Life in Chocó, Colombia

Human intergroup relations are profoundly flexible. Our science needs to catch up.

– by Anne Pisor

Is intergroup aggression part of human nature? Or is intergroup tolerance part of human nature?

Yes and yes.

While such simple headlines make great clickbait, they oversimplify – yet both have a grain of truth. Humans are both profoundly hostile and profoundly tolerant toward out-groups. We’re profoundly flexible.

Flexible intergroup relations have deep evolutionary roots. Though chimpanzees are often thought of as hostile toward out-group members and bonobos as tolerant, there is some variation in chimpanzee intergroup relations and quite a bit of variation in bonobos. Given the range of opportunities for conflict and cooperation in humans – from defending resources and protecting ourselves, to exchanging resources and ideas – the profound flexibility of human intergroup relations shouldn’t surprise us.

Indeed, as Cody Ross and I write in a new piece in Evolution & Human Behavior, our behavior toward members of other groups is influenced by a whole pathway of things, starting with context (are resources scarce?) and individual characteristics (did my past interactions go poorly?) that affect our beliefs, attitudes, and motivations – our internal states. Context, individual characteristics, and internal states influence how we behave.

For example, take research led by Cody in rural Colombia, where indigenous Emberá and Afrocolombians live side by side – sometimes with discord, sometimes without. In one community, Emberá have more control over natural resources and there’s a history of intergroup tensions. Even though Afrocolombians are wealthier than Emberá in that community, Afrocolombians feel that intergroup tensions are high and cooperation low – and they share less money and food with Emberá households accordingly. In another community with less unequal resource control and less history of intergroup tensions, wealthy Afrocolombians share with poorer Emberá. The impact of context on our internal states and our subsequent cooperative behavior is not to be underestimated.

Capturing the profound flexibility in human intergroup relations requires methods that document it accurately. In our Evolution & Human Behavior article, Cody and I focus on a subset of intergroup relations called parochial altruism: in-group favoritism paired with out-group hostility. Variance in parochial altruism is best documented using a combination of methods, we argue, like experiments that measure who people prefer to share with, observations on who they actually share with in everyday life, and self-reported internal states.

Using just one method can generate bias. For example, as Cody has documented in Colombia, people may not reciprocate sharing in real life because they can’t afford it, but will preferentially repay real-life sharing in an experiment when researchers provide the money. In short, to triangulate reality, researchers must approach it from a variety of angles.

If intergroup behavior is so flexible in humans, why are simple headlines about it so common? One reason is that they often seem to either confirm or challenge our own internal states – “yes, of course humans are inherently violent”; “no, violence isn’t part of human nature!” Our own internal states are themselves products of our experiences and cultural contexts, among other things. Journalists know that headlines that confirm or challenge our internal states excite our emotions, making us more likely to click.

But these headlines are also common because researchers have their own internal states too, and these influence what research actually gets done. As Brian Hare and Vanessa Woods remind us in Survival of the Friendliest, research on intergroup violence ticked up after World War II: researchers wanted to understand how atrocities could be committed on such massive scales. Science can be guided by researchers’ own experiences or by history, which impact researchers’ beliefs about intergroup hostility, tolerance, and peace.

When there is a greater diversity of experiences among researchers, science is the better for it. It increases the diversity of research questions researchers ask, and having a range of research questions can better tap the range of the human experience – our flexibility in intergroup relations, for one. In turn, this data can be leveraged for policy recommendations and action – for example, what features of context, individual characteristics, and internal states have the greatest downstream influence on intergroup behavior? Which lever should we pull to intervene, reducing intergroup hostility?

As Cody and I highlight, answering these diverse questions about intergroup relations requires data that accurately reflect the diversity of human experiences – our profound flexibility. Ensuring data collection reflects research questions, triangulating across multiple types of measures, striving to ensure measures reflect reality – this will improve our understanding of human intergroup relations and the upstream factors that influence it.

War in Israel and Gaza, tensions over fossil fuels at COP28, impasses in parliaments and US Congress – these stories bring to mind humans’ profound intergroup hostility. Communities helping one another after a storm, organizations standing together on picket lines – these bring to mind humans’ profound intergroup tolerance. For researchers and non-researchers alike, our beliefs, attitudes, and motivations are affected by what’s around us and by our past experiences. When researchers bring that diversity of experiences to science, our understanding of human nature can also become more accurate – but only if researchers also get accurate measures of what humans are up to. Existing data already undercut the narrative that humans are doomed to favor in-groups and be hostile toward out-groups: the data instead reveal profound variability. Recognizing this variability can push scientists to challenge their own preconceptions about human nature and to draw upon a more diverse toolkit, improving our understanding of the flexibility of intergroup relations. The better we understand it, the better positioned we’ll be to address the pressing social issues of the 21st century.

Read the original article here: Pisor, A.C., & Ross, C. (in press). Parochial altruism: what it is and why it varies. In press at Evolution & Human Behavior.

Author’s note: the author thanks Cody Ross, Kris Smith, and Eleonora Zanetti for helpful comments on this piece. Photo credit: Karl Frost.