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Cats and Dogs, Tortoise and Hippos… Can Animals of Different Species Really Be Friends?

June 04, 2015

Story at-a-glance

  • Examples of cross-species friendships abound both anecdotally and in scientific literature
  • Baboons and dolphins are just two examples of species that show strong friendships between individuals
  • Some cross-species bonds may be formed in captivity as a result of human interaction, however, such bonds have also been witnessed in the wild

By Dr. Becker

Have you ever had a dog and cat who were best buds? Or a bird and a rabbit that seemed to get along uncannily well? Such animal friendships are more intriguing than they are unusual. You may have even witnessed one yourself, and if not have probably viewed videos of cross-species animal friendships online.

In some cases, such as when a hamster appears to be “playing” with a snake… there could be another explanation aside from friendship… like the snake not being hungry at the moment. But in others there’s a mutual bond that’s apparent, even if we don’t fully understand it.

Science Shows Animals Forge Human-Like Bonds

Biologists and anthropologists have long listed friendship as a uniquely human trait. Cooperation and communication between other species was dubbed more of an evolutionary tactic for survival and nothing more. That is, until observations told a different story.

There are countless tales of animals sharing far more than instincts for survival. Dr. Barbara Smuts, a primate researcher at the University of Michigan, described bonds between female baboons as “friendship” back in 1985. She told the New York Times:1

“We know this is happening between all sorts of species. I think eventually the scientific community will catch up.”

Dr. Smuts also witnessed a special relationship between her German Shepherd mix, Safi, and a donkey named Wister. She wrote in an essay:2

Each dawn, after being released from his corral, Wister would stand outside our door and bray until I let Safi out, and then they would play and wander together for hours.”

TIME magazine also featured several scientific observations of strong animal bonds:3

“Take the pair of wild chimps known as Hare and Ellington, unrelated males who would hunt together, share food, and hoot in communication over great distances when they were separated. A favor done by Hare today might not be returned by Ellington for months — far longer than the quick quid pro quo of reciprocal altruism.

The favor was, well, just a favor. And then, too, there was the deep period of what could only be described as mourning that Hare went through when Ellington died.

Or take the three old female dolphins in Sarasota Bay — Nicklo, Squiggy, and Black Tip Double Dip, who would spend hours, indeed whole days, swimming, playing, and resting in one another’s close company.

The trio would hunt fish together too — which can be nothing but a feeding tactic, since dolphins that cooperate better, eat better as well. But it was the serene Golden Girls time they shared that seemed the true marker of their friendship.”

What Makes an Animal Bond a True Friendship?

Just because two animals that wouldn’t normally get along tolerate each other, it doesn’t constitute a true friendship. Dr. Barbara J. King, an anthropologist at the College of William and Mary, suggested building a database of cross-species interactions as the first step to understanding such relationships. She also suggested criteria for what defines a friendship, which includes:4

  • Must be sustained for a certain period of time
  • There must be mutuality, with both species engaged and interacting
  • Accommodation of some sort taking place in the service of the relationship (such as a modification to behavior or communication)

Some experts, such as Clive Wynne, a professor of Psychology at Arizona State University, believe many cross-species relationships occur only because the animals live in a human-controlled, i.e. captive, environment, and present examples of human impact on the environment.5

At the San Diego Zoo and Safari Park, for instance, the New York Times reported that trainers pair cheetahs with dogs from an early age because the dogs help to socialize the otherwise skittish cats. The animals eventually learn to play together and show a genuine fondness of each other as well, by engaging in grooming and finding unique ways to communicate.6

While it’s true that stressed animals in captivity may seek comfort from other animals, even unlikely animals from other species, such bonds are also known to occur in the wild. Marc Bekoff, professor emeritus of Ecology and Evolutionary Biology at the University of Colorado and author of books on animal emotions, told Slate:7

“I think the choices animals make in cross-species relationships are the same as they’d make in same-species relationships. Some dogs don’t like every other dog. Animals are very selective about the other individuals who they let into their lives.”

Even predators and prey (including his dog and a bunny) can form relationships—which as he points out requires ‘incredible trust’ from the prey animal.”

Can Your Pet Be Your Best Friend?

Does the possibility for cross-species friendship extend to humans and their dogs? A series of studies by Miami University researchers suggests it does.8 Using standard psychological measures of social needs fulfillment, they found that dogs helped their owners feel socially content and better about life in general.

The social satisfaction derived from pets was helpful to their owners regardless of how much support they received from other humans. The researchers also asked college students to think about a time when they felt excluded or rejected in a human relationship.

Then the students were asked to do one of three things: write about a best friend, write about a favorite pet, or draw a map of their school’s campus. The students who chose to write about friends or pets felt better after the exercise and experienced a rebound of feelings of self-worth and happiness after experiencing painful memories of a time when they felt rejected and isolated.

For the pet owners in the student group, thinking about a pet elevated their feelings just as much as thinking about a best friend. According to the researchers, “one’s pet was every bit as effective as one’s best friend in staving off social needs deficits.” They also noted:

In summary, pets can serve as important sources of social support, providing many positive psychological and physical benefits for their owners.”

Perhaps Cross-Species Friendships Give Us Hope…

There is something inherently alluring about two species that should be enemies ending up as friends, and perhaps that “something” is hope. As the New York Times reported:9

At Haller Park in Kenya — where Mzee, a 130-year-old tortoise, tends to Owen, an orphaned baby hippo — a man visiting the park with his child gazed at the unlikely couple and remarked, during a documentary about the pair, ‘If two very different creatures get along like this, then why cannot Iraqis and the British, Americans, Palestinians, the Israelis not get on?’”

To see more examples of cross-species friendships in action, check out the video below.

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Sources and References

  • 1, 2, 4, 5, 6, 9 New York Times January 27, 2015
  • 3 TIME February 9, 2015
  • 7 Slate November 29, 2013
  • 8 J Pers Soc Psychol. 2011 Dec;101(6):1239-52.
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