How Fear and Anxiety Drove Human Evolution | Nat Geo Explores

The heart races. Deep breaths are hard to find. Blood rushes through the body; that's fear. Anxiety, scientifically, we tend to talk about fear as being a response to immediate threats, which is right there in front. First, anxiety is where there's the possibility of danger, but it's kind of looming on the horizon. We're trying to work out how probable is it, how bad might it be, what can we do to avoid it?

Think of a lion right in front of you; that's an immediate threat. Looming in the distance, not as scary, but still something to be worried about. Evolutionarily, think about the hyper-vigilance that goes along with anxiety as a very adaptive trait. Because a long time ago, the world was super dangerous, and humans needed to use that hyper-vigilance as a way to evolve.

It all starts here, specifically in this region. The amygdala is kind of flashing away, saying there's something dangerous; we need to react to it. We release various neurotransmitters, and we need some of those to have a good level of attention, to be able to be focused. We'll see the blood being shunted away from our extremities and into the larger muscle groups. Because if we needed to escape, it would be necessary those organs be heavily involved.

The world has changed, and threats typically aren't as clear-cut as a lion in front of you. So let's take a look at how our brains respond to uncertain threats. When we're faced with potential danger, uncertain situations, we feel better if we feel in control. We find it harder when probabilities are changing rapidly.

After what we rely upon are these kind of simulation mechanisms, where we try and imagine if we were to engage in different courses of action. But that's also after where biases can come in, like zero risk bias, which might explain the behavior of panic buying. As humans, we have a strong desire for absolute certainty. So when we can't eliminate the risks out of our control, zero risk bias may persuade us to completely eliminate certain perceived risks, regardless of how irrational they may be.

Some panic buy while others experience optimism. Boys, we kind of had this very self-protective intrinsic desire to build the world's a safe place and nothing bad will happen to us. When probabilities are hard to estimate, often those optimism biases kick in.

No. This is real; this can have consequences.

Ok, back to the brain. The amygdala going into overdrive is necessary for short-term threats but can have negative consequences when threats persist for the long term. So we can think of neurons in the brain as being a bit like trees with branches, and those branches are called dendrites. In the prefrontal cortex, which is involved in reasoning and decision-making, we actually see those branches begin to kind of wither and die back. While it's in the amygdala, we see those branches kind of grow into bulla.

So that can lead us to have stronger responses to danger and for them to be less regulated. This deregulation can further lead to anxiety and, in some cases, show a correlation with depression and trauma. But these factors aren't permanent, and positive approaches to mental health can help reduce them over time.

Our ancestors saw situations that challenged their safety and well-being, but overcame them. Humans are adaptable; we are resilient, and we have that in us. So even when fearful and anxious, we'll do what we've always done: use our emotions to evolve.

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