For the vast majority of human history, people have been embedded in small tribes. Only in the brief last five minutes of that history have we found ourselves in groups of millions of people. It's a problem, psychologically.

As I write this I am surrounded by about a hundred people in a large crowded restaurant. I don't know those people, they don't know me. We all live within a few miles of each other, we mostly shop at the same stores. We nearly all speak the same language with approximately the same regional accent.

But we are not a tribe.

I don't have any scientific back up for this—though I think there is some—but I believe human beings are the most psychologically healthy when they are embedded in a tribe of about 10-30 people. Usually this is an extended family group but a circle of friends works the same, better in some cases.

As humans, we seek out this emotionally satisfying situation. We enjoy dinner parties, sewing circles, informal team sports, bridge clubs. Megachurches have figured out this obvious fact. The church may have 9,000 members but they have hundreds of small support groups, study groups, discussion groups. You can't get a true emotional connection with a tribe of 9,000 people but you can have great warmth and affection for the 8 members of your young adult backgammon group.

When our tribe needs us, we have their backs. We fight for them, defend them. We applaud their good behavior. They do that for us. We excuse and defend their bad behavior and they do that for us too. That's all wonderful. It makes us feel safe and happy.

It's the good side of tribalism. We want it, we need it, and when we are smart enough to understand those facts and get those needs met, we are happy campers,

But tribalism has a dark side as well.

The Heysel Stadium Disaster occurred on 29 May 1985 when escaping fans were pressed against a wall in the Heysel Stadium in Brussels, Belgium before the start of the 1985 European Cup Final between Liverpool of England and Juventus of Italy. Thirty-nine Juventus fans died and 600 were injured.

Approximately one hour before the Liverpool-Juventus final was due to kick off, a large group of Liverpool fans breached a fence separating them from a "neutral area" which contained rival Juventus fans. The Juventus fans ran back on the terraces and away from the threat into a concrete retaining wall. Fans already seated near the wall were crushed; eventually the wall collapsed. Many people climbed over to safety, but many others died or were badly injured. The game was played despite the disaster in order to prevent further violence.—Wikipedia

I believed until the bitter end that Anthony Weiner didn't Tweet pictures of his crotch to women he didn't even know. Weiner was a “member of my tribe.” He was something I adore—a fiery liberal. I doubted he'd ever be president, but Speaker of the House? Yeah, baby! You bet! Woo-hoo!

Those weren't pictures of him. Nobody in my tribe would ever do something that stupid! In addition to that, the news came from Andrew Brietbart who is a member of an enemy tribe. Therefore the information was automatically false.

But Weiner isn't and never was a member of my tribe. He is a man I don't know. He's a stranger who lives thousands of miles away, whom I have not met and will never meet.

Our tribal affiliation was an illusion, a powerful one. This time the illusion was merely disappointing, but illusions can easily be dangerous, damaging, even fatal.

We love our tribes, and it's very easy for a penumbra of love and need to spread out to other tribe-like groups.

The good urge to be part of a small group translates into loyalty and allegiance to a much bigger group—the 9,000 member megachurch, the state, nation, political party, football team.

However, we can't belong to a 9,000-member tribe or a 9-million member tribe. Those feelings of tribal affiliation are an illusion. And when illusion starts getting substituted for reality, really bad things can happen. A situation can go horribly wrong, really fast.

The Rwandan Genocide was the 1994 mass murder of an estimated 800,000 people in the small East African nation of Rwanda. Over the course of approximately 100 days (from the assassination of Juvénal Habyarimana and Cyprien Ntaryamira on April 6) through mid-July, over 500,000 people were killed, according to a Human Rights Watch estimate.[1] Estimates of the death toll have ranged between 500,000 and 1,000,000,[2] or as much as 20% of the country's total population. It was the culmination of longstanding ethnic competition and tensions between the minority Tutsi, who had controlled power for centuries, and the majority Hutu peoples, who had come to power in the rebellion of 1959–62 and overthrown the Tutsi monarchy.[3]--Wikipedia

Democrats, liberals, Republicans, conservatives, Americans, Green Bay Packer fans are not your tribe. Those groupings can't be treated as tribal members. It doesn't mean you must be disloyal or avoid joining these enormous affiliational groups but they can't be viewed with the came cozy intensity as a tribe.

So vote Democrat or Republican, cheer for the Rangers or the Cowboys, chant “USA!” at political rallies. Those things are fun. They feel good. But know that those people are not your tribe and never can be.