What is the first thing you do when you walk into a room for a meeting? You might think that you look for a chair to sit in, or that you put your papers on the table before going to get a coffee. But that’s not the first thing you do. What you actually do operates below your level of conscious awareness. Your brain is concerned with a single question: What do I need to do to survive? You obsessively search for cues that you are safe.

Daniel Coyle, author of The Culture Code, calls these belonging cues. Eye contact, body position, and the energy in the room tell us whether we belong or whether we are an outsider. The obsession is physical, embedded deep in our brains in a structure called the amygdala. The human amygdala is particularly sensitive to socially unsettling circumstances where someone is unsure of their place.

Crucially, the amygdala plays a logical role in social and emotional decision-making. The amygdala injects an implicit distrust and vigilance into our social decision-making (am I in or am I out?). Humans trust by default, but the amygdala learns distrust and vigilance.

If you bite into rancid food, the insular cortex lights up in gustatory disgust. But the amygdala also activates when you think about something morally disgusting—for example, a violation of a social norm that is important to you. These deep, fast neurological reactions are present in all our decisions, whether we know it or not. Robert Sapolsky is a professor of biology and neurology at Stanford University who studies the biology of humans at our best and worst says this suggests there is a limited role for logic and reason. We form our beliefs by belonging not by thinking.

Humans are compassionate and altruistic but also brutal and violent. We have a particular unique quality in the animal world. We make moral judgments based on repugnance. All animals can exhibit in-group bias and can turn on outsiders. But only humans think about it. This means that humans can be manipulated by something about someone that invokes a sense of kinship. This pseudo-kinship has us do and think all sorts of things we might otherwise not do, ostensibly to de-speciate “the other.”

The role of disgust and repugnance is to get us to do hard things. Disgust is perhaps evolutionarily the oldest emotion. It’s a good example of how evolution repurposes old structures for new uses. Disgust—pulling away from or rejecting substances that may harm us—evolved hundreds of millions of years ago. Yet we now use it for moral reasoning. People exposed to nauseating environments are more likely to make morally harsh judgments.

The role of connection and belonging is to get us to do the harder things, to dig deep and find strength we didn’t know we had. The flipside is the anxiety we experience if we sense we are excluded.

Humans think in terms of “us” and “them” which is an important driver of sensemaking. The need to belong makes sense. Our survival depends on being part of the group. When we are part of a new group, our amygdala tells us that these people who were strangers before are now on our side. This is a switch that totally reconfigures our entire motivational and decision-making system.

But our need to belong in a group exists in tension with our individualistic desires. Consider for a moment a random passerby you happened to notice in the past couple of days. It could be someone who served you at a store or sat across from you on the subway. What do you think their inner life is made up of? What are their ambitions? What are their routines? Do they have idiosyncrasies and inherited crazies that their friends or family make fun of? Sit with this image for a minute. How does it feel when you suddenly realize that they are living a life as vivid and complex as yours? The word for that feeling is sonder.

It can be a jolt to suddenly realize the complexity of others’ minds. Over the course of evolution, our brains developed specialized areas, which resulted in differentiation between individuals. Brain areas that became specialized were reinforced, because innate talents are more rewarding and thus practiced more. With a community of experts, we combine our computational capacity, one of the three big limitations on human cognition.

But being part of a community where others have talents that you lack comes with a downside; it makes others seem more foreign and less familiar. We feel psychological distress—self-doubt, jealousy, and shame. This leads to interpersonal conflict. To alleviate this, humans developed neural mechanisms for sharing knowledge and social coherence. The resulting behaviors help dissipate tensions and to “encourage strangers to cohere.” The rituals of art, ceremony, and story evolved to serve our community of shared thinking. This is what we experience as culture.

Great Human Strength: Our in-group bias creates loyal, caring groups which are more successful than individuals. We have no choice but to trust others so we are very sensitive to signals of trustworthiness.

Great Human Weakness: Our in-group bias predisposes us to mistrust, cruelty, and violence towards those not in our group.

Machine Opportunity: Designs which enhance trust.

Machine Threat: Designs which destroy trust.