Behave summary

Right before an aggressive behavior takes place, the brain must make several split-second decisions. Two specific parts of the brain are critical in this process: the amygdala and the frontal cortex.

The amygdala is the region associated with aggressive behavior and fear. We know this because brain scans show activity in the amygdala when people are shown images that stimulate anger or fear.

Whether it’s the sight of a flashing blade or a light touch on your hand, the five senses are constantly sending information to the brain. These signals are known as sensory cues.

It turns out that visual cues, such as people’s faces, alter our perception of strangers and our attitudes toward them. Critically, it’s been proven that our brains are extremely attuned to skin color.

It’s well known that hormones are chemical messengers that affect different parts of the brain; they form in various glands and are released into the bloodstream. Just think of testosterone, which forms in the male testes or female ovaries.

But the relationship between hormones and behavior isn’t as simple as you might think.

As the brain matures, behavior also changes. Interestingly, even though the brain is 85 percent fully developed in the first two years of life, it's the remaining 15 percent that is essential for determining behavioral development.

Believe it or not, the frontal cortex doesn’t finish developing until we're in our mid-20s.

We’ve seen so far that grasping the physiology of the brain is essential if we want to understand the roots of human behavior.

But there’s more going on than neurobiology. After all, if murder is 450 times more likely in Honduras than in Singapore, inevitably, the experience of growing up in one country or the other will have a profound impact on your behavior.

Collectivist and individualist cultures across the globe didn’t develop by chance; rather, each is dependent on its environment and situation.

That is to say, it’s not just cultural background that informs behavior. The ecological and geographical background to this cultural development is also critical, and it’s a centuries-long process.

It’s no great shock to learn that the brain plays a part in determining political views and morals. But the way it does so will surprise you.

In fact, there’s a correlation between neurobiological conditions and whether someone has a liberal or conservative worldview.

If you witness a needle being pushed into someone’s finger, your response will be physical. You might even find your own hand closing up tightly as an empathetic response. This type of reaction is telling because it shows that empathy is actually closely connected with avoiding pain.

When you perceive others’ pain, the Anterior Cingulate Cortex (ACC) is activated. It’s a region of the brain that’s linked to both the frontal cortex and the amygdala. The ACC is responsible for helping us learn to fear observable bad experiences. These neurological connections indicate that empathy actually has more to do with self-preservation than with a desire to help others.