Our emotions are the product of evolution and are still attuned to the concerns of our ancestors.

If you’ve ever been embarrassed after crying your eyes out during a Pixar movie, you may have wished you could make your emotions less visible. But outward displays of emotion like these are actually very useful evolutionary tools.

In fact, these sometimes uncontrollable emotional reactions are innate, and they’re still triggered by the same things that our ancestors had to deal with.

For instance, animals were a main threat to our ancestors, and some of these predators have been around so long that they’ve become imprinted on our brain, always eliciting a fearful reaction.

Swedish psychologist Arne Ohman tested this theory in 1993. He wanted to determine whether people today are more sensitive to things like spiders and snakes, which would have been a threat to our ancestors as well.

So, Ohman showed his subjects an image of a spider accompanied by an electric shock. He then repeated this procedure with an image of a pretty flower, also accompanied by a shock.

A single electric shock coupled with the picture of the spider was sufficient for people to react with fear when shown the image of the spider alone. In contrast, it took many more shocks to condition people to fear the image of the flower.

Okay, but what about a more modern threat, like guns?

Ohman repeated the experiment, this time pairing a shock with an image of a modern gun and then with an image of a spider.

Again, the ancient fear proved more powerful: test subjects took just as long to react fearfully to the gun as they did to react to the flower, while the spider remained innately frightening.

This is strong evidence, suggesting that our emotions, especially fear-based ones, are hand-me-downs from our ancestors and their experiences.