Experts say we're hardwired to become fascinated with true-crime cases like Gabby Petito's

• 22-year-old Gabby Petito was reported missing on September 11 and subsequently found dead.
• The case has sparked major interest, both from news outlets and social-media users.
• Insider spoke to experts about why Petito's case spread so rapidly on social media.

Gabby Petito's disappearance and death have dominated the conversation across both traditional news outlets and social media. Her case began to unfold earlier this month when 22-year-old Petito was reported missing after her fiancé returned from a cross-country road trip without her.

Petito's death has been ruled a homicide and her fiancé Brian Laundrie, who was named as a person of interest in the investigation, has been missing from the family home since September 17.

According to social-media analytics site Social Blade, Petito's purported Instagram account, which remains live, has increased by over 1 million followers since her case gained worldwide attention.

Other Instagram accounts dedicated to Petito's case have popped up, often gaining thousands of followers. The moderator of the r/GabbyPetito discussion subreddit, which currently has over 100,000 followers, told Insider the growth of the community was "unseen," while the #gabbypetito hashtag on TikTok currently stands at almost 1 billion views.

The huge interest in the case has also been slammed by critics who note missing or murdered women of color rarely garner the same level of media attention.

Insider spoke to experts about why Petito's case spread so rapidly on social media.

An evolutionary fear response could be at play

Dr. Pamela Rutledge, a psychologist who studies human behavior, told Insider Petito's disappearance may have led to a "fight-or-flight response" - a physiological reaction to a perceived threat triggered by a release of hormones that prepare your body for one of two options: to stay and confront it or flee to safety, according to "Adrenal Responses to Stress," by neurocardiologist Dr. David S. Goldstein.

Rutledge told Insider that people's brains are "hardwired" to pay attention to things that might harm them, regardless of whether the threat is actually directed to us or not.

"Our brains weren't designed for a mediated world, so we have an innate tendency to respond to media reports as if they could actually affect us," she said.

Rutledge said the ongoing uncertainty around Petito's case adds to the interest. "Uncertainty creates a cognitive 'itch' that wants to be scratched with answers," she explained.

The interactive nature of social media can make people feel they're part of something bigger

As reported by Vice, social media users are turning to amateur sleuthing to "solve" the case, analyzing Petito's old Instagram pictures for clues or traveling to search for leads in person.

This can help provide people a sense of "being involved in something bigger than who you are, as part of a collective project," according to psychologist and life coach Dr. Perpetua Neo.

Dr. Saul Rosenthal, a psychologist specializing in cognitive behavioral therapy, told Insider the interactive nature of social media platforms means users see themselves as "active players" in the case as opposed to passive recipients of information.

He said social media reactions to Petito's case are heightening the emotional stakes, which can influence how people respond to the story.

"Social-media platforms like TikTok, Reddit, and Twitter serve to enormously amplify what we might call the 'intensity' of a story," Rosenthal said. "The posts that spread most are those that play on the most extreme and emotional aspects, ending up with a distorted emphasis."

According to Rosenthal, people are reacting to the "amplified emotional aspects" of this case in different ways. Some, he said, express anger at those involved, while others feel the need to "save the day" and solve the case.

Sensationalizing the case may help people find comfort

On Twitter, a search for "Gabby Petito Netflix" shows dozens of tweets from people saying they feel they are following a true-crime drama in real-time and "need" a Netflix documentary about her case.

This voyeuristic dimension may be the result of "living in a digital age of the TikTok tabloid," according to Dr. Jenna Drenten, who is an associate professor of marketing at Loyola University Chicago and studies digital consumer culture.

Drenten coined the phrase "TikTok tabloid," to refer to how the app's features can give a sensational style to videos, keeping viewers engaged with "talking head" newsreaders or ending videos on cliffhangers.

"There is a tabloid talk show vibe to all of this," Drenten told Insider. "We are seeing a real person - a real family's - trauma unfold in real-time through the eyes of people far removed from the circumstances."

While such "tabloid-like" content has sparked criticism, Rutledge tells Insider there may be a psychological reason for it, explaining that treating it as a story can "let us explore the darker side of human nature at a safe distance."

"True crime follows a narrative arc and creates the same cognitive uncertainty. Once invested, people get caught up and follow for the comfort of resolution - to 'see what happened,'" she said. "When there is uncertainty in the world, people crave resolution to restore order."

For more stories like this, check out coverage from Insider's Digital Culture team here.