Had lunch with my rheumatologist the other day. We break bread a couple of times a month and talk about the joy of writing and traveling, and about the increasingly chaotic state of the world.

Even though we’re sitting there at the Lebanese restaurant as two private individuals, he understandably can’t quite leave work behind. He always asks how I’m doing, whether the arthritis is behaving itself, and whether I need anything in addition to the disease-modifying medication I take daily, Rinvoq.

This time, we moved fairly quickly from my sick joints to the world’s even sicker leaders. While we enjoyed hummus, tabbouleh, crispy falafel, and sambousek, the doctor floated a theory about why human beings, despite having spent a few hundred thousand years on the planet, are still so terribly bad at learning from their mistakes. Especially when it comes to conflicts that almost always begin with two groups disagreeing and surprisingly often end with one of them bombing the other.

Not entirely unexpectedly, we got onto the subject of religion. As usual, we were in complete agreement that there can hardly be a single divine entity with exclusive rights to the truth. With a few thousand religions, sects, and genuinely twisted beliefs, such as Scientology, the randomness of it all becomes almost cosmically comical.

If you’re born in India, there’s a good chance Hinduism will seem perfectly natural. If you’re born in Brazil, there’s a considerably greater chance that you’ll be raised in a Catholic tradition where the Pope has a direct line to God. If you’re born in another part of the world, you get an entirely different explanation of our existence and what happens afterward.

The oldest versions are fairly elaborate fables that generation after generation have been fed since childhood and absorbed with their mother’s milk.

At the same time, the need to believe in something is perfectly understandable. Death, after all, is one of life’s few absolute certainties and at the same time its greatest mystery. You never know when the Grim Reaper will come knocking.

An old friend whom I hadn’t seen in a long time died a couple of weeks ago. His heart stopped in the middle of a workout at the gym. That’s how quickly the curtain can come down.

RIP Aadu Aruvald.

So the fact that religion can serve as a life preserver, a source of comfort or an insurance policy against the unknown makes perfect sense to both my extremely well-educated rheumatologist and a considerably simpler fellow like myself. The problem begins when you feel compelled to oppress, persecute, or kill someone who happens to have signed up for a different heavenly subscription.

Then we got to genetics.

The doctor’s lunchtime theory, greatly simplified, was that biologically speaking, human beings haven’t progressed very far compared with the world they themselves have built. His more provocative point was that genetically, we are still far too similar to our ancestors for our emotional reflexes to have caught up with technology. Technologically, development has moved at rocket speed. In what amounts to a historical instant, we have gone from stone tools to nuclear power, satellites, and artificial intelligence.

Collectively, Homo sapiens has been phenomenal at inventing things. Individual members of Homo sapiens are a completely different story.

Emotionally, we’re still dragging around a brain shaped for small groups, territory, hierarchy, fear and survival. We can send a spacecraft to Mars, yet still go crazy if the neighbor believes in the wrong god, wears a red cap or lays claim to the wrong piece of land.

And when testosterone, fear, prestige and groupthink kick in, a few thousand years of civilization can apparently be reduced pretty quickly to:

My cave. My tribe. My God. Shut your mouth.

We finished lunch, paid the bill with our phones and went our separate ways. Artificial intelligence in our pockets. The Stone Age between our ears.

My arthritis, fortunately, seems to be kept in check by Rinvoq. Humanity clearly needs much, much stronger medication.

Photo: Charlotte Raboff