Friendship

• 1. Introduction

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  Friendship, at its core, is a relationship of mutual affection between people. It sits above the acquaintance and the colleague on the ladder of human connection, and yet most people have far fewer close friends than they assume. A survey of 2,000 American adults found that the average person had just two close friends, defined as people they had discussed important matters with in the past six months. A 2023 Pew Research Center survey found that 8% of respondents reported having no close friends at all, with another 7% reporting only one. Something this central to human well-being turns out to be surprisingly fragile, and surprisingly rare. What makes friendship different from other bonds? Why does it form, why does it dissolve, and what does it do to the body and the mind when it is present or absent? Those are the questions this documentary will explore.

• 2. How Friendship Forms

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  Forming a friendship takes more time than most people expect. Research suggests it takes around 20 to 60 hours of interaction in the first weeks after meeting someone to establish a basic friendship, and more than a hundred hours to develop a close one. Friendships are foremost formed by choice, on the basis that the parties involved admire each other and enjoy commonality and socializing. Most people also consistently underestimate how much other people like them, a tendency researchers call the liking gap, which makes initiating friendships harder than it needs to be.

  Communications professor Jeffery Hall identified six areas that most friendships depend on through tacit, unspoken agreement. The first is positive regard: the friends genuinely like each other, not merely as a social tactic. The second is self-disclosure, meaning the friends feel they can discuss topics of deep personal significance. The third is instrumental aid, the practical help friends offer one another. The fourth is similarity in worldview, whether through shared culture, class, religion, or life experience. The fifth is enjoyment, the belief that spending time together is fun and easy. The sixth is agency: one friend may have valuable information, skills, or resources the other lacks. Not every friendship balances these six areas equally. Women tend to place greater weight on genuine positive regard and deeper self-disclosure. Men tend to place greater weight on agency.

• 3. Childhood and Adolescence

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  Children understand friendship in concrete, proximity-based terms. Young children use cues like sharing snacks or sharing secrets to determine whether someone is a friend, and they weigh how close in space another child is more heavily than abstract qualities like loyalty. Based on reports from teachers and mothers, 75% of preschool children had at least one friend. That figure rose to 78% by the fifth grade. About 15% of children were found to be chronically friendless, going through periods of at least six months without a mutual friend.

  Eileen Kennedy-Moore describes three key ingredients that help children form friendships: openness, similarity, and shared fun. Drawing from the research of Robert Selman, Kennedy-Moore also outlined developmental stages in how children understand friendship. These range from the self-focused "I Want It My Way" stage through "What's In It For Me?" and "By the Rules," toward the more reciprocal stages of "Caring and Sharing" and finally "Friends Through Thick and Thin."

  By adolescence, the basis of friendship shifts substantially. Adolescents seek out peers who can offer qualities like sharing, frankness, and spontaneity in a reciprocal relationship. Their friendships become more grounded in shared morals and values than in the physical proximity that defines childhood bonds. A large study of American adolescents found that those less likely to engage in problematic behavior, such as stealing, fighting, or truancy, tended to have friends who did well in school, avoided drinking, and maintained good mental health. Whether a given adolescent was influenced toward problem behavior depended on how much time they spent with those friends and whether the friendship group fit in at school. Friendships formed during post-secondary education tend to last longer than those formed earlier in life.

• 4. Adulthood and Older Age

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  Adult friendships carry real practical obstacles. The workplace creates particular difficulty because competition makes people guarded, and work relationships can take on a transactional quality that blurs the line between networking and genuine friendship. Many adults place a higher priority on the financial security their job provides than on deepening connections with coworkers.

  Older adults report a different pattern. Even as the total number of friends tends to decline with age, older adults report high levels of personal satisfaction in the friendships they retain. Maintaining friendships in later life is linked to an increased ability to carry out daily activities, a reduced decline in cognitive abilities, fewer hospitalizations, and better rehabilitation outcomes. Among the elderly, friendships also serve as a buffer against depression and loneliness, and can compensate for reduced support from family members who are no longer available.

  Carstensen's Socioemotional Selectivity Theory offers an explanation for why the number of friends declines as people age. The theory holds that as people grow older, their motivation shifts from gathering new information toward regulating their emotions. To maintain positive emotional states, older adults narrow their social world to those with whom they already share a strong emotional bond. One review of research across the past four decades found that older adults reporting the highest levels of happiness and general well-being also reported strong, close ties to numerous friends.

