Life on earth has spread from the same DNA base as far back as we can see, from the simple single-celled extremophiles lurking in undersea volcanic vents. There’s a lot of change from that point to us, but along the way life repeatedly encounters similar patterns and relationships. Our genes are shaped by these patterns. Predator/prey relationships, for example, are a biological universal. I’m going to argue they are a key factor in defining human temperament.

Social species that cluster in large groups gain advantages in fending off predators, especially in rough neighborhoods. Social fish species remain together in groups because survival in their neighborhood is a numbers game. The bigger the crowd, the easier it is to hide from danger. Fish that don’t get this don’t last.

Over time, this strongly tilts instinctual fish behavior towards cooperatively defensive groups. But there are also advantages in breaking from the crowd, such as locating food and mates outside the group. So what happens in a population? A distribution develops toward the optimal mix of temperaments to keep population balanced. This mix adjusts to prevailing economic conditions.

Social species need some funky renegades temperamentally capable of taking risks to find opportunities, while the core of the group remains tightly bound to tradition to protect the bulk of the population. Populations need both rigidity and flexibility. Over time, this is what temperamental variation provides.

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Much human behavior is essentially monkey-see, monkey do – it’s imitative. There’s a reason for that. Think back to the school of fish; they swarm together tightly when predators lurk. Behavioral instinct; the hardwired genetic imperative says do it this way or die, no second chances.

And so it goes as social animals emerge on land. Everywhere you go, from the anthill to the elephants, there are strict local rules; don’t eat that or you die. Stay out of this area during floods. Winter comes; stock up. Whatever rules are needed to avoid becoming prey or a victim of environmental conditions fall into this category.

This creates a built-in bias toward absolutes as key to survival. It is acquired, haphazardly and not always successfully, among animals through imitation; the trait persists among humans and is most strongly expressed among conservative fundamentalists and nationalists. Notice that absolutes are usually binary – do this or die; don’t do this to live. Binary thinking is characteristic of conservatives.

In an economic contraction, conservatives gain more power. In expansions, progressives gain. In the context of the animal kingdom, this makes sense; when times are hard, security becomes a deeper concern; you’re competing with all the other life forms in the neighborhood. Aggression becomes a positive.

When times are good, we can wiggle and giggle and agree that soft-serve ice cream is simply the greatest. Abundance gives us the luxury of broader cooperation, and it’s also smart survival strategy – cooperation makes harvesting abundant resources easier and more effective.

Herds only endure when they contract and expand in tandem with available resources.

When a herd is fragmented, it exposes a larger attack surface to predators.

Which is a pretty good description of the Republican party’s mode of operation. Divide and conquer.