Hint: It’s not either of these guys!

Bite the Bullets (A quick summary if you don’t want to read the whole article)

  • Human behavioral biology is a multidisciplinary field that describes the fundamental biology behind what we do
  • There is a balancing mechanism in our bodies we cannot escape called allostasis. Almost everything our body does is dictated by it.
  • All we eat and do affect us on many different biological levels, which in turn affect our behavior and thinking in a “allostatic” way.
  • How we think affects our biology, which in turn affects how we think in a feedback loop
  • That’s why when we make decisions, it’s important to keep that in the back of our mind. It informs the context in which we make decisions.
  • For all these reasons you are your greatest enemy, but you can be your own best friend!

The great contradiction

There is a devilish problem in our society. It tricks even the smartest of us into making easily avoidable mistakes. It’s one of the reasons we get mad in our cars, why we get into fights and it’s very simple. It was the thing that our current president constantly exploits. The great contradiction is: we are irrational but we make decisions as if we are not. It’s not a terrible thing by itself, that we don’t act rationally most of the time. However, pretending we do means that we are often wrong without even knowing it. How can we limit how much our biology is exploited?

Enter behavioral biology!

This field describes the patterns of our decision making in a way that can help us deal with the fact that we’re irrational. In order to get clear on how our brains are manipulating us, we need to go through some of the building blocks of our brain itself. There are three crucial systems that are important to know to understand the symphony that is our behavior.

These fellas work together to make you who you are! It’s going to seem like we’re walking away from the core concept at first. Really, we’re on a grand journey that gives us a big picture understanding of what’s going on when we do and feel things. I promise it’s worth it!

We are irrational but we make decisions as if we are not. Share on X

Allostasis means balance

Yin and Yang: the elegant fight for balance of the universe. It turns out that the concept of yin and yang is spot on for describing a very important facet of our behavior as it relates to our biology: allostasis. Allostasis is the concept that your body maintains balance by adapting to changes. When you read allostasis, just think balance.

For every action in your body, there is a reaction that serves as a balancing force. There’s a really interesting example of this: temperature. Under normal conditions, we sweat when we’re hot, and that cools us down.

That’s allostasis or balancing process. Something in our brain senses a change that puts our body’s temperature out of balance. Then, it sends signals to regain balance. The Yin of being hot, the Yang of sweating to cool down. As you can imagine, there are countless more processes just like this! All of them in a constant state of organized chaos.

Just a taste of how complex this gets: when our body balances the acidity of our blood, it causes an imbalance in our temperature, so we sweat. That causes an imbalance in the amount of salt in our blood stream and that causes us to get thirsty. When we happen to drink a beverage that is acidic (like soda), the whole thing starts over. This goes on and on for as long as we’re alive.

It’s this beautiful and complex orchestra playing inside of us, balancing and counterbalancing all the important systems in our bodies. That’s important part of allostasis: if you change something in one place, it changes something else somewhere entirely different. These systems are all interconnected, all following a similar pattern. For every Yin there is a Yang. This process, of course, affects our behavior.

The squishy squirty thingies in your head

What actually happens inside of you when your body gets hot and needs to cool down? There is a thermometer inside the part of your brain known as the hypothalamus (don’t worry about what it’s called). It senses heat and then tells other glands to send the message to parts of your body to cool down. That process is mediated by hormones in your bloodstream. (For the curious: this system of sensing something and then sending out some hormones is called the endocrine system).

That thermometer accepts signals from other regions of the brain and connects to this system through a weird little sack dangling off of it called the pituitary gland. In this analogy, this is like an A/C unit. That’s what sends the signal to cool you down.

Here’s all you need to remember: one part of your brain tells another part of your brain to squirt some hormones to some other glands that then cause your whole physiology to change. It’s just like a thermometer tells the A/C unit to turn on and start pumping cool air through the vents to change the temperature of the house.

There are little blobs in your head, squirting hormones in your bloodstream right now as you read this. It’s the same reason you feel your heart race when you get on a roller coaster, or get those butterflies in your stomach when you hold hands with that special someone. Utterly crazy.

There are little blobs in your head, squirting hormones in your bloodstream right now as you read this. Share on X

The child in your head

We now know about allostasis: things stay in balance for the most part and when they get out of balance, a bunch of things happen to balance them again. We also know that there is a system of glands squirting hormones around telling our bodies to react to help maintain that balance. What’s kicking off the process?

There is another collection of brain blobs are together known as the limbic system. Most of our basal emotions and, just for fun, where some of our learning happens, occurs in the limbic system [1]. The important part for us to explore at the moment is that the limbic system on a whole covers a lot of stuff from emotion to learning to consciousness.

It’s a long list, but the thing to remember is the gross oversimplification that it regulates emotion by telling the first gland (hypothalamus) in that process we covered above to kick things off. It’s the kid in you that just wants to go after things impulsively, or gets irrationally scared in the dark. That kid is stomping on the sack triggering your hormone releases.

It’s also important to remember specifically the piece that’s telling you to specifically excrete fear and arousal hormones. It’s called the amygdala and we’ll see it again in a bit.

The monk in your head

Whew, that was a lot of brain blobs that we just covered. There is one final blob we need to get through for this crash course. That’s the most interesting and important blob of all: the frontal cortex! I’ll steal the description of what it does straight from Robert Sapolsky’s book Behave. He describes the function of the frontal cortex as “doing the harder thing when it’s the right thing to do.”

