What do horror movies and marmots have in common? Screams

animals

Dan Blumstein was gently holding a yellow-bellied marmot pup, conducting research, when he first heard one scream.

"I was sort of shocked by this scream and almost dropped this animal," he says. "I had this sort of emotional response to this scream."

Blumstein, a behavioral ecologist and conservation scientist at the University of California, Los Angeles, leads one of the world's longest-running experiments on a wildlife population: Yellow-bellied marmots living high in the mountains of southern Colorado.

He's trapped thousands of them for his research, so he's no stranger to their sounds. Over the years, he's heard them chirp, call and even whistle. But the sound of this particular scream — a high-pitched noise almost like a baby's cry — triggered something deep in his gut. And his curiosity.

What is it about screams that make them so universally unnerving?

Blumstein listened to recordings of different animals screaming, hunting calls designed to attract predators, and horror movies. And he found that screams are different from normal alarm calls. Screams are made when a distressed mammal overblows its vocal folds, pushing air through its vocal folds faster than normal. Waveforms of screams are marked with "nonlinear phenomenon" – irregularities in the sound that are alarming and attention-grabbing across species.

Researchers have found that even some animals that don't make vocalizations themselves, like skinks and lizards, act differently when they hear those nonlinear sounds.

Screams signal urgency, Blumstein says. The irregular noise in them is meant to grab others' attention. And that attention has likely helped keep us and other animals alive.

So this Halloween, if you're scared by a neighbor's creepy display of skeletons and spiders, Blumstein says, remember: Fear is natural.

"We are who we are because of who our ancestors were — and not just our primate ancestors, but across the lineage of life," he says. "So I think we should embrace our inner marmot and be happy that we're scared by those things."

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This episode was produced by Hannah Chinn. It was edited by Rebecca Ramirez and fact-checked by Nathan Rott and Tyler Jones. The audio engineer was Kwesi Lee. Copyright 2024 NPR