Are our brains limited by our evolution?

Just like every other part of the human body, the way our brain works is largely determined by evolution.

Firstly, evolution has determined the limits of our cognitive functioning.

The range of thoughts we can think is actually limited to things that were useful for our ancestors. For example, if you try to visualize a five-dimensional cube, you’ll find it impossible. This is because the ability to see five-dimensional objects did not provide any evolutionary advantage.

The range of tasks we are adept at is also pretty limited. For instance, we are actually fairly bad at performing large mathematical computations because our ancestors never really needed them as hunter-gatherers. On the other hand, they did need the ability to navigate social problems like detecting and punishing cheaters, so humans today are fairly adept at this.

Secondly, evolution also guides our preferences in matters of taste and attraction.

Most people find things like apples, eggs and potatoes tasty. Why? Because they contain sugars, proteins and vitamins, all of which were useful for our ancestors’ survival.

We also have a strong aversion to even the idea of eating fecal matter. Why? Because it contains harmful microbes that would make us sick, so presumably any ancestors who were drawn to it died out long ago.

If we look at what kind of creatures we’re sexually attracted to, this also tends to make evolutionary sense: we’re not attracted to frogs, but rather other humans. This is because cross-breeding with other species is not possible, so being attracted to them would be pointless from an evolutionary standpoint.

Our Battling Brains

Do you think of yourself as having a single, unified personality? Most people do.

But in fact, if we examine our brains more closely, we see that this is an oversimplification: the brain comprises several subsystems that each have a different function, and that often compete for control over our behavior.

For example, we clearly have separate rational and emotional brain systems. As you might guess, the rational system is in charge of coolly and calmly analyzing situations, whereas the emotional system generates feelings like anger, fear, desire, and so forth.

Often the two are at odds, but both are necessary for a normal life. For example, if you lacked the emotional system, you would spend all your time overanalyzing the world around you, without being able to make even the simplest decision. Emotions may be swift and irrational, but they help you to quickly make the unimportant decisions needed in daily life.

The understanding that there are several subsystems in your brain competing for control of your behavior helps explain some peculiar phenomena.

For example, have you ever considered how bizarre it is for a person to curse at herself? This odd behavior can only be explained by the division in the brain: one faction of the brain is berating the other.

Or consider how odd it is for a smoker who wishes to quit to nevertheless keep smoking. Clearly it’s possible for one part of the brain to want to quit, while another strongly desires to continue.