This is Hidden Brain, I'm Shankar Vedanta.

Look up at the sky in most places in the world

and you will see flocks of birds.

Look carefully and you'll see these flocks are usually made up

of the same kind of birds.

Pigeons flap around with other pigeons,

crows with crows,

starlings congregate with well,

lots and lots of other starlings.

Somewhere along the way,

someone coined a memorable phrase,

birds of a feather flock together.

Sociologists have noticed that this phenomenon is not restricted to birds.

Humans tend to do the same thing,

except because we are complex creatures,

the things that draw us together are not just physical similarities,

but cultural constructions,

such as social class,

shared interests and common cuisines.

We think nothing of the fact that music lovers hang out with other music lovers

or that book readers congregate in book clubs

and that gardeners form their own societies.

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