Why does your brain care more about some groups of people than others?

Why do we so naturally form in groups and outgroups?

And what does any of that have to do with George W. Bush's political commercials, or the Greeks,

or psychopaths, or or Syndrome E or propaganda posters

and how to develop immunity against them.

Welcome to Inner Cosmos with me, David Eagleman. I'm a neuroscientist and an author at Stanford,

and in these episodes we sail into our three-pound universe to understand why and how our lives look the way they do. Today, we're going to talk about why we're so wired to have in-groups and out-groups,

and what the consequences are, and how some knowledge on this goes a long way to making us a little smarter in the face of propaganda.

This is a topic of enormous importance in no small part because repeatedly throughout history,

groups of people have inflicted violence on other members of their population.

Think of the Nazis and their killing of millions of people,

Jewish communities and gypsies and others based on religious and ethnic and political affiliations.

Or look at the Nanking massacre in 1937 when the Japanese invaded China

and killed hundreds of thousands of unarmed civilians and systematically

raped between 80,000 and 100,000 people. And in 1915, there was a systematic killing of the

Armenian population by the Ottoman Empire. It's estimated that about one million Armenians were

killed during this.

And then in 1994, in a period of 100 days, the Hutu in Rwanda killed 800,000 Tutsi.

And this was accomplished mostly with machetes.

And at the peak of this, they were actually achieving a higher killing rate with machetes

than the Nazis had accomplished with gas chambers.

And so the question is, what is going on here?

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