I met Mohammad in 2004 in Baghdad when we were both in our early 20s. I was an American soldier, and he was a local interpreter for my platoon during our 1-year deployment. Mohammad’s job was dangerous because Iraqis who worked with the Americans were targeted by insurgent forces.

So when I didn’t hear from him for a couple of weeks, I was worried and assumed the worst. But when he did return, rather than being clean shaven, like he usually was, he had a short beard.

He explained that he had been mourning the death of his uncle, an important man in his life, and that not shaving for a period of time was part of his Shiite Muslim mourning practice.

I was reminded of when my father told me about having grown up Catholic in the Azores islands, an archipelago about 930 miles (nearly 1,500 kilometers) off the coast of Portugal. He had told me that like other young men of that time, he had not shaved for the prescribed 7-day mourning period when my grandfather and great-uncles died.

As an anthropologist who studies social bonding during times of crisis, I now understand how cultural religious traditions – even when they seem different – can create unexpected connections.

Culture and human connection

Social psychologist Jonathan Haidt describes people as “groupish,” giving examples of the wide range of communities from which we seek a sense of belonging.

Researchers have shown how easily humans form group loyalties based on shared similarity. In one landmark experiment published in 1971, social psychologists showed a dozen abstract paintings to a group of teenage boys from Bristol, England. They then divided the boys into teams, based on which image they selected. Even that insignificant similarity led participants to show preference to members of their own group.

Experimental research suggests that people are more trusting and empathetic toward those who share their own religion and ethnicity. Even children show preferences toward those they perceive as belonging to their group – even if that group is randomly assigned.

Cultural traditions help strengthen group identities and reinforce in-group sentiments. Rituals and traditions like national anthems, religious ceremonies and national events and holidays create a sense of shared meaning. Some unite entire nations or religions, while others bring together close friends and family.

Researchers studying Brazilian cultural festivals found that people who danced and sang together during shared celebrations reported feeling more connected to their ethnic and racial community; they also felt more connected to their national identity afterward.

The most common traditions, like birthdays, weddings and funerals, are usually celebrated with close friends and family – face to face – making them particularly meaningful.

How similarity can bridge divides

Most often, traditions feel familiar because they take place with groups we already share deep community ties with. But sometimes, shared traditions can help bridge the gap between groups that otherwise have little in common.

In 2022, researchers randomly divided over 500 Americans into three groups before measuring their attitude and willingness to compromise to prevent violence in a fictional scenario. The first and second groups reflected either on their similarity or differences with the person they would negotiate with. The third group was the control, and simply described their location. Those who reflected on shared similarity viewed the other as more intelligent, cooperative and trustworthy, and they were more willing to compromise than the group that emphasized differences.

Students and teachers who discover common interests develop stronger relationships, resulting in better academic outcomes.

Patients also report greater satisfaction with healthcare providers who share aspects of their background, such as language, race, religion or social class.

When people interact directly, they have an opportunity to form friendships and see each other as individuals rather than generic stereotypes. Psychologist Gordon Allport proposed the “intergroup contact theory,” which states that under the right conditions, positive and meaningful contact between people from different groups can reduce negative prejudices and increase cooperation. When people perceive shared emotions, values, attitudes or goals, it makes them more open to recognizing each other’s humanity.

Finding similarity and common ground is often an important step in reducing prejudice and resolving conflict.

Cultural traditions between enemies

In times of conflict, cultural differences can be used to reinforce in-group loyalties by making clear and often malevolent distinctions between “us” and “them.” Yet people on opposing sides can still bond over similarities.

Historians have highlighted how propaganda has been used in most modern wars to portray enemies as fundamentally different. During World War I, for example, Germans were depicted as savage “Huns” and “Prussian butchers” by the British and Americans. And by the time the Holocaust began, Nazi propaganda had already been dehumanizing Jews for years by calling them “vermin.”

The global war on terror – the post 9/11 counterterrorism campaign around the world, including the wars in Afghanistan and Iraq – was called a “crusade” by then U.S. President George W. Bush. This language evoked the conflict as a struggle between good and evil and, for some, even a clash of civilizations.

I am not suggesting that shared cultural traditions are an antidote to conflict. After all, wars do happen between people who share the same language or cultural traditions.

Even so, during war, people may sometimes find an opportunity for connection. Throughout history, opposing sides have often paused hostilities to honor shared religious or cultural traditions. Perhaps most notably, in several areas along the Western Front during World War I, British and German troops spontaneously observed an unofficial truce to celebrate the Christmas holiday and bury their dead. The Christmas Armistice of 1914 was done without permission from the military.

A shared story

Mohammad and I were different in many ways: Mohammad was Iraqi, and I was American. He was a civilian, and I was a soldier. He was Muslim, and I was Catholic.

My interaction with Mohammad and his mourning ritual revealed a tradition that had traveled through generations and cultures.

Many years after my military service, during the final days of my father’s life, my large family kept vigil beside him. Sitting with my siblings, mother and dozens of nieces and nephews, I told them this story. It was the first time they had heard about my experience with Mohammad. And most of my family didn’t know that my father had not shaved for a week when his father died. Yet it seemed to resonate with many of the young men of my family.

As my father’s heartbeat faded and his life quietly slipped away, several of my nephews decided to honor him with what they believed had been an outdated tradition. They did not shave for a week after my father died.

Steve S. Medeiros does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.