In his book Influence: the Psychology of Persuasion, American psychology and marketing professor Robert Beno Cialdini lists likability as one of the 6 key principles of influence.
And a way to get people to like you, Cialdini argues, is to “rapidly seek out commonalities” with that person. Moreover, the connection doesn’t have to be unique or meaningful – a shared interest in sports or a similar vacation location are both sufficient to help make someone like you.
Small talk allows people to find commonalities quickly, and thus to have influence over each other right from the beginning.