by Adar Eisenbruch from Marist College, this seemingly maladaptive face heuristic is, in fact, an impressively honed psychological adaptation, just one that’s not well-suited to our modern lives. In my last entry, we saw how human bodies evolved a type of starvation insurance plan, in the form of an efficient fat-storage system designed to cope with recurring stretches of food scarcity in ancestral environments. Today’s obesity epidemic is largely the result of the junk-food industry capitalizing on our species’ otherwise smart preference for calorie-rich foods. Similarly, argue Eisenbruch and his coauthors in a recent article in Evolution and Human Behavior, our tacit reliance on facial cues when judging competence in the workplace is just another outcome of adaptive mechanisms being shoehorned into (evolutionarily novel) modern problems.

It turns out that while we may be godawful at figuring out whether, say, it’s John or Mike who is more likely to land those private equity deals just by looking at their LinkedIn profile pics, we’re preternaturally skilled when it comes to knowing, from face pics alone, that Ngaola will outhunt Madura on the savanna woodlands of Africa. It doesn’t matter that you’ve never crossed paths with any Hadza men in real life, or even if you’ve never heard of this nomadic tribe of hunter-gatherers before. It doesn’t even matter that your experience with hunting amounts to bending over to grab that cellophane-wrapped porkchop from the meat and seafood aisle at Walmart. You know the face of a good hunter when you see one.

That, at least, is what Eisenbruch et al.’s research seems to have revealed. The project involved two broad stages of data collection. The first was ethnographic work conducted over several years with two indigenous groups: the Hadza from northwestern Tanzania, and the Tsimané people of central lowland Bolivia. Both are ancient foraging societies with a clear sexual division of labor. Among the Hadza, men mostly hunt large game and collect honey (often by scaling tall baobab trees), whereas women forage for tubers and berries and other plant goods. The Tsimané are horticulturalists, with both sexes contributing to the cultivation of plantains, rice, corn, and sweet manioc; however, men’s hunting and fishing activities still add significantly to the group’s diet, with women doing most of the food processing.

Anthropologists photographed faces of dozens of men and women from both societies. Then, using a variety of measures, the people shown in the photos were rated or ranked on their foraging skills by their fellow tribe members. In other words, the researchers were measuring local hunting reputations (men) and gathering (women) “acquired over years of personal observation and supplemented by social knowledge.”

With this collection of male and female Hadza and Tsimané faces, alongside peer ratings of the targets’ foraging competency, the investigators began the second phase of the project. In an online study, those very faces were shown to hundreds of naïve American participants. Each participant saw a randomized sample of either Hadza or Tsimané faces, and were asked three “ancestral productivity” questions about each indigenous stranger in turn:

Imagine that this person went on a long camping trip, where they had to find their own food, make tools, etc. How well do you think this person would do on this camping trip, compared to other people of the same sex and age?

If this person were stranded on a desert island, how good do you think he (she) would be at getting food, compared to other people of the same sex and age?

Imagine that this person lived 100,000 years ago, when humans had to hunt or gather food and find or build shelter. How productive a member of their group would this person have been, compared to other people of the same sex and age?

For Tsimané faces, participants answered using a seven-point scale, with 1 being “far below average” and 7 being “far above average.” The Hadza faces were ranked in comparison to those of other group members. In both cases, the Americans’ judgments—based on a single photo—matched the male targets’ actual hunting reputations among their peers. “Male hunting is a competence that would have been highly consequential to our ancestors,” surmise the authors, “so we suggest that this perceptual capacity [to detect hunting skill using faces] exists due to natural selection for the ability to choose productive social partners.”

Precisely which facial cues the Americans were using to inform their correct intuitions isn’t clear. Statistically, the results couldn’t be accounted for by the targets’ age or any obvious biometric contenders (asymmetry, facial width-to-height ratio, measures of testosterone-fueled masculinity/strength, etc.). Maybe it’s something more subtle—some je ne sais quoi visage. “It could be related to expression, posture, skin features, or other traits that elude landmarking techniques,” the authors speculate. “Perhaps there is a universal self-presentation related to confidence that stems from having a reputation for locally relevant skills.” After all, although most of the images were carefully cropped to remove any non-face stimuli (hair, clothes, etc.), and targets were all instructed to look directly at the camera and to make a neutral expression, there was still “variability,” meaning that some couldn’t help but crack a slight smile, or maybe bite their cheeks coyly. Nevertheless, Eisenbruch and his coauthors contend, “people can judge a man’s hunting ability simply by looking at his face.”

For female faces, however, not so much. In fact, the Americans got that exactly wrong. The Hadza and Tsimané women who were judged the weakest on the ancestral productivity items were the very same women with reputations for being the most skilled foragers in their own communities. Older women, especially, were underestimated in this way. Western stereotypes about age and female productivity may be at play, the researchers point out, but “women’s production also is more affected by reproductive events like pregnancy and lactation than men’s, making it less trait-like and therefore perhaps less observable from the face.”

The study wasn’t perfect. The authors would agree. Yet these novel findings of people accurately gauging hunting skill in a briefly presented photo of a foreign stranger’s face are striking. They imply, oddly, that we may be unknowingly making decisions in board rooms and voting booths based, at least in part, on facial impressions of a male candidate’s ability to bring a fresh baboon carcass back to camp, or to flush out large juicy rodents from their dens.

Okay, I’ll leave the political puns to you. But you get the idea. “Evolved perception,” the researchers conclude, “may be the key to understanding contemporary (mis)perception.”

Eisenbruch, A. B., Smith, K. M., Workman, C. I., von Rueden, C., & Apicella, C. L. (2024). US adults accurately assess Hadza and Tsimane men's hunting ability from a single face photograph. Evolution and Human Behavior, 45(4), 106598

Questions? Concerns? Ideas? Email the corresponding author directly: Adar Eisenbruch adar.eisenbruch@marist.edu