The human obsession with shock, horror, spills and thrills dates all the way back to our tribal ancestors, according to Professor Luke O’Neill.

On The Pat Kenny Show this morning, the Trinity Professor took a deep dive into the human hankering for horror ahead of the Halloween weekend.

He said scary stories trigger the same part of the brain our ancestors needed for survival – leading to the release of adrenaline and other endorphins.

“The amygdala is the part of the brain,” he said. “An ancient, almond-shaped part of the brain that fires up basically and releases adrenaline, is the big thing that happens.

“So, you feel this fight or flight response famously and you get very agitated essentially.

“It evolved as a way to deal with danger. So, when you watch a horror movie, that same process is triggered. Then you get the sweaty palms and the sinking feeling in your stomach by the way – that is all to do with blood rushing from your stomach to your muscles and you feel this dip in your stomach and your heart rate goes up.

“It is all to prepare you for danger basically. If you’ve watched a nasty horror movie then that mimics that effect and that pulse of adrenaline is beneficial.”

Fight or flight

Prof O’Neill said a study in Denmark tested people’s endorphins to learn why they enjoyed a good scare.

“They put lots of people through a haunted house with 70 actors frightening people and they measured various hormones in their bodies to see how they reacted,” he said.

“You get the adrenaline pulse and then when it is over, you get the endorphin rush. So, your body beings to relax again and you feel this high I suppose, as a result of the initial shock.

“So, it is very hormonal in a way and again, you might be drawn to that as well and you want to repeat it. Dopamine goes up as well by the way afterwards and dopamine motivates us to seek the same behaviour again.”

Scream

It is not just the fight or flight release that is linked to our ancient past, however. Prof O’Neill said there was also a practical use for the human scream.

“The scream is interesting,” he said. “So why do we scream? That is a reflex action … you scream on a rollercoaster.

“You’re warning the tribe of danger. So, screaming again is built into our system as a way to warn everybody there is danger here.”

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