Ideas spread for lots of reasons.  It might be a catchy tune or a funny joke that you’ve heard that sticks in the brain and makes you want to propagate it, to tell others.  But one reason that we know that ideas stick and spread is because they’re useful.  The useful ones propagate. 

So an example is the wheel.  The wheel was invented in Egypt but it was improved upon hundreds of years later in Sumaria by going from a solid disk to spokes.  How did it get to Sumaria?  Well, merchants used it to travel and spread their goods from point A to point B.  So that utility to them, the fact that it was a useful invention helped the invention itself spread from place to place.  It was carried by humans to other places where then it was improved upon by other people. 

60 Second Reads is recorded in Big Think's studio.