Polarizing debate and people

Things have become more polarized than ever in Washington DC among the nation's political leaders.   It seems that there has become an "us and them" mentality across party lines. This is also prevalent in social media. Why is this?

In his book "Us and Them: Understanding your tribal mind", David Berreby notes how people are often keen to create "human kinds" aka classifications based on categories such as race, nationality, culture and political movements.  These human kinds are what occurs when the real world meets our human minds.  They aren't perceptions, but rather beliefs.

The tendency to place too much stress on supposedly unchanging traits rather than the impact of situations is called a fundamental attribution error. Social psychologist, Lee D. Ross first defined this human tendency. As these beliefs become engrained there becomes an expectation of "essentialism", whereby it is expected that people be "the same" in all times and places.  

What is the solution to this gridlock by "red" and "blue" politicians?  A number of veteran politicians have suggested that people across party lines need to socialize more, and they just might discover they have far more in common than they do in differences.  

We would all do well to get to know others outside of our ethnic backgrounds, nationality, or political movements. We are indeed just one human race.