Why Do We Love Our Pets?

Good Morning America

There's a deep-rooted reason why we humans surround ourselves with dogs and cats and other animals. New research finds we are hardwired to respond to other critters, and the mechanism that makes us do that probably dates back hundreds of millions of years to the time when vertebrates were first evolving.

The secret is buried deep in a very old part of the brain, called the amygdala, long recognized as the seat of emotional reaction. Scientists at the California Institute of Technology and the University of California at Los Angeles were able to measure brain activity in 41 persons on a cell-by-cell level and found that neurons in the amygdala became extremely active when participants were shown pictures of animals.

"Our study shows that neurons in the human amygdala respond preferentially to pictures of animals, meaning that we saw the most amount of activity in cells when the patients looked at cats or snakes versus buildings or people," Florian Mormann, lead author of a paper and a former postdoctoral scholar at CalTech said in releasing the study. The paper was published online in the journal Nature Neuroscience.

Mormann, who is now at the University of Bonn in Germany, said in an email that he and his colleagues were a bit surprised to discover that the type of animal -- whether it be a deadly snake or a cuddly puppy -- made no difference. They found the same level of brain activity for all animals.

"Given the amygdala's prominent role in fear conditioning, we were indeed expecting stronger responses to hazardous animals such as spiders or snakes, but it turned out that all kinds of animals, dangerous and cute, elicit responses in the amygdala," he said.

"This preference extends to cute as well as ugly or dangerous animals, and appears to be independent of the emotional contents of the pictures. Remarkably, we find this response behavior only in the right and not in the left amygdala."

That's significant because it supports other research indicating that early in vertebrate evolution the right hemisphere of the brain took on the role of responding to environmental stimuli, including the presence of other animals, which could be either prey or predator.

"This is somewhat in line with recent findings that the amygdala is also involved in reward processing and generally mediates vigilance," Mormann said.

The intense brain activity triggered by photos of animals "may reflect the importance that animals held throughout our evolutionary past," the study notes. It also suggests that early vertebrates, and by extension humans, really needed to know if there were other animals around, some of which could be eaten, and some of which could do the eating.

The researchers were able to carry out their work because 41 epilepsy patients at the Ronald Reagan UCLA Medical Center were willing to participate. They were already being monitored for brain activity related to seizures. So the researchers could use electrodes that were already in place to record single-neuron responses in the amygdala as the participants viewed pictures of animals, people, landmarks and other objects.

They also monitored two other areas of the brain, the hippocampus and the entorhinal cortex, as control regions because they "weren't expecting any stimulus preference there," Mormann said via email. As expected, there was no significant response in the two control regions, but the response in the amygdala was almost off the charts.

So the research suggests that in the early evolution of vertebrates, one key to survival was the recognition of the presence of other animals that could be harmful, or could be harvested. That ability was honed to perfection in the part of the early brain that was responsible for reacting to changes in the environment, including the sudden appearance of other critters, "both aversive and cute," the study notes.

As evolution continued on its long, gradual course, the amygdala remained important even to this day, because it's still useful to know if that fuzzy animal down the road is a dog or a wolf.

But it's still surprising that the intensity of the brain activity would be no greater for a wolf than a dog, long regarded as man's best friend. So which emotion is the strongest, the urgent need to avoid the wolf, or the friendly urge to pet the dog?

A recent event in my hometown of Juneau, Alaska, might shed a little light on that. A couple of weeks ago, a young woman found her 15 minutes of fame when the local newspaper disclosed that she had punched a bear in the nose to keep it from killing her dog.

Apparently, compassion for her pet outweighed her fear of the bear, which backed away and quietly retreated into a nearby forest.

So perhaps what it boils down to is her amygdala recognized the presence of two animals, one loved, the other feared. In this case, love trumped fear. Or perhaps her fear for her dog was greater than her fear of the bear.

By the way, both woman and dog are doing fine. Condition of bear's nose unknown. And hitting a bear to save a dog is not recommended by wildlife experts.

View Comments (2)

Recommended for You

  • George Stephanopoulos: What You Need to Know About DNC Day 3

    Hillary Clinton made history last night when she became the first woman to secure the presidential nomination of a major U.S. party Tuesday night. Several prominent speakers will address the DNC tonight, including President Obama and former New York City Mayor Michael Bloomberg. ABC News’ George…

    Good Morning America5 mins ago
  • Vice President Joe Biden: ‘Moral’ Sanders Supporters ‘Can’t Vote for Trump’

    To so-called “Bernie-or-Bust” supporters who are adamant that they won’t vote for presumptive Democratic presidential nominee Hillary Clinton, vice president Joe Biden said he’d offer the following message: “If you’re as moral and centered as you say you are, I know you can’t vote for Trump. …

    Good Morning America17 mins ago
  • 'The Bachelorette' Recap: Chad Returns to Stir Up Trouble on 'Men Tell All'

    The eliminated contestants on the current season of "The Bachelorette" reunited for the "Men Tell All" special Tuesday night. "Bachelorette" JoJo Fletcher joined host Chris Harrison and company, but finalists Jordan Rodgers and Robby Hayes were not present. It was subsequently revealed that Chad…

    Good Morning America8 mins ago
  • College Student Injured by Central Park Explosion Returns Home, Family Says

    A college student who was injured by an explosive device in New York's Central Park earlier this month has returned home and is recovering, his family said this week. Connor Golden of Fairfax, Virginia, was climbing rocks in the park on July 3 with friends when the explosion badly mangled a…

    Good Morning America12 mins ago
  • The Potential Dangers of Pressure Washers

    Pressure washers can help homeowners blast through many summer cleaning projects, but with the power of a pressure washer also comes potential danger. Ben Skidell makes a living working with outdoor tools but it was a pressure washer that the New York man said almost took off part of his knuckle. …

