Hello Reader,

The other day, I looked at the long list of contacts in my phone. Hundreds of names—many I hadn’t messaged in years. It struck me that for all our digital reach, the people I keep up with, the ones I’d call when something big happens, still fit in a small circle. That’s Dunbar’s Number in action.

Dunbar’s Number is a mental model that suggests humans can only maintain about 150 meaningful relationships at once. It’s based on brain size and the cognitive limits of tracking emotional connections. You can know more people, but you can’t truly stay close with all of them.

That’s why this model lives inside Re:Mind, our toolkit for clearer thinking and better decisions. We hit $8.5K on Kickstarter and unlocked both stretch goals—thank you for backing it. Late pledges are still open.

Why Use It

Humans evolved in tribes, not cities. Dunbar’s Number reminds us that there are natural limits to how many people we can stay emotionally close to. Use this model to:

• Prioritize meaningful relationships in a world of infinite connections
• Build teams and communities that reflect cognitive reality
• Rethink how scale affects culture, trust, and cohesion

When to Use It

This model is helpful anytime relationship depth matters:

• When forming teams or restructuring departments
• When curating your personal or professional circles
• When evaluating how much community a platform or event can hold

How to Use It

In The Breakfast Club, five students from different social circles are forced to spend a Saturday together in detention. By the end of the day, meaningful bonds form—not because they shared interests, but because they had the time and space to connect. The film shows how intimacy and trust are more likely in small, well-bounded groups—something Dunbar’s Number helps us design for.

Here’s how to use this model with intention:

1. Map your close circle: Who’s in your 5, 15, 50, and 150? (Think inner circle, sympathy group, clan, and tribe.)
2. Design for intimacy: If you’re building a team, remember that smaller groups foster stronger trust.
3. Reinforce bonds: Schedule low-stakes touchpoints to keep your essential ties alive.

Next Steps

Make a short list of people you want to stay close with this year. Not followers or fans, true connections. Then make time to reach out. Dunbar’s Number isn’t a limit to fear—it’s a design constraint to honor.

Where It Came From

Anthropologist Robin Dunbar proposed the number in the 1990s after studying primate brain sizes and social groups. He found that humans likely evolved to comfortably handle about 150 stable social relationships—a number that shows up across history in military units, Neolithic villages, and company org charts. The model has since been refined but continues to explain why emotional closeness doesn’t scale.

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Until next time, keep exploring and questioning. Your unique perspective is your greatest asset.

Think Independently, JC

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