• 5. Friendship and Health

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  Researchers have described friendship networks as a "behavioral vaccine" that boosts both physical and mental health. Studies have found that strong social supports improve a person's prospects for good health and longevity. Conversely, loneliness and a lack of social supports are linked to an increased risk of heart disease, viral infections, and cancer, as well as higher mortality rates overall.

  A 2004 study published in the American Journal of Public Health found that lack of friendship plays a role in increasing the risk of suicidal ideation among female adolescents. The same study noted that having more friends who are not themselves friends with one another also carries this risk. No similar effect was observed for males. A World Happiness Database study found that people with close friendships are happier, though the absolute number of friends did not increase happiness by itself.

  Research on mental health found that having more close friends is correlated with improved mental health and cognitive ability, but only up to a point. That benefit levels off once a person has around five friends. Beyond that number, having more friends is no longer linked to better mental health and is actually correlated with lower cognition. People with very few or very many friends also showed more symptoms of attention deficit hyperactivity disorder and were less able to learn from their experiences. Children who have friendships of high quality may be protected against the development of anxiety and depression. Conversely, having few friends is associated with dropping out of school, aggression, adult crime, and loneliness.

• 6. Culture, Gender, and the End of Friendship

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  Which relationships qualify as friendship varies substantially across cultures. In English-speaking cultures, people tend to include relatively weak relationships under the label of friend. In Russian and Polish cultures, only the most significant relationships earn that designation. A Russian might have one or two friends plus a large number of acquaintances, while a Canadian in similar circumstances might count all of those relationships as friendships.

  Aristotle identified three kinds of friendship in ancient Greece: those grounded in pleasure, those grounded in advantage, and those grounded in virtue. Greek friendships of that era were also more utilitarian than affectionate, based on obligation and reliance, though different Classical communities understood friendship in different ways. In Western cultures today, friendships are often viewed as secondary to family or romantic relationships.

  Gender shapes friendship in distinct ways. Female friendships tend to focus on interpersonal connection and mutual support; male friendships more often center on social status and shared physical experiences. Male-male friendships are generally more alliance-like, while female-female friendships are more attachment-based. That distinction means that the end of a male friendship tends to be less emotionally disruptive than the end of a female friendship. One study found that women in Europe and North America were slightly more likely than men to report having a best friend.

  Friendships can end through gradual drift as people grow more distant physically and emotionally, or through a sudden rupture, such as discovering that a friend holds incompatible values. The dissolution of a friendship is often experienced as a personal rejection. Disruptions of friendships are linked to increased guilt, anger, and depression, and can be highly stressful, especially in childhood. Those negative effects may be reduced if the dissolved friendship is replaced by another close relationship.

• 7. Why Friendship Evolved

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  Evolutionary approaches to friendship ask what friendship actually does for individuals at a functional level. One framework is the theory of Reciprocal Altruism, which proposes that friendship allows people to exchange benefits with one another and to track those exchanges so they can avoid cooperating with someone who takes without giving in return. A related perspective treats friendships as something like insurance investments: before forming a new friendship, an individual assesses whether the potential friend would be willing and able to help in the future and whether the friendship is worth pursuing given the range of other friendships available.

  The Alliance Hypothesis offers a different lens. It argues that friendship exists primarily to build alliances for future conflicts. Conflicts can typically be won, the hypothesis holds, by the side that recruits more allies. Because relative rank among potential allies matters more than absolute strength, people should seek friendships with those who rank themselves highly among their peers. The choice of ally involves strategies like bandwagoning or selecting someone known for loyalty in future disputes.

  Friendship-like bonds also appear across the animal kingdom. A meta-analysis examining grooming behaviors in 14 different primate species found that grooming elicits exchanges of support and aid for future conflicts within the species. Male bottlenose dolphins use synchronous surfacing to assess potential male allies. Female bottlenose dolphins use gentle contact behaviors with other females in response to harassment from males. Female spotted hyenas, whose groups follow a strict dominance hierarchy, form coalitionary bonds to unseat higher-ranking individuals. Feral female horses develop alliances with other mares to avoid harassment from males, and those alliances also improve the survival chances of their offspring.