Brain chemicals cause herd behavior in politics. When a mammal runs with the herd, its brain releases a chemical called oxytocin. That produces a pleasant feeling, which motivates the mammal to stick with the herd. Separating from the herd triggers a mammal’s cortisol, the brain chemical that signals imminent survival threat. Sticking with a herd or pack or troop promotes survival in the state of nature, and natural selection produced a brain that makes you feel good when you do things that promote survival. No conscious deliberation is involved.

Humans have the same neurochemicals as other mammals. Underneath your big cortex, you have the same basic limbic system (amygdala, hippocampus, hypothalamus, etc.) emitting them. You don’t always act on your mammalian impulses because a big cortex is good at inhibition. This cortex of ours is also good at hatching reasons for doing things that trigger good feelings without awareness of the underlying neurochemistry.

No one says to themselves, “I think I’ll follow the herd to protect myself from predators.” We don’t see herd behavior in ourselves, even though it’s easy to see in others. Our two brains are literally not on speaking terms. The mammal brain cannot process language, so when you talk to yourself, it’s all in your cortex.

Understanding the mammal brain gives you more power over it. For example, it helps me understand the icky cortisol feeling I get when I know I am separating from the herd. I remind myself that I am not about to be eaten by a lion, even though my limbic system sees it that way.

Everyone I know is a mammal. Their cortex generates lofty principles to justify the kind of herd behavior that comes natural to mammals. I often find myself wanting to scream at people “Don’t you realize you’re just repeating whatever the New York Times says!!!” But I don’t. I remind myself that they won’t realize it, because they are mammals with a big cortex attached.

That doesn’t mean I just give in to the herd behavior that surrounds me. Sometimes I go off in my own direction regardless of the potential threat. Sometimes I try reasoning with the herd. And sometimes I feel like the herd is approaching the edge of a cliff and I blurt out something crude.

This happened recently while I was watching Saturday Night Live. I used to love this show and my kids grew up watching it with me. But the partisan nastiness eventually triggered more cortisol than I could stand. “Don’t you see?” I snapped at my family. “The Republican is always portrayed as a moron! Nixon was a moron. Ford was a moron. Reagan was a super moron. The Bushes were extreme morons. And now, the enlightened information analysts at Saturday Night Live have discovered that Romney is a moron, too.”

You can probably guess that my family did not see. In their minds, Republicans are morons, so why shouldn’t they have a laugh over it. They could not imagine their sophisticated political positions being influenced by the good feeling of belonging to the ridicule-Republicans herd.

How can you convince a person that their cortex is not in charge? Oliver Sacks provides a great example in his encounter with a patient whose limbic-cortex connection was severed. The patient seemed normal but could not choose a date for his next appointment. He endlessly analyzed the pros and cons of each available slot without reaching a conclusion. The cortex is adrift in a sea of data until the mammal brain releases the neurochemicals that give you a good feeling or a bad feeling about an input. Your mammal brain transforms data into preferences.

Herd animals get their information from hostile jibes, witty innuendo, and nasty reparté. This is all the data they need because their neurochemicals are guiding the way. I am a mammal and so are you. The more aware you are of your neurochemical self, the less likely you are to act on your mammalian impulses.

But it’s not easy being a mammal. My next post will describe the “mirror neurons” that cause primates to mimic each other. Until then, there’s more about herd behavior on my website, www.imammalthebook.com.