Ties form disproportionately between similar people, so networks segregate without anyone intending it.
McPherson's summary: birds of a feather flock together. Segregated networks require no prejudice at all, only mild preference, which is why integration does not follow automatically from contact opportunity.
In practice
- A hiring pipeline built on referrals reproduces the existing team's background without a single biased decision.
- A book club that grows by members inviting friends reads a narrower range each year and nobody chose the narrowing.
- Further reading
- Wikipedia
- Subject
- Networks & Collective Behavior
- Essay
- How connections shape what crowds do