In this case, “right” doesn’t mean morally right, but what’s the right thing in the context of what’s happening. What will offer the most utility in a situation. Lying is a great example, because it requires a ton of suppression of other parts of your brain, and thus a lot of work on the part of the prefrontal cortex. It’s usually not the morally right thing to do, but it’s the harder thing to do and you are telling your brain it’s the thing that’s happening. That’s what we mean by “right” in this case.

For our purposes, the calming of the kid in our brain is what the prefrontal cortex does. It’s like a very meditative monk that can drop the wisdom on the kid before she’s about to stomp around and release a bunch of hormones into your bloodstream. This is mediated by a lot of systems working together, but we’ll keep things simple for now [2].

“I know you’re afraid of the dark, but this is your home and there are locks on the door. There is nothing to be afraid of.” Remember how I just mentioned the amygdala? Quelling your fears is an example of the amygdala first telling you there is something wrong and then your prefrontal cortex telling your amygdala that all is quiet and well.

All together now

We’ve covered the building blocks of what causes our rationality and decision making to totally fall apart. It all comes down to these systems that we just explored working together in harmony (or disharmony if you’re trying to get something difficult done).

Imagine a scenario: you see a cutie that you’d like to chat with. What’s actually going on in your head? First the visual sensory information flows in. It bounces around the processing centers and you might get a little initial hit of arousal from the amygdala telling the hypothalamus to squirt some excitement hormones in you. Then the prefrontal cortex comes in!

It starts to go over all the terrible things that could go wrong in the hypothetical situation of you talking to this stud muffin across the room. It also tells the amygdala to trigger, but this time it’s a fear response! Now your endocrine system thinks you are in physical danger, so you start sweating in a classic fight or flight response.

Maybe you end up talking to this person and saying some completely silly stuff that you normally wouldn’t say. Now it should make a lot of sense why it’s so hard to accomplish such a simple task! Your prefrontal cortex, limbic system AND endocrine system are doing a lot of work. With all that extra burden, how can you expect to be clever?

A vital part of this interaction is seeing that the effects are a two-way-street. That is to say: you feel and think things because of your biology, which in turn causes your biology to change. You can think your body into having a physiological reaction and you can calm your thinking by say, slowing your breathing [3].

Of course, I’m leaving out a lot of steps in this process, but that’s the basic ping pong that happens in your brain any time anything happens to you. This is the beauty of human behavioral biology and how this affects you is really extensive. Think about every time you make a decision, try to convince someone of something, or need to get some important work done. There is a cocktail of context that you might be neglecting: your biology.

There is also a wealth of information in observing your own behavior with this tinting your self-reflection. The thing that I’ve mentioned several times on this site is the example of people getting irritable when they’re hungry, which is a pretty common occurrence. Taking that concept further, and knowing everything is interconnected, imagine how your thinking, attitude and mood are affected by something like chronic stress.

When things don’t go exactly as planned, you end up with a lot of valuable and actionable insights about your body specifically. Your personal internal interactions are worth getting to know intimately, because no one on earth can feel what physical responses you experience to certain stimuli. It sort of muddies the lines between the quirks each of us have individually. Every action has a reaction, which probably tugs on some string in another part of the unravelling sweater of systems inside of you.

The simple bow on these very complex systems and information is this: it’s useful to remember specifically how human you are in a biological context. When you’re trying to learn a new behavior or a habit, your strategy might start with how you’re going to navigate the interactions between the parts of your brain. When you’re getting impatient with yourself or reacting, let the fact that this is a symphony of hormones remind you to slow down and take a breath. Your body has to balance a whole lot after all.

When you’re getting impatient with yourself or reacting, let the fact that this is a symphony of hormones remind you to slow down and take a breath. Share on X

Who is your greatest enemy? YOU ARE! You’re brain is constantly out to get you. The good news is, you can learn to become your best friend. Mastering your biology is a step towards overall self mastery.


[1] Parts of the limbic system and what they do:

  • The amygdala, which means almond.
    • Responsible for fear, arousal and motor outputs.
  • The hippocampus, which is latin for seahorse.
    • Does a bunch of things and still isn’t fully understood, but at least tackles emotional processing, memory consolidation and spatial cognition (i.e. remembering where your house is).
  • The septum, a term for any structure that’s the “midline” of something.
    • In this case it’s the midline of the brain. Connects a bunch of parts of the limbic system.
  • The thalamus, the thing above the hypothalamus.
    • It relays sensory input such as pain.
  • The ventral tegmental area and nucleus accumbens.
    • Cores to dopamine transport.

[2] Speaking of complex systems, dopamine is another super interesting topic that we don’t have time in this overview to dive into. Since you’re here in the annotations, I’ll tell you the most interesting counterintuitive tidbit about dopamine. It’s not so much of a reward hormone as it is an anticipation hormone. That is to say, dopamine peaks in our bloodstream when we anticipate we’re going to get a treat rather than after we get it. We’re most excited and elated to get the new shiny and it’s all over as soon as we get it. Tragedy of the human race, isn’t it?

[3] Before any of you come at me with pitchforks: I’m not saying you can cure a serious illnesses by just thinking. Additionally, don’t take this to your friend with major depression and say “look, thinking can change your physiology!” This is a much more complex mental illness and I’m not endorsing the concept of “just think your way to being happy.” If you must connect this concept to something like mental illness, the place to look is in cognitive behavioral therapy (CBT). This is the same physical mechanism, and backed by supporting scientific evidence. Here’s a place to start: https://www.mayoclinic.org/tests-procedures/cognitive-behavioral-therapy/about/pac-20384610

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