50 Creepy Facts That Are More Disturbing Than Most Horror Movies

While comedy can be pretty divisive in the sense that not everyone agrees on what's funny and what's not, there's usually less variance in the things that scare us.

"When you see the stock market fall 1,000 points, that's the same as seeing a snake," says Joseph LeDoux, professor of neuroscience and psychology at the Center for the Neuroscience of Fear and Anxiety based at New York University. "Fear is the response to the immediate stimuli. The empty feeling in your gut, the racing of your heart, palms sweating, the nervousness—that's your brain responding in a preprogrammed way to a very specific threat."

LeDoux adds, "Since our brains are programmed to be similar in structure, we can assume that what I experience when I'm threatened is something similar to what you experience."

Fear even transcends species. "We come into the world knowing how to be afraid, because our brains have evolved to deal with nature," LeDoux says, noting that the brains of rats and humans respond in similar ways to threats, even though the threat itself might be completely different.

However, even though the feeling is as natural to us as breathing, science still doesn't fully understand it: despite more than 100 studies into how the body reacts to fear, there still is no reliable way to quantify it.