Why stereotypes linger

I just got out of a class where we discussed the avant-garde movement
in 1920s Paris's fascination with black culture. Much of the art and
entertainment of the period was really based on stereotypes of
Africans and African-Americans and not their true cultures.

This got me thinking about stereotypes in general. My professor asked
the class why racism lingers in society, and I think that the
pernicious and tenacious nature of stereotypes is largely responsible.
They carry a kernel of truth, if ever so slight. They are also shallow
truths and therefore easy to propogate. They degrade a group of
people to one or a handful of characteristics as their defining
features.

Once a person or society has a fuller experience within a different
culture, these rough caricatures begin to lose their staying power.
Just a random thought.