The Science of Friendship

How We Make Friends and How Those Bonds Evolve

Brenton Kirschner, M.MFT, LPC, LMFT, HPCP

Halt your reading! Right now in your phone is that friend, that no matter how long it’s been, you could just pick up where you left off. They need to see this because they are going to get a chance to experience this with you.

If you are that friend and you just got a text with this article, then welcome and know that someone loves you. What an honor that is! This means you hold residence in someone's heart and mind as a source of laughter, strength, and memory.

Now time for the good stuff:

You might think you became best friends at the first inside joke, but research says something different. Below is your challenge. No matter if you are already best of buds or just met recently, it’s time to have that DTR and kick it up a gear!

Best Friend Challenge.pdf

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Friendship is more than just a source of joy; it’s a cornerstone of our happiness, well-being, and even our long-term health. But how do friendships actually form, and how do they change as we move through life’s stages? Drawing on two fascinating studies, one exploring the hours it takes to build a friendship (Hall, 2018), and another examining how the quality of our closest bonds shifts during emerging adulthood (Langheit & Poulin, 2022), let’s dive into the science behind our most meaningful relationships.

How Friendships Form: The Role of Time and Shared Activities

The Social Brain Hypothesis

Humans are wired for connection, but there’s a limit to how many close relationships we can maintain. According to the social brain hypothesis, our cognitive and temporal resources cap our “friendship circle” at around 150 people, with only a handful occupying the innermost, most intimate layers (Hall, 2018).

Stages of Friendship: How Many Hours Does It Take?

Friendship isn’t an instant process; it’s built through shared experiences and time invested together. Research shows that:

• 40–60 hours together can turn an acquaintance into a casual friend.

• 80–100 hours are needed to move from casual friend to friend.

• 200+ hours of shared time can transform a friend into a good or best friend (Hall, 2018).

But not all hours are created equal. Time spent in leisure activities, such as hanging out, watching movies, gaming, or simply relaxing, predicts greater closeness than time spent together at work or school (Hall, 2018).

The Power of Everyday Talk

It’s not just about being together; it’s about how we communicate. Meaningful conversations, catching up, joking around, and affectionate exchanges, also called “striving communication episodes,” foster deeper bonds. In contrast, small talk and mundane topics don’t contribute much to relationship development (Hall, 2018).

Friendship Quality: How Our Closest Bonds Change in Emerging Adulthood

As we transition from our late teens into our thirties, our friendships evolve in complex ways. A longitudinal study tracked four key features of best friendship quality: intimacy, companionship, reliable alliance, and conflict, across this pivotal decade (Langheit & Poulin, 2022).

Key Features and Their Trajectories

• Intimacy: Slightly increases in the early 20s, then declines more steeply after age 25.

• Companionship & Reliable Alliance: Both rise modestly in the early 20s, then decrease as adult responsibilities mount.

• Conflict: Steadily declines with age, as we become better at managing disagreements or simply spend less time with friends (Langheit & Poulin, 2022).

Gender Differences

Women tend to report higher levels of intimacy and companionship, and less conflict, in their best friendships at age 19. However, intimacy with best friends diminishes more for women over time, while men’s intimacy levels remain stable (Langheit & Poulin, 2022).

The Impact of Romantic Relationships

As romantic relationships become more central, they can influence friendship dynamics. Investment in romantic life at age 19 is linked to a softer decline in intimacy with best friends, suggesting that those who are more invested in romance may maintain deeper connections with their closest friends (Langheit & Poulin, 2022).

Why Friendships Change: Life Transitions and Social Priorities

Emerging adulthood is a time of identity exploration, new responsibilities, and shifting priorities. Entering the workforce, forming romantic partnerships, and starting families all compete for our time and attention (Langheit & Poulin, 2022).

Time Constraints and Friendship Stability

With more demands on our schedules, it’s no surprise that the time available for friends shrinks. Many people change best friends several times between ages 19 and 30, reflecting the fluid nature of social networks during this period (Langheit & Poulin, 2022).

Practical Takeaways: Building and Maintaining Strong Friendships

So, what can we do to nurture our friendships in the face of life’s changes?

• Invest Time Wisely: Prioritize leisure and meaningful interactions over obligatory contact. It’s the quality, not just the quantity, of time that matters (Hall, 2018).

• Nurture Quality: Focus on deepening intimacy and engaging in striving communication episodes, especially during transitions like starting a new job or relationship (Hall, 2018; Langheit & Poulin, 2022).

• Adapt to Change: Accept that friendship closeness may ebb and flow with life stages. It’s normal for relationships to evolve, and sometimes, to fade (Langheit & Poulin, 2022).

Conclusion

Friendships are dynamic, living connections that require time, intention, and adaptability. Whether you’re forging new bonds or maintaining old ones, understanding the science behind friendship can help you invest in relationships that enrich your life, now and for years to come (Hall, 2018; Langheit & Poulin, 2022).

References

Hall, J. A. (2018). How many hours does it take to make a friend? Journal of Social and Personal Relationships, 36(4), 1278–1296. https://doi.org/10.1177/0265407518761225

Langheit, S., & Poulin, F. (2022). Developmental changes in best friendship quality during emerging adulthood. Journal of Social and Personal Relationships, 39(11), 3373–3393. https://doi.org/10.1177/02654075221097993