People make sense of the world by organizing things into categories and naming them. "These are circles." "That's a tree." "Those are rocks." It's one way we tame our world. There's a weird correspondence between different cultures, though — even though we come from different places and very different circumstances, cultures everywhere develop largely the same categorizations.
"But this raises a big scientific puzzle," says Damon Centola of the University of Pennsylvania. "If people are so different, why do anthropologists find the same categories, for instance for shapes, colors, and emotions, arising independently in many different cultures? Where do these categories come from and why is there so much similarity across independent populations?"
Centola is the senior investigator of a new study in the journal Nature Communications from the Network Dynamics Group (NDG) at the Annenberg School for Communication that explores how such categorization happens.
Some have theorized that these categories are innate—pre-wired in our brains—but the study says "nope." Its authors hypothesize that it has more to do with the dynamics of large groups, or networks.
The grouping game
Some of the shapes used in the experiment
Credit: Guilbeault, et al./University of Pennsylvania
The researchers tested their theory with 1,480 people playing an online "Grouping Game" via Amazon's Mechanical Turk platform. The individuals were paired with another participant or made a member of a group of 6, 8, 24, or 50 people. Each pair and group were tasked with categorizing the symbols shown above, and they could see each other's answers.
The small groups came up with wildly divergent categories—the entire experiment produced nearly 5,000 category suggestions—while the larger groups came up with categorization systems that were virtually identical to each other.
Says Centola, "Even though we predicted it, I was nevertheless stunned to see it really happen. This result challenges many long-held ideas about culture and how it forms."
Nor was this unanimity a matter of having teamed-up like-minded individuals. "If I assign an individual to a small group," says lead author Douglas Guilbeault, "they are much more likely to arrive at a category system that is very idiosyncratic and specific to them. But if I assign that same individual to a large group, I can predict the category system that they will end up creating, regardless of whatever unique viewpoint that person happens to bring to the table."
Why this happens
The many categories suggested by small groups on the left, the few from large groups on the right
Credit: Guilbeault, et al./Nature Communications
The striking results of the experiment correspond to a previous study done by NDG that investigated tipping points for people's behavior in networks.
That study concluded that after an idea enters a discussion among a large network of people, it can gain irresistible traction by popping up again and again in enough individuals' conversations. In networks of 50 people or more, such ideas eventually reach critical mass and become a prevailing opinion.
The same phenomenon does not happen often enough within a smaller network, where fewer interactions offer an idea less of an opportunity to take hold.
Beyond categories
The study's finding raises an interesting practical possibility: Would categorization-related decisions made by large groups be less likely to fall prey to members' individual biases?
With this question in mind, the researchers are currently looking into content moderation on Facebook and Twitter. They're investigating whether the platforms would be wiser when categorizing content as free speech or hate speech if large groups were making these decisions instead of lone individuals working at these companies.
Similarly, they're also exploring the possibility that larger networks of doctors and healthcare professionals might be better at making diagnoses that would avoid biases such as racism or sexism that could cloud the judgment of individual practitioners.
"Many of the worst social problems reappear in every culture," notes Centola, "which leads some to believe these problems are intrinsic to the human condition. Our research shows that these problems are intrinsic to the social experiences humans have, not necessarily to humans themselves. If we can alter that social experience, we can change the way people organize things, and address some of the world's greatest problems."
You've likely heard it like this: for most of history, women foraged, secured water, and partook in minor agriculture while men went out to hunt. Even if this was the end of the story, women still provided an inordinate amount of calories for the tribe, as fruits, vegetables, and nuts accounted for the bulk of sustenance.
As with many myths, this longstanding story might not be completely accurate. Thanks to recent archaeological findings in Peru's Andes Mountains, published in the journal Science Advances, up to half the women in mobile groups in the Americas were big-game hunters.
University of California, Davis archaeologist Randall Haas started shifting his view of ancient hunting practices in 2018 while leading his crew 13,000 feet above sea level in Wilamay Patxja. Upon uncovering the remains, he automatically assumed one body was male due to the proximity of weaponry.
He was wrong.
The team unearthed a total of over 20,000 artifacts, including the remains of six bodies in five burial pits. One pit, which contained a teenage woman, included a toolkit with spearpoints and shafts. Tools for dissecting game were also discovered. In total, 24 stone tools were unearthed, including projectile points for killing large game, heavy rocks for stripping hides and cracking bones, and red ocher to preserve hides.
Previously, such tools were thought to be used for cutting or scraping when discovered near female remains. Haas says we need to rethink that approach, which is likely the result of modern bias. Buried near these pits were the remains of Andean deer and vicuña, two commonly hunted animals in Peru.
Haas's group then reviewed the remains of 429 bodies spread over 107 sites in the Americas. These individuals lived between 6,000 and 12,500 years ago. Big-game hunting tools were buried with 11 women and 16 men. The Wilamay Patxja dig is not an outlier.
Credit: Randall Haas, University of California, Davis
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Extrapolating from the most recent dataset, Haas estimates that between 30-50 percent of big-game hunters were women. This doesn't imply that it's a global phenomenon, although female warriors were recently identified in California, dating back roughly 5,000 years. Likewise, women warriors were discovered in Mongolia 1,500 years ago and in Scandinavia about a millennium ago.
Researchers say these findings challenge our understanding of gender identities. Modern analysis can discover the biological sex of these individuals, though we cannot make assumptions about the role of men and women by current standards. As University of Miami archaeologist, Pamela Geller says,
"With few exceptions, the researchers who study hunting and gathering groups—regardless of which continent they work on—presume that a sexual division of labor was universal and rigid. And because it is commonsensical, they then have a hard time explaining why female-bodied individuals also bear the skeletal markers of hunting or have hunting tool kits as grave goods."
There's always the possibility that hunting tools were ritualistically buried alongside varied members of the tribe, including women. Yet we also have to remember that there were no supermarkets on the savanna. Tribal life was an all-hands-on-deck affair. Female hunters should surprise us no more than stay-at-home dads today. Societies are fluid dependent on circumstances, and the ancient world provided challenges we can only dream of today.
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Stay in touch with Derek on Twitter and Facebook. His new book is "Hero's Dose: The Case For Psychedelics in Ritual and Therapy."
