Have you ever wondered why the planets in our solar system are moving in such an orderly manner? Their orbits are so neatly arranged in (roughly) concentric circles, and they are all (generally) moving in one single plane. Why aren’t they whirling around chaotically, like some cosmic misbehaved children?

I was amazed to learn that the answer to this question is the same as the one which explains how complex life managed to appear back here on Earth: evolution. Planets are under the selective pressure of natural selection as well, just as living things. If the planets moving around a star would have disorderly orbits that intersect each other, they would simply smash themselves out of existence. The population of planets in our solar system evolved into what we observe today: a tidy formation of polite cosmic adults.

I kept on being amazed to learn that a lot of other seemingly unrelated phenomena can be explained by the same reasoning. Companies are under selective pressure to make profit, and therefore markets evolve to contain profitable companies. Online content is under selective pressure to gain your attention, and therefore social media platforms evolve to contain attention-grabbing content. The list goes on and on.

A particularly fascinating domain in which this evolutionary rationale can be applied is in ideas. Any idea, really. Ideas live. We keep them alive by thinking them. However, we can’t think of that many things at the same time. Ideas die out, because we lose interest in them. There are scarce resources in this cognitive ecosystem in which ideas proliferate. However, ideas also spread. I can tell you about an idea in writing, then you can tell someone about it through speech, and so on. In a sense, the idea is creating offspring, it is reproducing itself into other people’s minds. Ideas evolve.

Take a moment to appreciate the complexity of our world. Planets evolved to not smash into each other. On at least one of them, complex life evolved to not die. Across multiple species, ideas evolved to not be forgotten. All this, with probably countless more levels beneath, above, and in parallel. An interconnected symphony of evolution.

Now, let’s explore the evolutionary operators which drive this proliferation of ideas. First and foremost, there is natural selection, caused by selective pressure. Ideas that are not thinked will eventually die out. But what makes an idea more thought of? What makes a fit individual of the population of ideas? The function of fitness for an idea may be determined by a combination of factors.

First, is it appealing? We usually stay with ideas that we like, that are compatible with our existing belief systems. An idea that is profoundly incompatible with our belief systems would cause cognitive dissonance, a painful sensation of inconsistency in our minds. We evolved to avoid that, and that’s why it’s painful. We also like when things click, when there is suddenly a harmonious consistency in our worldview. Keep in mind that the evolved population of humans is actually the environment for the population of ideas. Therefore, ideas that are appealing to us are more likely to stick around.

Second, is it helpful? Ideas that cause counterproductive ways of thinking would harm their hosts. But ideas can’t survive without them. Therefore, ideas that are harmful are at a disadvantage.

Third, is it contagious? There are ideas that we feel like sharing. Of course, these ideas have an evolutionary advantage: they manage to spread.

Another operator which facilitates evolution in general is mutation. A tiny chance of individuals changing in a subtle way. When you tell me an idea, and I misunderstand it, I obtain an idea that is different than yours. This can be seen as an error in reproduction, which is a common source of mutation in biological evolution as well.

Last but not least, another important one is cross-over. It refers to the way in which parents create an offspring that is a combination of the two. With ideas, you can think of the situation in which you connect multiple ideas and give rise to a new one. A cognitive psychologist might call this process convergent creativity.

It is fascinating to see how the same mechanics that supported the development of complex life on Earth can be applied to the proliferation of ideas in human culture. It’s even more fascinating to think about ideologies. These are belief systems, or maybe… “societies” of ideas: a whole new level of complexity above ideas, just like human societies emerge from humans. They are collectively subject to the same evolutionary operators, but in a deeper way.


An influential species of ideologies are religions. For thousands of years, they have caused both torment and ecstasy in human culture. Many religions are often at odds with evolutionary thinking, and creationism versus evolutionism is still a fierce debate. However, we can think of creationism, and religions as a whole, as a product of ideologic evolution, and in so doing reconcile the two sides of the debate in a mutually-compatible worldview.

Widespread religions seem to also fit the criteria for fit individuals based on selective pressure. They are appealing because they provide consistency in our reasoning, they provide attractive causal explanations for phenomena in the outside world and in our personal lives. That’s why it happened, because this deity wanted to punish you. That’s how it all came about, so-and-so deity created the world.

They’re also usually (but definitely not always) helpful. For example, jews follow the Kosher rules for eating. These prescribe some general guidelines for food. For example, they prohibit the consumption of pork. If you think about it, that’s quite a good rule of thumb, because eating a lot of red meat is detrimental to your health. One might imagine a religion which dictated counterproductive ways of living, for example eating a lot of pork. Such a religion would be at an evolutionary disadvantage because it is harmful for its followers, it is damaging its environment.

Religions also spread. Most of the popular religions evolved intricate rituals for dominating cognitive territory. In most religions, parents are encouraged to pass on their religious heritage to their child. Another widespread practice is when religions constrain their followers to marrying someone with the same religion, which pressures many to convert. A religion without missionaries wouldn’t proliferate.

It therefore makes sense why religions, especially the ones that are currently popular, are so widespread. They are quite appealing, usually helpful, and very contagious. Maybe it was inevitable for such ideologies to develop on the foundation of human thought.

If you see yourself on team Darwin as opposed to team Moses, take a few moments to ponder the complex evolutionary dynamics which may have given rise to the ideologies you are interacting with. You’re on the same team.