One of the interesting things he talks about (toward the end) are how we are similar to animals in having a biological basis for an "us vs. them" behavior. BUT, he says that in humans this behavior can be based off of ideas, rather than territory or blood relation.

So it made me think.. This ability to abstract patterns rather than just respond to them right away has proven to be very efficient for survival. You don't rely on stimuli alone to preserve yourself - you have the ability to predict the future.

So now at some point once this cognitive way of functioning developed, it endured. Now you have a whole bunch of these creatures walking around making decisions based on their IDEAS. So what it means for you as an individual animal, is that your life and survival now depends on other people's ideas more than the usual factors that existed for other species in the past (like blood relations and territory).

This creates an evolutionary pressure (I think that's the right term), to monitor and respond to other people's ideas, as a high priority - maybe even higher than factors like the tit-for-tat behavior he mentions or things like blood relations. That's why people can be so angry at someone's political views that they could end a friendship over it.
Ideas are THAT important to our species.

It is an inevitable behavior... and happened for the same reason why abstract thought came about in the evolution of brains. I think...

Turns out I am a big time biology nerd. This stuff is fascinating. Understanding who we are and why we are the way we are.
And isn't it cool that so many living things have existed not having a clue of their own complexity. Having self-awareness was not required to survive. You were an amazing feat of engineering crawling or running around the earth not having a clue that that is what you are.