I have known Gary Porter for over a quarter of a century. Gary and I share an interest in Mormonism and in politics. I’m delighted to be able to share this guest post from him.

In America today Republicans and Democrats live in alternate realities.

Nearly everyone recognizes that this is so, and yet no one understands how this is even possible. This is testament to our own lack of understanding of humans, of ourselves.

What are the evolutionary traits that led to human survival? Which traits, conservative or liberal, through the 200,000 years of human survival, led to who we are today?

What is truth? Is it that which leads to our survival? Is it somehow different from the mathematical rules of the universe? Can 2+2 somehow equal 5 when human survival depends on it?

Did following the group, either rightly or wrongly, lead to human survival? And if so, did human evolution program our minds to be unable to recognize truth in certain circumstances?

President Trump famously asserted that President Obama didn’t have a US birth certificate and thus wasn’t a legitimate President. There was an objective truth that could be easily verified. But a larger question is whether President Trump really believed Obama didn’t have one. Was Trump purposely lying about something that could so easily be proven false? Why could so many people believe it when he said this? How does he have such a strong hold on the Republican party in the face of easily disprovable falsehoods?

To solve this puzzle let’s perform a thought experiment. Suppose we are hunter gatherers 150,000 years ago. Thirty of us have been living in a certain cave for 3 generations. It’s not the best cave, but it works. Some of us will die, perhaps earlier than necessary, but the group itself will survive by staying there.

Every now and then a child is born who is a wanderer. He’s not good at following rules. He may not contribute his share to the group’s work because he is impractical. He wanders off getting farther and farther from the safety of the group.

One day he finds a place entirely better for survival than the cave he has been living in. It has the resources to support 150 people instead 30.

However, when he comes back and starts telling people what he has discovered, will he be welcomed? Or is he a threat to the group’s existence? The group will survive more generations by staying in the cave. But it might not survive at all by moving to a new one.

During the 200,000 years of human evolution most people chose to follow the group, even when they heard about a better cave. Mathematically, over time, more people survived by doing so. The benefits of following the group are simply too strong.

In the mid 1800’s Mormons settled the Salt Lake Valley, a place with almost no natural resources. There was better land almost anywhere else than Utah, and gold had been discovered in California. However, their belief in a fantastical story, and their ferocious devotion to the group, led them to survive and eventually to prosper. Similar analysis can be made about the Japanese, the Jews, and many other groups who believe suspect ideas, but who have fanatical devotion to the group.

In the hunter-gather stage of human existence, getting this right was not just an academic experiment. It meant survival, life or death, both as an individual and as a group. We fear death more than anything else. It is infinite loss.

Most people, if offered a choice between losing their home, and gaining 10 times the value of their home, when the odds are 50-50, will choose keeping their home, even when the mathematics favor taking the risk. Losing one’s home can mean total destruction. It can mean infinite loss. Gaining ten times its value is nice, but not infinitely so.

Mormons, Jews, Japanese (during Japan’s war years), Germans (during the country’s war years), and many Christian groups today, depend on stories of persecution to unite the group. Even invented stories of persecution can unite groups by touching a part of the human genome. It is the threat, however remote, of total destruction. If a group is threatened, even preposterously, humans lose their capacity to think in rational terms.

Almost none of us is aware of the degree to which this happens.

Consider Fox News. All day long its messages are about ‘threats’ to the group. Each anecdotal story, repeatedly told, reinforces some threat to the group’s existence.

Trump’s messages also are about threats to the group. Rationality ceases. Preposterousness becomes truth as long as a threat is perceived.

This characteristic of humans is not confined only to conservatives. For example, today the actuality of the threat facing the US from other countries is mathematically preposterous. Yet liberals are taken in by United States national security propaganda, as much or even more so than conservatives. Fanatics and demagogues today have sway in the US in the same way as they did in Germany and Japan during World War 2.

In the hands of demagogues, our genetic fear of our own group’s destruction has many consequences. Yet few of us today even begin to understand it.