    Good Morning America15 mins ago
  • Stephen Marley's New Album Mixes Hip-Hop With His Dad's 'Signature Reggae Style'

    This week Fountains Of Wayne vocalist Chris Collingwood debuts his new project Look Park, Stephen Marley brings along a ton of guests while infusing a bit of hip-hop into his family’s famous reggae sound, Swedish band The Amazing release their fourth album and blues artist Breanna Barbara drops a…

    Good Morning America15 mins ago
  • 'Jason Bourne': 10 Burning Questions Answered

    That is a great question and one that took Matt Damon the better part of a decade to answer, so going into this weekend's "Jason Bourne" not knowing that is OK. ABC News invited a Bourne newbie to the screening of Damon's latest thriller and told her simply, "Ask me anything!" And she did. 1 -…

    Good Morning America17 mins ago
  • Former NFL Player Steve Gleason, Wife Open Up on His ALS Battle as First-Time Parents, Emotional 'Gleason' Doc

    Former New Orleans Saints defensive back Steve Gleason remembers the moment well when he was hailed as an NFL hero. Early in the game, Gleason blocked a punt, helping to clinch the win for his team and uplifting the community that had lost so much. But in 2011, five years after that historic…

    Good Morning America17 mins ago
  • Coast Guard Releases Video of 46-Person Bering Sea Rescue

    The U.S. Coast Guard released video this morning of the rescue of several dozen crew members from a capsizing fishing vessel located almost 700 miles from Alaskan shores.Good Samaritan vessels reached the scene first and rescued 46 people Tuesday night. The crew had abandoned their sinking trawler…

    Good Morning America18 mins ago
  • In Leaked Recordings, DNC Shown Controlling Donor Access

    The release of a trove of “embarrassing” hacked internal emails and private voicemail recordings reveal not only the unseemly deal-making involved in recruiting high-dollar donations for political campaigns, but the role fundraising officials play in approving and denying access to President Obama…

    Good Morning America
  • $3M Lotto Winner Pleads Guilty to Using Prize Money to Fund Illegal Meth Ring

    A Georgia man who won millions in the lottery could face life in prison after pleading guilty to using a portion of his prize to invest in a crystal meth operation. Ronnie Music Jr., 45, of Waycross, Georgia, pleaded guilty last week to federal drug and gun charges after U.S. attorneys presented…

    Good Morning America
  • Iowa Football Player Mistaken for Robber During 'Pokemon Go' Game in Park

    Police released bodycam footage showing an encounter last week between a black University of Iowa football player and officers who were looking for a robbery suspect. The video was released Tuesday and shows defensive end Faith Ekakitie being stopped and searched by police in Benton Hill Park in…

    Good Morning America
  • Kim Kardashian West as Keynote Speaker for BlogHer Conference Divides Bloggers

    Kim Kardashian West may be a master at leveraging social media and nurturing her own enduring brand, but news that she is a keynote speaker at next month's BlogHer conference was met with both cheers and jeers from fellow bloggers. Kardashian West is scheduled to speak August 5 at BlogHer,…

    Good Morning America
  • Democratic National Convention 2016: Fact-Checking the Speakers

    Clinton voted for some and against others. Background: Trade has become a major point of contention in Hillary Clinton’s presidential campaign, and while this claim is true, Clinton has also touted support for trade agreements in the past. Notably, Clinton voted against the Dominican…

    Good Morning America
  • Democrats Shift Away From Trump Talk, Keep Focus on Clinton

    ABC News is reviewing transcripts from the Democratic National Convention this week to determine how many times Democrats say Donald Trump's name. Democrats shifted their strategy on the second night of the convention, drastically slashing the number of times they mention Donald Trump’s name in…

    Good Morning America
  • 5 Things to Watch on Day 3 of the Democratic National Convention

    The convention heard from two former presidents last night (President Jimmy Carter by video and President Bill Clinton in person) and now tonight, delegates are going to be hearing from current and soon-to-be former President Barack Obama and Vice President Joe Biden. Both men have already…

    Good Morning America
  • ANALYSIS: Hillary Clinton Seeks Fresh Start, With Boosts From Bill, Bernie and History

    Hillary Clinton is trying to start over –- at a lower temperature, but with grander historical sweep.On night two of the Democratic National Convention, the now-official nominee sought a fresh slate. Her campaign did it by tapping into powerful historical forces, with the kind of direct appeals…

    Good Morning America
  • Stars Come Out for Hillary Clinton at DNC in Philadelphia

    A trove of celebrities stumped for Hillary Clinton and slammed Donald Trump at the Democratic National Convention Tuesday night, including Oscar-winner Meryl Streep and "Girls" star Lena Dunham. Actress Elizabeth Banks, actor Tony Goldwyn, singer Andra Day, actress Erika Alexander, actress Debra…

    Good Morning America
  • Hillary Clinton Makes Surprise Satellite Appearance at DNC: 'This Is Really Your Victory'

    Hillary Clinton made a surprise appearance via satellite at the Democratic National Convention on Tuesday evening. Earlier on Tuesday, delegates officially nominated Clinton as their party's nominee -- making her the first woman in U.S. history to become the nominee of a major political party. …

    Good Morning America
  • Bill Clinton Tells DNC Hillary Is the 'Best Darn Change-Maker'

    In the speech, the two-term president recounted the beginnings of his relationship with the former Secretary of State, detailed her decades of advocacy work and extolled her drive in public service. "In the spring of 1971 I met a girl," the 42nd president told the crowd in Philadelphia.

    Good Morning America