Learn about Dunbar's Number
About this idea
Discover why humans can only maintain about 150 meaningful relationships—a cognitive limit rooted in our evolutionary past. This quick lesson explains why social media's thousands of 'friends' don't align with how our brains actually work.
On this page
How to get started
STEP 1
the discovery (3 minutes)
- British anthropologist Robin Dunbar studied primate social groups
- Found correlation between brain size and social group size
- Predicted humans can maintain ~150 stable relationships
- This became known as 'Dunbar's Number'
- Not friends - but people you could ask a favor from without it being weird
STEP 2
the layers (5 minutes)
- Relationships form concentric circles:
- - 5 people: closest confidants (family/best friends)
- - 15 people: good friends (regular contact)
- - 50 people: friends (monthly contact)
- - 150 people: meaningful connections (could ask for help)
- - 500 people: acquaintances (recognize)
- - 1500 people: can put a face to a name
- Each layer takes time and cognitive energy to maintain
- Moving someone from outer to inner layer requires sustained investment
STEP 3
why the limit? (4 minutes)
- Your neocortex (brain region for social processing) has limits
- Tracking relationships requires remembering:
- - Person's history and context
- - Your history with them
- - Their relationships with others
- - Social norms and obligations
- - Emotional states and patterns
- This cognitive load maxes out around 150 people
- Hunter-gatherer tribes averaged ~150 members
- Military companies traditionally ~150 soldiers
- Successful companies often split departments at ~150 people
STEP 4
implications for modern life (3 minutes)
- Facebook friends, Instagram followers don't change brain capacity
- You're still limited to ~150 meaningful relationships
- Social media creates illusion of more connections
- But 'friends' beyond 150 are shallow - you can't maintain them properly
- Quality vs quantity matters more than we think
- Your brain evolved for tribal life, not global social networks
What you’ll need
- none
Recommended resources
Tutorials & Learning
Progress milestones
Track your progress with these key achievements:
1
5 minutes
Understand Dunbar's Number
2
10 minutes
Grasp relationship layers
3
15 minutes
Apply to modern social media
Common challenges
Every beginner faces obstacles. Here's how to overcome them:
I have way more than 150 Facebook friends!
Solution: Test this: Could you comfortably ask each of them for a favor? Have a meaningful conversation? Remember details about their life? Most 'friends' are actually acquaintances.
Share your progress
Celebrate your achievements and inspire others:
- • Reflect on your actual close relationships
- • Discuss quality vs quantity of friendships
- • Share this concept with social media users